AP BIOLOGY STUDY GUIDE
EVOLUTION
1. Discuss
organic variation and environmental changes as causes of change in living
population.
2. Explain the
theory that reduction of the canine teeth is related to tool-making.
3. The theory
of recapitulation is often stated: "ontogeny recapitulates
phylogeny." Does this statement
accurately describe the facts? Explain.
4. Frogs (Eleutherodactylus) were not found in
Bermuda before being introduced by humans in 1880 but were prevalent in the
islands of the West Indies. Can you
explain why they were found in one location and not the other?
5. The
evolutionary history of mollusks and reptiles is known much better than that of
flatworms. Why?
6. The Kaibab
squirrel has long ears and a white belly and lives on the north rim of the
Grand Canyon. The Abert squirrel, which
lives on the south rim, is quite similar in appearance although it has a black
belly.
(a) How can you account for the presence of
these two similar, but distinguishable, populations?
(b) What possible futures might await these
squirrels if the canyon should be obliterated?
7. Fossil
evidence indicates that evolutionary changes in honeybees have taken place
unusually slowly. Can you think of a
possible reason why natural selection might operate particularly slowly in this
group?
8. Most of the
so-called "living fossils" are found in the sea. Can you think of a reason for this?
9. Considering
the strong selection pressure against the gene for hemophilia, what reasons can
you give for the continuing presence of the gene in the human population?
10. How can
the Darwinian theory of evolution account for the long neck of the
giraffe? How does this differ from
Lamarck's explanation?
11. Under what
circumstances is hybridization between species selected against?
12. There are
polyploid animals in some groups, but they are far less frequent than they are
among plants, particularly perennial plants. Why do you think this might be so?
13. Could
artificial selection by human beings (as for dogs) eventually lead to the
production of new species? Outline the basis for your answer.
14. Can
species ever originate in a single step? If so, what are some of the ways in
which this could occur?
15. How can
you tell if a new species will give rise to a whole new group of organisms?
Under what circumstances is it most likely to do so?
16. Why do you
think that at least 2 billion years of evolution preceded the origin of
multicellularity, and more than 3 billion years preceded the invasion of the
land? What kinds of information would you need to test your ideas?
17. There
seems to be on iridium layer preserved in the rocks from four of the five major
periods when mass extinction occurred. How could one account for these four
events?
18. In Central
Africa there is a low frequency of a third hemoglobin allele called C, in
addition to the A and S alleles found in sickle cell anemia among the Bantu
people. Individuals that are
heterozygous for C and the normal allele A are susceptible to malaria just as
AA homozygotes are, but CC individuals are resistant to malaria – and do not develop anemia! Assuming that the
Bantu people entered Central Africa relatively recently from a land where
malaria is not common (we think this is what happened), and that among the
original settlers both C and S alleles were rare, can you suggest a reason that
CC individuals have not become predominant?
19. In Fred
Hoyle’s science fiction novel, The Black
Cloud, the earth is approached by a large interstellar cloud of gas. The
cloud orients itself around the sun. Scientists soon discover that the cloud is
feeding, absorbing the sun’s energy though the excitation of electrons in the
outer energy levels of cloud molecules, a process similar to photosynthesis
that occurs on earth. Different portions of the cloud are isolated from one
another by associations of ions created by this excitation. Electrons currents
pass between these sectors, much as they do on the surface of the human brain,
endowing the cloud with self-awareness, memory, and the ability to think. Using
static electricity produced by static discharges, the cloud is able to
communicate with humans and describe its history, as well as to maintain a
protective barrier around itself. It tells human scientists that it once was
smaller, having originated as a small extrusion from an ancestral cloud, but
has grown by the adsorption of molecules and energy from stars like our sun, on
which it has been grazing. Soon the cloud moves off in search of other stars?
Is it alive? Defend your position.
20. While the
first organisms may have subsisted on organic molecules in the primordial soup,
it seems clear that photosynthesis evolved very early in the history of life.
Since light provides an inexhaustible source of energy, why do you suppose that
heterotrophs and food chains ever evolved? Why aren’t all organisms autotrophs?