bio 030 introduction to biology - dutchess community college...bio 030 tentative schedule summary...

BIO 030 INTRODUCTION TO BIOLOGY

Lab Manual

2016

AHBS Dutchess Community College

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Welcome to BIO 030 Introduction to Biology

Course Description

This course is designed for students in programs requiring Biology who are unprepared to enter a 100 level course as shown by testing and/or background. Course content includes study techniques, the nature of science, the scientific method, the metric system, biochemistry, the cell, the laboratory report and basic laboratory techniques. This course requires basic mathematical skills. A grade of C or better is required to take BIO 130. This course is a prerequisite for Bio 130 for those students referred after testing.

The purpose of this course is to provide background & skills for students taking Bio 130 or any college level biology course.

Student Learning Outcomes

Students will use the scientific method.

Students will apply the metric system to basic laboratory procedures.

Students will relate the structure of an atom to bonding properties.

Students will compare the structures of some organic groups and compounds.

Students will use models to demonstrate dehydration synthesis and hydrolysis.

Students will demonstrate the proper use of a compound light microscope.

Helpful Tips to be Successful in This and Other Biology Courses

1. See your instructor BEFORE you fall behind. Instructors are available during office hours and

through scheduled appointments.

2. Take notes during class. Ask your instructor for best methods of note taking or inquire about

the Modified Cornell Method.

3. Rewrite your class notes the same day the notes were presented in class.

4. When reading, take notes by putting the information into your own words in such a way that the

notes are easy for you to understand.

5. You should be studying 10 hours a week for this course. Do not wait for the last minute to study

or just study before an exam.

6. Study in half-an-hour (30 minute) blocks. Studying for 30 minute intervals improves retention of

material.

7. Rote memorization will not help you, make sure you thoroughly understand the topics.

8. Form study groups. You could potentially have several classes with the same students. Studying

with other students is extremely helpful.

9. Make study cards to help learn the vocabulary.

10. Take advantage of free tutors and open lab. These services are free to all DCC science students.

Academic Accommodations

Students with disabilities who believe they may need accommodations in this class are encouraged to contact the Office of Accommodative Services at 845-790-3631 as soon as possible to better ensure that such accommodations are implemented in a timely fashion.

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AHBS Lecture and Laboratory Policies and Procedures Keep for future reference

1. You are expected to read, know and follow the Code of Conduct as described in the Student

Handbook at all times. You can find the Student Handbook by going to MyDCC online. It is expected

that all people will be treated with respect and honor.

2. Honesty and integrity in all aspects of student life are expected. Any behavior contrary to the Code

of Conduct will be dealt with according to the Student Handbook. Academic dishonesty is a very

serious offense and will be treated according to the published guidelines and college policies.

Penalties for academic dishonesty will result in a minimum of no credit for the academic work in

question and may result in failure in the course.

3. All cell phones and other electronic devices must be turned off in the laboratory and classrooms

(no texting). It is not proper to leave the class to answer a phone call as this disturbs you, the

instructor and other students. In cases of "expected emergencies" ask the instructor for the proper

procedure. Laptop computers may be used in the front row only.

4. Your attendance is expected at all classes - both lecture and laboratory. It is your responsibility to

"make-up" the work missed in lecture. In addition, please make every effort to be on time for class,

for your benefit and to minimize distraction to others. This is especially important in laboratory since

important protocol and safety information is given at the beginning of each lab.

5. Please do not wear hospital attire (scrubs or uniforms) to school. Work clothes should be replaced

with street clothes that have not been in the hospital environment. Shoes should cover your feet for

protection.

6. Make-up lecture exams or labs are a privilege, not a right. Please remember that make-ups are only

offered with advance notice for legitimate emergencies that can be verified. It is up to you to notify

the instructor in advance and provide the instructor with valid proof for having missed the exam or

lab. Make-up exams are scheduled at the instructor's convenience and usually are a different format

and time than the regularly scheduled exams. Laboratory exams may not be made up.

7. If you miss a lab and do not make it up, the penalty will be a deduction of 10% your grade for each

of the first 2 missed labs. If 3 labs are missed and not made up, you will receive a grade of F for

the course. If a lab report is due for the missed lab, you may not get credit for the lab report unless

the lab is made up in another section of the same course or a similar lab in a different course. The

Lab Makeup Form must be signed by the instructor (of the makeup lab class) and submitted with

the lab report. It is your responsibility to inform the lab instructor in advance when the makeup

work will be done.

8. It is the responsibility of the student to determine the times when the lab can be made up, and

request permission from the instructor (of the makeup lab), in advance to attend a lab for which

you are not registered. If no lab section in the same course is available, your lab instructor may

approve attendance at some other lab in some other biology course as an acceptable makeup for

the missed lab. However if a lab report is associated with the missed lab, you will not receive credit

for the lab report.

A Laboratory Makeup Form is to be signed by the instructor (of the makeup lab) to verify that

you have attended a makeup lab. This form must be submitted to your regular lab instructor within

a week of the time that the lab was made up.

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9. In compliance with SUNY and OSHA requirements, no food or drink is allowed in the labs at anytime. This will be strictly enforced. Personal property not required for the lab should be stowed in the cubicles provided for this purpose. The floor is not a proper place for backpacks etc., where they are a tripping hazard in the lab.

10. Cleaning solutions are in each of the laboratories. Lab tables should be wiped down before and after each laboratory.

11. All laboratory equipment and supplies are the property of Dutchess Community College. Please treat them better than you would if they were yours. We do not want you to have to replace any broken or wasted material.

12. Protective gear must be worn for appropriate laboratories. Any wet lab requires the use of eye protection. If you do not have your own, you must use the goggles we provide. You will be expelled from the lab for noncompliance.

13. Any bodily fluids, or materials contaminated with bodily fluids must be “red bagged” for proper disposal. Do not lay contaminated material on the lab surfaces. If you suspect any contamination, glove and immediately wipe all surfaces with the disinfectant provided in the laboratory.

14. Do not touch broken glass with your skin. Glass should be swept up and placed in the broken glass containers in each room. Never reach into a broken glass container.

15. All accidents must be reported to college personnel. 16. Many students share our equipment and materials. Please be considerate of others. Scheduled classes

have first priority on all equipment and materials. 17. Study times and rooms are subject to change. Check with college personnel before you count on

study availability. The weeks that lab exams are being given will have greatly restricted access to time, rooms and material.

18. Learning is fun! Enjoy the laboratories safely please.

Tear on dotted line and return to instructor please

I have read the above information, and any questions regarding these policies and procedures

have been answered to my satisfaction .

I understand and agree to follow these policies and procedures for the duration of my enrollment in this laboratory course.

print name signature date/course & section

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Laboratory Make-up Form

1. If you miss a lab and do not make it up, the penalty will be a deduction of 10% from your grade for each of the first 2 missed labs. If 3 labs are missed and not made up, you will receive a grade of F for the course. lf a lab report is due for the missed lab, you may not get credit for the lab report unless the lab is made up in another section of the same course or a similar lab in a different course. The Lab Makeup Form must be signed by the instructor (of the makeup lab class) and submitted with the lab report. It is your responsibility to inform the lab instructor in advance when the makeup work will be done.

2. It is your responsibility to determine the times when the lab can be made up, and request permission from the instructor(of the makeup lab), in advance, to attend a lab for which you are not registered. If no lab section in the same course is available, your lab instructor may approve attendance at some other lab in some other biology course as an acceptable makeup for the missed lab. However if a lab report is associated with the missed lab, you will not receive credit for the lab report.

A Laboratory Makeup Form is to be signed by the instructor (of the makeup lab) to verify that you have attended a makeup lab. This form must be submitted to your regular lab instructor within a week of the time that the lab was made up.

Student Name____________________________ Course and section ------

To be filled in PRIOR to the makeup laboratory

Signature of Instructor of Missed Laboratory Date _

Name of Missed Laboratory -----------------------------

Signature of Instructor of Make-up Laboratory Date _

Date, time and location of Make-up Laboratory -----------------------

To be filled in After or During the Make-up Laboratory

The student named above has successfully completed the__________________________laboratory.

Signature of lnstructor of Make-up Laboratory ________________Date ________

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BIO 030 Tentative Schedule Summary

Week Lecture Material Lab

1 Intro, Metric System, Study Techniques, and Vocabulary

Lab 1: Measurements

2 Scientific Method, Theory, Law, and Graphing

Lab 2: Scientific Method and Graphing

3 Characteristics of Life Lab 3: Characteristics of Life

4 Energy, Matter, and Atomic Structure Lab 4: Atoms and Models

5 Ionic, Covalent Bonding, Hydrogen Bonding

Lab 5: Ionic and Covalent Bonding

6 Chemical Equations and the Mole

Lab 6: Moles and Conversions

7 Water Properties, Solutions and Concentrations

Lab 7: Percent Solution and Molarity

8 Acids, Bases, and Buffers

Lab 8: pH and Buffers

9 Functional Groups and Organic Molecules

Lab 9: Functional Groups and Macromolecules

10 Carbohydrates and Lipids Lab 10: Macromolecules and Nutrition

11 Nucleic Acids and Proteins

Lab 11: Enzymatic Activity

12 Cell Theory, Cell Types, and Cell Structure

Lab 12: Microscope and Cells

13 Cell Membrane and Passive Transport Lab 13: Diffusion and Cell Size and Temperature

14 Active Transport and Cell processes Lab 14: Osmosis

15 Comprehensive final

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Table of Content

Common Science Prefixes and Suffixes pg. 7-11

Lab 1: Measurements pg. 13-24

Lab 2: Scientific Method and Graphing pg. 26-34

Lab 3: Characteristics of Life pg. 36-42

Lab 4: Atoms and Models pg. 44-55

Lab 5: Bonding pg. 57-66

Lab 6: Moles and Conversions pg. 68-75

Lab 7: Percent Solution and Molarity pg. 77-86

Lab 8: pH and Buffers pg. 88-94

Lab 9: Functional Groups and Macromolecules pg. 96-107

Lab 10: Macromolecules and Nutrients pg. 109-113

Lab 11: Enzymatic Activity pg. 115-120

Lab 12: Microscope and Cells pg. 122-133

Lab 13: Diffusion and Cell Size pg. 135-142

Lab 14: Osmosis pg. 144-151

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Common Science Vocabulary

Prefix- or –Suffix Definition Example

a-

Not, without Atypical

ab-

From, away Abnormal, abduction

-ad-

To, toward Dorsad, adhere

-algia

Pain Neuralgia, analgesic

amyl-

Starch Amylase, amylogenesis

an-

Not, without Anhydrous

ana-

Up, upon Anabolism, anabolic

angio-

Related to blood vessels Angiotensin, angioplasty

ante-

Before, in front of Antenna, anterior

apo-

Off, from, away from Apocrine, apoplexy

aqua-

Water Aquatic

-ase

Designation an enzyme Lactase, amylase

auto-

Self Autosuggestion

bi-

Two, twice Biceps, bifocal

bio-

Life Biology

calor-

Heat Calorimeter

-ceps

Heads Biceps, quadriceps

cerebro-

Brain Cerebrospinal

chondo-

Cartilage Chondrocyte

chrom-

Color Chromosome

-cidal

Killing Bactericidal

-costal

Ribs Intercostal

corpus-

Body Corpuscle

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-cyte, cyto-

Cell cytoplasm

delt-, delta-

Triangular Deltoid

-dermic

Skin Hypodermic

di-

Two, twice Dichromatic, disaccharide

dia-

Through, between Diabetes, diaphragm

dys-

Bad, difficult Dysfunctional, dysuria

-ectomy

Cut out Appendectomy, tonsillectomy

em-, en-, endo-

In, into Embolism, endoskeleton

-emia

Blood Anemia

entero-

Intestine Enterokinase

epi-

On, above, upon Epiglottis, epidural

erythro-

Red Erythrocyte

eu-

True Eukaryote, eupnea

ex-,exo-

Out, leave, go to surface Exit, exocrine

-fer

To carry, transport Afferent, efferent

-fract

To break Fracture, refraction

-gatro-

Stomach, belly Pneumogastric

-gen, genesis

To produce, begin Genetics, amylogenesis

-glosso-

Tongue Hypoglossal, glossopharyngeal

-glyc-

Glucose, sugar Glycosuria

-gnosis

Knowledge, to know Diagnosis

-graph

To write Cardiograph

hemo-

Blood Hemorrhage

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hetero-

Different, other Heterozygous

homo-

Same, alike Homozygous

hydro-

water Hydrolytic, hydrophobic

hyper-

Over, more than Hypersecretion

hypo-

Under, less than Hypotension

inter-

Between, together Intercostal

intra-

Within Intrathoracic

ir-

Not Irregular

iso-

Same Isotonic

-itis

Inflammation Appendicitis

-karyot, -caryot

Nucleus Prokaryote

-kata, cata-

Down Catabolism

kin-

To move, active Kinetic

-lac-

Milk Lactase, prolactin

-lemma

Layer Neurilemmal, sarcolemma

leuko-

White Leukocyte

lipo-

Fatty substance Lipolysis

-logy

Study of, knowledge, science Physiology

lymph-, lympho-

Lymph Lymphocyte

-lysin, -lysis, -lytic

Dissolve, split, destroy Hemolysis

macro-

Large Macrophage

-meter

Measure Nanometer

micro-

Small Microorganism, microscope

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mono-

One Monocyte

myo-

Muscle Myosin, myoglobin

neuro-

Relating to nerves Neurilemmal

nephr-

Kidneys Nephritis

-ogen

Inactive form Pepsinogen

-oid

Like, similar to Lymphoid, amoeboid

-ole

Small Bronchiole, arteriole

-oma

Swelling, tumor Sarcoma, lymphoma

-opia

Sight Myopia, hyperopia

-ose

Sugar Glucose, sucrose

-osis, -esis

Condition, process Cyanosis, phagocytosis

os-, oste-, osteo-

Bone Osteology, osteocyte

ovi-

Egg Oviduct, ovary

para-

Near, by, beside Parathyroid

patho-

Disease, suffering Pathology

pept-

Protein Peptide, peptone

peri-

Around, near Pericardium, perimeter

phago-

To eat Phagocyte, phagocytosis

phil-

Loving Basophil, eosinophil

-plasm-

Substance Cytoplasm, plasmolysis

-pnea

Breathing Dyspnea, apnea

pneumo-

Air, lungs Pneumonia

-pod

Foot Pseudopod

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poly-

Many Polysaccharide

post-

After, behind Postganglionic, postmortem

pro-

Before, giving rise to Prokaryotic, prothrombin

proprio-

One’s own Proprietor, proprioceptor

proto-

First Protoplasm

pseudo-

False Pseudopod

psyco-

Mind Psychology

pulmo-

Lung Pulmonary

quadi-

Four Quadriceps, quadrangle

-renal

Kidney adrenal

-rrhea

Flow Diarrhea, leucorrhea

-saccharide

Sugar Monosaccharide, disaccharide

sacro-

Flesh, muscle Sarcoplasm, sarcoma

soma-

Body Somatoplasm

-some

Body Chromosome

tri-

Three Triceps, tricycle

-thrombo

Clot, coagulation Thrombin, thrombocyte

-tome, -tomy

To cut Tonsillectomy, anatomy

-trophic

Feeding Autotrophic

tropic-

Attracted to Phototropic

-ule

Small Saccule

-uria

Pertains to urine Glycosuria

vaso-

Pertains to blood vessel Vasodilatation

zygo-

Joined homozygous

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Lab 1 Measurements

Measurements are used in every field of science. It is important to understand how to utilize the tools for measurement and be able to select the correct tool for each task. Since the scientific community utilizes the International System of Units (SI), it is important to learn the metric system. The most common metric units are listed in the table below:

Measurement Metric Unit Symbol Device used to measure

Length meter m Metric stick/ruler

Mass gram g Triple Beam balance/metric scale

Volume liter L Graduated cylinder

Temperature Degrees Celsius; Kelvin ◦C; K Metric Thermometer

Time seconds s Stop watch

Scientific notation Scientific notation is a method used to make very large numbers or very small numbers easier to manipulate. When adding, subtracting, multiplying, and dividing large and small values, it becomes easy to make errors when entering these values into the calculator. Scientific notation reduces the likeliness of human error. It is based on factors of 10.

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Practice problems:

1. 2,300,0000

2. 0.0002

3. 1,365.00

4. 0.0000603

5. 98,000

6. 0.0023

7. 0.00000000071

8. 602,000,000,000,000,000,000,000

9. 0.005603

10. 0.1

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Prefixes and the metric scale

Every time you measure an object, you must include the unit of measurement. For example, if you are measuring the mass of a chemical and used a metric scale, you would not say my mass is 6. The number 6 has no meaning without a unit. You would express the number as 6 g (6 grams). The metric system is used to measure both very large quantities and very small quantities. In order to do so, prefixes are added to the base measurement to give the number meaning. The metric system is based on factors of ten. When you move from one prefix to the next, you are increasing or decreasing the size by a factor of 10.

Prefix Symbol Meaning Scientific notation

Giga G 1,000,000,000 1.0 X 109

Mega M 1,000,000 1.0 X 106

Kilo k 1,00 1.0 X 103

Hecto h 100 1.0 X 102

Deca da 10 1.0 X 101

Base Unit (meter, liter, gram)

m, L, g 1 1.0

Deci d 1/10 or 0.1 1.0 X 10-1

Centi c 1/100 or 0.01 1.0 X 10-2

Milli m 1/1000 or 0.001 1.0 X 10-3

Micro μ 1/1,000,000 or 0.000001 1.0 X 10-6

Nano n 1/1,000,000,000 or

0.000000001

1.0 X 10-9

The units in red or above the base unit represent large numbers and the units in blue or below the base unit

represent small numbers

Order of units from largest to smallest

M __ __ k h da unit (m, l, g) d c m __ __ μ __ __ n

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Conversions The most common units you will be working with are below in order from largest to smallest. Each unit represents a factor of 10. The blanks represent units not commonly used but still represent factors of ten. The blanks are placeholders. M __ __ k h da unit (m, l, g) d c m __ __ μ __ __ n

By knowing the prefixes, you can convert numbers through the use of the metric system. Follow the steps below. Example for larger units going to smaller units: A chemical weighs 6g. How much would this be in milligrams (mg)?

1. Find your starting measurement on the list of unit (grams) 2. Find the unit you are converting to on the list of units (milligrams) 3. Count how many places the new unit is away from the original unit


4. Since it took 3 movements to the right to go from grams to milligrams, that means that you would need to move the decimal point 3 factors of ten to the right

6. = 6000.

6g=6,000mg Example for smaller units going to larger units: A chemical weighs 6g. How much would this be in kilograms (kg)?

1. Find your starting measurement on the list of unit (grams) 2. Find the unit you are converting to on the list of units (kilograms) 3. Count how many places the new unit is away from the original unit


4. Since it took 3 movements to the left to go from grams to kilograms, that means that you would

need to move the decimal point 3 factors of ten to the left

6. = .006 6g=.006kg

1 2 3

1 2 3

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Practice problems Convert the following measurements to the correct units

1. 662 µl to l

2. 0.2 dag to mg

3. 0.000635 Mm to cm

4. 126 hl to dl

5. 15,648 ng to mg

6. 12 mm to cm

7. 6.62 kl to l 8. 16.65 dm to dam

9. 0.065 l to nl

10. 16.89 kg to Mg

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Significant figures When using a tool to measure an object, the number obtained from that device is called a measured number. The digits of the measured number are called significant digits or figures. The first significant figure in the measurement is the first non-zero number. The last significant figure is the estimated digit in the measurement. Below is an image of a metric ruler. Each small graduation (or line) is equivalent to 1 millimeter and each large graduation (or line) is equivalent to 1 centimeter. As you learned in the last section, 1 cm=10mm. If you use the ruler to measure the length of the line, it would measure exactly 2cm. The correct way to represent this measurement would be 2.00 cm. By writing this number as 2.00 you are indicating by your measurement that the object you are measuring ends EXACTLY at the 2 cm line. This is based on your eyesight and the device. Based on what you see, you are estimating the line fell exactly on 2. So the three numbers are significant to your measurement. 2 and the first 0 are your exact numbers and the second 0 is your estimated number. It is estimated because it looks like the line is exactly on 2.0 but your eyes are not good enough to say for sure, so you estimate it is exactly at 2.0 by adding the extra zero. Now look at the measurement above. The line measures between 2.0 and 2.1 cm. You cannot say it is at the 2.0 mark and you cannot say it is at the 2.1 mark. Both of those measurements would not accurately measure the line. What is known is that the line definitely measures 2.0, however, you will need to estimate the distance the line falls past the 0 mark. A good estimation would be 2.05 cm. The 2 and 0 being exact numbers and the 5 being the estimated number. So your true measurement for this second line is 2.05 cm.

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Practice measuring the lines below. Remember to include units.

1. What is the measurement of this line? Which digits are exact? Which digit is estimated? How

many significant digits in the measurement?





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Precision and Accuracy You might think that estimation is not necessary, however, small mistakes in science can lead to catastrophic results, especially when dealing with very small measurements. It is important to be both accurate and precise when making measurements. Accuracy-what is being measured in its true value Precision-ability to obtain the same measurement repeatedly

Precision Look at the bullseye bellow. The three circles on the bullseye represent three darts that hit the board in relatively the same spot. This means the person was precisely hitting the board because the same spot was hit three times; however, the person was not accurate since the center or the bullseye was never hit. Accuracy Look at the bullseye bellow. There are three circles on the board. The board was hit three times in the center circle but in very different locations. This means the person was accurate but was not precise, because although the center or bullseye was hit three times, the darts are not close. Precision and Accuracy It is extremely important that when making scientific measurements that you are both accurate and precise. Look at the bullseye below. There are three circles on the board. All three darts hit relatively in the same place and the center of the bullseye.

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Lab activities Materials 2 Centimeter rulers 2 Meter sticks Triple beam balance 10 cm piece of string Paper clips Small rubber stoppers Small test tube (10 ml) 10, 25, 100 ml graduated cylinder 100 g or higher calibration weights Part 1: Measuring Length

a. Remembering significant digits in all your measurements. (Look back in the lab if you forget.) Measure the following for you and your partners:

Width of finger nail

Distance around your wrist

Length of your lower leg from heal to knee

Height

Item to measure Length in significant digits

Measured digits Estimated digit Total number of significant digits

Width of finger nail

Distance around your wrist

Length of your lower leg-from heal to knee

Your height

b. Have each member of your lab team measure the line below individually and fill in their separate measurements below.

Your measurement: Partner 1: Partner 2: Partner 3: _________________ _________________ _________________ _________________ Which digits of the measured line should be the same as your partners? Which number may be different? Why?

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Part 2: Measuring Volume

a. Look at the lines on each of the three graduated cylinders. There are unmarked lines on each cylinder. On each cylinder, the unmarked lines may stand for a different volume. Explain how you would figure out the volume of each of the unmarked lines. Explain in the space below:

b. What volume does each of the unmarked lines represent?

____________ ____________ ________________ 10 ml cylinder 25 ml cylinder 100 ml cylinder

c. When reading volume from a graduated cylinder, you always read from the bottom of the meniscus. What would be the volume in the graduated cylinder to the left?

d. Fill a test tube to the top with water and empty it into the 10 ml cylinder. Do the same procedure for the 25ml and 100ml cylinders.

10 ml cylinder 25 ml cylinder 100 ml cylinder

Volume of water in the test tube

Measured digits

Estimated digit

Number of significant digits

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e. Volume of a solid through water displacement. 1. Fill the 100 ml cylinder to the 50 ml mark 2. Add the small stopper to the cylinder 3. Record the final volume 4. Subtract the final volume from the original volume

Final volume

Original volume

Volume of stopper

Measured digits

Estimated digit

Number of significant digits

f. Estimate the volume of three stoppers

1. Knowing the volume of one stopper, estimate what the volume of three stoppers would be and place that information in the chart below.

2. Find the actual volume of the three stoppers using the same method in part e. 3. Calculate the percent error using the equation below:

Actual volume-Estimated volume

Percent error= Estimated volume X 100

Estimated Volume of 3 stoppers

Actual Volume of 3 stoppers Percent error

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Part 3: Measuring Mass Using the triple beam balance, weigh the following objects:

1 Stopper

10 paper clips

1 Pencil/pens

100 gram or higher calibration weight

Item to measure Mass in significant digits

Measured digits Estimated digit Total significant digits

Stopper

10 paper clips

All group members pencils/pens

Calibration Weight

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Observations

•Look at the world around you

•What is happening

Problem or question

•Describe a problem or generate a question from your observations

Hypothesis

•Educated guess

•Predictions are made after the hypothesis is created

Experimentation

•Design and implement an experiment to test your hypothesis

Conclusion

•Organize data

•Draw conclusions based on the data collected

Communicate

•Share results with scientific community

Lab 2: Scientific Method and Graphing

The scientific method is a systematic approach to solve and understand problems and phenomena in the natural world. Whether you have selected a favorite product or you are trying to figure out why your car is not running properly, you have used the scientific method. Below are the steps to the scientific method:

Example of the Scientific Method in use 1. Observation: A scientist notes that humming birds seem to be attracted to the color red. Every morning she sees the humming birds flock to the red flowers in the yard. 2. Question/Problem: She would like to attract as many humming birds as she can. She usually makes a sugar solution and puts this in her humming bird feeder every week. She poses the question: Would I attract more humming birds if I put red dye in the humming bird food? 3. Hypothesis: When writing a good hypothesis, follow these criteria:

Stated as a fact/declarative statement

Is Objective

Contains one independent variable(IV)- (what is being tested)

Contains one dependent variable(DV)- (what is being measured as a result of the IV) There are many different hypotheses that can be made from one problem or question. Here is one possible hypothesis: Ex. Red-colored sugar water will attract more humming birds. IV-Red-colored sugar water is the independent variable. This is what the scientist will test and believes will cause her desired outcome. DV-Number of humming birds it the dependent variable. This is what she will measure based on her IV.

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10,0007,250

5,0007,750

0

5,000

10,000

15,000

predicted observed

Nu

mb

er o

f fe

edin

gs

Types of Sugar Water

The Effects of Sugar Water Color on Humming Bird Feeding

Red-colored sugar water Clear sugar water

Once the hypothesis is established then a prediction can be made. What would you expect to see if this hypothesis is true? A good prediction for this hypothesis could be: If red-colored sugar water is placed in a humming bird feeder, then it will attract 50% more humming birds. 4. Experiment: When designing a good experiment, use the following criteria:

Many subjects/Good sample size

Multiple trials

The experiment runs for an appropriate amount of time

Control group: group testing the absence the IV. Used for comparison

Experimental group: group testing the presence of the IV

Establish a mode for collecting data (qualitative/quantitative)

All other variables are held constant for the control group and experimental group Here is an example for this experiment: In a bird observatory room, there will be 100 humming birds. No birds can leave or enter. There is a clear glass plane separating the scientist from the subjects. The scientist will set up ten feeders that contain the red-colored sugar water and ten feeders that contain the clear sugar water. Both feeders will contain a 25% sugar solution at 22°C. Once the experiment is set up. The scientist will count how many birds visit the red-colored sugar water opposed to the clear-colored sugar water and record this in a data log. She will observe the birds for 8hrs a day during peak feeding times for 3 weeks. 5. Conclusions She recorded 15,000 feedings during the 3 week period. The data collected was totaled in the table below:

Total observed feedings: 15,000 Predicted Observed

Red-colored sugar water

10,000 7,250

Clear sugar water

5,000 7,750

She graphed her data using a bar graph. See the graph below:

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Note some important aspects of her graph:

It has an appropriate title

Both the X and the Y axis are labelled

The Y axis represents the Dependent Variable

The X axis represents the Independent Variable

There is a legend/Key Based on this scientific data, the scientist concluded that there is no relationship between color of sugar water and the attraction of humming birds. 6. Communicate

She contacts other scientists in her field and she shares her findings. She contacts the Audubon Society and publishes her findings in their monthly journal.

Lab Activities

Part 1. Graphing: You will need to graph the following sets of data. For each graph you must remember to do the following:

1. Write a possible hypothesis for the data set 2. Indicate the IV and DV 3. Include a title for the graph 4. Label the X and Y axis 5. Include a key or legend

A. Bacterial growth-Make a line graph for this data set

Number of Days Number of Bacterial Colonies Predicted

Number of Bacterial Colonies Observed

1 0 0

2 2 2

3 6 4

4 8 8

5 10 12

6 20 24

7 40 48

8 60 80

9 80 80

10 80 80

Graph this data on the following page:

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Title:

1. What is a good hypothesis for this experiment?

2. What is the dependent variable?

3. What is the independent variable?

4. Did the predicted data match the expected data? Explain.

5. What is your X axis label?

6. What is your Y axis label?

7. What symbols/marks did you use in your legend?

8. Would you accept your hypothesis based on this data?

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B. Grades and study time-make a bar graph

Number of Hours Used to Study for 1 subject per week

Predicted Grades Observed Grades

1 85 10

2 85 20

3 85 30

4 85 40

5 85 50

6 85 60

7 85 70

8 85 80

9 85 90

10 85 100

Title:

Questions for this graph are on the next page.

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1. What is a good hypothesis for this experiment?

2. What is the dependent variable?

3. What is the independent variable?

4. Did the predicted data match the expected data? Explain?

5. What is your X axis label?

6. What is your Y axis label?

7. What symbols/marks did you use in your legend?

8. Would you accept your hypothesis based on this data?

Part 2: Applying the Scientific Method Materials 3-250 ml Beakers 3 glow sticks 3 thermometers Tap water Hot plate Ice cubes Metric rulers Centimeter rulers

Background: You are in the biology section of a large research and development company. They have

been asked by the World Fisherman’s Association (WFA) to look into the claim that glow sticks can

actually be used as cheap, environmentally friendly, and highly effective fishing lures. The WFA would

like to be able to increase its yearly catch of fish in order to help feed the rapidly growing world

population. You have been assigned the job of investigating the effect of temperature on glow stick

brightness. The glow sticks supposedly work best as lures when they are glowing brightly. You are

limited to the above materials.

You need to develop a plan for how you will perform your experiment.

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1. Clearly state the problem or question you are trying to solve.

2. Hypothesis (based on the facts you already know).

Independent variable:

Dependent variable:

Prediction:

3. Create a detailed step by step procedure of your experiment. Refer to what needs to be included for

a good experiment.

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4. Think about the data you will collect and create a chart to keep your data organized. You have to

come up with some way to measure brightness with the tools you have. Your experiment must be at

least 10 minutes and you must have 10 data points for each temperature.

Once you have designed your experiment and have your data table ready, conduct your

experiment.

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5. Graph your results below. Remember to include all the information necessary when graphing and

remember that the x-axis is the independent variable here and the y-axis is the dependent variable.

Questions:

1. Did your findings support your initial hypothesis? Explain.

2. How could you make your experiment better if you were to repeat it?

3. What were some experimental biases (mistakes-either human or equipment) your group faced?

4. When you think about how the lure is going to be used, why do you think temperature might

not be a good variable to look at?

36

Lab 3: Characteristics of Life

What is life? Life is complex and difficult to define. Rather than defining life, scientists use characteristics or properties that all living things have in common. Below is a list of characteristics that all living things share:

1. Cells All living things are composed of at least one cell. Unicellular organisms consist of only one cell and multicellular organisms are composed of more than one cell. Cells range from being primitive (prokaryotic cells) to very complex (eukaryotic cells).

2. Reproduction Continuation of a species through the production of offspring. There are two types of reproduction: 1. Asexual-the passing on of genes by only one parent to the offspring, and 2. Sexual-the passing on of genes by two parents to produce offspring with unique genetic makeup

3. Responds to stimulus All living things respond to changes in their external and internal environment. The change in the environment is the stimulus and how the organism reacts is the response.

4. Homeostasis Organisms maintain an internal balance.

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Evolution

Species change overtime. Those organisms with adaptations better suited for their environment will survive and reproduce and those without those adaptations will go extinct. Extinction as a result of environmental change has been in existence since life began on this planet.

5. Hierarchy of Organization All organisms have levels of organization.

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6. Growth and development All living things increase in size (multicellular organisms increase in cell number from point of conception). Complex organisms can have developmental markers in which certain morphological changes occur during specific times in life cycle of the organism.

7. Obtain and utilize energy The sun is the ultimate source of energy for all living things on Earth. Energy is the ability to do work. There are two types of energy:

1. Kinetic energy-energy in motion 2. Potential energy- stored energy.

Organisms that can convert sunlight energy (kinetic) to stored chemical energy (potential) are called autotrophs. Those organisms that must consume other organisms to obtain energy are called heterotrophs. The total of all chemical reactions in an organism is called metabolism.

For this lab, we will be focus on obtaining and utilizing energy.

39

Cellular respiration Cellular respiration is the processes of converting energy stored in food, such as sugar, into cellular energy called ATP (adenosine triphosphate). There are two types of cellular respiration:

1. Aerobic Respiration-production of energy (ATP) in the presence of oxygen. Sugar + OxygenCarbon Dioxide + Water +

2. Anaerobic Respiration-production of energy (ATP) in the absence of oxygen.

The two types of anaerobic respiration are lactic acid fermentation and ethanol fermentation. Sugar ethanol + Carbon Dioxide + Or Sugar Lactic acid +

Question:

1. Yeast are unicellular organisms (Fungi) that perform ethanol fermentation to obtain energy for life. How could you prove this? Explain how you would design an experiment to demonstrate that yeast utilize energy.

ATP

ATP

ATP

40

Part 1: Ethanol fermentation and CO2 production Materials Beaker 1: Potential Organism A four 500ml or 1000ml flasks Beaker 2: Potential Organism B Sugar Hot plates CO2 Vernier probe Scale Parafilm Stirring rods 35⁰C Water 5% Sugar Solution Graduated cylinder Question: Look at beaker 1 and beaker 2. Which container holds a living organism that can perform ethanol fermentation? What proof do you have from your observation that this sample is living and can perform respiration? Look at the materials you are given, create a hypothesis that would be appropriate for proving the sample you selected is living and can perform ethanol fermentation.

Experiment 1: Beaker 1 + No Sugar:

1. Add 200ml of 35°C water to a flask. Set a hot plate to low to maintain this temperature. 2. Add 7 g of Organism A from beaker 1 to the flask and stir.

CHECK THE TEMPERATURE!! TEMPERATURES OVER 37°C WILL KILL ANY ORGANISM BEING USED!

3. Place the CO2 probe securely on the flask and fasten it using parafilm to prevent the loss of any

gas. 4. Attach the probe and start collecting data immediately and in 5 minute interval for 30 minutes.

Record your data in Table 1

Experiment 2: Beaker 2 + No Sugar:

1. Add 200ml of 35°C water to a flask. Set a hot plate to low to maintain this temperature. 2. Add 7 g of Organisms B from beaker 2 to the flask and stir.


3. Place the CO2 probe securely on the flask and fasten it using parafilm to prevent the loss of any gas.

4. Attach the probe and start collecting data immediately and in 5 minute interval for 30 minutes. Record your data in Table 1

41

Experiment 3: Beaker 1+ Sugar: 1. Add 100ml of 35°C water to a flask. Set a hot plate to low to maintain this temperature. 2. Add 100ml 5% sugar solution to the flask and stir 3. Add 7 g of Organism A from beaker 1 to the flask and stir.




Experiment 4: Beaker 2+ Sugar:

1. Add 100ml of 35°C water to a flask. Set a hot plate to low to maintain this temperature. 2. Add 100ml 5 %sugar solution to the flask and stir 3. Add 7 g of Organism B from beaker 2 to the flask and stir.




Flask CO2 0 minutes

(ppm)

CO2 5 minutes

(ppm)

CO2 10

minutes (ppm)

CO2 15

minutes (ppm)

CO2 20

minutes (ppm)

CO2 25

minutes (ppm)

CO2 30

minutes (ppm)

Organism A Beaker 1 no sugar

Organism B Beaker 2 no sugar

Organism A Beaker 3 sugar

Organism B Beaker 4 sugar

Graph your results on the next page. Remember to include a title and label the x and y axis.

42

Questions:

1. Which beaker contained a living organism? How do you know?

2. How could you increase CO2 production?

3. Why is it difficult to determine whether something is living by just observing it?

4. How else could you prove your organisms are living? Explain.

44

Laboratory 4: Atoms and Models

Atoms are the smallest unit that make up all matter. Matter is anything that has volume and mass.

Volume is how much space a substance occupies and mass is the amount of matter in a substance.

Atoms are made up of three basic particles:

1. Protons-positive charge (p+) 2. Neutrons-neutral (n0) 3. Electrons-negative charge (e-)

Each particle has a different property or characteristic. Based on the picture below, you can see that the protons and neutrons are located in the center of the atom (called the nucleus) and the electrons are located outside the nucleus. There are several terms used to describe the area that may contain electrons, such as, energy level, electron cloud, electron orbital, and electron shell. Many people use these terms interchangeably. Protons and neutrons contribute mass to the atom. Although electrons have mass, it is so small it contributes a negligible amount of mass to the atom and are not included in the overall mass of the atom. Below are some terms that you need to be extremely familiar with in order to understand the basics of atoms: Atomic number: This number defines the type of atom. This number cannot change or you change the chemical and physical properties of the atom, hence, the atom itself. This number is also the same number as the number of protons an atom has. Atomic Weight: This number is the average mass of the atom, taking into consideration the different isotopes found in nature. This number is represented with a decimal on the periodic table of elements. Isotope: An atom that has varying numbers of neutrons giving the atom a different mass. Mass number: This number is the number of protons and neutrons in the nucleus. Each proton and neutron is designated with the mass of 1 Atomic Mass Unit (AMU) or 1 Dalton (Da). In the above atom, the nucleus contains 4 protons and 4 neutrons. That means that this atom has the mass number of 8 or its mass is 8 AMU. Element: A pure substance containing only one type of atom and cannot be broken down into smaller parts. Neutral Atom: The number of protons equals the number of electrons or positive charges equal negative charges.

Ion: An atom with a different number of protons than electrons. These atoms have a charge.

45

Periodic Table of Elements: An organized chart that arranges atoms based on certain chemical and physical properties. Here is a typical Periodic Table of Elements. Every Periodic chart is organized the same way, some are more colorful and highlight certain properties while others are just black and white. On every chart, you will see the same number of row and columns. The rows are called periods and the columns are called groups or families.

Below is a closer look at carbon from the Periodic Table of Elements. There is some very useful information listed for each element. Looking at this we know the following information:

Carbon has the Atomic Number of 6, that means it has 6 protons

Carbon’s symbol is C

Carbon’s Atomic Weight, if rounded, gives us the Mass Number of 12

Periods

Groups

46

Knowing the information given in the Periodic Table we can calculate the following information: Mass number – atomic number = number of neutrons 12 - 6 = 6 Since all atoms in the Periodic Table are considered neutral, if we know the number of protons for carbon is 6, then the number of electrons is six. The positive charges are equal to the negative charges

p+ p+ p+ p+ p+ p+ = e- e- e- e- e- e-

Try this example: Atomic number ______ Number of Protons ______ Atomic Weight ______ Mass number ______ Number of Neutrons ______ Number of Electrons______ Practice Problem Using the Periodic Table of Elements, fill in the missing information for each atom.

Name of Element

Atomic Symbol

Atomic Number

Number of

Protons

Mass Number

Group Number

Period Number

Number of

Neutrons

Number of

Electrons

Nitrogen

O

20

9

H 1

3 3

19

53

47

1 1

Isotopes Isotopes are atoms with a varying number of neutrons. As you learned earlier, neutrons contribute mass to the atom. When atoms loose or gain neutrons, the mass number changes. Remember that proton number does not change or you change the actual atom. If you look at the two atoms above, you will see that they both have the same atomic number. Since the two atoms represent the same atom (carbon), the number of protons must be the same. The only thing that is different for the two atoms is the number of neutrons. If you calculate the number of neutrons for C12 (if you are unsure how to do this, refer back to the last practice problem), you will get 6 as the number of neutrons. If you calculate the number of neutrons for C14, you will get 8 as the number of neutrons. Since neutrons contribute to mass, the mass number will change based on whether neutrons were added or lost. Practice Problems Provide the missing information for each isotope

Element H2

H3 Element

Number of p+ Number of p+

6 6

Number of n0 Number of n0

7 8

Number of e- Number of e-

Mass number Mass number

48

Element

Element

Number of p+ Number of p+

2 2

Number of n0 3 5 Number of n0

4 5

Number of e- 3 3 Number of e-

Mass number Mass number

Models Models are useful tools to represent concepts in science. There are two models commonly used to represent atoms: 1. Bohr model 2. Lewis Electron Dot formula. While Bohr’s model is used to show the atom as a whole, the Lewis Dot Formula is used to show just valence electrons (outer most electrons). Each are useful models when studying how atoms behave. Bohr’s model Although Bohr’s model inaccurately displays the movement of electrons, it is a good model to use in an introductory course to visualize the atom. For this model, the center represents the nucleus containing protons and neutrons and the rings represent the electron shells. The period number represents the number of electron shells an atom has. There are 7 electron shells and each shell holds a certain number of electrons. For this class, we will only focus on atoms that have a maximum of 4 shells. Below are the shells and maximum number of electrons each can hold: 1st Shell holds a maximum of 2e- 2nd Shell holds a maximum of 8e- 3rd Shell holds a maximum of 18e- 4th Shell holds a maximum of 18e- Here is an example: Carbon C Mass number= 12 Atomic number (protons)= 6 Number of neutrons=6 Number of electrons=6 Period= 2 If you look at the model, you can see that the protons and neutrons are placed in the nucleus. The two circles around the nucleus represents the 1st and 2nd electron shells. Since carbon has six electrons, two are placed in the first shell. Two electrons is the maximum number of electrons in that shell. Four electrons are left over and are placed in the second shell. The 2nd shell represents the valence shell containing the valence electrons.

49

Pratice Problems on next page Oxygen symbol Mass number= Atomic number (protons)= Number of neutrons= Number of electrons= Period=

Sulfur symbol Mass number= Atomic number (protons)= Number of neutrons= Number of electrons= Period=

Nitrogen symbol Mass number= Atomic number (protons)= Number of neutrons= Number of electrons= Period=

Hydrogen symbol Mass number= Atomic number (protons)= Number of neutrons= Number of electrons= Period=

Phosphorous symbol Mass number= Atomic number (protons)= Number of neutrons= Number of electrons= Period=

Calcium symbol Mass number= Atomic number (protons)= Number of neutrons= Number of electrons= Period=

Chlorine symbol Mass number= Atomic number (protons)= Number of neutrons= Number of electrons= Period=

50

Short-hand for the Bohr’s Model Since it is known how many electrons go in each shell, you can use short hand to represent the model instead of drawing all of the shells. Below is an example of short-hand. Carbon C Short-hand for Carbon Mass number= 12 Atomic number (protons)= 6 Number of neutrons=6 Number of electrons=6 Period= 2 Practice problems Draw the short hand for the atoms below. Oxygen Hydrogen Sulfur Nitrogen Sodium Chlorine

51

Lewis Dot Formula This model is used to represent only the valence electrons of an atom. Valence electrons are those electrons found in the outer most shell. For this model we will be focusing on the group A elements. The transition elements behave differently and you will learn about them in chemistry. The group A elements are indicated in the Periodic Table below. The group in which an atom is located indicates how many valence electrons the atom has (Helium is the exception. Helium has only 2 electrons). For example, carbon is in group 4A. That means that carbon has 4 valence electrons. You represent these electrons by placing one dot on each side of the atomic symbol as seen below. You do not double up electrons on a side until each side has one electron. Arsenic is in group 5A. That means that arsenic has five valence electrons. You represent these electrons by placing one dot on each side of the atomic symbol. Once each side has an electron then you begin to double them up.

As

52

Boron is in group 3A. That means that boron has three valence electrons. You represent these electrons by placing one dot on each side of the symbol. One side will not have electrons.

B Practice Problems Draw the Lewis dot formula for the following elements Hydrogen Helium Oxygen Sulfur Phosphorous Nitrogen Sodium Chlorine Argon Neon

53

Questions 1. How are the Bohr’s model and the Lewis Dot Formula similar?

2. How are the two models different?

3. Why are models often used in science?

4. Which particle number does not change or the actual element changes?

5. There were two samples of a new element discovered. The scientist weighs the two elemental samples and notices the masses are different. How would this scientist know that the two samples are the same element if they have different masses? What would cause the difference in mass?

54

Ions and the Octet rule Ions are atoms that have lost or gained electrons. Atoms may gain or lose electrons in order to become stable and have a complete valence shell. Noble gases are stable, inert elements that have a complete outer shell. These atoms are located in group 8A. Most of the group A family is represented below. Notice that the elements in group 8 all have eight valence electrons.

Atoms in groups 1, 2, and 3 tend to lose electron in order to establish the noble gas electron configuration

Atoms in groups 5, 6, and 7 tend to gain electrons.

When atoms lose or gain electrons, those atoms are no longer neutral and are now considered ions.

This diagram shows the sodium atom becoming a sodium ion.

Sodium is in group 1A so sodium tends to lose 1 electron. Chlorine is in group 7A so chlorine tends to gain electrons to each 8 or a stable electron configuration.

11p+=11e-. This is a

neutral atom 11p+>10e-. This is a

positive ion. There is

one more proton than

electron.

17p+=17e-. This is a

neutral atom

17p+<18e-. This is a

negative ion. There is

one more electron

than proton.

55

Practice problems Fill in the missing information for the chart.

Element Number of p+ Number of e- Number of valance e-

Gain or loss of e-

Symbol when Ion is formed

Sodium

11p+

11e-

1e-

Lost 1 e-

Na+

Oxygen

8p+

8e-

6e-

Gain 2 e-

O-2

Lithium

Sulfur

Iodine

Barium

Aluminum

Calcium

Nitrogen

Phosphorous

Argon

Potassium

Questions:

1. How are ions different from isotopes?

2. Can an atom be both an ion and an isotope? Explain your answer.

3. Which atom on the chart above did not form an ion? Why?

57

Lab 5: Bonding

Atoms that do not have a complete valence (outer) electron shell are unstable and are very reactive. For most atoms, an atom is stable when there are 8 valence electrons. In order to achieve a stable electron configuration or shell, atoms will bond together. When atoms bond, this bonding is called a chemical reaction. The substance/s that begin the reaction (called the reactants) are different chemically and physically than the substances at the end of the reaction (called products). There are two common types of bonds atoms will form: 1. Ionic bonds and, 2. Covalent bonds. Ionic bonds Ionic bonds typically occur between metals and nonmetals. As you learned in lab 4, metals are elements in groups 1, 2, and 3 tend to lose electrons in order to have a stable valence shell, whereas, atoms in groups 6, 7, and 8 tend to gain electrons in order to have a stable valence shell. Below is an example of the formation of a sodium ion. A positive ion is called a cation. Below is an example of the formation of a fluoride ion. A negative ion is called an anion.

58

An ionic bond or ionic compound forms when atoms transfer electrons and the resulting ions are held together through the attraction of opposite charges. Look at the example below for sodium and chlorine. One image is showing the Bohr’s model and the other image is showing the Lewis Dot Formula. Bohr’s Model Electron Dot Formula Both diagrams are showing the same chemical reaction. The overall chemical reaction is indicated below:

Na + Cl NaCl Reactants Product This reaction is saying that one atom of sodium is reacting with one atom of chlorine to form the compound sodium chloride. For ionic compounds, the cation is written first and the anion is written second. Also, for the anion, the suffix –ide is added to the end of the name. So the compound formed here is sodium chloride. This product is much different chemically and physically than the reactant that bonded.

59

Keep in mind that when a chemical reaction takes place, there are typically billions of atom reacting. Let’s look at another example. Since potassium is in group 1 that means that it has 1 valence electron. Since sulfur is in group 6 that means it has 6 valence electrons. In order for potassium to become stable it must give up one electron. Sulfur receives this electron. Potassium is stable; however, sulfur is still reactive because it only has 7 valence electrons. Since there are billions of atoms reacting, a second potassium can donate another electron to sulfur. Since each potassium lost one electron, the charge on each potassium cation is +. Since sulfur received two electron, the sulfur anion is -2. The overall reaction is below. The resulting ionic compound is called potassium sulfide. K2S is the chemical or molecular formula. This formula tells you which atoms are in the substance and how many of each type.

This indicates that two potassium atoms bonded with one sulfur atom. 1 is assumed when no

subscript is written.

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Practice Problems Draw the Lewis Dot Formula for the two atoms. Show the transfer of electrons from the metal to the nonmetal. Add additional atoms if necessary (like in the example on the previous page). Show the charge of each ion, write the chemical formula, and then name the compound. Follow the example below.

1. Calcium and chlorine

2. Rubidium and fluorine

3. Magnesium and nitrogen

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Part 1: Bonding with partners Materials Laminated atom card Pencil

1. You will be given a card that represents a metal or nonmetal. If your card has a pink dot, your atom is a metal. If your card has a green dot, your atom is a nonmetal.

2. Once you receive your card with your atom write the Lewis Dot Formula on this sheet in the space indicated.

3. You will then find a person in the lab that has the opposite card from yours, i.e., if you have a metal, your partner needs to have a nonmetal.

4. Record the following information:

The dot formula for both elements

The transfer of electrons and any additional atoms needed in on order for all atoms to be stable

The cation and anion formed along with indicating how many

The chemical formula for the compound

The name of the compound

Each bond should look like the example from the practice problems. 5. You will be given 3-4 minutes to complete your bond. 6. Once you are finished wait for your instructor to tell you to switch partners. You should have

about 8 different bonding partners by the end of this activity. Name of your atom. _________________Metal or Nonmetal______________Dot Formula___________ Bond 1 Bond 2 Bond 3

62

Bond 4 Bond 5 Bond 6 Bond 7 Bond 8

63

Covalent bonds Covalent bonds typically occur between nonmetals. Although hydrogen is in group 1, hydrogen tends to form covalent bonds. The atoms involved in this type of bond do not have enough energy to pull electrons away from other nonmetals. So instead of transferring electrons, atoms in covalent bonds tend to share electrons. There are two types of covalent bonds: 1. Nonpolar covalent bonds, and 2. polar covalent bonds. In nonpolar covalent bonds, the atoms involved in the bond equally share the valence electrons. In polar covalent bonds, the atoms involved in the bond unequally share the valence electrons. Some atoms have a stronger pull on the shared electrons. This pull is called electronegativity. The atoms in a polar covalent bond do not have enough energy to pull the shared electrons from the bonding atom; however, the pull is strong enough that the two atoms sharing the electrons do not share them evenly. Because of this unequal sharing of electrons, one atom becomes slightly negative( )and the other atom becomes slightly positive ( ). Below are examples of the bonds discussed in this lab.

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In a covalent bond, atoms can share one, two, or three pairs of electrons in order to become stable. When drawing covalent molecules, the structural formula is often used. The structural formula uses lines to indicate a shared pair of electrons. Take the chemical methane (CH4). Based on the chemical formula, we know that there is one carbon atom bonding with four hydrogen atoms. The structural formula for this model is represented below: Although we draw atoms in two dimension, they are actually three dimensional structures. For this next part of the lab, we will be working with molecular model kits. Part 2: Covalent bond and molecular model kits Materials 1 Molecular Model kit for each group of two For each of the molecular formulas given, you will build the three-dimensional model and draw the structural formula in the given space. The balls in the kit represent a specific type of atom. Each ball has a certain number of holes. These holes represent unpaired electrons or open bonding sites. The number of holes represents the number of bonds needed in order to be stable. Take a look at your kit. Find the following atoms and fill in how many times that atom can bond.

65

Color Atom Number of Bonding sites Red Oxygen White Hydrogen Black Carbon Blue Nitrogen plug one hole Green Chlorine Blue Phosphorous plug one hole

The sticks represent the covalent bonds that will hold the atoms together. Notice some of the sticks are flexible. These sticks are used for building those molecules that have double and triple bonds. Building molecules

1. First look at the molecular formula. This tells you which type of atoms you need from the kit and how many. For example, H2. This tells you that you need two white balls from the kit.

2. Take a stick and attach the two atoms together. Are all of the bonding sites full and each stick attached to an atom? If the answer is yes, then your model is complete and draw the structural formula.

3. If the answer to number two is no, then that means there is a double bond or triple bond between the atoms. For example, O2. This tells you that you need two red balls from the kit. Take a stick and attach the two atoms. You will see that there are still to open bonding sites, one on each oxygen atom. For this bond, you will need the long flexible sticks. Attach the sticks to one oxygen atom and bend the stick until they fit into the second oxygen atom. Draw the structural formula.

4. Try this for N2. Draw the structural formula below.

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Build and draw the structural models for the molecules in the chart below.

Water H2O

Ammonia NH3(remember to plug a site for nitrogen)

Carbon tetrachloride CCl4

Hydrogen peroxide H2O2

Carbon dioxide CO2 Propane C3H8

Ethane C2H6

Ethyne C2H2

Ethylene C2H4

68

Lab 6: Moles and Conversions

As you learned in lab 4, atoms make up all matter and matter is defined as anything that has mass and

volume. The number of neutrons and protons found in an atom’s nucleus determines the mass of an

atom. When atoms bond together they make an element (if atoms of the same substance bond) or a

compound (if atoms of different substances bond).

Element of Oxygen Compound of Carbon Dioxide

O O O C O

The calculated mass of an element or compound is called the molecular weight. To find the molecular

weight, you need to know the molecular formula for the substance.

Example: Oxygen. The molecular formula for oxygen is O2. The formula tells us that the atom oxygen is

bonding and there are two oxygen atoms involved in the bond.

To calculate the molecular mass, follow the chart below:

Type of atom Number of Atoms X Mass number = Total Mass O 2 16g or AMU 32 Example: Carbon dioxide. The molecular formula for CO2. The formula tells us that one atom of carbon is bonding with two atoms of oxygen.

Type of atom Number of Atoms X Mass number = Mass C 1 12g or AMU 12

O 2 16g or AMU 32

Total Mass 44g or AMU

O2 CO2

O2 Type

of

atom

Number

of atoms

CO2

Types of

atoms

Number of atoms

69

Practice Problems: Calculate the molecular weight for the following elements and compounds: Cl2 C6H12O6 H2SO4 Mg(OH)2 6O2 2C6H6 Ca3(PO4)2

70

Moles and Avogadro’s number The mole is a unit of measurement indicating the amount of a substance. Avogadro’s number in the number of atoms or molecules that are in one mole of a substance, which is always 6.02 X 1023 atoms or molecules. These terms can be a little difficult to understand at first but let’s look at an analogy that is familiar to us. A dozen is a unit of measurement indicating the amount of a substance. We know that one dozen of something means that you have 12 of that something. You also know that if you have a dozen of two very different things that those things will have very different weights. Look at the example below: Amount Number Mass 1 dozen feathers 12 feathers 1 g of feathers in 1 dozen 1 dozen elephants 12 elephants 4.8 X107 g of elephants in 1 dozen 2 dozen feathers 2(12)=24 feathers 2(1 g)=2 g of feathers in 1 dozen So now let’s apply this to chemistry: Amount (mol) Avogadro’s number Molecular Mass 1 mol of O 6.02X1023 atoms of O 16 g O (O) 1 mol of O2 6.02X 1023molecules of O2 32 g O2

(O O) 1 mol of CO2 6.02X1023moleculues of CO2 44 g CO2

2 mol of CO2 or 2CO2 2(6.02X1023) molecules of CO2 2(44g)=88g CO2

Practice Problems: Fill in the information for the chart below:

Element or Compound Number of moles Number of molecules present

Mass of element or compound (molecular

mass)

NH4

6 H2O

2 CH3O

N2

5 Ca3(PO4)2

71

Part 1: Measuring Different Amounts of Moles and conversions Materials 8 weigh boats Electronic scale NaCl C12H22O11 (Table sugar) 2-500 ml beakers

1. Place a weigh boat on the scale and zero/tare the tray. 2. Measure out 1 mol of NaCl (review the lab if you are unsure) 3. Place the salt into an empty 500 ml beaker and label the beaker 4. Place the weigh boat on the scale and zero/tare the tray. 5. Measure of 1 mol of C12H22O11 6. Place the sugar into an empty 500 ml beaker and label the beaker

Questions:

1. When looking at the mole of sugar compared to the mole of salt, what is the difference between them? What is causing this difference since both substances are equal to 1 mole?

2. How many molecules make up each mole of sugar? Each mole of salt? Explain how you know that information.

3. In your own words, explain the relationship between mole, number of molecules, and molecular mass.

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Conversions Once you understand the relationship between moles and molecular mass, you can easily make the conversions between the two units. That means when are you given a value in grams (molecular mass), you can calculate the number of moles or if you are giving a value in moles, you can calculate the number in grams (molecular mass). You need to remember this relationship:

1 mol of a substance= the molecular mass of that substance (in g or amu) There are two different methods used to calculate conversions: 1. Dimensional analysis and 2. Proportions Your instructor will decide which method to use in class.

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Practice Problems. Show all work.

1. How many grams are in 2.6 moles NaOH?

2. How many moles are in 2.6 g NaOH?

3. How many moles are in 180g C6H12O6?

4. How many grams are in 6 mol HCl?

5. How many moles are in 59g H2SO4?

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Part 2: Measuring and converting grams to moles

1. Make sure you zero/tare your scale with one of the trays before you begin this activity. You will use this one tray to tare before each measurement. We will assume that all trays way the same.

2. With your 7 weigh boats randomly scoop out different amounts of NaCl into your seven trays. 3. Weigh each of your samples of salt and log the mass in Table 1 below. 4. Convert the mass into moles and complete the information in Table 1.

5. Label each tray with the tray number and the amount of moles you calculated. DO NOT WRITE THE MASS!!!!

Table 1 Tray Number Grams of NaCl in tray

Moles of NaCl in Tray

1

2

3

4

5

6

7

Show work for all trays below:

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Part 3: Measuring and converting moles to grams 1. Switch your seven trays with another group. 2. Once you have 7 new trays from a different group, record the number of moles for each tray in

Table 2 3. Convert the number of moles recorded into grams in Table 2 4. Weigh each tray to see if the actual mass was similar to the calculated mass. 5. Calculate the percent difference in mass:

Calculated mass – Actual Mass Actual Mass

6. Compare numbers with the group you obtained the tray from.

Table 2

Tray Number Moles of NaCl in Tray

Calculated grams in tray

Actual mass of tray

Percent difference

1

2

3

4

5

6

7

Show work for mole to gram conversions for all trays: Show work for percent difference in mass:

X 100 = Percent difference in mass

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Solute

Percent solution= Solution X 100

(solvent + solute)

Lab 7: Percent Solution and Molarity

Solutions are mixtures consisting of solute/s and solvent.

Solute: The part of the mixture that is being dissolved and is in the smaller quantity. Solvent: The part of the mixture that is dissolving and is in the larger quantity. Put simply: Solution=solute+solvent

Typically, water is the solvent when discussing biological systems. Substances that are ionic compounds

or polar readily dissolve in water. Since the types of substances that can dissolve in water are so

diverse, water it is considered the universal solvent. Water has the same mass in grams as volume in ml.

So if you measure out 100 ml H2O, the mass of 100ml would equal 100g H20.

Concentration Concentration describes how much solute is dissolved in a solution. When there is a high amount of solute in a solution that solution is said to be concentrated. When there is a low amount of solute in a solution that solution is said to be dilute. There a several ways that scientists use to express concentration. This lab will focus on percent solution and Molarity. Percent solution Percent solution is used to express the portion of the solution that consists of the solute. This percent can be expressed as volume/volume, mass/mass, or mass/volume representation. Below is the equation for calculating the percent solution: For example, if 25g of NaCl were added to 100g H2O, what percent of the solution would be NaCl? Solute=25g NaCl 25g NaCl Solvent=100g H2O 125 solution X 100= 20%NaCl solution Solution= 25g + 100g (125g) (solvent +solute) It is also possible to calculate the number of grams needed to make a specific percent volume of solution.

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For example, how much salt and water is needed to make 200 g of 15% NaCl solution. Steps

1. Convert the percentage back into a decimal (divide by 100 or move the decimal two places to the left)

2. Multiple the solution by the decimal in step 1 to get the amount of solute 3. Subtract the solution volume by the amount of solute

0.15 X 200= 30g NaCl (solute) then 200-30=170g H2O So to make 200g of a 15% salt solution, mix 30g of NaCl with 170g of H20 Practice Problems (Make sure the units are the same if ml, all unit must be ml. If g all units are g. Convert ml to L if necessary)

a. What percent ethanol solution results when adding 20ml of ethanol to 300ml of H2O?

b. What percent HCl solution results when adding 15ml of HCl to 550ml of H2O?

c. How many grams of sugar and water are required to make 500g of a 5% sugar solution?

d. How many ml of ethanol and water are required to make 600L of a 40% ethanol solution?

e. How many grams of sodium bicarbonate and water are needed to make 200g of a 20% sodium bicarbonate solution?

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Molarity Molarity or molar solution is used to express the number of moles of a solute per liter of solution. If there is a 1M NaCl, that means 1 mole of NaCl is present in 1 liter of solution. To make this solution, 1 mole of NaCl would need to be measured and added to water for a final volume of 1L. From lab 6, you learned that 1 mol of any substance is equal to the molecular weight for that substance. Atoms Number of atoms Mass Total Na 1 X 23 = 23 Cl 1 X 35 = 35 58g 1 mol NaCl=58g NaCl. So 58g of salt would be added to water until the final volume of the solution was 1 L. This would make a 1M NaCl solution. Here is another example: How many grams of NaCl would be needed to make a 0.5 M NaCl solution? 0.5M means .5mol/L. Since we know the relationship between moles and grams we can do a simple conversion following the steps from lab 6. .5mol NaCl 58gNaCl 1 1 mole NaCl 29g NaCl would be added to make 1L of solution If moles and the volume of solution are given, it is easy to calculate the molarity. For example, 2mol NaCl are dissolved in .5L of solution, what is the molarity? 2mol NaCL 0.5L 4mol/L NaCl or 4M NaCl Make sure that the volume is always in liters. If you are given a volume in ml, make sure you convert the units into liters before proceeding with the problem.

mol M =Liter of solution

X =

=

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Practice Problems

Determine the molarity of these solutions:

a) 4.67 moles of Li2SO3 dissolved to make 2.04 liters of solution.

b) 0.629 moles of Al2O3 to make 1.500 liters of solution.

c) 4.783 grams of Na2CO3 to make 10.00 liters of solution. (Hint: convert grams to moles first)

d) 0.897 grams of (NH4)2CO3 to make 250 mL of solution. (Hint: convert grams to moles first)

e) 0.0348 grams of PbCl2 to form 45.0 mL of solution. (Hint: convert grams to moles first)

Calculate the grams needed to make the following solutions:

f. How many grams are needed to make a 2.5M solution of HCl?

g. Challenging: How many grams of Ca(OH)2 are needed to make 500 ml of 1.66 M Ca(OH)2 solution? (hint: use a conversion factor to cancelled out ml so you are left with moles)

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Conductivity Conductivity is a material’s ability to conduct electricity. When ionic compounds are placed in an aqueous solution (the solvent is water), the cation and anion will dissociate or separate from one another. These separated ions are also called electrolytes and they can conduct electricity. Electrolytes are an important part of an organism’s physiology. The more electrolytes that are present in a solution, the more conductive a solution is. Conductivity can be measured in decisiemens per meter or dS/m. For this lab, you will be making different percent salt solutions and measuring the conductivity of each solution. By graphing your known percent solutions’ conductivity, you will be able to predict the percent solution of unknown solutions.

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Part 1: Making Percent Solutions Materials 6 250ml Flasks Distilled Water NaCl Electronic Scale Weigh boats Chemical scoop 1 250ml graduate cylinder Hot plate

1. You will need to make 150 g of the following NaCl solutions. Refer to the instructions at the beginning of this lab:

0% NaCl

2% NaCl

4% NaCl

6%NaCl

8%NaCl

10% NaCl Example: 2%=0.02gNaCl Solute=0.02 X 150=3g NaCl Solvent= (solution-solute) 150-3=147g H2O. To get a 2% solution, you would add 3g NaCl to 147mL of H2O Place this information in Table 1

2. Label each flask with a specific % solution like the picture below.

3. Add the correct amount of salt and water to each flask. Stir until dissolved. Heat may be required to help with dissolving the salt.

4. Once the six solutions are dissolved, using the graduated cylinder, measure the volume of each solution and record this in Table 1. Be very accurate and precise here because these measurements will be used later.

5. After measuring, RETURN SOLUTION TO ORIGINAL FLASK!

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Table 1

Flask Grams (g)

NaCl Grams (g) H2O Total Solution

NaCl Volume of

Solution (mL) Measure with

graduated cylinder

0% NaCl

150 g

2% NaCl

150g

4% NaCl

150g

6% NaCl

150g

8% NaCl

150g

10%NaCl

150g

Part 2: Measuring Conductivity Materials 6 solutions from part 1 dH2O wash bottle Kim wipes Conductivity probe and unit 1-250 ml Beaker

1. Connect the conductivity probe to the computer interface. Check to be sure the Conductivity Probe is set to 0-20,000 dS/m

2. Carefully raise the first flask to the conductivity probe until the hole near the probe end is completely submerged in the solution

3. Briefly swirl the flasks contents. Once the conductivity reading in the meter has stabilized, record the value in Table 2.

4. Before testing the next solution, clean the electrodes by surrounding them with a 250mL beaker and rinse them with distilled water from a wash bottle. Blot the outside of the probe end dry using a Kim wipe. It is not necessary to dry the inside of the hole near the probe

5. Repeat for all flasks Table 2

Flask Conductivity dS/m

0%

2%

4%

6%

8%

10%

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Graph your results below. Percent solution is the X axis and conductivity is the Y axis. Be as accurate and precise as possible. You will be using this graph for the next section.

Make sure that you use the line of best fit. Your instructor will inform you how to do this.

Part 3: Determining Unknowns Using the Standard Curve The above graph represents a standard curve. A standard curve uses known values to determine unknown values. You plotted the conductivities of known percent solutions of NaCl. Using this curve, you will be able to determine the percent solutions of unknown salt concentrations. Look at the following set of date:

Percent solution

Conductivity dS/m

0% 0

5% 500

10% 1000

15% 1500

20% 2000

25% 2500

This information is plotted in the graph on the following page.

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0

500

1000

1500

2000

2500

0

500

1000

1500

2000

2500

3000

Co

nd

uct

ivit

y

Percent Solution

The Effects of Percent Solution on Conductivity

0% 5% 10% 15% 20% 25%

dS/m

A solution of unknown concentration of a NaCl solution is tested and reads 1250dS/m. To find the percent solution, find the location of 1250dS/m on the Y axis. Using a ruler, draw a straight line from the Y axis until it reaches the line of best fit. Draw a perpendicular line from the line of best fit to the X axis. This gives you the unknown concentration. Looking at the orange lines on the graph, we can deduce that the unknown solution has the concentration of 12.5%. Find the concentration of the following unknowns and complete the information in Table 3. Table 3

Unknown Conductivity dS/m Percent Solution Based on

Standard Curve

Actual Percent Solution (obtain this information

from your instructor)

Unknown Sample A

Unknown Sample B

Unknown Sample C

Unknown Sample D

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Part 4: Conversion of Percent Solution to Molarity Take the information from Table 1 to fill in the missing information in Table 4 below: Table 4

Flask Grams (g) NaCl

Volume of Solution (mL)

Measured with graduated cylinder

Molarity of solution (mol/L)

0% NaCl

2% NaCl

4% NaCl

6% NaCl

8% NaCl

10%NaCl

Review your practice problems for molarity. Remember to convert gmol then divide mol by total solution in LITERS. Show your work below: 0%= 2%= 4%= 6%= 8%= 10%=

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Lab 8: pH and Buffers Water is an essential molecule for all life. Not only are its properties of adhesion, cohesion, and high specific heat important for living things to survive, water also determines whether a substance is an acid or a base depending on how that substance behaves when dissolved in water. Water is a polar covalent molecule. That means oxygen has a stronger pull on the shared electrons than hydrogen. This uneven pull causes oxygen to become slightly negative and hydrogen to become slightly positive. Occasionally (1 in 550 million) the oxygen in a water molecule will pull the electron completely away from one of the bonded hydrogen atoms. When this happens, a hydroxide ion (-OH) forms and a hydrogen ion forms (H+). The hydrogen ion often will stick to another water molecule forming a hydronium ion (H3O+).

In pure water, every time a hydroxide ion is formed, a hydronium ion is formed. So in pure water:

H3O+=-OH When a substance is added to water and it disrupts this balance, we call that substance an acid or a base depending on HOW it disrupts this balance. Acids, Bases, and pH Acids are substances that will increase the H+ concentration when that substance is added to pure water. Acids are sour to the taste and are corrosive. Acids are also called proton donors. So in an acidic solution:

H3O+>-OH

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Bases are substances that will decrease the H+ concentration or will increase the –OH concentration when that substance is added to pure water. Bases are bitter to the taste, slippery, and are emulsifiers. Bases are also called proton acceptors. So in a basic or alkaline solution:

H3O+<-OH The pH scale measures the molarity of the hydrogen ion concentration (or hydronium ion) in a solution. The amount of hydrogen ion in pure water is 1X10-7M H3O+. That means that the hydroxide ion in pure water must also be 1X10-7M –OH since the two are equal. This number is so small because of the infrequency of water to dissociate. pH is based on a logarithmic scale. Knowing this, we say that water has a pH of 7. Your instructor may show you how to do this calculation on a scientific calculator. Whenever you increase the amount of H+, the exponent will decrease and so will the number on the pH scale. When the H+ in solution is increased by 10 fold, the solution will now have 1.0X10-6MH+. This solution would measure 6 on the pH scale. Even though we only changed the number by one pH unit, the solution has 10X the amount of H+ than pure water. Part 1: Testing the pH of known and Unknown Substances Material 2 spot plates pH paper Forceps Pipettes Knowns Unknowns

WEAR GLOVES AND GOGGLES DURING THIS WHOLE LAB!

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1. Place a paper towel on your lab bench 2. Wash and dry your spot plates and place them on your paper towel 3. Using forceps, rip small pieces of the pH paper and place them in your wells, one piece per well.

Do not use your fingers 4. Place two to three drops of the different knowns each in a separate well 5. Read color change immediately (within 30 seconds) and record your results in the data table

Known/Substance pH Strong or Weak Acid or Base/Neutral

0.1 M HCL

0.1 M NaOH

1.0 M NaHCO3 (sodium bicarbonate)

H2CO3 (carbonic acid)

dH2O

Salt Water

Coke

Antacid

Lemon Juice

Ammonia

Drain Cleaner

Tomato Juice

Part 2: Test Unknowns

1. Throw the used pH paper in the trash (NOT THE SINK!). 2. Thoroughly rinse and dry the spot plates. 3. Using forceps, rip small pieces of the pH paper and place them in your wells, one piece per well.

Do not use your fingers 4. Place two to three drops of the different unknowns each in a separate well 5. Read color change immediately (within 30 seconds) and record your results in the data table

Unknown Substance pH Strong or Weak Acid or Base/Neutral

Based on your known data, what is the substance?

A

B

C

D

E

F

G

H

I

J

K

N

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Buffers Buffers are substances that can resist change to pH to a certain concentration. Buffers consist of weak acid/base pairs. Buffers work by adding or removing protons from solution when a strong acid or bases is added to that solution. Part 3: Making a buffer Materials Phenolphthalein 0.1 M NaOH 2-250ml flasks 1 straw Graduate cylinder Question: What will happen to the pH of a buffered solution when adding a strong base? Hypothesis: Prediction:

1. Add 100 ml of tap water to both flasks 2. Label 1 flask control and one flask buffer 3. Add two drops of phenolphthalein to both flasks 4. Take the straw and blow gently into the buffer flask for 2 minutes 5. Slowly add one drop at a time of NaOH to the control flask. Swirl the flask after each drop.

Count how many drops it takes for the flask to turn pink 6. Do the same thing for the flask labelled buffer. Count how many drops it takes for the flask to

turn pink. Swirl after adding each drop. 7. Log your information in the table below.

Flask Number of drops

Control

Buffer

Questions:

1. What do you think breathing into the water added to the water?

2. How many more drops did it take to change the pH of the unbuffered solution opposed to a buffered solution?

3. Blood has a pH between pH 7.35-7.45. Why do you think buffers are so important in the blood?

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Part 4: Buffer and saturation Water vs. Blood plasma when exposed to Strong Acids and Strong Base Materials Beakers Graduated cylinder dH2O Blood plasma 0.1 M NaOH 0.1 M HCl 2 spot plates Distilled Water and Acid

1. Put paper towel down on the table 2. Measure 5 ml of dH2O and put it in a beaker. Label the beaker dH2O. 3. Measure 20 ml of 0.1 M HCl and put it in a beaker. Label the beaker HCl. You will use this HCl

for the whole lab 4. Tear small pieces of pH paper and place the paper in the wells 5. Take the stirring rod and mix the dH2O. Immediately touch the stirring rod to the pH paper and

record the pH of just the dH2O 6. Add three drops of HCl to the dH2O. Stir with the stirring rod and immediately touch the stirring

rod to a new piece of pH paper. Record the pH of the dH2O 7. Add another three drops of HCl to the dH2O. Stir with the stirring rod and immediately touch

the stirring rod to a new piece of pH paper. Record the pH of the dH2O 8. Continue step 7 until you have added 30 drops of HCl

Wash spot plates between trials.

Plasma and Acid

1. Put paper towel down on the table 2. Measure 5 ml of plasma and put it in a beaker. Label the beaker plasma 3. Tear small pieces of pH paper and place the paper in the wells 4. Take the stirring rod and mix the blood plasma. Immediately touch the stirring rod to the pH

paper and record the pH of just the blood plasma 5. Add three drops of HCl to the blood plasma. Stir with the stirring rod and immediately touch the

stirring rod to a new piece of pH paper. Record the pH of the plasma 6. Add another three drops of HCl to the plasma. Stir with the stirring rod and immediately touch

the stirring rod to a new piece of pH paper. Record the pH of the plasma 7. Continue step 7 until you have added 30 drops of HCl


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Distilled Water and Base 1. Put paper towel down on the table 2. Measure 5 ml of dH2O and put it in a beaker. Label the beaker dH2O. 3. Measure 20 ml of 0.1 M NaOH and put it in a beaker. Label the beaker NaOH. You will use this

NaOH for the whole lab 4. Tear small pieces of pH paper and place the paper in the wells 5. Take the stirring rod and mix the dH2O. Immediately touch the stirring rod to the pH paper and

record the pH of just the dH2O 6. Add three drops of NaOH to the dH2O. Stir with the stirring rod and immediately touch the

stirring rod to a new piece of pH paper. Record the pH of the dH2O 7. Add another three drops of NaOH to the dH2O. Stir with the stirring rod and immediately touch

the stirring rod to a new piece of pH paper. Record the pH of the dH2O 8. Continue step 7 until you have added 30 drops of NaOH


Plasma and Base

1. Put paper towel down on the table 2. Measure 5 ml of plasma and put it in a beaker. Label the beaker plasma 3. Tear small pieces of pH paper and place the paper in the wells 4. Take the stirring rod and mix the blood plasma. Immediately touch the stirring rod to the pH

paper and record the pH of just the blood plasma 5. Add three drops of NaOH to the blood plasma. Stir with the stirring rod and immediately touch

the stirring rod to a new piece of pH paper. Record the pH of the plasma 6. Add another three drops of NaOH to the plasma. Stir with the stirring rod and immediately

touch the stirring rod to a new piece of pH paper. Record the pH of the plasma 7. Continue step 7 until you have added 30 drops of NaOH

Drops of HCl dH2O pH Plasma pH Drops of NaOH

dH20 Plasma pH

0 0

3 3

6 6

9 9

12 12

15 15

18 18

21 21

24 24

27 27

30 30

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Y2-Y1

X2-X1

Graph your data below

Find the slope of the line

Slope=

1. Where is the slope of the line for the blood plasma 0? Show your calculations.

2. What does this having a slope of 0 mean when discussing buffers?

3. If the buffer line had a steep slope, what would that mean?

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Lab 9: Functional Groups and Macromolecules

Organic molecules are carbon-containing molecules that are made by livining things (CO2 is not included

in this definition). All organic molecules have a hydrocarbon backbone. Below are some examples of

common hydrocarbons.

Functional groups are groups or arrangements of atoms located on hydrocarbons that determine the

physical and chemical properties of the organic molecule along with the chemical reactivity of that

organic molecule. Below are some common functional group that are located on organic molecules.

Name of Functional Group

Structural formula Example of molecule

Carbonyl

Aldehyde (-CHO)

Ketone (-CO)

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Carboxyl

(-COOH)

Hydroxyl

(-OH)

Ethanol

Phosphate

(-PO4

-2)

Nucleotide

Amine or Amino

(-NH2)

Amino Acid

Methyl

(-CH3)

Methanol

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Practice Problems

For the molecules below, circle and name all of the functional groups for the given molecules. 1.

Functional group/s__________________________ 2. Functional group/s____________________________ 3. Functional group/s__________________________________

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Part 1: Building Hydrocarbons and Functional groups Materials Molecular model kits (1 kit for each pair of students) Build and draw the structural formulas for the molecules below. For the molecules that contain functional groups, the atoms of the functional group are written separately from the formula. Example: C2H5OH Refer to the functional group chart for molecular formulas for functional groups. Follow these rules:

build the carbon skeleton first

add the functional groups and atoms besides H

add the H last

fill in missing bonding sites with double bonds

1. C2H6 5. C3H7CHO

2. C3H6 6. C2H3COOH

3. C2H6O 7. C4H5PO2(OH)

4. C2H5OH 8. NH2CH2COOH

OH represents the functional group alcohol

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Macromolecules Macromolecules are large carbon-containing molecules that are essential to life. There are four main categories of macromolecules and each has a different structure and serves a different function in the body:

1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic Acids

Each macromolecule has single units that define that specific type of molecule. These single units are called monomers. Through the process of dehydration synthesis, monomers can bond together to form polymers with the loss of water. Think of it as stringing paper clips together. Each paperclip (monomer) is a single unit and when you string them together you make a larger structure (polymer)

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Polymers can be broken down into the individual monomers through a process called hydrolysis. Similar to if you unhooked paperclips from the chain. You would get the individual paperclips back. Notice in the diagrams for both dehydration and hydrolysis they both involve water. In dehydration synthesis, a H atom is removed from one monomer and a hydroxyl group is removed from an adjacent monomer. By disrupting the bonds of the monomers, the monomers can bond together in order to complete the valence shell, and in the process, a water molecule is created. For hydrolysis, the reverse happens. The bond between the stable monomers of the polymer chain is broken. In order to make the monomers stable, a water molecule is also broken into an H atom and hydroxyl group. The H atom fills the bonding site on one monomer and the hydroxyl group fills in the bonding site on the adjacent monomer. Both dehydration synthesis and hydrolysis occur in the presence of an organic catalyst called an enzyme (we will discuss these structures later).

Carbohydrates The monomers of carbohydrates are called monosaccharides. The three major monosaccharides are:

Glucose

Fructose

Galactose Each of these monomers has the same molecular formula but different arrangements of atoms. These types of molecules are called isomers. The molecular formula for each is C6H12O6. Below is a diagram of the different arrangement of each monomer. Notice the ratio of carbon, hydrogen, and oxygen is 1:2:1.

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Part 2. Building Carbohydrates Materials Molecular model kits (1 kit for each pair of students)

1. Build the glucose molecule below using your kits. Remember that the molecular formula is C6H12O6.

2. Using the diagram and your model locate carbons 1-6. Bonding together

1. Now that you have built your glucose monomer, find another lab group and bond together through dehydration synthesis. You must remove a hydrogen from one monomer’s 4 carbon and an OH group from the other monomer’s 1 carbon to make a disaccharide. See below:

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2. Continue bonding with other pairs in your class. Be careful moving the molecule because it is fragile. The resulting polymer is called starch.

3. Perform hydrolysis to get you original monomer (glucose) back.

Questions: 1. How many monomers went into making the polymer?

2. How many water molecules were made?

3. What is/are the functional groups found on glucose?

Lipids Lipids are extremely hydrophobic molecules due to the high proportion of carbon and hydrogen. Unlike carbohydrates, the proportion of carbon and hydrogen is much greater than that of oxygen. The hydrocarbon chains that comprise lipid molecule are what makes lipids so nonpolar. The two units that make up the polymers of most lipids are fatty acid chains and glycerol molecules.

Glycerol Fatty acid chains Notice that the fatty acid chains can be both saturated and unsaturated. Saturated means that all of the available bonds in the carbon chain are bonded with hydrogen. Unsaturated means that there is at least one double bond in the carbon chain. Polyunsaturated means there are at least 2 double bonds in the chain.

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Part 3: Building a triglyceride Materials Molecular model kits (1 kit for each pair of students)

To make a triglyceride, a polymer of lipids, you need one glycerol molecule and three fatty acid chains.

1. There will be four different groups. Build the molecule you were assigned Group 1-Build a glycerol molecule Group 2-Build a saturated fatty acid (7 carbons long) Group 3-Build an unsaturated fatty acid (7 carbons long) Group 4-Build a polyunsaturated fatty acid chain (7 carbons long)

2. Through the process of dehydration bond the three fatty acids to the glycerol molecule. Remember that one water molecule must be made for each time a molecule bonds. See the diagram below to understand how to bond:

3. Once you have bonded with three other groups to form the triglyceride, go through hydrolysis to get your original molecule back.

Questions:

1. Lipids contain a lot of stored energy. What might contribute to this fact?

2. What is/are the functional groups on the glycerol molecule?

3. What is/are the functional groups on the fatty acid molecule?

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Proteins Proteins are the result of gene expression. The polymer of a protein is called a polypeptide chain. The monomers that make up the chains are called amino acids. There are 20 different amino acids that make up our proteins. The different combinations of these amino acids give us each our unique characteristics. Amino Acid The R group stands for the residue group. The arrangement of atoms located at the R position are unique for each of the 20 different amino acids. Example: Glycine Alanine Part 4: Building a polypeptide chain Materials Molecular model kits (1 kit for each pair of students)

1. Build either a glycine molecule or an alanine molecule 2. Once you have built your molecule, find another lab pair and go through dehydration

synthesis to make a dipeptide. See below:

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4. Continue bonding with other pairs in your class. Be careful moving the molecule because it is fragile. The resulting polymer is called polypeptide.

5. Perform hydrolysis to get you original monomer (amino acid) back. Questions: 1. Since proteins give you your unique characteristics, which molecule holds the instructions for

making proteins?

2. What is/are the functional groups for amino acids?

Nucleic Acids The building blocks for nucleic acids are called nucleotides. Nucleotides have three components: 1. Nitrogenous base, 2. Phosphate group, and 3. Five-carbon sugar. Nucleotides bond together to form two types of polymers: 1. RNA and 2. DNA.

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DNA will be white and will float to

the top after the bubbles disappear

Part 5: DNA Extraction Materials 10% sterile salt water solution 25% dish detergent solution 15 ml test tubes Dixie cups Plastic wrap Cold 95% ethanol 10 ml graduated cylinder

1. Obtain a Dixie cup containing 2ml of salt water solution 2. Vigorously swish the salt water solution in your mouth for two minutes and spit solution back

into Dixie cup 3. Transfer spit solution into a 15 ml test tube 4. Add 2 ml of soap solution to the test tube 5. Tightly cover test tube with plastic wrap and GENTLY invert the test tube ten times 6. Measure 7ml of cold ethanol and slowly run the ethanol down the inside of the test tube but DO

NOT SHAKE! 7. You will see two separate layers: 1. Soap layer 2. Ethanol layer 8. DNA will precipitate between the two layers.

Questions:

1. Knowing that DNA is unique for each individual, what part of the DNA would be different? What part would be the same?

2. Why can’t you see the double helix when looking at your DNA sample?

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Lab 10: Macromolecules and Nutrition

Background The most common macromolecules (organic compounds) found in living organisms are lipids,

carbohydrates, proteins, and nucleic acids. As you learned previously, each of these groups are made up

of singular units called monomers. Monomers bond together through dehydration synthesis to form

polymers. Foods are also combinations of these monomers and polymers. Some of these compounds

can be detected by taste, while others cannot.

Introduction: You are getting prepared to take a “Man vs. Wild” hike. You will be able to take a two month’s supply of food but you can only bring two food products from the list below. The two foods you select should have the macromolecules you would need to sustain a healthy life for two months. You will also need to select two foods that you would not take because they would not provide what the body would need for that duration of time. You will test each organic molecule class using the following standards: Glucose (Simple Carbohydrate), Albumin (Protein), Oil (Lipid), and Starch (Complex Carbohydrates). Materials Indicators Standard samples 5-Test Tubes Benedict’s solution (indicator for glucose) glucose Test Tube Rack Iodine (indicator for starch) starch Hot Plate Sudan (indicator for lipids) vegetable oil Pipettes Buiret (indicator for proteins) albumin solution Graduated Cylinders 250ml beakers dH2O Unknowns 1. Orange juice 2.Milk 3. Eggs 4. Chicken 5.Potato chips 6 .Onion 7. Apples/juice 8.Flour 9.Cereal 10. Syrup Problem: What two foods would you bring with you if you had to survive the perils of two month in the

wilderness?

Hypothesis 1: Why did you select food substance one? Hypothesis 2: Why did you select food substance two? Hypothesis 3: Why did you select the two food substances that you would not bring?

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Procedure Lipid Test

1. Obtain five test tubes

2. Label four tubes with the foods you will be testing (the two you are taking and the two that you will not take)

3. Label the fifth tube distilled water

4. Add two pipette full of the food you are testing

5. Add 5 drops of Sudan III stain to each test tube.

6. Gently shake the contents of each test tube. CAUTION: Use extreme care when handling Sudan to avoid staining hands or clothing.

7. Sudan will dissolve in lipids and stain them red. In the Data Table, write a “+” if lipids are present or a “-“ if lipids are not present. Compare to the vegetable oil and dH2O standards.

WASH TEST TUBES BEFORE PROCEEDING!!!!!!!!!

Protein Test 1. In your cleaned test tubes, add two pipette full of the food you are testing 2. Add 5 drops of Biuret Reagent to each test tube (including one with distilled water).

3. Gently shake the contents of each test tube. CAUTION: Biuret Reagent contains a strong base.

If you splash any on yourself wash it off immediately with water.

4. Biuret Reagent changes color from blue to violet in the presence of protein. In the Data Table, write a “+” if protein is present or a “-“ if protein is not present. Compare to the albumin and dH2O standards.


Simple Carbohydrate Test 1. In your cleaned test tubes, add two pipette full of the food you are testing

2. Add 5 drops of Benedict’s solution to each test tube.

3. Gently shake the contents of each test tube.

4. Place the test tubes in the hot water bath for 3-5 minutes. Remove the test tubes using test tube holders.

5. A rusty brown color in response to Benedict’s Solution indicates a large amount of simple sugars. An orange color indicates a moderate amount and a green or yellow color indicates a small amount of sugar. A blue color indicates no sugar present. In the Data Table, write a “+” if simple carbohydrates are present or a “-“ if simple carbohydrates are not present. Compare to the glucose and dH2O standards.


Complex Carbohydrate Test 1. In your cleaned test tubes, add two pipette full of the food you are testing

2. Add 5 drops of Iodine stain to each test tube.

3. Gently shake the contents of each test tube.

4. Iodine causes complex carbohydrates to turn dark blue or black. Substances without starch are colored brown by the iodine, but do not react with it. In the Data Table, write a “+” if complex carbohydrates are present or a “-“ if complex carbohydrates are not present. Compare to the starch and dH2O standards.

WASH TEST TUBES WHEN FINISHED!!!!!!!!!

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DATA TABLE:

Lipids (+/-) Protein (+/-) Simple Carbohydrates (+/-)

(note color if +) Complex Carbohydrates (+/-)

distilled water

orange juice

milk

eggs

chicken

potato chips

onion

apple juice

flour

cereal

syrup

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Analysis:

1. Explain why you made the food selections to bring with you?

2. Explain why you made the food selections not to bring with you?

3. Which macromolecules were present in your food substances? Include information from your data table.

4. Does this agree or disagree with your hypothesis? Explain.

5. Look at all the food substances and the results; were your food choices the best selection to survive for the two months? Explain and support your answer using your information from your research and from your results (data table).

6. People with diabetes are instructed to avoid foods that are rich in carbohydrates. How could your observations in this investigation help you decide whether a food should be served to a person with diabetes?

7. What macromolecule didn’t we test for? Explain.

8. What conclusion could you make if a positive test for any of the macromolecules occurred in the

test tube containing only distilled water?

9. Describe at least two errors you may have made while completing this lab. Explain how these

errors may have impacted your results.

10. To show your understanding of organic compounds, identify the type of organic compound shown in each diagram on the following page.

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Many large organic compounds are made of multiple repeats of smaller building block compounds. Starch, proteins, and nucleic acids are examples of this type of organic compound. Circle a building block in the starch, protein, and nucleic acid figures, and write the name of the building block in the fourth column.

Type of Organic

Compound

Functions

Which test is used to detect this compound or type of compound?

Name of building

block

Diagram of Structure of Organic Compound

Not tested for

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Lab 11: Enzymatic Activity

Enzymes are highly active proteins. Enzymes are biological catalysts. A catalyst speeds up a reaction and reduces the amount of energy needed to start that reaction. The energy needed to start a reaction is called activation energy. Without enzymes, the chemical reactions that occur in our bodies would happen too slowly to sustain life. Enzyme-accompanied reactions take place up to 1 million times faster than uncatalyzed reactions. Enzymes are not destroyed in the chemical process. These proteins can react over and over again. Enzymes react more or less efficient depending on a number of factors. Some of these factors include substrate concentration, pH, and temperature. Enzymes have an active site in which substrate/substrates can bond. Once the substrate/s bonds, the enzyme goes through a conformational change. This change in shape puts stress on the substrate/s to either bond two substrate molecules together to become a single product or to break the bonds of the substrate to become two products.

Living cells produce the compound hydrogen peroxide (H2O2) as a waste product. If the H2O2 is not removed from the cell, it will destroy the cell. Cells synthesize an enzyme called peroxidase in an organelle called the peroxisome that breaks down hydrogen peroxide (H2O2) into water (H2O) and oxygen (O2)

2 H2O2 + enzyme2H2O + O2 + enzyme

For this experiment, you will be testing how two different variables (temperature and concentration) affect enzymatic activity. You will be submerging filter discs into a potato extract that contains peroxidase. Once the disc is saturated, you will then submerge the discs into a chamber containing hydrogen peroxide. As the enzyme breaks down the H2O2, O2 bubbles will form and will cause the disc to rise. You will time how long it takes the disc to rise from the bottom to the top of the chamber.

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Chamber

Depth in cm

Part 1: Temperature Experiment

Materials Hydrogen peroxide 100 ml graduated cylinder 4 water baths (ice, room, body temp, hot) 4 thermometers Peroxidase (Prepared by blending 1 potato chopped with 200ml water) Centimeter ruler Forceps Filter paper Scissors 4 chambers/vials (used for fruit flies) Stopwatch Question: At which temperature will enzymes have the most activity (ice, room, body temp, hot)? Hypothesis: Prediction: Procedure:

1. Place 20ml of hydrogen peroxide four chambers. 2. Measure and record the depth of the H2O2 in your data table.

3. Outline a quarter on filter paper four times and cut out each disk. You may want to make a few more; you may need them later. 4. Bring the chamber to one of the four water baths that have the enzyme suspended in the bath

and record the temperature of the enzyme (not the water) at the station.

5. Submerge the disk using forceps into the enzyme for 10 seconds (use your stop watch, clock, or timer-not counting out loud).

6. Drop the disc into the chamber and make sure it touches the bottom of the chamber (you can use the forceps to help, make sure you rinse between trials). Once the disc touches the bottom, time how long it takes the disc to travel from the bottom to the top of the chamber. Record this time in your data table.

7. Repeat 4-5 until you have tested all four temperatures.

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Data Table for Temperature

Temperature Remember to record the temperature

Depth H2O2 in cm Time in seconds Group data rate Depth/time

Class Data rate Depth/time

Ice Bath=

Room=

Body Temp=

Hot=

Graph both your group’s results and the class average for temperature below. Remember to include all the criteria for a good graph

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Part 2: Concentration of substrate experiment

Materials

Distilled H2O, 1% H2O2, 2% H2O2, 3% H2O2 Stock solution of peroxidase at room temperature Ruler Filter paper Forceps 4 chambers Stopwatch

Make sure you rinse the chambers before progressing to the next activity! Question: Which concentration will increase enzyme activity? (Distilled H2O, 1% H2O2, 2% H2O2, 3% H2O2) Hypothesis: Prediction: Procedure:

1. Label the four chambers with your group’s initials and dH2O, 1%, 2%, 3%. 2. Add 20 ml of the four different hydrogen peroxide solutions to the appropriately labeled

chamber (make sure you wash the chambers between trials). 3. Record the depth of H2O2 of each chamber. 4. Outline a quarter on filter paper four times and cut out each disk. You may want to make a few more; you may need them later. 5. Dip your filter paper in your enzyme stock solution for 10 seconds using your forceps. 6. Submerge your disc into the chamber making sure the disc touches the bottom of the chamber. 7. Record the time it takes for the disc to rise. 8. Record your results in mm in your data table.

Data Table for Concentration of Substrate

Concentration Depth H2O2 in mm Time in seconds

Group data rate Depth/time

Class Data rate

dH2O

1% H2O2

2% H2O2

3% H2O2

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Graph both your group’s results and the class average for concentration below. Remember to include all the criteria for a good graph

Questions:

1. At what point are the enzymes most active or at the optimal conditions for temperature? Least

active for temperature? Explain why you think this is true.

2. At what concentration is the rate of activity the highest? Lowest? Explain why you think this is

true.

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3. Explain what happened to the enzyme at the highest temperature?

4. Ectothermic organisms have body temperatures that vary with the temperature of their surroundings. Discuss the effect that temperature might have on the function of enzymes in these organisms.

5. If peroxidase from humans was used instead of potatoes, would you expect to see different results? Explain your answer.

6. What are the monomers of enzymes and why are enzymes biological importance?

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Lab 12: Microscope and Cells

Scientists use microscopes to see objects that are too small to be seen clearly (if at all) with the naked

eye. There are many different types of microscopes, such as, the scanning electron microscope,

transmitting electron microscope, dissecting microscope, and the compound microscope. The most

common microscope people are familiar with is the compound microscope. A compound microscope

utilizes two lens in order to magnify the object being viewed. One lens is called the ocular lens or

eyepiece and the other lens is called the objective lens. The ocular lens magnifies objects 10X their

actual size. The objective lenses are located on the rotating nose piece. Typically, there are three or

four objective lenses on this nose piece. Each objective lens has a different magnification. Below is a

table of the different magnifications for the objective lenses.

Lens name Color/size of Lens Magnification

Scanning Red/shortest lens 4X

Low Power Yellow/a little longer than scanning

10X

High Power Blue/a little longer than low

40X

Oil Emersion White/a little longer than high

100X

The color and magnification of the lens may be different based on the manufacture and the specific uses

of the microscope. To verify the magnification of each objective lens, look at the lens itself. Written on

the lens, it will have the magnification with an X after it. So if the lens is marked 4X that means that lens

magnifies the objects being viewed 4X.

Total magnification refers to the magnification of both the ocular lens and the objective lens to which

the nosepiece is set. To calculate the total magnification, multiply the magnification of the ocular lens

with the magnification of the objective lens.

Fill in the table below:

Objective Lens Magnification Ocular Lens Magnification Total Magnification

Scanning: 4X 10X

Low Power: 10X 10X

High Power: 40X 10X

Oil Emersion:100X 10X

Vocabulary to be familiar with when working with the microscope:

Resolution-ability to see between two points

Working distance-the distance between lens and object being viewed

Depth of field-the 3-D space between the bottom and top of slide

Parfocality-all objective lenses are in reasonable focus at the same time Study the part of the microscope on the next page. After studying the parts, try filling in the missing names for the microscope on the following page.

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Ocular lenses or

Eye piece

Rotating Nose Piece

Objective lenses

Red lens-scanning

Yellow lens-low

Blue lens-high

White lens-oil

emmersion

Stage

Mechanical

stage knobs

Coarse adjustment knob

Fine adjustment knob

Iris Diaphragm

Light source

Mechanical stage clip

Base

Body tube

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Part 1: Focusing on the letter “e”

Materials Letter “e” slide Lens paper Lens cleaner Microscope

1. Obtain a microscope from the cabinet. Firmly place one hand on the handle and the other hand under the base for support

2. Place the base of the microscope approximately a finger’s distance from the edge of the counter and plug the microscope in away from any hazard

3. Clean all glass parts of the microscope and stage using LENS PAPER and lens cleaner. Do not

use any other material to clean the microscope 4. Set the rotating nosepiece to the scanning lens 5. Using the coarse adjustment knob, raise the stage until it comes to a stop. 6. Turn the light on and adjust the amount of brightness so it does not hurt your eyes 7. Adjust the diaphragm to match the objective lens 8. Clean the letter “e” slide. Place the slide containing the letter “e” securely on the stage using the

stage clip 9. Center the letter over the light 10. While looking through the eye pieces, bring the down using the coarse adjustment knob until

you can see the image 11. Use the fine adjustment knob to get the image into clear focus. Adjust brightness if necessary Sketch the image under scanning power:

Total Magnification _____________ Questions: 1. Does the image of the letter “e” look different under the microscope than it did when looking

with a naked eye? Explain the differences.

2. When looking at the image under the microscope and you move the slide to the left, visually which direction does the letter “e” move?

3. When looking at the image under the microscope and you move the slide up, visually which direction does the letter “e” move?

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12. By turning the rubber portion of the nosepiece, change the objective lens to low power. Change the diaphragm to match the objective. Use the coarse adjustment and the fine adjustment knobs to clear focus the image.

Sketch the image under low power:

Total Magnification _____________

13. By turning the rubber portion of the nosepiece, change the objective lens to high power. Change

the diaphragm to match the objective. Use ONLY the fine adjustment knob to focus the image.

If you use the coarse adjustment knob under high power, you can easily lose focus and you must start again from the beginning. Also, you can break the slide.

Sketch the image under scanning power:

Total Magnification _____________ Questions:

1. What were the differences you noticed in the image when you went from scanning to low? From low to high?

2. Why is it so important to only use the fine adjustment knob on high power?

You must be able to focus an image under high power within two minutes. You will have a practical on this skill.

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Part 2: Wet Mount and Cheek Cells Materials Methylene Blue Tooth picks Clean slide Cover slip

1. Obtain a clean glass slide and cover slip. 2. Take a toothpick and GENTLY rub it against the skin on the inside of your cheek 3. Take the toothpick and rub it on the surface of the center of the slide. You might see moisture

but you will not see cells 4. Place a drop of methylene blue on top of your cheek smear 5. Hold the coverslip at a 45° angle to the dye and break the surface tension and drop the cover

slip. See figure below

6. Set the nosepiece to scanning, focus the image, and draw a few cells under scanning power. Your image may look like the one below.

Sketch the image under scanning power:


7. Set the nosepiece to low, focus the image, and draw a few cells under low power. Sketch the image under scanning power:


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8. Set the nosepiece to high, focus the image, and draw a few cells under high power. Your image should look like the one below. Sketch the image under scanning power:


Part 3: Estimating size of an object under the microscope The field of view or vision is the circular area you see when looking through the eyepiece of a microscope. When you know the diameter of the field of view, you can estimate the size of an object. Each objective lens has a different diameter for the field of view. See the chart below: Lens Diameter Image Scanning Lens Diameter = 4,500μm Low Power lens Diameter= 1,800μm High Power Lens Diameter= 450μm To calculate the estimated size of an object, you deduce how many of those objects can fit across the diameter of the field of vision. Example: Looking at that cell, you can deduce that approximately 5 cells could fit along the diameter. Knowing that information you can calculate the estimated size of the cell. Diameter of field of vision 4,500μm Esitmated number of objects 5

4,500μm

1,800μm

450μm

4,500μm

= Estimated object size = 900μm

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Similarities

1. Both are cells

2. Both have the 4 macromolecules

3. Both have plasma or cell membranes

Eukaryotes

1. Contains a nucleus, for humans, 23 pairs of

chromosomes

2. DNA is in strands

3. Contain membrane-bound organelles

4. Typically larger than 10µm

5. Larger ribosomes

6. Kingdoms: Protist, Fungus, Plant, Animal

Prokaryotes

1. Contains no nucleus, DNA located in nucleoid region

2. DNA is circular

3. Contains no membrane-bound organelles

4. Typically smaller than 10µm

5. Smaller ribosomes

6. Kingdoms: Archaeabacteria and Eubacteria

Calculate the estimated size of your check cells under scanning, low, and high power. Check with instructor for actual size.

Objective Lens Diameter of field of view

Estimated number of cells that fit across the

diameter

Estimated size of on cell (μm)

Scanning

Low

High

Cells The cell theory states:

1. All living things consist of at least one cell, 2. Cells are the basic unit of structure and function in all living things, and 3. Cells come from preexisting cells.

The two types of cells are prokaryotic and eukaryotic. The chart below distinquishes the major differences and similarities between these two cell types.

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For this portion of the lab, we will be looking at eukarotic animal cells only. Part 4: Cell Parts and function Materials Cell Models

1. Located the following structures on the cell model

Nucleus Double envelope: 1. chromosomes 1. Genetic information Openings called nuclear pores 2. nucleolus 2. Assembly of ribosome subunits 3. nuclear lamina 3. Strucutral support Ribosome none Complex of RNA and protein Protein synthesis Endomembrane system Rough Endoplasmic single, contains receptors network of branching sacs, protein synthesis and processing Reticulum for entry of selected proteins ribosomes associated Golgi Apparatus single; contains receptors for stacks of flattened membranes modification of molecules and shipping in vesicles Products of rough ER Smooth Endoplasmic single;contains enzynes for network of branching sacs contains enzymes for synthesizing lipids, drug detoxification Reticululm synthesizng phospholipids Lysosomes single; contains proton pumps enzymes for hydrolysis digestion and recycling Peroxisome single; contains transporters contians the enzyme peroxidase oxidation of fatty acids, ethanol, or other compounds for selected macromolecules Vacuole single contains transporters varies in animals and plants storage of pigments, carbohydrates, and water (not shown on model) for selected macromolecules Mitochondria double; inner contains enzymes cristaea and matrix site of aerobic respiration for ATP production Chloroplast double; plus membrane-bound stroma and thylakoid site of photosynthesis (not shown on model) sacs in interior membrane Cytoskeleton none actin filaments, microtubules, structure and support; movement of materials and organelles (not shown on model) and intermediate filaments Plasma or cell membrane single; contains transport and phospholipid membrane with selectively permeable membrane, maintains cell environment Receptor proteins transport proteins and receptors Centriole none microtubules play a role in cell division

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Practice Problem: Label the structure indicated on the diagram below. Make an analog for the function of each organelle to help you remember its importance in the cell. For example, the mitochondria is like an electrical company because the mitochondria supplies power to the cell in the form of ATP.

Name Analogy 1.__________________________________________________________________________________ 2. __________________________________________________________________________________ 3. __________________________________________________________________________________ 4. __________________________________________________________________________________ 5. __________________________________________________________________________________ 6. __________________________________________________________________________________ 7. __________________________________________________________________________________ 8. __________________________________________________________________________________

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9. __________________________________________________________________________________ 10. __________________________________________________________________________________ 11. __________________________________________________________________________________

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Microscope Check-list

Be able to complete these steps in 2 minutes. Practice this skill in Open Lab.

1. Used lens tissue and lens cleaner to clean ocular and objective lenses.

2. Proper slide placement on mechanical stage.

3. Centered slide over light using the mechanical stage knobs.

4. Adjusted light level with iris diaphragm.

5. Started with scanning objective.

6. Used coarse focus to bring stage up to automatic stop.

7. Focused away with coarse focus on scanning.

8. Used proper grip when turning rotating nosepiece to low power.


10. Used coarse focus with low power objective.

11. Used proper grip when turning rotating nosepiece to high power.


13. Used fine focus only with high power objective.

14. Specimen is in decent focus.

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Lab 13: Diffusion and Cell size

As you observed in lab 11, cells are extremely small. Typically, you cannot see cells with the naked eye.

You may have also observed that cells come in a variety of shapes. The shapes of these cells correlate

with function of that cell type. Cells constantly have to exchange materials with their surroundings, such

as nutrients and waste. To maintain life, nutrients need to move in while wastes need to move out. In

order to move substances into and out of the cell, these substances must pass through a selectively or

semi-permeable cell membrane. Selectively permeable membranes freely allow some substances to

pass while restricting others. Diffusion is the movement of molecules from an area of high

concentration to an area of low concentration. In cells, when substances move freely across the cell

membrane based on diffusion, it is called passive transport or more specifically, simple diffusion.

Several factors influence the rate of diffusion, such as, the size of the cell, the charge of the molecules,

the size of the molecules, concentration, temperature, and time. This lab will focus on cell size and

temperature.

Part 1: Cell size and rate of diffusion For this lab, you will make three “cuboidal cells” with the dimensions below:

1cm

1cm

1cm

2cm 2cm

2cm

3cm 3cm

3cm

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You will place each of the three cells in a solution that will be called cell media. This media contains the

nutrients the cell needs to survive. The media must reach all portions of the cell interior in order for

proper cell function.

Question: In a ten minute time period, which cell will allow for maximum diffusion of the media to all

portions of the cell?

Hypothesis:

Prediction:

Materials 3-100ml beakers Paper towels Centimeter ruler 1 plastic knife/scalpel 1-3cm x 3cm x 6cm block of phenolphthalein agar 1 plastic spoon 200 ml of 0.04 M NaOH (cell media) Thermometer

You must wear goggles and gloves for this entire lab! 1. Using 1 of the agar blocks at your station, CAREFULLY cut three cuboidal cells with the following

dimensions:

a. Cell 1: 1cm X 1cm X 1cm

b. Cell 2: 2cm X 2cm X 2cm

c. Cell 3: 3cm X3cm X 3cm

2. Place one cell in each of the three beakers. Cover each cell with enough cell media so no part is

exposed to air. Gently stir cubes with the spoon, periodically flipping the cube so all sides have even

exposure. Leave cells in the media for 10 minutes.

As the cubes soak, use the following equations to complete Data Table 1. Surface area = length x width x number of sides (remember the units)

Volume = length x width x height (remember the units)

3. After 10 minutes, use the spoon to remove the agar cubes and carefully blot them dry on a paper

towel.

4. Carefully cut each of the cubes in half. You will notice the agar has turned from brown to pink.

Pink represents the area of the cell in which the media diffused (A in the

diagram below)

Brown represent the area of the cell in which the media did no diffuse (B in the

diagram below)

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The total width is C (C= 2A + B) Or labelled=

5. Using the centimeter ruler, measure the distance in centimeters that the diffusion medium diffused

into each cube (A-the area from pink to brown, or from the edge to the middle if the whole cube is

pink). Remember your significant digit while measuring. Record the data in Data table 2.

6. Record the Data in Data table 2: Calculate the rate of diffusion (A/time)

7. Record the Data in Data Table 3: Calculate the extent of diffusion into each cube as a percent of the

total volume. Use the diagram on the previous page to help with the following calculation:

Total cube volume (C3) - volume of cube that did NOT change (B3) x 100 = extent of diffusion

Total cube volume (C3)

Results: Data Table 1: Agar Cubes

Cube size Surface area (cm2)

Volume (cm3)

Surface area/volume (cm2/cm3)

3cm

2cm

1cm

Data Table 2: Rate of diffusion

Cube size Distance media diffused

(A in cm)

Time (min.)

Rate of diffusion (cm/min)

3cm

2cm

1cm

Data Table 3: Extent of diffusion

Cube Size Total Volume of Cube (C3)

Total Volume of undiffused agar

(B3)

Percent volume of cube which has changed color

(extent of diffusion)

3cm

2cm

1cm

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Draw the cross-section of each of your cubes “to scale” showing the colors of each area

Questions:

1. According to Data Table 3, which cube showed the highest extent of diffusion – the largest or

smallest?

2. Did the Data in Table 3 support or reject your hypothesis? Explain.

3. If each cube represented a living cell and the diffusion medium a substance needed within the

cell, what problem might exist for the largest cell?

4. Examine your data in Data Table 2 for a relationship between cube size and the rate of diffusion

into the cube. Make a generalized statement about the relationship between the cell size and

the rate of diffusion.

5. Examine your data in Data Table 1. Describe what happens to the surface area, the volume and

their ratio as a cell grows larger. How would this effect each cell?

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Part 2: Temperature and rate of diffusion 3-100ml beakers Paper towels Centimeter ruler 1 plastic knife/scalpel remaining phenolphthalein agar from part 1 1 plastic spoon 200 ml of 0.04 M NaOH (cell media) Thermometer Ice water Cool water (fridge) Room temperature water For this part of the lab you will make three “cells” with the following dimensions:

You will be placing each of the cells in a different temperature NaOH bath: Ice bath, refrigerator, and

room temperature.

Question: Which temperature will allow for maximum diffusion of the media through the cell in the

given time of 15 minutes?

Hypothesis:

Prediction:

3cm

3cm 3cm

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You must wear goggles and gloves for this entire lab! 1. Using 1 of the agar blocks at your station, CAREFULLY cut three cuboidal cells with the following

dimensions:

a. Cell 3: 3cm X3cm X 3cm

2. Place one cell in each of the three beakers at the specific temperatures (Ice, refrigerator, room),

make sure you record the temperature in Data table 1. Cover each cell with enough cell media

so no part is exposed to air. Gently stir cubes with the spoon, periodically flipping the cube so

all sides have even exposure. Leave cells in the media for 15 minutes.

3. After 15 minutes, use the spoon to remove the agar cubes and carefully blot them dry on a

paper towel.

4. Carefully cut each of the cubes in half. You will notice the agar has turned from brown to pink.

Pink represents the area of the cell in which the media diffused (A in the

diagram below)

Blown represent the area of the cell in which the media did no diffuse (B in the

diagram below)

The total distance is C (C= 2A + B)

Or labelled=

5. Using the centimeter ruler, measure the distance in centimeters that the diffusion medium

diffused into each cube (A-the area from pink to brown, or from the edge to the middle if the

whole cube is pink). Remember your significant digit while measuring. Record the data in Data

table 1.

6. Record the Data in Data table 1: Calculate the rate of diffusion (A/time)

7. Record the Data in Data Table 2: Calculate the extent of diffusion into each cube as a percent of

the total volume. Use the diagram on the previous page to help with the following calculation:

Total cube volume (C3) - volume of cube that did NOT change (B3) x 100 = extent of diffusion

Total cube volume (C3)

A A

B

C

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Data Table 1: Rate of diffusion

Temperature Actual recorded temperature

Distance media diffused

(A in cm)

Time (min.)

Rate of diffusion (cm/min)

Ice Bath

Refrigerator

Room

Data Table 3: Extent of diffusion

Temperature Total Volume of Cube (C3)

Total Volume of undiffused agar

(B3)

Percent volume of cube which has changed color

(extent of diffusion)

Ice Bath

Refrigerator

Room

Questions:

1. Using the information in your chart explain how temperature affects the rate of diffusion? Use kinetic energy in your answer.

2. How would getting a temperature when you are sick influence diffusion in your body? Why?

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Part 3: Cell shapes and function

For this next section, your group will look at various cell types/tissues and try to match the cell function

with the structure of the cell.

Functions:

a. Fat storage. Can fill space between organs.

b. Lines body surfaces. Can be found in the lining organs.

c. Aborption of nutrients. Can be found in intestines

d. Communication of signals. Can be found in the nervous system.

Letter________ Letter _________

Reasoning: Reasoning:

Letter ________ Letter________

Reasoning: Reasoning:

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Lab 14: Osmosis

Osmosis is the movement of water across a semipermeable membrane. In living systems, water is the

most abundant solvent. Many of the solutes that are dissolved in water are impermeable to the cell’s

membrane. Water will pass through the membrane depending on the concentration of the solution on

both the inside and the outside the cell. Recall from previous labs that the concentration of solutions

can be expressed as either molarity or percent solution. If the molarity is the same on both sides of the

cell, the net movement of water into and out of the cell is equal.

This type of solution is called an isotonic. The cell is at equilibrium. No net movement of water.

When the concentration of solution is higher outside the cell than the concentration of solution inside

the cell, the outside of the cell is considered hypertonic.

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When the concentration of solution is lower outside the cell than the concentration of solution inside

the cell, the outside of the cell is considered hypotonic.

Part 1: Determining Molarity of a Cell Materials 6 dialysis cells in an unknown Molar solution 6-250 ml beakers 6 solutions: distilled water (0.0M sucrose), .2M sucrose, .4M sucrose, .6M sucrose, .8M sucrose, 1.0M sucrose. Electronic Scale Weigh boat Observe the cells and the different molar solutions. Questions: What is the molarity inside the dialysis cell? Hypothesis: Prediction: Questions:

1. Explain what will happen to the mass of the cell if placed in a hypotonic solution. Which

solutions do you think will be hypotonic?

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2. Explain what will happen to the mass of the cell if placed in a hypertonic solution. Which

solutions do you think will be hypertonic?

3. Explain what will happen to the mass of the cell if placed in an isotonic solution. Which

solutions do you think will be isotonic?

Procedure:

1. Take cells out of the original solution and pat each cell dry.

2. Take the mass of each cell one at a time using the weigh boat. Do not place the cell directly on

the scale. Record the mass in Table 1.

3. Label each beaker with the corresponding molar solution concentration

4. Place one cell in each beaker. Make sure you know which cell you are placing in each beaker

5. Cover the cells with the appropriate solution

6. After 30 minutes, remove cells from solution, pat dry, and take the mass

7. Record the information in Table 1

8. Calculate the percent change in mass:

Final mass of cell – Original mass of cell

Original Mass of cell

Cell Molarity of Solution

Original Mass (g)

Final Mass (g) Percent Change

Class Average Percent change

1

Distilled water 0.0M sucrose

2

0.2M sucrose

3

0.4M sucrose

4

0.6M sucrose

5

0.8M sucrose

6

1.0 sucrose

X 100 = Percent change in mass

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Graph: Graph your data for percent change in mass for your group and class data.

Questions:

1. Based on your graph, what was the molarity of the cells? Explain how you reached your answer?

2. Did the class data match your group’s data? Explain.

3. Did your hypothesis match your data? Explain.

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Part 2: Observing blood cells in different solutions Materials 4 slides Cover slips Blood 0.9% saline solution 10% saline solution 0.0 % saline solution (distilled water)

1. Label the four slides as followed: a. Blood b. 0.9% c. 10% d. Distilled water

2. Place one drop of blood on slide a. Place a cover slip on the blood. Observe and sketch what the blood cells look like under high power.

3. Place one drop of blood on slide b. Add one drop of the 0.9% solution to the drop of blood.

Place a cover slop on the blood. Observe and sketch what the blood cells look like under high power.

4. Place one drop of blood on slide c. Add one drop of the 10% solution to the drop of blood.

Place a cover slop on the blood. Observe and sketch what the blood cells look like under high power.

5. Place one drop of blood on slide d. Add one drop of the 0.0% solution or distilled water to the drop of blood. Place a cover slop on the blood. Observe and sketch what the blood cells look like under high power.

Area to sketch is on the next page.

Questions:

1. Which cells were in a hypotonic solution? How do you know by observing the cells?

2. Which cells were in an isotonic solution? How do you know by observing the cells?

3. Which cells were in a hypertonic solution? How do you know by observing the cells?

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Blood 0.9% solution

Solution type____________________ Solution type_____________________

10% solution Distilled water

Solution type________________________ Solution type______________________

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Part 2: Observing plant cells in different solutions Materials 3 slides Cover slips Onion in Distilled water Onion in a 20% salt solution Onion in a 0.9% salt solution Iodine

1. Peel off the outer layer of the onion from the beaker labelled distilled water. You want to make sure the layer is only one cell thick.

2. Place the onion skin on a slide. Add a drop of iodine and place a cover slip on the top. Observe and sketch the cells under high power.

3. Peel off the outer layer of the onion from the beaker labelled 20% salt solution.


5. Peel off the outer layer of the onion from the beaker labelled 0.9 % salt solution.


Questions:

1. Which cells were in a hypotonic solution? How do you know by observing the cells?

2. Which cells were in an isotonic solution? How do you know by observing the cells?

3. Which cells were in a hypertonic solution? How do you know by observing the cells?

4. How do plants cells look different from animal cells (blood) when exposed to the same solutions (hypertonic, isotonic, and hypotonic)?

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20% solution 0.9% solution

Solution type____________________ Solution type_____________________

Distilled water

Solution type________________________

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