BIO 45 -- Exam 1 Answer Key 10 October 2002

INSTRUCTIONS:

1. Put your name on this page only - Transfer the exam number to each page of the exam.

2. Read each question very carefully. You need to figure out exactly what each one asks. Give us concise, short answers. Do not write on the back of the page unless you have had to change your answer. Writing legibly will often help more than adding sentences. We will take off points for errors even if the correct answer is given.

3. When examples are asked for, give preference to well documented ones. Do not use hypothetical or anecdotal information (unless it is asked for). Citing species names and names of those who did the experiments will reduce ambiguity in your answers.

4. Do not use the same example more than once on the exam.

5. If you feel a question is ambiguous - ask for clarification! Some questions are meant to be confusing unless you have a solid grasp of the material. Do not hesitate to ask - some ambiguities are not intended and will be corrected during the exam.

6. Terms:

Explain = Show that you understand what is going on - don't just list facts.

Cite or Identify = Who did the work on what species and some details relevant to the question. If you can't remember names, give enough detail for us to identify the study you mean.

List = You do not have to go into detail. Make sure the items in your list are really distinct.

Briefly = a few well-chosen words or phrases will suffice.

1. This is the final grading key. The grade distribution is posted on the web site. The mean was 38 out of 50 pts.

2. Many points were lost due to your not being able to use the vocabulary and concepts correctly in reading and answering questions. Note the words emphasized with bold and underlined text on the exam and in the answer key below.

3. I will be happy to talk about your exam and to go over it in detail. I ask that you first study the answer key and your exam to see if you can spot some of the reasons you lost points in general as well as in specific cases. If you felt you really understood the material going into the exam (it made sense to you) and did poorly, chances are that you haven't fully come to grips with the difference between something making sense to you and your being able to use it in general and specific ways. We can work on that.

4. If you did poorly on the exam -- especially less than 25 points you need to figure out what went wrong in your approach to the exam. I would like to talk with you about it -- often an adjustment can be made in studying or thinking that will clear up the problem. You haven't ruined your grade yet, but you do need to have a solid grasp of the concepts and terminology since they will be on the next exam as well. Do this before the second exam!!!

5. RE-GRADE REQUESTS:

A. Carefully go through the answer key with your exam.

B. Write me a short note about the problem and leave it and the exam in the envelope on my door in Walter Hall (room 208).

C. Do that before 3 PM Friday 18 October

D. I will go over the entire exam to see if points can be added or taken off.

Bio 45 - 2002 Exam 1 Page 1 EXAM NO.____

1 (8 pts). Cite an example for each of the following:

A. Paternal effects on the development of a behavior.

Mater = mother, Pater = father. These had to be non-genetic effects on behavior development due to male (father's) contributions to the developmental environment.

Grading criteria: Appropriate example-not parental effect, but paternal, how fathers phenotype or genotype affects development of a behavior (not other trait).

Explanation of how example demonstrates paternal effect, show understanding of concept and be able to explain clearly. Citing a specific study better than generalizations. Also, is study correctly explained/interpreted.

Answers that got up to 4 pts: Mest gene in mice, seahorses

Answers that got up to 3 pts - oystercatchers (both parents care for young), water bugs, song tutoring by male birds (not often the father who does it)

B. Developmental homeostasis

My oversight - this material is in pages 103-109 in Alcock and thus not information you read.

Everyone who answered the question received 4 pts

2. (8 pts.) One of the following statements is false. Briefly explain why it is false.

1. "It is not possible to demonstrate a genetic basis for behavioral traits unless you can identify the gene(s) involved."

2." In order to study how natural selection acts on individuals with a particular trait, you do not have to know if the trait has a genetic basis."

Statement _1__ is false because ...

You can show a genetic basis by:

Response to selection experiments, transplant experiments, hybridization studies, and Mendelian crosses. You needed to point out one of the techniques used.

Note: you need to have explained your answer not just stated it.

Saying "show that it breeds true" got no credit because it did not answer the question (how do you show a genetic basis? You show there is a genetic basis.)

3. (8 pts) Answer both of the following:

A. Under what circumstances would a trait that improves the survival chances of an organism be an adaptation?

If it has a genetic basis. This was the necessary answer. For the detailed definition of adaptation, the historical origin is also necessary - "selected for" is covered by the statement

B. Under what circumstances would a survival-enhancing trait be selected against? Just identify and explain one.

This one caused trouble for two reasons:

1) Some of you read the question such that a survival enhancing trait could become non-survival enhancing if selection (environment) changed). The statement actually says that the trait is survival enhancing period. Thus the answers would include, trade-offs, constraints, lowers reproductive success.

2) You had to identify (use and example) and explain one. Not just say why.

Bio 45 - 2002 Exam 1 Page 2 EXAM NO.____

4. (6 pts) There Is a lot of debate over whether or not dogs see color. Briefly describe an experiment you could do to find out if they can. Obviously, you would model it after one you had read about in this course. Just tell us the basic behavioral test you would do to determine the presence or absence of color vision.

This question asked if you read and understood the basic approach used by Bigersson et. al. In their study of color vision in fallow deer.

1. see if the dogs could distinguish between a color and a gray (achromatic)

2. control for brightness, such that it could not be used as a clue

The question could not be answered by using two colors, or by testing for colorblindness

5. (8 pts) Ignatz has been studying a population of frogs in Rhode Island. A few years ago he started seeing frogs with red spots. Over the next few years the frequency of frogs with red spots increased until most frogs in the population had them. He claims that the red spots are adaptive. You can think of two alternative explanations for the increase in red spotted frogs.

His claim is that it is adaptive. Your hypotheses have to be alternatives to his. Thus an adaptive explanation for the red spots was not a correct answer.

We gave credit for genetic drift even though it is highly unlikely.

Best answers were: hitchhiking (trait linked to one under selection), a disease, an environmental effect (changing environment = causing red spots)

Combining "chance" and "drift" or "incidental effect" and "hitch-hiking" got only 4 pts since they overlap too much as causes.

6. (12 pts) Chipmacs (like chipmunks but with golden arches on their sides) live underground in Styrofoam nests. Each day they go out to find French fries which they bring back and store in their nests to eat at night. Zelda noted that chipmacs often sit up on their hind legs and sniff the air. She hypothesized that they use smell to find their nests. She tested this hypothesis by showing that the frequency of sniffing was greater when they were further away from their nests. She also showed that they sniffed vigorously when they first emerged from the nest -- as if they were memorizing the smell of the nest area. Ignatz says Zelda did a weak test and is wrong.

A. (4 pts) Why is Zelda's test a weak one? Just a sentence here -- no essay!!

She only tested one hypothesis. She used correlation rather than a direct test

B. (8 pts) Briefly describe the experiment you would do to make a strong test of the function of sniffing. By the way, chipmacs will die if you touch them.

Most of you read the question as how she would test the function of sniffing – finding nest versus another function (e.g., detecting predator, food, mates).

Many of you read the question as how she would test the "how do they find their nest" question. (note that "function of sniffing" was in bold type and underlined).

We decided to give you credit if you could make a strong test of either reading of the question.

That means:

propose an alternative to her one hypothesis

describe a test that would distinguish between them – or exclude one of them

Identify any necessary controls (if you did a manipulation – e.g., adding an odor)

NOTE: describing and experiment to test Zelda's hypothesis is not doing a strong test – you have to be testing relative to another hypothesis or at least a null hypothesis. If it was unclear that you were doing so, we took off points.