ZO 315 -- COMPARATIVE ANATOMY

EXAM 2

1. FUNCTIONAL SIGNIFICANCE: State the functional significance of 7 of the following 8 items.
You may answer the 8th item for extra credit, but be sure to indicate which one is to be graded
as the bonus by writing "EC" next to the question. [5 pts. each]

a) loss of dorsal aorta between 3rd and 4th aortic arches:
b) antagonistic muscle pairs:
c) ductus arteriosus:
d) hepatic portal system:
e) tendon:
f) elastic walls of truncus arteriosus:
g) cross-sectional area of muscle:
h) foramen ovale:

2. Given the fact that muscle fibers exhibit an "all or none" (contract or relax) response to nerve impulses, how can an animal regulate the strength of contraction of an entire muscle? [5 pts.]

3. In fishes, what is the disadvantage of having two capillary beds in series? What is the significance of this problem in relation to the evolution of the circulatory system? [10 pts.]

4. The pulmonary circuit of air-breathing vertebrates is separate and parallel to the systemic
circuit. What is the advantage of this arrangement? How is this arrangement significant in
the evolution of the heart? [10 pts.]

5. Changes in musculature during the evolution of tetrapods are correlated with the demands
of terrestrial life on the musculo-skeletal system. Describe one specific example of a change
in vertebrate musculature associated with each of the following: (you must answer 3, the
fourth may be answered for bonus credit, but be sure to label the "EC" answer) [15 pts.]

a) mode of support and locomotion:
b) development of head movements independent of the trunk:
c) shift from gill respiration to pulmonary respiration:
d) development of a mobile tongue:

6. Describe three (3) ways in which the mammalian venous system differs from that of other vertebrates. You may include features that are unique to mammals, as well as features that no longer appear in mammals. [9 pts.]

7. How is plasticity involved in the loss of connection between the renal portal vein and
posterior cardinal vein in anuran amphibians? [8 pts.]

8. What are the relationships between muscle fiber orientation and muscle function? [8 pts.]