BISC 102 - SAMPLE FINAL EXAMINATION

SECTION I.
Questions in this section require short answers of a few words or sentences.

1. In the circulatory system of a dog, the total cross-sectional area of the aorta is 0.8 cm². The total cross-sectional area of all capillaries is 600 cm². How does this difference in cross-sectional area of blood vessels facilitate exchange of dissolved materials between the blood and the tissues?

2. List the three conditions necessary for natural selection.

3. Distinguish clearly between the following pairs of terms:
a. Stabilizing selection / Directional selection
b. Determination / Differentiation

4. In the honeybee, all males (drones) are haploid and all females (queens and workers) are diploid. Why are recessive mutations such as white eye color observed much more frequently in drones than in workers?

5. Name two events during meiosis that contribute to genetic variation in the resulting daughter cells.

6. List the gametes that could be produced by a parent with the genotype AabbCC.

7. What biological traits define a female? a male?

8. Clearly explain how courtship may function as a reproductive isolating mechanism.

9. Geerat Vermeij has documented a number of features of the fossil record that demonstrate an evolutionary escalation in predator-prey interactions. Name four such features of the fossil record, illustration each one with a specific example.

10. a) Would genetic drift act to increase, decrease or maintain the genetic variation within a population?
b) Would immigration act to increase, decrease or maintain the genetic variation within a population?

11. 1 out of 10,000 babies born in North America is affected by cystic fibrosis, a recessive condition. Assuming that the North American population is in Hardy-Weinberg equilibrium for this trait, what percentage of the population are heterozygous for this trait?

12. Define the term 'germ line.'



SECTION II.
Write a short paragraph answer for each of these questions. Point form answers are acceptable.

1. About 600,000 years ago, a pregnant fruit fly was blown by winds from Sumatra to one of the Hawaiian islands. Today, there are four related fruit fly species found in Hawaii, with some islands having two or more species. Clearly outline the factors that may have led to such a speciation event.

2. In a lecture on bubble-feeding of humpback whales, Fred Sharpe described the well-developed sensory nodules evident on the head of these mammals. These nodules function as mechano-receptors, allowing humpback whales to detect the movements of prey, the movements of other whales and water motion itself. Fred said that these sensory nodules are thought to havenodules of humpback whales and hair follicles of other mammals are thus homologous structures.
a. What evidence would you suggest has led biologists to conclude that sensory nodules and hair follicles are homologous structures?
b. Explain, in general terms, how a complex, well-designed structure like a humpback whale's sensory nodule might have evolved from an ancestral hair follicle.

3. Joanne Siderius lectured on the behavior of the Eastern kingbird, Tyrannus tyrannus. As its species name suggests, the Eastern kingbird defends its nest very aggressively, flying out to attack and drive away much larger predatory birds such as crows and ravens.
a. Suggest a proximate hypothesis to explain this bird's behavior.
b. Suggest an ultimate hypothesis to explain this bird's behavior.
c. Name one possible cost of this behavior.
d. Name one possible benefit of this behavior.

4. Sexual reproduction carries clear costs to reproductive individuals.
a. Name three costs of sexual reproduction.
b. Describe one of these costs fully, illustrating your description with an example.

5. The best understood major extinction event in the history of life on earth is the one that ended the Cretaceous period. One widely held theory proposes that this extinction was triggered when a 10 km wide meteorite struck the earth.
a. Briefly outline how such a collision may have triggered a mass extinction.
b. List three pieces of evidence supporting this theory.
c. What is the significance of this extinction in the evolutionary history of the Class Mammalia?

6. David Wiggins investigated the heritability of body size in tree swallows. He cross-fostered tree swallow broods by switching eggs from one nest to another. Body size measurements were obtained for nestlings and compared with measurements of natural and foster parents.
Wiggins compared three aspects of body size - body mass, tarsus length and bill length. He found significant variation among broods in measurements of tarsus length and body mass. No significant variation in bill length was found among broods.
Wiggins compared offspring tarsus length and body mass to mid-parent values for true and foster parents. Significant resemblances were found between mid-parent values of natural parents and offspring in comparisons of tarsus length, but offspring did not resemble their foster parents. However, there were no significant resemblances between offspring and natural or foster parents in comparisons of body mass.

If you wished to investigate the effect of natural selection on some aspect of body size in tree swallows, which aspect - body mass, tarsus length or bill length - would you select? Why are the other two aspects of body size unsuitable?


SECTION III.
Answer each of these questions in one or two paragraphs. Do not use point form answers.

1. The tabloid Weekly World News had an article titled 'Dinosaurs wiped themselves out by playing chicken!'. (Jimison, S., Weekly World News, March 21, 1995.) The excerpt below is taken from this article.

Dinosaur bones found in the Great Sandy Desert have revealed the shocking true reason why dinosaurs became extinct: they killed themselves off playing chicken! Dr. Annabelle Crocker, an American paleontologist, has uncovered a 25 mile square section of the desert where every inch was littered with dinosaur bones. The tract contained an odd geological formation approximately 10 miles long, a stretch of terrain which had been formed of densely compacted earth. The vast majority of the skeletons in this area belonged to animals killed by severe head injuries or broken necks. Dr. Crocker claims that "The ponderous beasts stood far apart and rushed down the track towards each other, just like teenagers playing chicken in their hot rods. We have concluded that the beasts ran at each other at high speed and smashed into each other with such force that their craniums were crushed to powder. Many of these creatures were not agile enough to swerve at the last minute. This fatal flaw may well have led to the disappearance of the entire group. We don't know why the ancient reptiles became addicted to this type of activitiy. Perhaps it's a reflection of their extremely low brainpower."

Considering the conditions necessary for natural selection to act in populations, explain why the hypothesis proposed in this article is nonsense.

2. Is the human population continuing to evolve? Clearly defend your answer.