BIOLOGY
Lab Manual
2006-2007

Link to: Absence From lab Lab Reports Safety Microscope Use Measurement Graphing and Tables

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Lab Manual:

As a biology student you will spend much time in the laboratory. It is here that you will discover the structures and functions of living things and their relationships to one another. And you will learn to use some of the methods and techniques employed by scientists. In addition, you will gain an understanding of how modern scientific research is done which will help you understand some of the current ethical issues facing society. Labs will be a major part of your grade each quarter (40-50%). This makes them very important for both AP Biology and Living Environment.

As part of the Living Environment requirements you must successfully (passing grade) complete 1200 lab minutes to be eligible to take the regents exam. Successful completion means that you must do the experiment and document what you did. In most cases, this documentation is a formal lab report. The grade on this lab report must be passing (65%- before any late points are subtracted or bonus points are added). I will usually refer to "lab credits" a lab credit is a lab in which a 40 minute block of time is spent on hands-on activity. The remaining time is the required pre-lab work as well as documentation.

I. Absence from lab:

If you miss a lab due to being absent from school you will have 1 week from your return to school to make it up. If you know you will miss a lab please come in and do it ahead of time. If you do not make it up before I have put the materials away, I will not get them out again. (reminder, Regents students need 30 lab credits and labs are a major portion of your grade.

II. Lab reports:

Every lab will require a pre-lab. You will need to read each lab before lab class. In many cases, you will be required to answer some questions prior to lab class. These will be part of your lab grade and you must arrive in lab class with them done.

Every lab that you do ( unless you are instructed otherwise) must be accompanied by a written lab report. Lab reports must be done neatly in pen or pencil. Bonus points will be given for typing. Grammar and spelling count. You should write a single lab report for all sections of the lab and staple it to the front of the lab.

The reports should follow the following format: (use headings as shown)
(AP Bio srudents may use this format or the one you use for chem. Just don't forget to include the questions in your conclusion.)

Title: This should be a one sentence description of the lab.

Purpose: This section should tell me what the objectives are in the lab (what you should learn.) or what questions you will be answering in the lab. Generally I will help you with this. be sure that it is a complete sentence. Begin by saying "The purpose of this lab is to

Materials: This must indicate all the materials used in the lab. You may say "see lab sheets" as long as the materials listed there are correct.

Procedure: In this section you must write a 3-5 sentence summary of how you did the lab. Be concise. No credit if you go over 3-5 sentences.

Observations: This part forms the basis of support for your conclusions. It is purely objective, just facts. Illustrations, graphs and data tables should be used if possible. You may say "see lab sheets" in most cases.

Conclusions: Interpret your results. Answer the questions you asked in the purpose. Tell me what you learned in the lab. Be sure to use complete sentences" In this lab I learned..."

Sources of error: list any errors which you might have made. Look back at your purpose and tell me what might have interfered with you reaching your purpose. You should not list human error.

LE students, remember, typing adds 10% to your grade. Ap Bio students, you must type all labs to get full credit (untyped labs strat at 95%)
Don't forget to do your pre-lab!

III. Safety:

We will be working with many potentially harmful substances and materials. Caution must be used at all times.

**If I see that you are not correctly following safety procedures I will give you a warning and I may remove you from lab that period. If you are removed from lab, you will have to stay after school to complete the lab with me as your lab partner.

General Instructions

Listen carefully to the teacher’s instructions and cautions.
Read the laboratory procedures completely, prior to coming to lab class,noting any possible hazards. If you are unsure about any of the procedures, ask your teacher for information.
Do not eat or drink any food or other substances in the laboratory.
Know the location of safety equipment, such as fire extinguishers, fire blankets, first-aid kits,eyewash and fire exits.
Report any accident or injury to the teacher immediately.
Tie back long hair. Do not wear loose-fitting clothing or long, dangling jewelry.
Handle live animals according to community or state health regulations.Do not put anything in teh fish taanks or animal cages.
Keep equipment and work tables clean. Return materials to their proper storage places.
Turn off electrical equipment, gas jets, and water faucets after use or at the end of the laboratory period or if there is a fire drill.
No horseplay.
You must remain at your lab station. No wandering!

Instructions for heating things

Wear safety goggles whenever heating substances in the lab.
Always handle hot test tubes or glassware with tongs or a hot mitt. Never handle heated equipment with your bare hands.
When heating chemicals in a test tube, always point the open end of the test tube away from yourself and others. Follow safety directions for heating various substances.
Keep flammable substances, such as alcohol, away from an open flame.
If you are heating something at your laboratory work station, do not leave it unsupervised.
You must remain standing at all times when heating substances.
If someone’s clothing catches on fire, smother the fire with a blanket. Notify your teacher or laboratory instructor immediately.

Working With Chemicals

Not all chemicals are dangerous. Some chemicals, such as acids and bases, are caustic and can irritate your skin or burn your clothing. Other chemicals are flammable – easily set on fire, or toxic – give off poisonous odors. Special precautions must be taken whenever chemicals are used.

Be aware of any warnings given in a laboratory activity about chemicals.
Follow the procedure for working with particular chemical substances.
When pouring chemicals from one container to another, be careful to avoid spills or drips.
Report any chemical spills to your teacher and follow clean up instructions given.
Wear safety goggles when working with chemicals.
Never taste a chemical or inhale (sniff or smell) the vapors from a chemical. It can be toxic.
Do not mix chemicals together unless you are directed to do so as part of the laboratory procedure.
Never add water to acids or bases.
You must remain standing when working with chemicals.
Do not return chemicals to stock containers unless directed to do so by your teacher.

Handling Dissection Instruments

Wear goggles at all time while you are dissecting..
Be sure a specimen is pinned down before dissecting it.
Never hold a specimen in your hand while dissecting.
Cut away from yourself and others.
Carefully wash and dry all dissection instruments and the tray.
Wash your hands and the lab table thoroughly after dissecting.

IV. Using the microscope:

The microscope is an essential tool for many of the labs we will be doing. You will be tested on focusing the microscope and making a wet mount slide. The following are guidelines for the use and care of a microscope.

* Always carry a microscope with two bands; one on the base and one on the arm.

*Never use anything except lens paper on the lenses of the microscope. Any other paper may scratch the lenses.

* If you spill anything on the stage of the microscope, wipe it up immediately.

*When you have completed using the microscope, be sure that it is clean and dry. Remove the slide from the stage. Rotate the low power objective into position, open the diaphragm all the way. Wrap the cord around your hand and place it over the eyepiece. Return the microscope to the cabinet in numerical order.

**Focus up off the slide. And, never use the coarse adjustment on high power.

1. Place the microscope on the desk in front of you with the arm towards you.

2. Plug it in and turn it on. (Many of our microscopes do not have an on/off switch).

3. Check to be sure that the diaphragm is fully open.

4. Place the slide on the stage, clip it under the stage clips and center it over the hole.

5. Watch from the side as you adjust the coarse adjustment away from you until the objective is all the way down.

6. Looking through the microscope, turn the coarse adjustment towards yourself (up) until you get an image. Get the image in sharp focus by using the fine focus.

To do high power:

7. Be sure the image is really clear on low power. Center the image. Do NOT change the focus . Carefully rotate the high power objective into place. You should have a rough image.( lf not, go back to step 5). Use fine focus only then observe. Use your diaphragm: By controlling the amount of light that you have going through your specimen, you can help clarify images on both low and high power.

Terms:

Working distance: The distance between the objective and the stage.

Total Magnification: eyepiece X objective. All our eyepieces are lOX.

Depth of field: the number of an object which you may observe.

V. Drawings with the microscope:

All drawings must be done in pencil and initialed by the lab instructor. This is your proof that you completed it in lab class.
You will not receive credit for unsigned drawings!

**Be sure to have the lab instructor initial and date drawings!!!

Sometimes we will have to do other drawings. These should also be done neatly and in pencil. Once again, labels should be printed in ink. And, remember to get your drawing signed.

V. Measurement with the Microscope:

When you observe an object with a microscope, you know what the magnification is, but you do not know the actual size of the object. To find the actual size of the object, you must compare the size of the object with something you can measure, such as the microscope's field of view. The field of view of a microscope is all of the space visible through the eyepiece. You can measure the field of view in the following way.

1. Place a transparent metric ruler on the microscope stage as shown in Figure 1. The metric ruler should cover exactly one-half of the stage.
2. Set the objective lens to low power. Focus on the millimeter lines of the ruler.

3. Move the ruler so that one millimeter line is cut in half by the left edge of the field of view, as shown in Figure 2. You will use the center of each line for measuring.

4. Use the metric ruler to estimate the width of the field of view in millimeters (mm). In Figure 2, the field of view is 1 mm plus part of a second mm wide. Estimate how much of the second mm you can see. In Figure 2, you can see .5 mm. Add this to the full mm to find the total field of view in mm. Multiply by 1000 to get the field of view in Micrometers ( microns). This field is 1500 micrometers.

If you know the size of the field of view for a microscope, you can estimate the size of an object you are studying. To do this, you must estimate what portion of the field of view the specimen takes up.

Look at Figure 4. The amoeba shown takes up about 1/4 of the field of view of this microscope. If the total field of view is 1 mm across, the amoeba is 1/4 of 1 mm or 0.25 mm across.
If the amoeba is 0.25 mm in size To get the number of microns (Micrometers) it is you multiply by 1000 micron/ mm so it is 250 microns.

Example #2: Assume that the field of view for a microscope is 2 mm. If a cell being looked at with this microscope takes up 1/3 of the field of view, how big is it in microns.
1/3( 1mm)= .333mm= 333 microns

You cannot measure the width of the high power field of view directly. To calculate the field of view for the high-power objective of a microscope, you can use the following formula:

low power magnification ₌ high power field width
high power magnification low power field width

Assume that a microscope has a lOOX low-power objective, a 400X high-power objective, and a field of view of 1500 microns. Using the formula above, the width of the high-power field of view would be 375 microns.
For example: lOOX ₌ high power field width
400 X 1500 microns

100/400 = 1/4, so the high power width is 1/4 of the low power width, or 1500/4, or 375 microns.

VII.Graphing and tables:

The purpose of a graph is to show relationships between data. They are prepared for the purpose of forming conclusions about the data in an experiment Bar graphs show comparisons between sets of data. Line graphs are used to represent two variables that change. They have two advantages over bar graphs: you can estimate data point between points plotted. In addition, it can be extended to predict data.The dependent variable is the one which changes as a result of the independent variable. Think of it like the results of your experiment. For example, in graph A4 below, the number of pieces of pizza remaining is a result of (dependent upon) the duration of the party. The dependent variable is always graphed on the Y axis. You must label both axis on all graphs with what you are measuring as well as the units you measured it in (e.g.. height in inches). In addition, each graph must have a title telling what it represents.

Tables record data in an orderly and concise manner for ease of interpretation and analysis. If is easier to compare one set of data with another when it is in a table. Columns in a table must also be labels with a title and units where applicable)

Basic Rules for a Good Graph

The following procedure applies primarily to graphs of experimental data that are going to be presented for critical evaluation. It does not apply to the kind of rough sketch thai we often use for purposes of illustration.

Every graph presented for serious consideration should have a good title that tells what the graph is about. Notice that we need more than just a title; we need a GOOD title. Before we try to make a good title, let us look at an example and try to decide what kind of title is a useful one.
Look at Figure A.4.

If you like pizza. it might be very useful to know when this party is being held. Without a title you cannot tell even whether the graph refers to any particular party at all. It might represent average figures for all the parties held last year. or it might represent the expected figures for a party that is going to be held tonight! Let us suppose that these data refer to a study party given by Advanced Placement Biology students on March 9. Here. then. are some possible titles:

(a) The APs Have a Party

(b) Pizza Belongs! Enjoy it with the AP

None of those titles is especially useful or informative, because none of them tells what the graph is all about. Now look at these two titles:

(d) Anticipated Consumption of Slices of Pizza at the AP Biology Party, March 9

(e) Anticipated Consumption of Slices of Pizza at the AP Biology Party, March 9, 199& 7:00PM 11:00PM

You should be able to see that only title (e) is helpful and useful. It enables you to tell, by glancing at a calendar, whether or not you can attend the party and help make that graph fall a little more steeply. The point we are driving at is that a GOOD title is one that tells exactly what information the author is trying to present with the -1. Although brevity is desirable, it should not substitute for completeness and clarity.

Now that you are clear on titles, look at the graph in Figure A.5. Its title tells you that here is some potentially useful information. The graph suggests that at least for 2001, there was an upper limit to the amount of time people could usefully spend in studying for the exam, and you might wonder, for example, how long you would have to study to make a perfect score.

In Figure A.6 below, the additional information has been supplied; information that seems to make the graph more useful to us in preparing for the exam

Figure A.6: Relation Between Study Time and Score on a Biology Exam in 2001

The diagram in Figure A.7 summarizes sorne features of a good graph.

Figure A.7: Relation Between a study time and Score on a Biology Exam In 2001