Botany 101 Lab ManualTacoma Community CollegeBiology Laboratory: Safety, Procedures, Emergencies

1. No open food or drink is permitted in the lab at any time, whether a lab is in progress or not. No eating, drinking, chewing of gum or tobacco is permitted. Never taste anything at all while in the lab rooms.1. Know the locations of the eye wash and shower stations, fire alarm, fire extinguisher, first aid kit, and emergency exits.1. Safety instructions are given at the beginning of each lab period. Always arrive on time so that you know what you are supposed to do and are informed of any specific safety concerns or safety equipment associated with the days lab activity.1. Wear any required personal protective equipment (lab coat, apron, goggles, etc).1. Stash book bags safely so that they wont trip people.1. Report all illnesses, injuries, breakages, or spills to your laboratory instructor immediately.1. Clean broken glass (glass that is not contaminated with any chemical reagents, blood, or bacteria) can be swept up using the dust pan and placed in the broken glass container. If the glass is contaminated in any way, keep the area clear to prevent tripping or laceration hazards, and consult your instructor for proper disposal guidance. A broken glass flow-chart is available in the lab to help you decide what to do. 1. Notify your instructor if any of the equipment is faulty.1. Clean up your entire work area before leaving. Put away all equipment and supplies in their original places. Disinfect your work surface if the lab activity involved any infectious materials.1. Use the appropriate waste containers provided for any infectious or hazardous materials used in lab.1. Safety information about hazardous chemicals used in the lab activities can be found in the Material Safety Data Sheets (MSDS), located in the Right-to-Know Binder in the safety station. We (faculty and students) should be fully aware of the properties of the chemicals we are using. Please use the MSDSs. If you cannot find the MSDS for the reagent you are using in lab, inform your instructor. They are also relatively easy to find online. A keyword example is Sodium Chloride MSDS.1. Use caution with the lab chairs. Because they are on casters, the can roll away when you are standing at your workstation. Make sure your chair is where you expect it to be before sitting down. Do not use your chair as a means of moving from one part of the lab to the other.1. Wash your hands before leaving the lab room.

Laboratory 1: Pea Lab - Principles of the Scientific MethodAdapted by permission from Steve Brumbaugh from the Green River Biology Lab Manual

Exercise: Applying the Scientific MethodThe work required for this lab spans about four weeks depending on a number of factors. Your instructor will explain the methods of storage for your experimental set-ups, and how to arrange for the use of the rooms and greenhouse to do your work.

Pre-lab AssignmentBefore coming to lab carefully read the sections of your textbook regarding the scientific method and the pages of this exercise then answer the pre-lab questions.

Goals of this Lab Exercise To understand the mechanisms used in the scientific method Design an experiment and carry out the steps of a scientific experiment To work cooperatively in establishing a protocol for a scientific experiment

IntroductionIn its simplest form, an experiment involves a check or control group compared with an experimental or test group. The control is held under constant conditions while the test group is exposed to the affects of various factors, one at a time. Any changes that occur in the test group, but not in the control group, are assumed to be the result of the condition that is changed. Each treatment, including the control, should be replicated, and the replicate organisms should be carefully distributed so that no individuals being treated will be favored more than others. In the activity that follows, you will design your own original experiment.

Materials (per group of four students)20 Little Marvel pea seeds and 2 flower potsAtomizer containing gibberellic acid solution

Growth medium (vermiculite in greenhouse)Atomizer of de-ionized water

Procedure

Each team should decide on its organization, discuss the problem/hypothesis, and plan the experiment. Gather the materials needed and begin the activity. Prepare your seeds planting by following the following method. 1. Seed Preparation - Place 20 pea seeds in a beaker and cover them with tap water so that the water level is about 2 cm above the level of the pea seeds. Label the beaker with team identification and date. Place it in a dark cupboard in the biology lab and let the pea seeds soak overnight (i.e. 12-24 hours). The soaked seeds should now be planted as directed below.2. After the seeds have soaked overnight take them to the greenhouse. Prepare 4 flowerpots by adding moistened soil to each. The containers should be about 3/4 full. In each pot, place 6 soaked seeds. Cover the seeds with another inch of moistened soil. Label each pot with team identification and date and keep them in the greenhouse. Keep the medium moist, but not soggy wet.3. When the seedlings are 2-3 cm high measure their height in millimeters. This is done by measuring the distance from the growth medium surface to the tip of the shoot apex. Measure each seedling and record your data. These lengths are the initial measurements. You will now apply your experimental treatment to your experimental group. First you need to decide what your experimental treatment will be! You can use one of the following suggestions, or come up with your own. If you use your own, please check your ideas with your instructor. a. Spray plants with gibberrelic acid, a growth hormoneb. Add a few fertilizer pelletsc. Grow your plants under blue or red lightd. Grow your plants in the shadee. pinch your plants when they are about 4cm high (this means plucking off the uppermost leaves)f. Grow your plants outside the greenhouse

4. On each day of class, measure & calculate the average number of leaves per plant, the average internode length, and the average height per treatment. Record your data on the data table in your in-lab report sheet.

Figure 1 Plant Anatomy This drawing is to be used to guide the measurement of the inter-node length.

Report SheetName .Pea Lab ExerciseGroup Names . . . .

Table1: Average internode length, number of leaves per plant, and height for the pea plant experimentDateAve. internode length (cm)Ave. # of leaves per plantAverage height (cm)Observations

Experimental Group

Control Group

Experimental Group

Control Group

Experimental Group

Control Group

Experimental Group

Control Group

Experimental Group

Control Group

Experimental Group

Control Group

1. Prepare a graph of the average daily heights for both the experimental and control groups. Properly title and label your graph (Appendix A). Graph both sets of data on the same graph by using different colors and a key. Attach this graph to your lab. In the space below, explain the results and trends seen in your graph:

2. Prepare a graph of the average internode lengths for both the experimental and control groups. Properly title and label your graph (Appendix A). Graph both sets of data on the same graph by using different colors and a key. Attach this graph to your lab. In the space below, explain the results and trends seen in your graph:

3. Prepare a graph of the average number of leaves for both the experimental and control groups. Properly title and label your graph (Appendix A). Graph both sets of data on the same graph by using different colors and a key. Attach this graph to your lab. In the space below, explain the results and trends seen in your graph:

4. What correlation(s) did you observe between number of leaves, internode length, and plant height?

5. List at least two observations of similarities and/or differences in the general growth of the experimental and control plants other than the observations recorded in question 4 above.

6. List at least three possible sources of error that may have influenced the data you collected.

7. Suggest 3 ways to provide more valid data or show other pertinent results. Be specific!!!

8. Did you confirm your hypothesis? YES / NO (Circle One)

Pre-Lab Report SheetPea Lab ExerciseName_________________________________

Note:Answer the following six questions before coming to lab, but after having read the previous pages of this handout!

1. Write a hypothesis using the "If .... Then" format for this experiment.

2. What is the independent variable for your pea experiment?

3. What is the dependent variable(s) for your pea experiment?

4. Name at least three controlled variables in the pea experiment?

5. Give a brief explanation of your experimental design:

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Laboratory 2: Microscopy

Parts of the Swift M5 Microscope

HeadpieceOcular lens (10X) Objectives 5X (red), 10X(yellow), 40X(blue),100X(white)Mechanical Stage holds the slide, is moved with the mechanical stage controlMechanical Stage Control moves the slideForward, back, left, and rightIris Diaphragm Lever controls the light that enters the condenser.Light SourceCondenser Lens Control Raises and lowers condenser lensLight Intensity ControlFine FocusCoarse FocusPower SwitchCondenser Lens focuses the light from the source. The blue filter is attached to the bottom of the lens, beneath the iris diaphragm.Arm

Microscopy

PurposeThis lab is designed to give the student a basic understanding of microscopy, and introduce proper techniques for using a compound, light microscope. The primary objectives of this lab are for the student to: Understand the importance of microscopy in viewing individual cells. Identify the parts of a compound light microscope and their function. Demonstrate and practice proper techniques for use and care of a compound light microscope. Make a wet mount slide preparation.

BackgroundThe basic unit of life and the smallest hierarchical level that can be considered alive is the cell. All living things, simple or complex, are made of cells and much has been learned through their analysis. The human eye is able to resolve objects less than a millimeter (1.0 mm) in size, but not much smaller than that. Although there are some cells that can be observed with the naked eye (human egg cell, squid giant axons, etc.) most cells are too small to be viewed without assistance. Today, in order to visualize small specimens such as individual cells, a light microscope is most commonly used. The first light microscopes were invented in the 17th century AD by Anton Von Leeuwenhoek, Von Leeuwenhoek was able to achieve a magnification of approximately 270X. The invention of the light microscope opened up a new world for biologists to study, and the field of Microbiology was born. Todays modern light microscopes are capable of magnifying images over 1000X, enough to clearly see even some of the smallest cells.

Exercises:

Part A: Using the Swift M5 Microscope and Viewing a Letter e

1. Carrying the Microscope: Always use two hands, one of which should support the base while the other holds the arm of the microscope. Microscopes contain delicate optical structures that could be damaged through impact. Thus, be very careful and gentle when setting down the scope and moving it.2. Setting up: The eyepieces (oculars), condenser lens, and light source should be clean and dust-free. You may want to wipe these surfaces with a lens-grade Kim Wipe prior to using the microscope.3. You will now prepare a wet mount of a letter e. Follow the steps below. You will use this slide to become oriented with using the microscope and to learn how to measure the field of view.a. Obtain a clean glass slide and a letter e.b. Place the letter e in the center of the slide, and, using the water dropper bottle, place a drop of water over the letter e.c. Place a cover slip over the drop of water and letter e. 4. Ensure that the lowest power (red) objective is pointing at the stage before placing your slide on the stage.5. Place your slide on the stage. Look at the stage, not through the eyepieces. Use the mechanical stage controls to position your slide such that the letter is directly over the condenser lens.6. Move the iris diaphragm lever to the left and use the condenser lens knob to raise the condenser lens to the highest position possible. Find the knob that raises and lowers the condenser lens under the left-hand side of the stage. You should not loosen the condenser lens with the pins that are used to hold it under the stage. 7. Turn on the microscope and use the rheostat wheel on the front of the stage to adjust the light so that it is not too bright or dim go for what is comfortable for your eyes.8. Look through the eyepieces- dont worry about focusing yet. What do you see? Two circles, one blurry circle, or one clear circle? Do not worry about whether you can see the slide clearly all you should be focusing on right now is the circle if you see two circles, you need to push your eyepieces together a bit. If you see a blurry circle, you need to widen them. When you find the right distance for your eyes, look at where the dial is between the eyepieces. You can select the best distance for you using that number whenever you need to use your microscope for the rest of the quarter.9. Finally, set the ocular lens focus. Bring the e into focus using the coarse focus knob and then the fine focus knob. Look through the right eyepiece with your right eye close your left eye. Use the fine focus to make the image as sharp as possible. Now look through the left eyepiece with your left eye and close your right eye. If the image is blurry in any way, sharpen it by rotating the left eyepiece clockwise or counterclockwise. 10. With each slide, ALWAYS start with the scanning (4X, red) objective. With the 4X objective, you may start with the coarse focus knob and then use the fine focus knob to sharpen the image. Look at your e. Draw what you see in on the In-Lab Report Sheet #1. 11. Next, look at the slide with the low power (10X, yellow) objective. The objectives should be parfocal, which means that you should only need to use the fine focus knob. Note how the objectives increase in length with magnification power. The coarse focus moves the stage up and down, and you may run the slide into the objective if you use coarse focus with the longer objectives. Draw what you see in the report pages. Draw what you see in on the In-Lab Report Sheet #1. 12. Finally, look at the slide with the high power (40X, blue) objective. Again, only use the fine focus knob you can turn it in either direction to sharpen the image. If the image does not become clear in a couple rotations in one direction, you should probably rotate the focus knob in the other direction. Draw what you see in on the In-Lab Report Sheet #1. 13. With your letter e slide still in place, answer the rest of the questions under part A on your In-Lab Report Sheet.14. When you are finished viewing your letter e, return it to the small dish from where you collected it. It will dry out. You can re-use your slide and cover slip for a later exercise.

Troubleshooting

The light doesnt work Ensure that the worktable is plugged in the worktables should be plugged into overhead electrical outlets. If your table is not plugged in, it wont have power. Ensure that your power cord is properly inserted into the base. The power cords are removable and sometimes come loose. Ensure that the rheostat is not dialed all the way down. If you have tried all of the above, and the light still does not work, notify your instructor. The lightbulb, power cord, or fuse may need to be replaced. Your instructor may have you use a different microscope for the time being. If your instructor is unable to repair the microscope, the lab technician should be notified.

I cannot see anything. Ensure that the scanning (4x, red) objective is fully locked into place. Make sure the light is on. Make sure your slide is centered properly and not upside down. Check the condenser to make sure the iris diaphragm lever is set to the left. You will need to use the coarse adjustment knob to raise the stage so that the slide is quite close to the objective before an image can be seen. If you have tried all the above and still cannot see anything, notify your instructor. You may be directed to put away your microscope and use a different one. In this case, the lab technician should be notified.

The image is blurry. First, make sure you followed all of the focusing steps described in steps 2 through 11. CLEAN EVERYTHING. Clean the ocular lenses, the light source, the condenser lens, the objective, and the slide. DO NOT REMOVE ANYTHING. You should be able to clean the objective without removing it. Make sure the slide is not upside down! If youve tried all of the above, and the image is still not sharp, please notify your instructor. Your instructor may attempt further cleaning or direct you to put the microscope away and use a different one. The lab technician should be notified in this case.

Putting the Microscope Away1. Select the scanning (4x, red) objective, and remove your slide from the stage.2. If you used methylene blue or any wet mounts, gently wipe the high power (40x, blue) objective with a dry lens tissue. If it is clean and dry, use the same tissue to wipe the eyepieces and stage. If you see fluid or stain on the tissue, use a small amount of lens cleaner to wipe the objective. Then wipe the eyepieces and stage.3. Center the mechanical stage so none of the gearing is hanging out on the side. The electrical cord should be bound with the velcro strap.4. Carry the microscope properly and place it in the appropriately numbered space in the cabinet with the arm facing outward. When the arm is facing outward, the number is visible, and the scope is more easily retrieved from the cabinet.

Parking Tickets5. If you put away your microscope improperly, the next user may write up a ticket and attach it to your microscope. 6. If you find something wrong with your microscope, notify your instructor. If it was put away improperly, you can write a ticket, and attach it to the arm so that it is visible from outside the cabinet. Your microscope will probably be used by at least 10 other students this quarter. The purpose of the tickets is to foster awareness for proper handling and use of the microscopes. They are very expensive, useful tools for your learning and should be respected as such.

Part B: Wet Mounts of Plant Cells1. Obtain one leaf of the water plant, Elodea. Make a wet mount of the leaf2. Properly focus the microscope and view the individual cells under the highest magnification. 3. Draw several cells (they are rectangular), paying attention to details and scale.4. Obtain a piece of red pepper. Using a razor blade, make a very thin slice of the pepper.5. Make a wet mount of your pepper slice.6. Draw several cells (they are rectangular), paying attention to details and scale.

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Lab 2: Microscopy In-Lab Report Sheet Your name_______________________________________________ Section____________Your group members names: ________________________________________________________________________________________________________________________________________________________

Part A: Using the Swift M5 Microscope and Viewing a Letter e

1. Wet Mount Letter e Slide. Draw the letter at three different magnifications.

________X________X________X

2. Looking at the drawings of your letter e above, what is magnification?

3. Slowly move the slide away from you using the mechanical stage control. Which way does the image move?

4. While looking into the ocular, slowly move the slide to the left. Which way does the image move?

5. Make a rough estimate of how much of the letter is visible when viewed under high power? (Give a percent based on the differences in the size of the field of views)

6. Why is it necessary to center your object (or the position of the slide you wish to view) before changing to high power?

7. Under high power is the illumination brighter or less bright than it is with low power?

8. Is it more desirable to increase or decrease the light when changing to a higher magnification?

Part B: Wet Mounts of Plant cells

________________________________X

________X________________________

Lab 3: Identifying Organic Compounds in PlantsName________________________Names of Group members___________________________________________

Introduction: This lab will introduce some simple qualitative methods for identifying basic types of organic compounds. Read through the lab, and the chapter on organic molecules in your book, and then answer the prelab questions at the end of the lab

I. CarbohydratesIa. Simple SugarsThe basic formula for simple sugars is (CH2O)n: where n is three or some greater number. For some of the most common sugars n = 6 and, hence, their formula is C6H12O6. Sugars with this formula include both glucose and fructose. Both of these sugars react with Benedicts solution as do all simple sugars.

Procedure (work in pairs):1. Take 5 ml of dilute honey and add 1 ml of Benedicts solution in a test tube. Heat this tube in beaker of boiling water. What do you observe?

This is a positive test for simple sugars such as glucose and fructose.

2. Repeat this test using a solution of sucrose (table sugar). Do you get a positive reaction?

3. Again add 5 ml of distilled water to a test tube. Place a piece of apple into the tube and crush it with a stirring rod. Pour the water into a clean test tube and test with Benedicts. Does apple have simple sugars?

4. The sugars in honey and apple are both monosaccharides. Given that honey is simply nectar gathered from flowers, what is the function of the sugars in nectar and fruit (how do they help the plant to survive to reproduce)?

5. Table sugar is processed from stems of the grass, sugar cane. Chemically it is the disaccharide, sucrose. Each molecule of sucrose consists of one glucose and one fructose bound together. With this chemical bond, electrons are not available to reduce the copper ion in Benedicts solution, hence, the negative reaction. Sucrose is the sugar transported by the phloem of plants. Speculate about why it may be adaptive for plants to produce monosaccharides in fruits and flowers, but transport sugars in their tissues in the form of a disaccharide.

Ib. Starches are long chains of the simple sugar glucose. Starch is easily identified using a solution of iodine and potassium iodide (I2KI).1. Fill a test tube one third full of distilled water, and add 2 drops of starch suspension. Swirl the tube and add one drop of I2KI. What happened? ________________________This result indicates the presence of starch.2. Cut a very thin slice of potato and make a wet mount using distilled water. Observe the tissues at 400x and make a drawing. Remove the slide. Put a drop of I2KI on one edge of the cover slip and blot water from the other edge using tissue paper. Put the slide back under the microscope and observe any changes. Draw the stained tissue.

Unstained Stained

3. Working with your partner take a precut corn grain and treat the cut surface with I2KI. Specifically what tissue of the grain tests positive for starch (see diagram below)?__________________________- Save this corn section for reference in Part III.

embryo

II. LipidsLipids are not one chemical class of molecules like carbohydrates. However, all lipids are nonpolar: they do not mix in water and they will dissolve certain nonpolar substances that will not dissolve in water. Triglycerides, phospholipids, waxes, and steroids are all examples of lipids. In this exercise we will consider only the triglycerides, which are commonly known as fats and oils.Procedure: Take a piece of peanut seed, cut a very thin slice and make a wet mount of the tissue. Observe the tissue under both low and high power. Now add I2KI as described previously and observe the distribution of starch in the tissue. Add Sudan IV stain to your wet mount using the same procedure previously described for adding I2KI to a wet mount. This stain is nonpolar and will move into the lipid droplets residing in the tissue.1. Can you think of why it may be more adaptive for a plant to store food in the form of oils in a seed than in the carbohydrates of a tuber?

2. Why dont animals lay down long-term energy stores in the form of starch?

III. ProteinsFrom your text you know that proteins are polymers of amino acids. The general formula of an amino acid is given below:

There are twenty different amino acids found in living systems. Each of these has a different R group. A huge number of proteins can be formed using different combinations of these twenty. One test for proteins uses concentrated nitric acid. The acid reacts with the R groups of certain amino acids.

III. Identifying Protein in a Corn Grain **This procedure will be demonstrated by your instructor, under the fume hood.Procedure: Observe the corn kernel you tested earlier with I2KI. Note where starch is located. Take another dry corn kernel that has been cut longitudinally, and place it in a petri dish. Add two drops of concentrated nitric acid to the cut surface of the half-kernel: be careful not to breathe the fumes!!! Wait three minutes and check for a yellowish coloration indicative of proteins. Compounds other than proteins will turn yellow after this treatment. To specifically test for the presence of proteins, add two drops of concentrated ammonium hydroxide to the yellowish tissue. Proteins should turn orange after this check step.WARNING: Both nitric acid and ammonium hydroxide are extremely caustic. Protect your eyes! Use safety glasses while working with the reagents, and avoid rubbing your eyes after using them until after you rinse your hands. Avoid breathing the fumes of either.

1. In what tissue is starch concentrated?

2. In which tissue is protein concentrated?

3. Why do you think starch and protein are located in different regions of a corn kernel?

Prelab Questions for Lab 3: Identifying Organic Compounds in Plants

Name_____________________________________

These questions must be answered from the lab introduction materials and turned in at the beginning of lab.1. What are the four main groups of biological macromolecules?

2. What is the monomer (building block) for each of these groups?

3. What monomers make up the polysaccharide starch?

4. I2KI is used to test the presence of which molecule?

5. Benedicts test is used to test the presence of which molecule?

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Lab 4: Cell Structure & Function

PurposeThis lab is designed to give the student a basic understanding of plant cell structure and function. The primary objectives of this lab are for the student to: Demonstrate competency with utilizing a light microscope including the visualization of both eukaryotic plant cells. Describe the structure of the major cell organelles and discuss how that structure facilitates the organelles specific functions. Demonstrate knowledge of safe lab practices. Demonstrate slide preparation and identification of stained and unstained structures.

Background

Elodea canadensis is a freshwater aquatic plant. It is native to North America but is an invasive species in most of the rest of the world. Elodea spends most of its life cycle entirely underwater, providing habitat for many protists and aquatic insects.

Laboratory Exercises

Part A: Kingdom Plantae1. Observation of Elodea. Prepare a slide of a leaf that has been vitally stained with Janus Green B. This is a vital stain. It colors the living mitochondria and membranes of the nucleus and vacuole making them more visible.2. Observe the plant cells under the highest magnification. 3. Look for cells exhibiting any internal movement. Scan the cells in your leaf until you find one demonstrating an obvious flowing movement of the chloroplasts around the edges of the rectangular cells. This movement is called cytoplasmic streaming. It is facilitated by the same two proteins responsible for muscle contraction in animals (actin and myosin). While observing a streaming strand of cytoplasm, look carefully for spherical structures about 10% of the diameter of the disc of the chloroplasts. These are mitochondria. Locate a nucleus (if you havent already). Often they will be found against one side of the cell in which case they will be hemispherical in outline. 4. Sketch several cells. In one cell, label the chloroplasts, mitochondria, vacuole, cell wall, and nucleus.5. Answer questions on your In-Lab Report SheetPart B: Plant cell structures6. Label the organelles of the plant cell

Part C: Diffusion and Osmosis in Plant Cells

1. You will view plant and animal cells in three different kinds of solutions: pure water (Solution A), 10% NaCl (table salt, Solution B), and 0.09% NaCl (Physiological saline, Solution C). 2. Label four microscope slides A, B, C, and D. Divide and conquer: have each person in your lab group prepare one of the four slides and view with the microscope under the highest magnification.3. Prepare the plant slides as follows: Slide D: place an Elodea leaf on the slide and add a cover slip. Observe the cells under the highest magnification. Sketch several cells on your In-Lab Report Sheet. Notice the size of the vacuoles and the distribution of chloroplasts. Can you see any of the chloroplasts moving? Slide A: place an Elodea leaf on a slide and add a drop of solution A. Add a cover slip. Observe the cells under the highest magnification. Sketch several cells on your In-Lab Report Sheet. Notice the size of the vacuoles and the distribution of chloroplasts. Can you see any of the chloroplasts moving? Slides B: Follow the same procedure as Slide A above, using solution B instead. Let the slide set for 5 minutes before viewing under the microscope. Slide C: Follow the same procedure as Slide A above, using solution C instead. 4. Answer questions on the In-Lab Report Sheet.5. Clean up: place all slides in the used slides container. Wash hands thoroughly and put microscopes away. Wipe down the surface of your lab counter with detergent to clean up any solutions that might have leaked or spilled.

Lab 4: Cell Structure & FunctionIn-Lab Report Sheet Your name_______________________________________________ Section____________Your group members names: __________________________________________________________________________________________________________________

Part A: Kingdom Plantae

__________________________

________X

1. Describe the distribution of the chloroplasts

2. What is the process called by which plants turn light into energy? ___________3. In which organelles does this process go on? ___________4. Give two examples of structures/organelles that are found in plant cells but not in animal cells. _______________________ ______________________5. What substance are plant cell walls made of? ________________________

Part B: Plant cell structures

6. Label the structures on the diagram below

Part C: Diffusion and Osmosis in Plant Cells1. Sketch several Elodea cells under the highest magnification in the circles below. Be sure to show the overall size, shape of the cells. Also note the distribution of chloroplasts and the size of the vacuole.

Slide D: Elodea only Slide A: 100% DI H20 Slide B: 10% NaCl Slide C: 0.9%NaCl

1. Which of the three solutions was hypotonic to the Elodea? Thoroughly explain your answer, describing the movement of water and the overall appearance of the cells.

2. Which of the three solutions was hypertonic to the Elodea? Thoroughly explain your answer, describing the movement of water and the overall appearance of the cells.

3. Which of the three solutions was isotonic to the Elodea? Thoroughly explain your answer, describing the movement of water and the overall appearance of the cells.

4. Elodea is a plant that has evolved in pond water. Thus we should expect it to be fairly well-adapted to its habitat. Would you expect pond water to be isotonic, hypo-tonic, or hyper-tonic to Elodea cells and why?

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Pre-Lab Assignment for Lab 4: Cell structure and function

Name__________________________________________ Section________

Directions: Please read the entire lab following this assignment before attempting to answer the following questions. Use the information in the lab and your textbook or lecture notes to help you answer the following questions

1) What is Elodea?

2) What is cytoplasmic streaming?

3) What molecule makes up the bulk of a plasma membrane? What is significant about the head and tail regions of that molecule?

4) What is the difference between diffusion and osmosis?

5) What is the difference between active and passive transport mechanisms? Thoroughly define each.

6) Go to the following website and watch the transport videos for Elodea cells in hypertonic, hypotonic, and isotonic environments. http://www.linkpublishing.com/video-transport.htm (alternatively, your teacher may show this in class).

a) What happened to Elodea when paced in a hypertonic environment?

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