custom lab manual - justanswercustom lab manual ... when finished, wash hands and lab equipment...
TRANSCRIPT
Custom Lab Manual UMUC BIOL 102/103
© 2012 eScience Labs, LLC
All rights reserved
www.esciencelabs.com • 888.375.5487
2
3
UMUC Custom Lab Manual for Biology 102/103 Lab 1: Introduc on to Science Lab 2: The Chemistry of Life Lab 3: Cell Structure & Func on Lab 4: Enzymes Lab 5: Meiosis Lab 6: Taxonomy
Lab 7: Ecology of Organisms Appendix: Good Lab Techniques
Table of Contents:
4
5
Lab Safety
Always follow the instruc ons in your laboratory manual and these general rules:
Lab Prepara on
Please thoroughly read the lab exercise before star ng!
If you have any doubt as to what you are supposed to be doing and how to do it safely,
please STOP and then:
Double‐check the manual instruc ons.
Check www.esciencelabs.com for updates and ps.
Contact us for technical support by phone at 1‐888‐ESL‐Kits (1‐888‐375‐5487) or by email
Read and understand all labels on chemicals.
If you have any ques ons or concerns, refer to the Material Safely Data Sheets (MSDS)
available at www.esciencelabs.com. The MSDS lists the dangers, storage requirements,
exposure treatment and disposal instruc ons for each chemical.
Consult your physician if you are pregnant, allergic to chemicals, or have other medical
condi ons that may require addi onal protec ve measures.
Proper Lab A re
Remove all loose clothing (jackets, sweatshirts, etc.) and always wear closed‐toe shoes.
Long hair should be pulled back and secured and all jewelry (rings, watches, necklaces,
earrings, bracelets, etc.), should be removed.
Safety glasses or goggles should be worn at all mes. In addi on, wearing so contact
lenses while conduc ng experiments is discouraged, as they can absorb poten ally
harmful chemicals.
When handling chemicals, always wear the protec ve goggles, gloves, and apron
provided.
eScience Labs, LLC. designs every kit with safety as our top priority.
Nonetheless, these are science kits and contain items which must be
handled with care. Safety in the laboratory always comes first!
6
Performing the Experiment
Do not eat, drink, chew gum, apply cosme cs or smoke while conduc ng an experi‐
ment.
Work in a well ven lated area and monitor experiments at all mes, unless instructed
otherwise.
When working with chemicals:
Never return unused chemicals to their original container or place chemicals in an
unmarked container.
Always put lids back onto chemicals immediately a er use.
Never ingest chemicals. If this occurs, seek immediate help.
Call 911 or “Poison Control” 1‐800‐222‐1222
Never pipe e anything by mouth.
Never leave a heat source una ended.
If there is a fire, evacuate the room immediately and dial 911.
Lab Clean‐up and Disposal
If a spill occurs, consult the MSDS to determine how to clean it up.
Never pick up broken glassware with your hands. Use a broom and a dustpan and dis‐
card in a safe area.
Do not use any part of the lab kit as a container for food.
Safely dispose of chemicals. If there are any special requirements for disposal, it will
be noted in the lab manual.
When finished, wash hands and lab equipment thoroughly with soap and water.
Above all, USE COMMON SENSE!
7
Approximate Time and Addi onal Materials Needed for Each Lab
** Note: If you are allergic to latex, please contact us and we will send you vinyl gloves**
Lab 1: Introduc on to Science Time: 1 hour Materials: None Lab 2: The Chemistry of Life Time: 1 hour (plus 24 hours prepara on me) Materials: Variety of household substances, plas c wrap, water, cu ng utensil Lab 3: Cell Structure & Func on Time: 1 hour (plus 24 hours for observa on) Materials: Water, square plas c food storage container, mixing bowl, house hold items for use as cell structures (plums, raisins, etc.) Lab 4: Enzymes Time: 1 hour (plus 2 hours prepara on me)
Materials: Water, watch or mer, string, ice, hot water, paper towel,
ginger root, at least 2 other food sources (potato, apple, etc.) Lab 5: Meiosis Time: 1.5 hours Materials: Blue and red markers Lab 6: Taxonomy Time: 1 hour Materials: Pencil
Lab 7: Ecology of Organisms Time: 0.5 hour (plus 7 days for observa on) Materials: Paper towel, water
8
Introduc on:
ESL Safety Video
Measuring Volume Using a Gradu‐ated Cylinder
Unit Conversions
Biological Processes:
ESL Biological Processes Video
The Structure of an Atom
Acid/Base Reac ons
Docking Tutorial
The Cell:
ESL Cell Video
Cell Structure Crossword Puzzle
Interac ve Videos of Meiosis
A Typical Animal Cell
Construc on of the Cell Membrane
The Cell Cycle
Cell Division
DNA Extrac on Virtual Lab
Addi onal Online Content Found at www.esciencelabs.com
Log on to the Student Portal using
these easy steps:
Visit our website,
www.esciencelabs.com, and click on
the green bu on (says “Register or
Login”) on the top right side of the
page. From here, you will be taken to
a login page. If you are registering
your kit code for the first me, click
the “create an account” hyperlink. Lo‐
cate the kit code, located on a label on
the inside of the kit box lid. Enter this,
along with other requested infor‐
ma on into the online form to create
your user account. Be sure to keep
track of your username and password
as this is how you will enter the Stu‐
dent Portal for future visits. This es‐
tablishes your account with the eSci‐
ence Labs’ Student Portal.
Have fun!
9
Kingdoms of Life:
ESL Kingdoms Video
Biology of Bacteria
Biology of Flagellates
Biology of Algae
Tree of Life Web Project
Plant Kingdom:
ESL Plant Kingdom Video
Biology of Plants
Addi onal Resources:
Stop Watch
Conversion Tables
11
Introduc on
Lab 1
Introduc on to Science
12
Lab 1: Introduc on to Science
13
What is science? You have likely taken several classes throughout your career as a student, and know
that it is more than just chapters in a book. Science is a process. It uses evidence to understand the his‐
tory of the natural world and how it works. Scien fic knowledge is constantly evolving as we understand
more about the natural world. Science begins with observa ons that can be measured in some way, and
o en concludes with observa ons from analyzed data.
Following the scien fic method helps to minimize bias when tes ng a theory. It helps scien sts collect
and organize informa on in a useful way so that pa erns and data can be analyzed in a meaningful way.
As a scien st, you should use the scien fic method as you conduct the experiments throughout this
manual.
The process of the scien fic method begins with an observa on. For example, suppose you observe a
plant growing towards a window. This observa on could be the first step in designing an experiment.
Concepts to explore:
The Scien fic Method
Observa ons
Hypothesis
Variables
Controls
Data Analysis
Unit Conversions
Scien fic Nota on
Significant Digits
Data Collec on
Tables
Graphs
Percent Error
Scien fic Reasoning
Wri ng a Lab Report
Figure 1: The scien fic method process
Lab 1: Introduc on to Science
14
Remember that observa ons are used to begin the scien fic method, but they may also be used to
help analyze data.
Observa ons can be quan ta ve (measurable), or qualita ve (immeasurable; observa onal). Quan ‐
ta ve observa ons allow us to record findings as data, and leave li le room for subjec ve error. Quali‐
ta ve observa ons cannot be measured. They rely on sensory percep ons. The nature of these obser‐
va ons makes them more subjec ve and suscep ble to human error.
Let’s review this with an example. Suppose you have a handful of pennies. You can make quan ta ve
observa ons that there are 15 pennies, and each is 1.9 cm in diameter. Both the quan ty, and the di‐
ameter, can be precisely measured. You can also make qualita ve observa ons that they are brown,
shiny, or smooth. The color and texture are not numerically measured, and may vary based on the indi‐
vidual’s percep on or background.
Quan ta ve observa ons are generally preferred in science be‐
cause they involve "hard" data. Because of this, many scien fic
instruments, such as microscopes and scales, have been devel‐
oped to alleviate the need for qualita ve observa ons. Rather
than observing that an object is large, we can now iden fy spe‐
cific mass, shapes, structures, etc.
There are s ll many situa ons, as you will encounter throughout
this lab manual, in which qualita ve observa ons provide useful
data. No cing the color change of a leaf or the change in smell of
a compound, for example, are important observa ons and can
provide a great deal of prac cal informa on.
Once an observa on has been made, the next step is to develop a hypothesis. A hypothesis is a state‐
ment describing what the scien st thinks will happen in the experiment. A hypothesis is a proposed
explana on for an event based on observa on(s). A null hypothesis is a testable statement that if
proven true, means the hypothesis was incorrect. Both a hypothesis and a null hypothesis statement
must be testable, but only one can be true. Hypotheses are typically wri en in an if/then format. For
example:
Hypothesis:
If plants are grown in soil with added nutrients, then they will grow faster than plants grown
without added nutrients.
Figure 2: What affects plant growth?
Lab 1: Introduc on to Science
15
Null hypothesis:
If plants are grown in soil with added nutri‐
ents, then they will grow at the same rate as
plants grown in soil without nutrients.
There are o en many ways to test a hypothesis. However, three rules must always be followed for re‐
sults to be valid.
The experiment must be replicable.
Only test one variable at a me.
Always include a control.
Experiments must be replicable to create valid theories. In other words, an
experiment must provide precise results over mul ple trials Precise results
are those which have very similar values (e.g., 85, 86, and 86.5) over mul ‐
ple trials. By contrast, accurate results are those which demonstrate what
you expected to happen (e.g., you expect the test results of three students
tests to be 80%, 67%, and 100%). The following example demonstrates the
significance of experimental repeatability. Suppose you conduct an experi‐
ment and conclude that ice melts in 30 seconds when placed on a burner,
but you do not record your procedure or define
the precise variables included. The conclusion
that you draw will not be recognized in the scien‐
fic community because other scien sts cannot
repeat your experiment and find the same results. What if another scien st
tries to repeat your ice experiment, but does not turn on the burner; or, uses
a larger ice chunk? The results will not be the same, because the experiment
was not repeated using the same procedure. This makes the results invalid,
and demonstrates why it is important for an experiment to be replicable.
Variables are defined, measurable components of an experiment. Controlling variables in an experiment
allows the scien st to quan fy changes that occur. This allows for focused results to be measured; and,
for refined conclusions to be drawn. There are two types of variables, independent variables and de‐
pendent variables.
Independent variables are variables that scien sts select to change. For example, the me of day,
amount of substrate, etc. Independent variables are used by scien sts to test hypotheses. There can
only be one independent variable in each experiment. This is because if a change occurs, scien sts need
to be able to pinpoint the cause of the change. Independent variables are always placed on the x‐axis of
a chart or graph.
Dependent variables are variables that scien sts observe in rela onship to the independent variable.
Common examples of this are rate of reac on, color change, etc. Any changes observed in the depend‐
If plants grow quicker when nutrients are added,
then the hypothesis is accepted and the null
hypothesis is rejected.
Accurate results all hit the
bulls‐eye on a target.
Precise results may not hit
the bulls‐eye, but they all
hit the same region.
Lab 1: Introduc on to Science
16
ent variable are caused by the changes in the independent variable. In other words, they depend on the
independent variable. There can be more than one dependent variable in an experiment. Dependent
variables are placed on the y‐axis of a chart or graph.
A control is a sample of data collected in an experiment that is not exposed to the independent variable.
The control sample reflects the factors that could influence the results of the experiment, but do not
reflect the planned changes that might result from manipula ng the independent variable. Controls
must be iden fied to eliminate compounding changes that could influence results. O en, the hardest
part of designing an experiment is determining how to isolate the independent variable and control all
other possible variables. Scien sts must be careful not to eliminate or create a factor that could skew
the results. For this reason, taking notes to account for uniden fied variables is important. This might
include factors such as temperature, humidity, me of day, or other environmental condi ons that may
impact results.
There are two types of controls, posi ve and nega ve. Nega ve controls are data samples in which you
expect no change to occur. They help scien sts determine that the experimental results are due to the
independent variable, rather than an uniden fied or unaccounted variable. For example, suppose you
need to culture bacteria and want to include a nega ve control. You could create this by streaking a
sterile loop across an agar plate. Sterile loops should not create any microbial growth; therefore, you
expect no change to occur on the agar plate. If no growth occurs, you can assume the equipment used
was sterile. However, if microbial growth does occur, you must assume that the equipment was contam‐
inated prior to the experiment and must redo the experiment with new materials.
Alterna vely, posi ve controls are data samples in which you do expect a change. Let’s return to the
growth example, but now you need to create a posi ve control. To do this, you now use a loop streak a
plate with a sample that you know grows well on agar (such as E. coli). If the bacteria grow, you can as‐
sume that the bacteria sample and agar are both suitable for the experiment. However, if the bacteria
do not grow, you must assume that the agar or bacteria has been compromised and you must re‐do the
experiment with new materials.
The scien fic method also requires data collec on. This may reflect what occurred before, during, or
a er an experiment. Collected data help reveal experimental results. Data should include all relevant
observa ons, both quan ta ve and qualita ve.
A er results are collected, they can be analyzed. Data analysis o en involves a variety of calcula ons,
conversions, graphs, tables, etc. The most common task a scien st faces is unit conversion. Units of me
are a common increment that must be converted. For example, suppose half of your data is measured in
seconds, but the other half is measured in minutes. It will be difficult to understand the rela onship be‐
tween the data if the units are not equivalent. The following page provides a sample calcula on.
Lab 1: Introduc on to Science
17
When calcula ng a unit conversion, significant digits must be accounted for. Significant digits are the digits in a number or answer that describe how precise the value actually is. Consider the following rules:
Addi on and subtrac on problems should result in an answer that has the same number of significant decimal places as the least precise number in the calcula on. Mul plica on and division problems should keep the same total number of significant digits as the least precise number in the calcula on. For example:
Addi on Problem: 12.689 + 5.2 = 17.889 → round to 18
Mul plica on Problem: 28.8 x 54.76 = 1577.088 → round to 1580 (3 significant digits)
Scien fic nota on is another common method used to transform a number. Scien fic data is o en very
large (e.g., the speed of light) or very small (e.g., the diameter of a cell). Scien fic nota on provides an
abbreviated expression of a number, so that scien sts don’t get caught up coun ng a long series of ze‐
roes.
There are three parts to scien fic nota on: the base, the coefficient and the exponent. Base 10 is almost
always used, and makes nota on easy to translate. The coefficient is always a number between 1 and
10, and uses the significant digits of the original number. The exponent tells us whether the number is
Rule Example
Any non‐zero number (1‐9) is always significant
45 has two significant digits
3.99 has three significant digits
248678 has six significant digits
Any me a zero appears between significant num‐
bers, the zero is significant 4005 has four significant digits
Zeros that are ending numbers a er a decimal
point or zeros that are a er significant numbers
before a decimal point are significant
45.00 has four significant digits
15000.00 has seven significant digits
Zeros that are used as placeholders are NOT sig‐
nificant digits 62000000 has only two significant digits
A zero at the end of a number with no decimal
can be a significant digit
50 cm exactly has two significant digits (not
rounded)
Lab 1: Introduc on to Science
18
greater or less than 1, and can be used to “count” the number of digits the decimal must be moved to
translate the number to regular nota on. A nega ve exponent tells you to move the decimal to the le ,
while a posi ve one tells you to move it to the right.
For example, the number 5,600,000 can be wri en as 5.6 x 106. If you mul ply 5.6 by 10 six mes, you
will arrive at 5,600,000. Note the exponent, six, is posi ve because the number is larger than one. Alter‐
na ve, the number 0.00045 must be wri en using a nega ve exponent. To write this number in scien‐
fic nota on, determine the coefficient. Remember that the coefficient must be between 1 and 10. The
significant digits are 4 and 5, so we can know that 4.5 is the coefficient. To determine the exponent,
count how many places you must move the decimal over to create the original number. Moving to the
le , we have 0.45, 0.045, 0.0045, and finally 0.00045. Since we move the decimal 4 places to the le ,
our exponent is ‐4. Wri en in scien fic nota on, we have 4.5 x 10‐4
Although these calcula ons may feel laborious, a well‐calculated presenta on can transform data into a
format that scien sts can more easily understand and learn from. Some of the most common methods
of data presenta on are:
Table: A well‐organized summary of data collected. Tables should display any informa on relevant to the hypothesis. Always include a clearly stated tle, labeled columns and rows, and measurement units.
Graph: A visual representa on of the rela onship between the independent and dependent variable.
They are typically created by using data from a table. Graphs are useful in iden fying trends and illus‐
tra ng findings. When construc ng a graph, it is important to use appropriate, consistent numerical in‐
tervals. Titles and axes labels should also reflect the data table informa on. There are several different
types of graphs, and each type serves a different purpose. Examples include line graphs or bar graphs.
Line graphs show the rela onship between variables using plo ed points that are connected with a line.
There must be a direct rela onship and dependence between each point connected. More than one set
of data can be presented on a line graph. By comparison, bar graphs: compare results that are inde‐
pendent from each other, as opposed to a con nuous series.
Variable Height Wk. 1 (mm) Height Wk. 2 (mm) Height Wk. 3 (mm) Height Wk. 4 (mm)
Control
(without nutri‐ 3.4 3.6 3.7
4.0
Independent
(with nutrients)
3.5 3.7 4.1 4.6
Table Example: Plant Growth With and Without Added Nutrients
Lab 1: Introduc on to Science
19
A er compiling the data, scien sts analyze the data to determine if the experiment supports or refutes
the hypothesis. If the hypothesis is supported, you may want to consider addi onal variables that should
be examined. If your data does not provide clear results, you may want to consider running addi onal
trials to develop a meaningful average or revise the procedure to create a more precise outcome.
Figure 3: Sample line graph. Plant growth, with and without nutrients, over me
Height (m
m)
Figure 4: Sample bar graph. Top speed for Cars A, B, C, and D. Note, since there is no rela on‐
ship between each car, each result is independent and a bar graph is appropriate.
Speed (kph)
Lab 1: Introduc on to Science
20
One way to analyze data is to calculate percent error. Many experiments perform trials which calculate
known value. When this happens, you can compare experimental results to known values and calculate
percent error. Low percent error indicates that results are accurate, and high percent error indicates
that results are inaccurate. The formula for percent error is:
Note that the brackets in the numerator indicate “absolute value”. This means that the number in the
equa on is always posi ve.
Suppose your experiment involves gravity. Your experimental results indicate that the speed of gravity is
10.1 m/s2, but the known value for gravity is 9.8 m/s2. We can calculate the percent error through the
following steps:
The scien fic method gives us a great founda on to conduct scien fic reasoning. The more data and
observa ons we are able to make, the more we are able to accurately reason through the natural phe‐
nomena which occur in our daily lives. Scien fic reasoning does not always include a structured lab re‐
port, but it always helps society to think through difficult concepts and determine solu ons. For exam‐
ple, scien fic reasoning can be used to create a response to the changing global climate, develop medi‐
cal solu ons to health concerns, or even learn about subatomic par cles
and tendencies.
Although the scien fic method and scien fic reasoning can guide society
through cri cal or abstract thinking, the scien fic industry typically pro‐
motes lab reports as a universal method of data analysis and presenta‐
on. In general terms, a lab report is a scien fic paper describing the
premise of an experiment, the procedures taken, and the results of the
study. They provide a wri en record of what took place to help others
learn and expedite future experimental processes. Though most lab re‐
ports go unpublished, it is important to write a report that accurately
characterizes the experiment performed.
Percent Error = |(Experimental—Actual)| x 100% Actual
Percent Error = |(10.1 m/s2 ‐ 9.8 m/s2)| x 100% (9.8 m/s2)
Percent Error = |0.3 | x 100% (Note the units cancel each other out) (9.8 )
Percent Error = 0.0306 x 100% = 3.1% (Remember the significant digits)
Figure 5: Lab reports are an
important part of science,
providing a way to report con‐
clusions and ideas.
Lab 1: Introduc on to Science
21
Title A short statement summarizing the topic
Abstract A brief summary of the methods, results and conclusions. It should not exceed
200 words and should be the last part wri en.
Introduc on An overview of why the experiment was conducted. It should include:
Background ‐ Provide an overview of what is already known and what ques‐
ons remain unresolved. Be sure the reader is given enough informa on to
know why and how the experiment was performed.
Objec ve ‐ Explain the purpose of the experiment (i.e. "I want to determine
if taking baby aspirin every day prevents second heart a acks.")
Hypothesis ‐ This is your "guess" as to what will happen when you do the
experiment.
Materials and
Methods
A detailed descrip on of what was used to conduct the experiment, what was
actually done (step by step) and how it was done. The descrip on should be
exact enough that someone reading the report can replicate the experiment.
Results Data and observa ons obtained during the experiment. This sec on should be
clear and concise. Tables and graphs are o en appropriate in this sec on. Inter‐
preta ons should not be included here.
Discussion Data interpreta ons and experimental conclusions.
Discuss the meaning of your findings. Look for common themes, rela on‐
ships and points that perhaps generate more ques ons.
When appropriate, discuss outside factors (i.e. temperature, me of day,
etc.) that may have played a role in the experiment.
Iden fy what could be done to control for these factors in future experi‐
ments.
Conclusion A short, concise summary that states what has been learned.
References Any ar cles, books, magazines, interviews, newspapers, etc. that were used to
support your experimental background, protocols, discussions and conclusions.
Part of the Lab
Report Purpose
Lab 1: Introduc on to Science
22
Exercise 1: Data Interpreta on
Dissolved oxygen is oxygen that is trapped in a fluid, such as water. Since virtually every living organ‐ism requires oxygen to survive, it is a necessary component of water systems such as streams, lakes and rivers in order to support aqua c life. The dissolved oxygen is measured in units of ppm—or parts per million. Examine the data in Table 1 showing the amount of dissolved oxygen present and the number of fish observed in the body of water the sample was taken from; finally, answer the ques ons below.
Ques ons
1. What pa erns do you observe based on the informa on in Table 1?
2. Develop a hypothesis rela ng to the amount of dissolved oxygen measured in the water sample
and the number of fish observed in the body of water.
3. What would your experimental approach be to test this hypothesis?
4. What would be the independent and dependent variables?
5. What would be your control?
Dissolved Oxygen (ppm) 0
Number of Fish Observed 0
2
1
4
3
6
10
8
12
10
13
12
15
14
10
16
12
18
13
Table 1: Water Quality vs. Fish Popula on
Lab 1: Introduc on to Science
23
6. What type of graph would be appropriate for this data set? Why?
7. Graph the data from Table 1: Water Quality vs. Fish Popula on table (found at the beginning of this
exercise).
8. Interpret the data from the graph made in Ques on 7.
Exercise 2: Testable Observa ons
Determine which of the following observa ons are testable. For those that are testable:
Determine if the observa on is qualita ve or quan ta ve
Write a hypothesis and null hypothesis
What would be your experimental approach?
What are the dependent and independent variables?
What are your controls ‐ both posi ve and nega ve?
How will you collect your data?
How will you present your data (charts, graphs, types)?
How will you analyze your data?
Observa ons
1. When a plant is placed on a window sill, it grows three inches faster per day than when it is placed
on a coffee table in the middle of the living room.
2. The teller at the bank with brown hair and brown eyes is taller than the other tellers.
Lab 1: Introduc on to Science
24
3. When Sally eats healthy foods and exercises regularly, her blood pressure is 10 points lower than
when she does not exercise and eats unhealthy foods.
4. The Italian restaurant across the street closes at 9 pm but the one two blocks away closes at 10
pm.
5. For the past two days, the clouds have come out at 3 pm and it has started raining at 3:15 pm.
6. George did not sleep at all the night following the start of daylight savings.
Exercise 3: Conversion
For each of the following, convert each value into the designat‐
ed units.
1. 46,756,790 mg = _______ kg
2. 5.6 hours = ________ seconds
3. 13.5 cm = ________ inches
4. 47 °C = _______ °F
Exercise 4: Accuracy and Precision
For the following, determine whether the informa on is accurate, precise, both or neither.
1. During gym class, four students decided to see if they could beat the norm of 45 sit‐ups in a mi‐
nute. The first student did 64 sit‐ups, the second did 69, the third did 65, and the fourth did 67.
Lab 1: Introduc on to Science
25
2. The average score for the 5th grade math test is 89.5. The top 4th graders took the test and
scored 89, 93, 91 and 87.
3. Yesterday the temperature was 89 °F, tomorrow it’s supposed to be 88°F and the next day it’s sup‐
posed to be 90°F, even though the average for September is only 75°F degrees!
4. Four friends decided to go out and play horseshoes. They took a picture of
their results shown to the right:
5. A local grocery store was holding a contest to see who could most closely
guess the number of pennies that they had inside a large jar. The first six
people guessed the numbers 735, 209, 390, 300, 1005 and 689. The gro‐
cery clerk said the jar actually contains 568 pennies.
Exercise 5: Significant Digits and Scien fic Nota on
Part 1: Determine the number of significant digits in each number and write out the specific significant
digits.
1. 405000
2. 0.0098
3. 39.999999
4. 13.00
5. 80,000,089
6. 55,430.00
7. 0.000033
8. 620.03080
Lab 1: Introduc on to Science
26
Part 2: Write the numbers below in scien fic nota on, incorpora ng what you know about significant
digits.
1. 70,000,000,000
2. 0.000000048
3. 67,890,000
4. 70,500
5. 450,900,800
6. 0.009045
7. 0.023
27
Biological Processes
Lab 2
The Chemistry of Life
Lab 2: Chemistry of Life
29
Introduc on
It is important to have a general understanding of chemistry
before you can begin to understand how living organisms
manage to reproduce, grow, move, eat, and perform a great
many more func ons. To begin understanding the myriad of
reac ons that occur within a cell, it is important to review the
basics of chemistry. Recall that anything that occupies space and has mass is called ma er; all ma er is
made of atoms.
Atoms are made of a nucleus and two kinds of subatomic par cles: electrons (nega vely charged par ‐
cles), protons (posi vely charged par cles), and neutrons (neutrally charged par cles). Elements are
pure substances that are made of only one type of atom. More than 90% of ma er is composed of
Concepts to explore:
Atoms
Elements
Compounds
Chemical bonds
Molecules/Macromolecules
Energy and metabolism
Concepts to explore:
Acids and bases
The effects of surface area
and volume
Remember: Mass is the quan ty of
ma er an object has; weight is the
force produced by gravity ac ng on
the mass of an object
Figure 1: The Periodic Table of elements categorizes all of the known elements
Lab 2: Chemistry of Life
30
combina ons of just four elements: oxygen, carbon, hydrogen, and
nitrogen. There are over 100 elements known, each with different
proper es. The periodic table has been used to categorize these
elements.
In nature, most elements are not found alone; atoms of most ele‐
ments combine with the same or different elements to make com‐
pounds. A compound is a mixture of two or more elements in defi‐
nite propor ons. These atoms are held together by chemical bonds,
bringing them to a stable state. Chemical bonds also store energy.
The two most common bonds are covalent bonds and ionic bonds.
Covalent bonds form when two atoms share electrons. Ionic bonds
form when an atom or molecule carries an electrical charge, which
a racts an atom or molecule of the opposite charge.
Very large molecules are termed macromolecules. All living organ‐
isms use the same four types of macromolecules for cellular metab‐
olisms and reproduc on. These common biological macromolecules
are proteins, nucleic acids, carbohydrates, and lipids. The proper es
they convey are of great importance to cell func on, and you will
learn about each in future labs.
Chemical reac ons take one or more substance and change it to create a new substance. This requires
energy. When chemical bonds are broken, energy is made available for the reac on to proceed. Most
reac ons also require energy to ini ate the reac on. This is called the ac va on energy, and it differs
for each reac on. Catalysts are chemicals that lower the ac va on energy. You will learn about biologi‐
cal catalysts called enzymes later in this manual.
Living things require a constant supply of energy. Throughout this manual, you will learn about the re‐
ac ons that take place inside of organisms. The sum of these reac ons is called metabolism, and is a
general term used to describe the energy require to keep those reac ons occurring.
Two important classes of compounds are acids and bases. Both have physical and chemical differences
that can be observed and tested. Typically, acids ionize in a solu on to increase the concentra on of
hydronium ions (H3O+). Alterna vely, bases typically dissociate in a solu on to increase the concentra‐
on of hydroxide ions (OH‐). A compound’s acidity or alkalinity (how basic it is) can be measured on a
scale called pH. The pH of a substance is a measure of the concentra on of hydronium ions. A solu on
that contains a lot of hydronium ions but few hydroxide ions is considered to be very acidic. In con‐
trast, a solu on that contains many hydroxide ions but few hydronium ions is considered to be very
basic. pH values range from 1‐14, with 1 being highly acidic, 14 highly basic, and 7 neutral.
Have you ever wondered why cells are the size they are? There are many reasons, but one important
one is the surface area to volume ra o. In subsequent labs, you will learn how cells divide once they
Figure 2: Have you ever drank or‐
ange juice right a er brushing your
teeth? Yuck! The displeasing taste
is a result of the acid/base reac on
that occurs when a weak acid
(orange juice) mixes with a weak
base (toothpaste).
Lab 2: Chemistry of Life
31
reach a cri cal size. Nutrients and oxygen need to diffuse through the cell, and waste needs to diffuse
out of the cell. This must happen quickly for the cell to survive – which happens when the surface area
to volume ra o of the cell is high.
Experiment 1: What household substances are acidic or basic?
There are chemicals, called pH indicators, which change color when they come into contact with an
acid or a base. In the following experiment, you will be using pH paper to determine the pH of various
household substances. The key below indicates the color the paper turns as a func on of the pH. In this
way, pH paper allows scien sts to determine to what degree a substance is acidic or basic and can pro‐
vide an approximate pH value.
Note: Remember to wear your gloves and goggles when working with chemicals!
Procedure
1. Find four household substances to test (ex: grape juice, lemon juice, dishwashing liquid, milk,
tomato juice, shampoo, corn starch solu on, etc.). You will use the vinegar (acidic) and sodium
bicarbonate (basic) solu on provided in your kit as standards.
2. Guess the pH of each substance before tes ng with pH paper. Record your guesses in Table 1.
3. Use the permanent marker to label each of the beakers with the name of one of the six solu‐
ons. It does not ma er which size beaker is used for the different solu ons.
4. Use the graduated cylinder to measure and pour 5 mL of vinegar into the beaker labeled
“Vinegar”. Repeat this step with each of the five remaining solu ons and beakers.
5. Measure the pH of each solu on by dipping the pad of the pH strip into the solu on for 5 ‐ 10
seconds and comparing it with the pH test strip key (located in the lab module). Record your
results in Table 1.
Materials
(10) 1 in. pH paper strips
5 mL Vinegar (<5% ace c acid)
5 mL Sodium bicarbonate solu on
(3) 100 mL Beakers
(3) 250 mL Beakers
10 mL Graduated cylinder
4 Liquid, household solu ons*
*You must provide
Lab 2: Chemistry of Life
32
Ques ons
1. Compare and contrast acids and bases in terms of their H+ ion and OH‐ ion concentra ons.
2. Name two acids and two bases you o en use.
Experiment 2: The effect of surface area and volume
Have you ever wondered why cells don’t grow past a certain size? There is a size limit for cells that
they cannot surpass. Once they reach their maximum size, they divide and form two smaller cells. Why
do they do that? We will look at the importance of surface area to volume ra os in this experiment to
help you understand.
Substance pH Guess pH Paper
Vinegar
Sodium bicarbonate solu on
Table 1: pH values of common household substances
Materials
(1) 125 mL Nutrient Agar Bo le 10 mL Bromothymol Blue Plas c wrap Pipe es Vinegar 2 mL Sodium bicarbonate (1) 250 mL beaker Rectangular mold
Ruler Underpad 10 mL Graduated cylinder Kitchen knife* Microwave* Hot pads* Paper towels* *You must provide
Lab 2: Chemistry of Life
33
Sample Experiment Calcula ons:
Surface Area:
Volume:
Surface Area can be calculated with the following equa on: Length x Width = Area To find the surface area of a cube, calculate the area of one side and mul ply that by the total number of sides. Surface Area Calcula on Example: Problem: If an equilateral cube is structured so that every side is 3 cm. long, what is the total surface area? Given: Length = 3 cm Width = 3 cm Total Number of Sides = 6 Solu on: 1. Solve for the area of each individual side: Length x Width = 3 cm x 3 cm = 9 cm2 2. Mul ply the area of one side by the total number of sides in the
shape. 6 sides x 9 cm2 = 54 cm2 Note: If the 3‐D structure you are measuring does not contain equilateral dimensions, you must deter‐mine the surface area of each side and add them up individually.
9 cm2
9 cm2
Volume can be calculated with the following equa on: Length x Width x Height = Volume
Volume Calcula on Example: Problem: Suppose you are working with the same cube as above. What is the total volume? Given: Length = 3 cm Width = 3 cm Height = 3 cm Solu on: 1. Plug your variables into the equa on to solve for volume: 3 cm x 3 cm x 3 cm = 27 cm3
Note: To determine surface area to volume ra o, simply divide the surface area by the volume.
Lab 2: Chemistry of Life
34
Procedure
Agar Prepara on
1. Remove or loosen the cap on the agar bo le and placing it in the microwave.
2. Heat the bo le in 10 second increments for approximately 1 ‐ 2 minutes. While in the micro‐
wave, watch the solu on for boil‐over. Agar solu ons can get very hot very quickly, so be cer‐
tain to watch the bo le at all mes. If it begins to boil‐over, immediately stop the microwave,
and allow the agar to cool down before proceeding.
3. A er hea ng for approximately 1 minute, check on your agar bo le. To do this, remove the
bo le with a hot pad, screw the lid back onto the bo le, and swirl the solu on. If the solu on
is not completely liquefied, remove the lid and place the agar bo le back into the microwave
for 10 second intervals, swirling in between, un l it is completely liquefied.
4. A er the agar is liquefied, let the solu on sit for a minute to cool down.
5. Once the agar solu on has cooled slightly, measure 40 mL into the 250 mL beaker.
6. Add 10 mL of the bromothymol blue solu on to the liquefied agar in the beaker.
7. Add 2 mL sodium bicarbonate to the beaker solu on. Pipe e the solu on up and down to
mix. This will nt the mixture and create a pH change.
8. Once the solu on is mixed, pour the solu on into the rectangular mold. Cover the mold with
plas c wrap.
9. Let the mold sit at room temperature for 24 hours to give the agar me to set.
Note: A er the 24 hours, the liquid agar should have firmed up to a jello‐like consistency. It will be
a gel‐like solid, but it will not be hard.
Experiment
1. Put on safety gloves, safety glasses, and an apron. Check to be sure the agar has set. If it has
not, let it sit for another 12 hours.
2. Invert the rectangular mold, and gently allow the agar block fall onto the underpad.
3. From this block, safely cut out a 1 cm x 1 cm x 6 cm cube. Note: It is helpful to measure out the
6 cm side first.
4. From the remaining agar, safely cut out a 1 cm x 1 cm x 1 cm block. Set the block aside.
5. From the remaining agar, safely cut out a 1 cm x 2 cm x 2 cm block. Set this block with the oth‐
ers.
6. Once all three blocks have been cut, dispose of the scraps of remaining agar. Do not dispose of
the blocks you just cut.
Note: This experiment requires 24 hour advance prepara on.
Lab 2: Chemistry of Life
35
7. Use a ruler to calculate the surface area, volume, and surface area to volume ra o for each
cube. Record the calcula ons in Table 2.
8. Fill the 250 mL beaker with 150 mL of vinegar. Gently place all three blocks into the vinegar
solu on.
9. Let the blocks rest in the vinegar for 7 minutes. Observe as the blocks begin to change color
(from blue to clear). Record how long it takes for each block to completely change colors (from
blue to clear). Note, use any of the blocks that do not experience total diffusion to measure the
distance of diffusion in Step 11.
10. A er 7 minutes, remove the blocks from the vinegar solu on. Pour the remaining vinegar so‐
lu on down the drain.
11. Gently blot the cubes dry and then safely cut the cubes in half. For each cube, measure the
distance the vinegar diffused into the gela n cube, as detected by the color change. Do this by
measuring from the outer edge of the cube to the blue rim inside the cube. Record that value
in Table 2.
Table 2: Results from surface area to volume experiment
Ques ons
1. How did the surface area effect the diffusion of the cube? What about the volume? What
about the surface area to volume ra o? Which of these had the greatest affect on the diffu‐
sion of the cube?
2. How does this experiment demonstrate the need for larger cells to divide?
3. Determine the surface area, volume, and surface area to volume ra o for the three cubes
shown on the following page. Then, circle the one you believe would be the most efficient as a
cellular morphology, and write a summary sta ng why.
Cube Dimensions Surface Area (cm2) Volume (cm3) Surface Area : Volume
Time Required for
Complete Color
Change
1 cm x 1 cm x 1 cm
1 cm x 2 cm x 2 cm
1 cm x 1 cm x 6 cm
Distance of
Diffusion
Lab 2: Chemistry of Life
36
1.5 cm x 1.5 cm x 1.5 cm
.5 cm x .5 cm x 6 cm
3 cm x 2 cm x 2 cm
37
The Cell
Lab 3
Cell Structure & Func on
38
39
Lab 3: Cell Structure & Func on
Introduc on
A cell is the fundamental unit of life. All living organisms originate from a single cell. Some remain as a
single cell, while others become mul ‐cellular (like you!). Though most cells are difficult to see with
the naked eye, using the microscope, cytologists have iden fied many of their features. These range
from the characteris cs of the outer membranes, to internal structures such as the nucleus and mito‐
chondria and have become the founda on for what is now known as “cell theory”.
Cell theory states:
All cells are generated from previous cells
All cells pass on their gene c informa on
All living things are made of cell(s)
Energy metabolism occurs inside cells
The chemical make‐up of cells is similar
Although all organisms are made up of cells, not all cells are iden cal. Prokaryotes and eukaryotes are
two structurally different types of cells.
Prokaryotes are the most primi ve and basic organisms, and span the taxonomic classes of
bacteria and archaea. They lack a membrane bound nucleus and membrane bound organelles
(specialized structures). The term prokaryote comes from the La n words “pro” (before) and
“karyote” (nucleus).
Eukaryote are much more complex organisms with two characteris cs that set them apart
from prokaryotes: a defined nucleus and membrane‐bound organelles. The term “eukaryote”
comes from the La n words “eu” (true) and “karyote” (nucleus). Pro sts, fungi, plant and ani‐
mal cells are all eukaryo c cell(s).
Concepts to explore:
What is a cell?
Prokaryotes
Eukaryotes
Cell structure
Func on of cell structures
Diffusion
Rare of Diffusion
Cytologists are scien sts who
study cells. The study of the
cell is known as cytology.
40
Lab 3: Cell Structure & Func on
Prokaryotes Eukaryotes
Bacteria and archaea (both prim‐
i ve cells) are the only prokary‐
otes
Are very small (.1µm to 2µm)
Reproduce asexually. This
means sexual reproduc on is
absent, and there is li le gene c
varia on between genera ons
Have simple cellular components
Are capable of living almost any‐
where and o en thrive in harsh
condi ons
Are unicellular
2 Billion years younger than pro‐
karyo c cells
Great biological diversity
All mul ‐cellular organisms are
eukaryotes
Significantly larger than most
prokaryo c cells
More complex shapes and inter‐
nal structure than prokaryotes
Some are capable of capturing
light energy (chloroplasts in
plant cells and cones and rods of
the eye)
Figure 1: A prokaryo c cell showing
some of the major structures
Nucleoid (nucleus-like) Region
41
Lab 3: Cell Structure & Func on
Both prokaryotes and eukaryotes have a plasma membrane (also known as the cell membrane) that
separates the cellular content from the external environment. This structure is o en referred to as a
phospholipid bi‐layer, as it is composed of two layers of lipids with proteins floa ng between these lay‐
Figure 2: Major structures of eukaryotes; Top: an animal cell; bo om le : a plant cell; Bo om right: a para‐
mecium.
Plant Cell
42
Lab 3: Cell Structure & Func on
ers. The proteins in the structure are responsible for carrying out the majority of the func ons specific
to the membrane and impart a selec vity to certain materials that can pass through the membrane.
Many cells within the prokaryo c and eukaryo c families have cell walls outside the cell membrane hat
help to protect them and provide support (note: animal cells and protozoa do not have cell walls). Un‐
like the cell membrane, this barrier is not selec ve and does not allow materials to pass through easily.
Prokaryo c cells have a thick, rigid cell wall composed of amino acids and sugars (pep doglycan), but
the cell wall composi on within eukaryotes varies (e.g., fungi cell walls include a polysaccharide called
chi n while plants exhibit cell walls with the polysaccharide cellulose).
In all cells, the plasma membrane encases the cytoplasm (also called cytosol), which is a semiliquid, gel‐
like substance that is the founda on of the cell. Within the cytoplasm of eukaryo c cells, a number of
membrane‐bound organelles exist to provide specific func ons within the cell. Prokaryotes do not have
these specialized bodies to compartmentalize the intercellular func ons and are therefore everything
is free‐floa ng within the cell. As you examine the structures of prokaryotes and eukaryotes in Figures
1 and 2, you will note these differences.
Some Organelles Found in Eukaryotes:
Nucleus: Houses the gene c content (DNA) of the cell.
Nuclear Envelope: An outer membrane that surrounds the nucleus.
Nuclear Pores: Holes in the nuclear envelope that permit communica on between the internal nuclear environment and the cytoplasm.
Nucleolus: (plural: nucleolus) A part of the nucleus that is made of RNA, Protein and Chroma‐n and manufactures RNA and ribosomes.
Ribosomes: Ribosomes are large molecules found in all living cells. Ribosomes are responsible for catalyzing protein forma on during transla on. A strand of mRNA docks onto a ribosome molecule and the correct amino acids are then recruited to the ribosome to create a protein.
Mitochondrion: (plural: mitochondria) The “power plant” of the cell. They are a membrane bound organelle (inner and outer membrane) with their own circular DNA, and make ATP (energy) for the rest of the cell.
Endoplasmic Re culum (ER): A series of membranes extending throughout the cytoplasm that can be peppered with ribosomes (rough ER) or not (smooth ER) and is the site of protein syn‐thesis within a cell.
Golgi Apparatus: (also called the Golgi Body) A series of fla ened sack‐like bodies that process‐es the cell’s proteins and lipids before they are released to their final des na on.
Peroxisomes: Contain enzymes that help the cell destroy toxins.
Lysosomes: A sack of enzymes found within the cell that aid in the diges on of food into usa‐ble products for the cell.
Cytoskeleton: The “skeleton” found in all eukaryo c cells that provides shape to the cell while also enabling it to move. It consists of three parts:
1. Microfilaments: Small strands that help the cell resist tension. Think of it as a piece of wire.
43
Lab 3: Cell Structure & Func on
2. Intermediate filaments: Anchors the organelles in the cell and provide addi onal stability.
3. Microtubules: Small hollow tubes that help the cell maintain its shape, move things around within the cell and form other key structures.
Centriole: Barrel shaped structures that help make cilia and flagella. They also play a key role in cell division.
Cilia: Small “hairs” on the outside of the cell. They help the cell move and are sensory recep‐tors.
Flagella: The structure of eukaryo c flagella is far more complex than prokaryo c flagella as the consist of mul ple filaments. They provide mobility by rota ng back and forth, they help transport fluids and serve as sensory receptors.
Chloroplast: Think of them as the plant version of mitochondria. The main difference is that they take light energy and convert it to mechanical energy.
Vacuole: Membrane bound “sacs” that provide storage and provide transporta on within the cell (excre on, secre on).
Vesicle: Plays a similar role to vacuoles, but are smaller.
Structure Prokaryo c Cell Eukaryo c Cell
Nucleus No Yes
Plasma Membrane Yes Yes
Cell Wall Yes Yes (in most cells)
Cytoplasm Yes Yes
Flagella and Pili Occasionally Flagella‐ Occasionally
Pili ‐ No
Cilia No Occasionally
Glycocalyx Occasionally Occasionally
Cytoskeleton No Yes
Endoplasmic Re culum No Yes
Mitochondria No Yes
Golgi Apparatus No Yes
Chloroplast No In plants and many pro sts
Ribosome Yes Yes
Lysosome No Yes
Peroxisome No Yes
Vacuole and Vesicle No Yes (in most cells)
Prokaryo c vs. Eukaryo c Cells
44
Lab 3: Cell Structure & Func on
Although prokaryo c cells do not have a nucleus, they do have DNA. The DNA is a closed loop and ex‐
ists freely in an unorganized manner within the cytoplasm, in an area known as the nucleoid region.
They can also have a slime coa ng, called the glycocalyx, which is used to protect the cell and enable it
to a ach to surfaces (such as teeth and lungs). Prokaryotes also have ribosomes to facilitate the pro‐
duc on of proteins. All cells, prokaryotes and eukaryotes, must have a means to regulate nutrients and
wastes, and also require a supply of energy to exist. Metabolic ac vi es such as photosynthesis and
respira on can be carried out by both cell types. In eukaryotes, photosynthe c ac vity ini ates in the
chloroplasts, while in prokaryotes it occurs in the thylakoid.
Regardless of the cell type or structure, diffusion of
molecules is almost always a factor. Molecules are
constantly in mo on due to the kine c energy pre‐
sent in every atom. This energy results in the net
movement of molecules from areas of high concen‐
tra on to areas of low concentra on, or diffusion
(Figure 3). If uninhibited, this movement will con n‐
ue un l equilibrium is reached and the molecules are
uniformly distributed.
The rate of diffusion depends on the medium used,
size of the molecule, and polarity of molecule. Be‐
cause the medium will not change in a biological sys‐
tem, the diffusion rate is usually dictated by molecu‐
lar characteris cs. Small, non‐polar molecules ex‐
hibit a higher rate of diffusion than large, charged
ones.
The direc on of diffusion depends on concentra on gradients, heat and pressure. The concentra on
gradient is the change of molecular density over a given area. Temperature and pressure typically re‐
main constant in biological systems, making the concentra on gradient the best indicator of direc on‐
ality. In general, molecules will move towards areas of lower concentra ons.
Figure 3 Diffusion through a semi‐permeable membrane
(lipid bilayer)
45
Lab 3: Cell Structure & Func on
Experiment 1: Iden fying Cell Structures
View the slide pictures and images below, paying a en on to detail, and note the different characteris‐
cs of prokaryotes and eukaryotes. On each picture, label the parts indicated if they are visible. If you
can not see them, draw and label them where they would be located.
Bacteria: Nucleoid region, cell wall, plasma membrane, ribosomes, flagella
Pro st: Macronucleus, micronucleus, plasma membrane, cytoplasm, contrac le vacuole
Figure 3
Figure 4
46
Lab 3: Cell Structure & Func on
Figure 6
Figure 5
Plant Cell: Nucleus, cell wall, plasma membrane, cytoplasm, chloroplast, mitochondria, vacuoles
Animal Cell: Nucleus, nucleolus, plasma membrane, cytoplasm, mitochondria, golgi apparatus, rough
ER, ribosome
47
Lab 3: Cell Structure & Func on
Ques ons
1. For each structure iden fied, do you think its loca on affects its ability to func on? Why or
why not? (Hint: those buried deep in the cell probably do different things than those closer
to the cell membrane)
2. Draw a labeled diagram of a small sec on of the plasma membrane and briefly describe its
structure and func on.
3. Describe the differences between animal and plant cells.
4. Which of the following structures are present in both prokaryo c and eukaryo c cells? Plas‐
ma membrane, Golgi apparatus, DNA, lysosomes and peroxisomes, cytoplasm
5. Where is gene c material found in plant cells?
6. Mitochondria contain their own DNA (circular) and have a double membrane. What explana‐
on for this observa on can you come up with?
(Hint 1: Where else do we see circular DNA?)
(Hint 2: What do you know about the rela ve age of eukaryo c cells?)
7. How is the structure of the plant’s cellulose‐based cell wall related to its func on?
8. Defects in structures of the cell can lead to many diseases. Pick one structure of a eukaryo c
cell and develop a hypothesis as to what you think the implica ons would be if that structure
did not func on properly.
48
Lab 3: Cell Structure & Func on
9. Using books, ar cles, the internet, etc. conduct research to determine if your hypothesis was
correct.
Experiment 2: Direc on and Concentra on Gradients
In this experiment, we will inves gate the effect of solute concentra on on osmosis. A semi‐permeable
membrane (dialysis tubing) and sucrose will create an osmo c environment similar to that of a cell.
Using different concentra ons of sucrose (which is unable to cross the membrane) will allow us to ex‐
amine the net movement of water across the membrane.
Materials
30% Sucrose solu on
4 15 cm Pieces dialysis tubing**
3 250 mL Beakers
8 Rubber bands
Concepts to explore:
Water*
Watch*
*You must provide
**Cut to exact length
Note:
Dialysis tubing can be rinsed and used again if you make a mistake.
Dialysis tubing must be soaked in water before you will be able to open it up to create the
dialysis “bag”. Follow the direc ons for the experiment, beginning with soaking the tubing
in a beaker of water. Then, place the dialysis tubing between your thumb and forefinger
and rub the two digits together in a shearing manner. This should open up the "tube" so
you can fill it with the different solu ons.
49
Lab 3: Cell Structure & Func on
Procedure
1. Submerge the four pieces of dialysis tubing into a 250 mL beaker
filled with 100 mL of water for at least 10 minutes.
2. A er 10 minutes, remove one piece of tubing from the beaker.
On one end (not the whole tube), gently twirl the tubing into a
long, thin cylindrical piece that is able to fit into the hole of the
yellow bead.
3. Insert the long cylindrical end of the tube into the center hole in
the yellow bead. Once it is through, pull the cylindrical end un l
there is about 1.5 to 2 cm of tubing extending beyond the bead
4. Take the extra tubing you just pulled through the bead and fold it back over the bead, towards
the remaining, non folded tube. Place a rubber band above the bead and around the extra
tubing as to be sure no solu on can leak out of the tube (see Figure 4).
To test that no solu on can leak out, add a few drops of water and look for water leakage.
Make sure you pour the water out before con nuing to the next step.
5. Repeat steps 2‐4 with the three remaining dialysis tubes, using each of the three remaining
bead colors (Figure 5).
6. Table 1 provides a dis nc on as to what bead belongs to which tube. Using a 10 mL graduated
cylinder, measure and fill the appropriate dialysis bag with the designated concentra on of su‐
crose solu on (3%, 15% or 30%) by adding the volumes of sucrose and water listed in Table 1.
Figure 4: Fold the bag un l
you have a piece narrow
enough to be threaded
through the bead.
Figure 5: Beads help to secure the ends of the dialysis bags and iden fy each one.
50
Lab 3: Cell Structure & Func on
7. Rinse the outside of the bags with water to remove any remaining sucrose.
8. Pour 150 mL of the stock sucrose solu on (30%) into the 250 mL beaker (beaker #1). Using the
graduated cylinder, measure 20 mL of the stock sucrose solu on and 180 mL of water to cre‐
ate a 3% sucrose solu on and place it into the 250 mL beaker (beaker #2).
9. Place bags #1‐3 (red, blue, yellow) into beaker 2 and bag #4 (green) into beaker 1 (Figure 6).
10. In Table 2, predict whether water will flow in or out of each dialysis bag.
11. Allow the bags to sit for one hour. While wai ng, dump out the water in the 250 mL beaker
that was used to soak the dialysis tubing in step 1. We will use this in the last part of the ex‐
periment.
12. A er allowing the bags to sit for one hour, remove them from the beakers.
Bead Color Bag Number Stock Sucrose Solu on Water
Yellow Bag #1: 30% sucrose 10 mL 0 mL
Red Bag #2: 15% sucrose 5 mL 5 mL
Blue Bag #3: 3% sucrose 1 mL 9 mL
Green Bag #4: 3% sucrose 1 mL 9 mL
Table 1: How to Make a Serial Dilu on of Sucrose
Figure 6: The
dialysis bags
are filled with
varying con‐
centra ons of
sucrose solu‐
on and placed
in one of two
beakers.
51
Lab 3: Cell Structure & Func on
13. Carefully open the bags, no ng that o en mes the tops may need to be cut as they tend to
dry out. Measure the solu on volumes of each dialysis bag using the empty 250 mL beaker.
Record your data in Table 2.
Ques ons
1. For each of the bags, iden fy whether the solu on inside was hypertonic, hypotonic or isotonic in
comparison to the beaker solu on it was placed in.
2. Which bag increased the most in volume? Why?
3. What does this tell you about the rela ve tonicity between the contents of the bag and the solu‐
on in the beaker?
4. What would happen if bag 1 is placed in a beaker of dis lled water?
Ini al Volume Sucrose % Predic on: Will water move in or out? Final Volume
Bag#1 10 mL
Bag #2 10 mL
Bag #3 10 mL
Bag #4 10 mL
Table 2: Water Movement
52
53
Biological Processes
Lab 4
Enzymes
54
Lab 4: Enzymes
55
Introduc on
Enzymes are specialized proteins that serve as biological catalysts to decrease the ac va on energy
normally needed for a reac on to occur. This means the reac on rate is up to millions of mes faster
than it would be without the enzyme. Most biochemical reac ons require enzymes for them to occur
at fast enough rates to be useful. Typical nomenclature for enzymes follows the pa ern using the
name of the substrate or the chemical reac on it catalyzes, and ends with “‐ase”, e.g. catalase, amyl‐
ase. (In other words, any me you see a word end in “ase” you know it is an enzyme).
Enzymes are extremely selec ve, and are o en described as having a “lock and key” fit (Figure 1).
Their shape determines which substrates they bind and interact with. The ac va on site
Figure 1: The specificity of enzymes is controlled by their lock and key fit with a spe‐
cific substrate.
Concepts to explore:
Enzymes
Selec vity
Catalysts
Ac va on energy
Ac va on site
Reac on rates
Concepts to explore:
Ac vators
Inhibitors
Lab 4: Enzymes
56
is the pocket where the substrate a aches and where the reac on occurs. A er the enzyme/substrate
complex forms and catalysis occurs, the “new” substrate is released from the ac ve site, and the en‐
zyme can repeat the process. Enzymes levels are not reduced or altered during the reac on. This
means they are efficient and can be used repeatedly.
Enzymes determine the rate at which the reac on occurs (not how it occurs). Their ac vity is affected
by temperature, pH, enzyme and substrate concentra on, and other chemicals that may be present
(such as salts, which can change the protein structure).
Varia ons in temperature and alkalinity can change the shape of the proteins, such as enzymes, which
makes them inac ve (they can no longer bind to their substrate). The pH can alter charge of the pro‐
tein, once again changing its shape and rendering them inac ve.
The concentra ons of both the enzyme and substrate determine the reac on rate (Figure 2). Remem‐
ber that high reac on rates do not always translate into rapid me of comple on (it also depends on
the amount of substrate!).
Ac vators are chemicals that bind to the ac ve site of the en‐
zyme and help it to bind to the substrate. They are some mes
called cofactors or organic coenzymes.
Inhibitors are chemicals that interfere with the binding of the
substrate to the enzyme. There are two types:
Figure 2: Substrate Satura on Curve
Many drugs and poisons are en‐
zyme inhibitors. For example, aspi‐
rin inhibits an enzyme that leads to
inflamma on.
Lab 4: Enzymes
57
Compe ve (can be replaced by the substrate)
Non‐compe ve (not removed by the substrate)
Normal cellular processes produce toxic substances (waste) such as hydrogen peroxide and free radi‐
cals that if not eliminated, will kill the cell. Luckily, yeast and other organisms (including humans) have
an enzyme called catalase that breaks down hydrogen peroxide into oxygen and water, both harmless
to cells.
Experiment 1: Effect of enzyme concentra on
Yeast cells contain catalase. The effect of catalase can be seen when yeast is combined with hydrogen
peroxide (Catalase: 2H2O2 ─› 2 H2O + O2). In this lab you will examine the effects of enzyme (catalase)
concentra on based on the amount of oxygen produced.
Procedure
1. Label three test tubes as 1, 2, and 3
with a permanent marker.
2. Fill each tube with 10 mL hydrogen
peroxide.
3. Label three beaker as A, B, and C.
4. Add 1/2 teaspoon yeast (1 g.) to 100
mL of warm water (30‐35 °C) in
Beaker A. Mix well by pipe ng.
Materials
Yeast
Measuring Spoon
3 Test tubes
Test tube rack
3 100 mL Beakers
Hydrogen peroxide
10 mL Graduated cylinder
Permanent marker
Ruler
String*
3 Balloons
Watch*
*You must provide
Figure 3: When catalsae is added to hydrogen peroxide, oxy‐
gen is released.
Lab 4: Enzymes
58
5. Make a serial dilu on of yeast solu on. To do this, measure 10 mL of the yeast solu on from
Beaker A and transfer it to Beaker B. Add 90 mL warm water (30‐35 °C) to Beaker B. Mix well
by pipe ng.
6. Measure 10 mL of the yeast solu on from Beaker B and transfer it to Beaker C. Add 90 mL
warm water (30‐35 °C) to Beaker C. Mix well by pipe ng.
7. Measure and pour 5 mL from Beaker A into the first test tube.
8. Quickly a ach a balloon to the top of the test tube so that it will fill with the oxygen produced
by the enzyme reac on. It is important to execute this step quickly so that every bit of gas pro‐
duced will be captured.
9. Swirl each tube to mix, and wait one minute.
10. A er one minute has passed, wrap the string around the center of the balloon to measure the
circumference. Measure the length of string with a ruler. Record the length in Table 1 below.
11. Repeat step 10 a er two more minutes have passed (three minutes total from the start of the
reac on); and again a er two more minutes have passed (five minutes total from the start of
the reac on). Record all data in Table 1.
12. If the reac on has not finished, con nue to monitor how long it takes for the reac on to com‐
plete, and measure the final balloon circumference.
13. Repeat steps 7 ‐ 12 for the remaining test tubes (use beaker B for test tube 2 and beaker C for
test tube 3).
Table 1: Effect of enzyme concentra on on the produc on of gas
Ques ons
1. What is the enzyme in this experiment? What is the substrate?
Tube Amount
of yeast
Circumference (cm)
A er 1 minute
1 0.05 g
2 0.005 g
3 0.0005 g
Circumference (cm)
A er 3 minutes
Circumference (cm)
A er 5 minutes
Time Required
to Complete
Final Circumference (cm)
Lab 4: Enzymes
59
2. Did you no ce a difference in the rate of reac on in the tubes with different concentra ons of
enzymes? Why or why not?
3. What was the effect of using less enzyme on your experiment?
4. Do you expect more enzyme ac vity if the substrate concentra on is increased or decreased?
Draw a graph to illustrate this rela onship.
5. Hydrogen peroxide is toxic to cells, yet is a common byproduct of the reac ons that occur in‐
side the body. How can this compound be changed to become non‐toxic (Hint: Look at the
chemical formula of hydrogen peroxide)?
Experiment 2: Effect of temperature on enzyme ac vity
This experiment looks at the effect of temperature on enzyme ac vity.
Procedure
1. With a permanent marker, label the test tubes as 1, 2, 3, and 4. Place the test tubes in the test
tube rack for support.
Materials
Yeast
Measuring spoon
4 Test tubes
40 mL Hydrogen peroxide, H2O2
10 mL Graduated cylinder
4 Balloons
2 Water bath containers*
Pot for boiling water*
Stove‐top*
Hot Pad*
4 Microwave‐safe cups*
Permanent marker
Test tube rack
Ruler
String*
Watch*
Thermometer
*You must provide
Lab 4: Enzymes
60
2. Use the 10 mL graduated cylinder to measure and pour 10 mL of hydrogen peroxide into each
test tube.
3. Fill a pot with approximately 2 ‐ 3 inches of water and place it on the stove (turned to medium‐
high se ng). The water should come to a boil (approximately 100 °C).
4. While the water is hea ng, place each tube in separate, microwave‐safe cups (or beakers).
5. Gather two containers that can be used as hot water baths. Each container should be wide
enough to fit the cup with the test tube in it.
6. Pour 2‐3 cups of water into a microwave‐safe container and heat the water un l it has reached
approximately 85 °C (use the thermometer to monitor this). Pour this water into the first hot
water bath.
7. Using a hot pad, pour the boiling water from the stove into the second hot water bath.
8. Immediate place the cup holding test tube 1 into the boiling hot water bath and the cup hold‐
ing tube 2 into the hot (but not boiling) water bath. Keep test tube 3 at room temperature, and
place the cup with test tube 4 in the refrigerator. You may need to add weight (e.g., coins, mar‐
bles, rocks, etc.) to the cups going into the water baths to keep them from pping over into the
water.
9. Record the ini al temperatures of each condi on in the table below. Let tubes sit for approxi‐
mately 15 minutes, and record the final temperature.
10. A er the elapsed me, remove the tubes from their respec ve environments.
11. Add 1/4 tsp. of yeast to the refrigerated test tube.
12. Quickly a ach a balloon to the top of the test tube so that it fills with the oxygen produced
from the enzyme reac on occurring in the tube. It is important to execute this step quickly so
that every bit of gas produced is captured.
13. Swirl the tube to mix, and wait one minute.
14. A er one minute has passed, wrap the string around the center of the balloon to measure the
circumference. Measure the length of string with a ruler. Record the length in Table 2 below.
15. Repeat step 14 a er two more minutes have passed (three minutes total from the start of the
reac on); and again a er two more minutes have passed (five minutes total from the start of
the reac on). Record all data in Table 2.
16. If the reac on has not finished, con nue to monitor how long it takes for the reac on to com‐
plete, and measure the final balloon circumference.
17. Repeat steps 11 ‐ 16 for the remaining three test tubes.
Lab 4: Enzymes
61
Table 2: Effect of temperature on the produc on of gas
Ques ons
1. What is the enzyme in this experiment? What is the substrate?
2. How does temperature affect enzyme func on?
3. Do plants and animals have an enzyme that breaks down hydrogen peroxide? How could you
test this?
4. How did the boiling water affect the overall reac on?
5. How can enzyme ac vity be increased?
6. Design an experiment to determine the op mal temperature for enzyme func on, complete
with controls. Where would you find the enzymes for this experiment? What substrate would
you use?
7. Draw a graph of balloon diameter vs. temperature. What is the correla on?
Tube Ini al
Temp. °C
Circumference
(cm) A er 1
minute
Refrigerator
Room temperature
Hot water (~85 °C)
Boiling Water (~100 °C)
Final Temp. °C
Circumference
(cm) A er 3
minutes
Circumference
(cm) A er 5
minutes
Final Circumference
(cm)
Time Required
to Complete
62
63
The Cell
Lab 5
Meiosis
64
Lab 5: Meiosis
65
Introduc on
Meiosis only occurs in organisms that reproduce sexually. The process generates haploid (1n) cells
called gametes (sperm cells in males and egg cells in fe‐
males), or spores in some plants, fungi, and pro sts, that
contain one complete set of chromosomes. Haploid cells
fuse together during fer liza on to form a diploid cell with
two copies of each chromosome (2n).
Genes are the units of heredity that have specific loci
(loca ons) on the DNA strand and code for inheritable
traits (such as hair color). Alleles are alterna ve forms of the same gene (brown vs. blue eyes). Homol‐
ogous chromosomes contain the same genes as each other but o en different alleles. Non‐sex cells
(e.g. bone, heart, skin, liver) contain two alleles (2n), one from the sperm and the other from the egg.
Mitosis and meiosis are similar in many ways. Meiosis, however, has two rounds of division—meiosis I
and meiosis II. There is no replica on of the DNA between meiosis I and II. Thus in meiosis, the parent
cell produces four daughter cells, each with just a single set of chromosomes (1n).
Meiosis I is the reduc on division– the homologous pairs of chromosomes are separated so that each
daughter cell will receive just one set of chromosomes. During meiosis II, sister chroma ds are sepa‐
rated (as in mitosis).
Concepts to explore:
Meiosis
Diploid cells
Haploid cells
Chromosomal crossover
Concepts to explore:
There are over two meters of DNA pack‐
aged into a cell’s nucleus. It is coiled and
folded into superhelices that form chro‐
mosomes, which must be duplicated be‐
fore a cell divides.
Each of the 23 human chromosomes
has two copies. For each chromosome,
there is a 50:50 chance as to which copy
each gamete receives.
That translates to over 8 million possi‐
ble combina ons!
Lab 5: Meiosis
66
Meiosis I:
Prophase I: The sister chroma ds condense and a ach to their homologous counterparts
(chromosomes with the same genes but poten ally different alleles). This is the stage
where crossing over occurs (homologous chromosomes exchange regions of DNA). The
centrioles, which will serve as intracellular anchors during division, appear.
Metaphase I: The chromosomes line up in the middle of the cell. The orienta on of each
pair of homologous chromosomes is independent from all other chromosomes. This
means they can “flip flop” as they line up, effec vely shuffling their gene c informa on
into new combina ons. Microtubules (long strands) grow from each centriole and link
them together while also a aching to each pair of homologous chromosomes.
Anaphase I: The microtubules pull the homologous chromosomes apart (the sister chro‐
ma ds remain paired).
Telophase I: One set of paired chromosomes arrives at each centriole, at which me a nu‐
cleus forms around each set.
Cytokinesis: The plasma membrane of the cell folds in and encloses each nucleus into two
new daughter cells.
Meiosis II:
Prophase II: Before any replica on of the chromosomes can take place, the daughter cells
immediately enter into Prophase II. New spindle fibers form as the nucleus breaks down.
Metaphase II: The sister chroma ds align in the center of the cell, while the microtubules
join the centrioles and a ach to the chromosomes. Unlike Metaphase I, since each pair of
sister chroma ds is iden cal, their orienta on as they align does not ma er.
Anaphase II: The sister chroma ds are separated as the microtubules pull them apart.
Telophase II: The chroma ds arrive at each pole, at which me a nucleus forms around
each.
Cytokinesis: The plasma membrane of the cell folds in and engulfs each nucleus into two
new haploid daughter cells.
We briefly discussed “crossing over” in Prophase I. Since the chromosomes of each parent undergoes
gene c recombina on, each gamete (and thus each zygote) acquires a unique gene c fingerprint.
The closeness of the chroma ds during Prophase I, creates the opportunity to exchange gene c mate‐
rial (chromosomal crossover) at a site called the chiasma. The chroma ds trade alleles for all genes
located on the arm that has crossed.
The process of meiosis is complex and highly regulated. There are a series of checkpoints that a cell
Lab 5: Meiosis
67
must pass before the next phase of meiosis will begin. This ensures any mutated cells are iden fied
and repaired before the cell division process can con nue.
One of the muta ons that is of par cular concern is a
varia on in the amount of gene c material in a cell. It
is cri cal that the gamete contain only half of the chro‐
mosomes of the parent cell. Otherwise the amount of
DNA would double with each new genera on. This is
the key feature of meiosis.
Figure 1: The stages of meiosis
Muta ons that are not caught by the cell’s
self‐check system can result in chromosomal
abnormali es like Down’s syndrome, in
which there are 3 copies of chromosome 21.
Interphase I: Cellular growth and DNA repli‐ca on occur to prepare cell for meiosis.
Metaphase I: Paired
chromosomes align
at metaphase plate.
Prophase I: Sister
chroma ds pair
up. Crossing over
may occur.
Prior to meiosis.
Anaphase I: Microtubules pull
chromosomes to opposite poles.
Sister chromosomes remain paired.
Telophase I: Paired
chromosomes arrive
at polar ends of cell.
Cytokinesis occurs
to bisect cell.
Prophase II: Daughter
cells immediately enter
Prophase II. Nuclei are
broken down
Metaphase II:
Sister chroma‐
ds align at
center of cell.
Anaphase II:
Sister chro‐
ma ds are
pulled apart.
Telophase II: Sister chroma ds
arrive at polar ends of cell. Nu‐
clei are created and cytokinesis
completes bisec on.
Lab 5: Meiosis
68
Experiment 1: Following chromosomal DNA movement
Every cell in the human body has two alleles that condense into single chromosomes held together by
a centromere. These “sister” chroma ds replicate and pair with the newly made homologous chromo‐
somes. In this exercise we will follow the movement of the chromosomes through meiosis I and II to
create haploid (gamete) cells.
Procedure
Meiosis I
A. As prophase I begins, chromosomes coil and condense in prepara on for replica on.
1. Using one single color of bead, build a homologous pair of duplicated chromosomes.
Each chromosome will have 10 beads with a different colored centromere in it.
For example, if there are 20 red beads, 10 beads would be snapped together to
make two different strands. In the middle of each of the 10 bead strands, snap
a different colored bead in to act as the centromere.
Now, repeat these steps using the other color of bead.
2. Assemble another homologous pair of chromosomes using only 12 (that’s 6 per
strand) of the first color bead. Place another, different colored bead in the middle of
each to act is its centromere. Repeat this step (2 strands of 6 beads plus a centro‐
Figure 2: Bead Set‐up
Materials
2 sets of different colored snap
beads (32 of each)
8 centromeres (snap beads)
Blue and red markers*
*You must provide
Lab 5: Meiosis
69
mere) with the other color of beads.
B. Bring the centromeres of two units of the same color and length together so they can be held
together to appear as a duplicated chromosome.
1. Simulate crossing over. Bring the two homologues pairs together (that’d be the two
pairs that both have 10 bead strands) and exchange an equal number of beads be‐
tween the two.
C. Configure the chromosomes as they would appear in each of the stages of meiosis I.
Meiosis II
A. Configure the chromosomes as they would appear in each stage of meiosis II.
B. Return your beads to their original star ng posi on and simulate crossing over. Track how this
changes the ul mate outcome as you then go through the stages of meiosis I and II.
C. Using the space below, and using blue and red markers, draw a diagram of your beads in each
stage. Beside your picture, write the number of chromosomes present in each cell.
Meiosis I
Prophase I
Metaphase I
Anaphase I
Telophase I
Lab 5: Meiosis
70
Meiosis II
Prophase II
Metaphase II
Anaphase II
Telophase II
Ques ons
1. What is the state of the DNA at the end of meiosis I? What about at the end of meiosis II?
2. Why are chromosomes important?
3. How are Meiosis I and Meiosis II different?
Lab 5: Meiosis
71
4. Name two ways meiosis contributes to gene c recombina on.
5. Why do you use non‐sister chroma ds to demonstrate crossing over?
6. How many chromosomes were present when meiosis I started?
7. Why is it necessary to reduce the chromosome number of gametes, but not other cells of an
organism?
8. If humans have 46 chromosomes in each of their body cells, determine how many chromo‐
somes you would expect to find in the following:
Sperm ___________________
Egg ___________________
Daughter cell from mitosis ___________________
Daughter cell from Meiosis II ___________________
9. Inves gate a disease that is caused by chromosomal muta ons. When does the muta on
occur? What chromosome is affected? What are the consequences?
72
73
Kingdoms
Lab 6
Taxonomy
74
Lab 6: Taxonomy
75
Introduc on
Taxonomy is the science of iden fying and naming organisms into related groups, a process called clas‐
sifica on. Originally, taxonomic classifica on of organisms was based solely on structural and physio‐
logical similari es. However, advanced technologies and informa on has allowed scien sts to specify
taxonomic classifica on using gene c informa on (phylogene c similari es) as well.
Over me, many different classifica on systems have been developed. Although many of them are sig‐
nificant, one of the most widely‐accepted system is called the Linnaean system. Carl Linnaeus devel‐
oped the Linnaean system in 1735. This system uses La n because, at the me, it was a language used
by most of the scien fic world. Although many of the exact terms set forth by Linneaus have been sub‐
s tuted, the Linnaean system is s ll respected by many scien sts as the fundamental taxonomic sys‐
tem.
The Linnaean system begins by assuming assumes that there are three kingdoms; the animal kingdom,
the plant kingdom, and the mineral kingdom (which has since been abandoned). Since the Linnean sys‐
tem was established, various life forms have been added to new kingdoms: Monera (for prokaryotes),
Pro sta (for pro sts and most algae), and Fungi. These five kingdoms are s ll far from ideal, and con‐
nue to evolve as scien sts learn more knowledge of genomes con nues to advance. Modern taxono‐
mists have also supplanted these categories by forming domains, the highest taxonomic ranking. The
three domains that are used are: Bacteria, Archaea, and Eukaryota. Each of the kingdoms listed above
are further divided into classes, orders, families, genera, and species.
Linnaeus also popularized the use of binomial nomenclature. Binomial nomenclature is the formal
naming system used for all living organisms. Every organism is iden fied with a two‐part name. The
first name signifies the genus that the species belongs to, and the second name signifies the species
within the genus. Prior to this nomenclature, animals were classified based on how they moved.
The specificity of the organism increases it is classified into smaller, more narrow categories (Figure 1).
In other words, the categories get smaller in terms of the number of organisms that are included, with
the smallest widely accepted category being “sub‐species”.
Concepts to explore:
Taxonomy
Linnaean system
Binomial nomenclature
Taxonomic vs. phylogene c classifica ons
Lab 6: Taxonomy
76
It is important to remember that taxonomy is highly
dependent on biology, par cularly anatomy and
physiology. In fact, one of many, but the most widely
accepted defini on of a species is that its members
can interbreed and create viable offspring. For exam‐
ple, it is physiologically possible for a lion and a ‐
gress to interbreed. However, because their off‐
spring (a liger) is sterile, it is not considered a viable
offspring. Therefore, lions and gers are not consid‐
ered the same species. However, a Labrador Re‐
triever and poodle can produce offspring that are not
sterile (the offspring is commonly called a labra‐
doodle). Thus they are considered the same species.
Remember, this is just one method of defining a spe‐
cies. There are many other tools and defini ons that
can be used to determine what organisms belong to
which species groups.
Looking at Figure 1, imagine you are standing at the
bo om of a large tree with many branches. While
on the ground you can see the whole tree (the trunk, large branches and small branches), but as you
begin to climb up the tree you can no longer see the whole tree, only the smaller branches. It’s the
same concept for classifica on. Star ng at the “bo om” (or the domain) many organisms are includ‐
ed, but as you move “up” the classifica on system, more are excluded and fewer remain. Table 1 illus‐
trates how you would classify a human being and a red maple tree.
Table 1: Classifica on of humans and a red maple tree
As illustrated in Figure 1, the Linnaean system classifies organisms into sequen al groups:
Domain
Kingdom
Example: Human Being Red Maple
Domain Eukarya Eukarya
Kingdom Animalia Plantae
Phylum Chordata Tracheophyta
Class Mammalia Angiospermae
Order Primates Sapindales
Family Hominidae Acerceae
Genus Homo Acer
Species Sapien Acer rubrum
Figure 1: Taxonomy Tree. To use this tree, one
would begin at the bo om and work up.
Lab 6: Taxonomy
77
Phylum
Class
Order
Family
Genus
Species
Sub‐species are used in some classifica ons and is generally well accepted, but not always included in
the Linnaean system.
A useful tool to remembering the order of the
Linnaean classifica on system is developed by
crea ng a mnemonic phrase using the first le er
of each classifica on. For example: Daring Kids
Pick Cauliflower Over Fresh Grown Strawberries.
Experiment 1: Classifica on of common objects
In this exercise, we will take common objects and group them into “taxonomic” categories.
Procedure
1. Spread the materials out on the table.
2. Use the flow chart (Figure 2; located in the back of this lab) to classify the objects. Answer the
ques ons for each object and place them in the proper groups. Fill in all the boxes along the way.
If the box says “ok” in it, only one object fits in this category. Next to that box, write the object
that is being described.
Make your own mnemonic phrase:
_______________________________________
Materials
Pencil* Permanent Marker Marble Bead (hole in the center) Ruler Straw
Washer Hexagonal nut Bu on Figure 2 (flow chart) at the end of the lab *You must provide
Lab 6: Taxonomy
78
Ques ons
1. Did you find that the items grouped together as you worked down the flow chart had similar char‐
acteris cs in terms of their appearance? What about func on?
2. Do you feel that the ques ons asked were appropriate? What ques ons would you have asked?
What objects would be grouped together with your system?
3. Pick 10 household items (e.g. spoon, book, paper clip, etc.) and design a taxonomic classifica on
system to categorize them, similar to the one in Figure 2.
4. Can you devise a different classifica on system for the objects used in this experiment that would
dis nguish each in as many, or fewer steps?
Experiment 2: Classifica on of organisms
Materials
Use Table 2 below as well as the “tree” (Figure 3) a ached at the end
of the lab.
Lab 6: Taxonomy
79
Table 2: Key characteris cs of some organisms
Procedure
1. Select the first organism from Table 2 (E. coli).
2. Use the “tree” (Figure 3; located at the back of this lab) start at the base, and answer each ques‐
on un l the organism reaches the end of a “branch”. Write the organisms name in the green box.
3. Repeat this for the remaining organisms.
4. A er classifica on, fill in Table 2 with the correct kingdom for each organism.
Ques ons
1. Did this series of ques ons correctly organize each organism? Why or why not?
2. What addi onal ques ons would you ask to further categorize the items within the kingdoms (hint:
think about other organisms in the kingdom and what makes them different than the examples
used here)?
3. Do you feel that the ques ons asked were appropriate? What ques ons would you have asked?
Organism Kingdom Defined Nucleus Mobile Cell Wall Photosynthesis Unicellular
E. coli
Protozoa
Mushroom
Sunflower
Bear
Lab 6: Taxonomy
80
Is the object cylindrical or
round?
Yes
Figure 2: Experiment 1: Classifica on of Common Objects Flow Chart
Start
1.
Is the object
used for
wri ng?
Is there permanent ink
on the object?
Is the object metal?
Is there a hole in or near the
center of the object? No
Yes
Is the object smooth on
the outside (no angles)?
Yes
No
2.
Yes No
Yes
Yes
3.
Yes No
Yes
4. 5.
Yes No
Yes 6.
No
Is the object longer
than 5 cm?
7.
Yes No
Does the object
have more than one
hole? 8.
9.
No
Lab 6: Taxonomy
81
Figure 3: Experiment 2: Classifica on of Organisms Flow Chart
Start
Does the organism have a de‐
fined nucleus?
Does the organism
perform
photosynthesis?
Is the organism mobile?
Kingdom:
Plant
Kingdom:
Fungi
Yes
No
Does the organism
have a cell wall?
Kingdom:
Animal
Yes No
Kingdom:
Pro st
Kingdom:
Bacteria
Yes No
Yes No
82
83
Lab 7
Ecology
Ecology of Organisms
84
Lab 7: Ecology of Organisms
85
Introduc on
Organisms have adapted and evolved anatomical, physiological, and behavioral characteris cs that
compensate for varia on within the environment. Organisms have the ability to compensate for mini‐
mal temporal and spa al varia on within their environment by regula ng their body temperature or
controlling the rate at which water is transpired however, there are limits to an organism’s ability to
compensate for environmental factors. No single species can tolerate all of earth’s environments. The
geographic distribu on of a species is thus limited by the physical environment. Species distribu on is
said to be limited by abio c factors or the non‐living components of our environment.
All species have a defined habitat tolerance which is the range of condi ons in which a species can live.
For example, some plant species can tolerate a broad range of soil varia on while others are confined
to a single soil type. If a species has a narrow habitat tolerance because of one or more abio c factors
then they are limited in their distribu on range. Organisms with a broad range of tolerance are usually
distributed widely whereas those with a narrow range have a
Figure 2 Dandelion (Taraxicum officionale)‐ species like the dande‐
lion are very common and show no aspects of rarity making them
very common handling a broad range of tolerances .
Figure 1 Mountain Gorilla (Gorilla gorilla beringei) ‐ mountain gorillas
have a restricted geographic range, a narrow habitat tolerance, and a
small local popula on classifying them in the “rarest” category, this
species is one of many that is highly vulnerable to ex nc on.
Concepts to explore:
Ecology of organisms
Range of tolerance
Concepts to explore:
Lab 7: Ecology of Organisms
86
more restricted distribu on. Habitat tolerance along with a species geographic range (limited vs. wide‐
spread) and the species local popula on size (large vs. small) determine a species commonness or rari‐
ty. Understanding a species range of tolerance helps to determine whether a species is common or
rare which can be a huge determinate in areas such as agricultural produc on and wildlife manage‐
ment.
Experiment 1: Effects of pH on radish seed germina on
Natural soil pH depends on the parent rock material from which it was formed and processes like cli‐
mate. Soil pH is a measure of the acidity or alkalinity of the soil. Acidic soils are considered to have a
5.0 or lower pH value whereas 10.0 or above is considered a strong basic or alkaline soil. The pH of soil
affects the solubility of nutrients in soil water and thus it affects the amount of nutrients available for
plant uptake. Different nutrients are available under differing pH condi ons.
In this lab we will look at the effect of pH on the germina on and growth rate of radish seeds in order
to determine the range of pH tolerance for the seed. Acidic or basic water will be used in order to
s mulate acidity or alkalinity in soil.
Procedure
1. Obtain your petri dishes and label them, one for each solu on
2. Cut out the paper towel to fit inside the petri dish. Wet each individual towel with its determined
solu on (vinegar, sodium bicarbonate, or water).
Materials
Vinegar solu on Radish seeds Sodium bicarbonate solu on Paper towel sheets (cut to fit into petri dish)* pH paper
Water* 3 Petri dishes Ruler * You must provide
Lab 7: Ecology of Organisms
87
3. Test pH of three solu ons and the paper towels containing the solu on, record your values.
4. Arrange 10 radish seeds on each paper towel in each petri dish. Make sure the seeds have space and are not touching.
5. Place the petri dishes in a sunny or well lit warm place. You must be sure to keep the paper towels moist for the length of the lab with the appropriate solu on and make sure that the solu ons re‐main at the same rela ve pH.
6. Observe seeds daily for 7 days and record the number of seeds that germinate (note when the seed cracks and roots or shoots emerge from the seed).
Note: During this observa on period, take pictures to document the radish seed growth. This can be done in a number of ways (example, mobile phone, camera, webcam, etc.). Images can then be scanned , uploaded via USB/cable connec on, etc. onto a computer and be integrated into your final document.
7. On the 7th day record the lengths of radish seed sprouts. Compare and graph sprout lengths below.
Don’t forget to tle your graph and label the axes.
Table 1: Radish Seed Observa on and Germina on
*You will need to expand on the table below to record your observa ons and results for all 7 days.
Solu on pH
Days 1‐2 Day 3 Day 4
Observa on Seeds
Germinated % Observa on
Seeds
Germinated % Observa on
Seeds
Germinated %
Water
Vinegar
Baking
soda
Lab 7: Ecology of Organisms
88
Ques ons 1. Was there any no ceable effect on the germina on rate of the radish seeds as a result of the pH?
Compare and contrast the growth rate for the control with the alkaline and acidic solu ons.
2. According to your results would you say that the radish has a broad pH tolerance? Why or why not? Use your data to support your answer.
3. Knowing that acid rain has a pH of 2‐3 would you conclude that crop species with a narrow soil pH range are in trouble? Is acid rain a problem for plant species and crops?
Figure 3: Sample set‐up for sprout lengths graph.
Seed
Len
gth (mm)
Seed Length vs. Environment Category
89
Appendix
Introductory Biology
Good Laboratory Techniques
90
91
Good Laboratory Techniques
Science labs, whether at universi es or in your home, are places of adventure and discovery. One of
the first things scien sts learn is how exci ng experiments can be. However, they must also realize
science can be dangerous without some instruc on on good laboratory prac ces.
Read the protocol thoroughly before star ng any new ex‐
periment. You should be familiar with the ac on required
every step of the way.
Keep all work spaces free from clu er and dirty dishes.
Read the labels on all chemicals, and note the chemical
safety ra ng on each container. Read all MSDS (provided
on www.eScienceLabs.com).
Thoroughly rinse labware (test tubes, beakers, etc.) be‐tween experiments. To do so, wash with a soap and hot
water solu on using a bo le brush to scrub. Rinse com‐
pletely at least four mes. Let air dry
Use a new pipet for each chemical dispensed.
Wipe up any chemical spills immediately. Check MSDSs for
special handling instruc ons (provided on
www.eScienceLabs.com).
.
Appendix: Good Lab Techniques
A benchcoat will prevent any
spilled liquids from contami‐
na ng the surface you work on.
A B C
Special measuring tools in make experimenta on easier and more accurate in the lab.
A shows a beaker, B graduated cylinders, and C test tubes in a test tube rack.
92
Appendix: Good Lab Techniques
Use test tube caps or stoppers to cover test tubes
when shaking or mixing – not your finger!
Specific instruc ons on prepara on. Weigh out the
desired amount of chemicals, and transfer to a
beaker or graduated cylinder. Add LESS than the
required amount of water. Swirl or s r to dissolve
the chemical (you can also pour the solu on back
and forth between two test tubes), and once dis‐
solved, transfer to a graduated cylinder and add the
required amount of liquid to achieve the final vol‐
ume.
A molar solu on is one in which one liter (1L) of
solu on contains the number of grams equal to its
molecular weight.
For example:
1M = 110 g CaCl x 110 g CaCl/mol CaCl
(The formula weight of CaCl is 110 g/mol)
A percent solu on can be prepared by percentage of weight of chemical to 100ml of sol‐
vent (w/v) , or volume of chemical in 100ml of solvent (v/v).
For example:
20 g NaCl + 80 mL H2O = 20% w/v NaCl solu on
Concentrated solu ons, such as 10X, or ten mes the normal strength, are diluted such
that the final concentra on of the solu on is 1X.
For example:
To make a 100 mL solu on of 1X TBE from a 10X solu on:
10 mL 10X TBE + 90 mL water = 100ml 1X TBE
Always read the MSDS before disposing of a chemical to insure it does not require extra
measures. (provided on www.eScienceLabs.com)
Avoid prolonged exposure of chemicals to direct sunlight and extreme temperatures.
Disposable pipets aid in accurate
measuring of small volumes of
liquids. It is important to use a new
pipet for each chemical to avoid
contamina on.
Lab 22: Plant Reproduc on
93
Immediately secure the lid of a chemical a er use.
Prepare a dilu on using the following equa on:
Where c1 is the concentra on of the original solu on, v1 is the volume of the original solu‐
on, and c2 and v2 are the corresponding concentra on and volume of the final solu on.
Since you know c1, c2, and v2, you solve or v1 to figure out how much of the original solu‐
on is needed to make a certain volume of a diluted concentra on.
If you are ever required to smell a chemical, always wa a gas toward you, as shown in the
figure below.. This means to wave your hand over the chemical towards you. Never direct‐
ly smell a chemical. Never smell a gas that is toxic or otherwise dangerous.
Use only the chemicals needed for the ac vity.
Keep lids closed when a chemical is not being used.
When dilu ng an acid, always pour the acid into the water. Never pour water into an acid.
Never return excess chemical back to the original bo le. This can contaminate the chemi‐
cal supply.
Be careful not to interchange lids between different chemical bo les.
Appendix: Good Lab Techniques
C1v1 = c2v2
Lab 8: Ecological Interac ons
94
When pouring a chemical, always hold the lid of the chemical bo le between your fingers.
Never lay the lid down on a surface. This can contaminate the chemical supply.
When using knives or blades, always cut away from yourself.
Wash your hands a er each experiment.
Appendix: Good Lab Techniques
95
96
1500 West Hampden Avenue
Building 2
Sheridan, CO 80110
888.375.5487 • www.esciencelabs.com