CHAPTER 39 MOTOR MECHANISMS AND BEHAVIOR
Scientific Skills Exercise
Teaching objective: Students build scientific skills by reading and interpreting a graph with log
scales on the energy costs of locomotion.
Teaching tips: A version of this Scientific Skills Exercise can be assigned in MasteringBiology.
Students may need to review the topic of logarithms. To help them appreciate the scale change
with each tic mark, have them convert the exponential notation to the long form of each number
on both axes.
Answers:
1. To make the small data values distinct, you would have to use scale with small intervals for
each axis; to fit the large data values on the graph with such small scales, you would have to
4. From highest energy cost to lowest: running, flying, swimming. Students may have expected
the energy costs of flying or swimming to be higher than that of running because humans are
Interpret the Data
Figure 39.20 A difference between two individual population lines could arise by a process,
such as genetic drift, that occurs randomly rather than in response to selection. Since the study
found that all three populations in one set behaved consistently and in a distinct manner from the
other populations in the other set, it is extremely unlikely that the difference arose randomly.
Suggested Answers for End-of-Chapter Essay Questions
8. Scientific Inquiry
Sample hypothesis: During sustained contraction, paramyosin prevents binding of new
9. Scientific Inquiry
One likely hypothesis is that the helper is closely related to one or both of the birds in the mated
pair. Because closely related birds share many genes, the helper bird is indirectly enhancing its
10. Focus on Evolution
The two explanations for falling in love (subjective feeling or reproductive fitness) are not
necessarily incompatible. Ultimately, the behaviors and feelings associated with falling in love
may have a strong tie to reproductive fitness. Among modern humans, falling in love is a much
11. Focus on Information
See the general information on grading short-answer essays and the suggested rubric at the
beginning of this document.
Sample key points:
Imprinting is a type of learning strictly constrained by an inherited program of response.
Sample top-scoring answer:
Information inherited in the form of DNA establishes the capacity for learning. For example,
imprinting is based on an innate (and thus inherited) tendency to make a connection with an
12. Synthesize Your Knowledge
Regarding proximate causation, a researcher might ask the extent to which the cooperative
behavior is learned, whether learning is individual or social, and when and under what
circumstances a helper transitions to the breeding population. Regarding ultimate causation, a