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Exam 2
BIOL 221
1. The most recent common ancestor of all land plants was probably similar to modernday members of which group?
A) green algae
B) red algae
C) charophytes
D) brown algae
E) angiosperms
2. Which of these is the smallest unit upon which natural selection directly acts?
A) a species' gene frequency
B) a population's gene frequency
C) an individual's genome
D) an individual's genotype
E) an individual's phenotype
3. Which of these illustrates the correct representation of the binomial scientific name for
the African lion?
A) Panthera leo
B) panthera leo
C) Panthera leo
D) Panthera Leo
E) Panthera leo
4. What is the correct sequence of the following four events during an animal's
development?
1. gastrulation
2. metamorphosis
3. fertilization
4. cleavage
A) 4  3  2  1
B) 4  3  1  2
C) 3  2  4  1
D) 3  4  2  1
E) 3  4  1  2
5. Which of the following terms or structures is properly associated only with animals?
A) Hox genes
B) cell wall
C) autotrophy
D) sexual reproduction
E) chitin
6. Which of the following statements about species, as defined by the biological species
concept, is (are) correct?
I.
II.
III.
Biological species are defined by reproductive isolation.
Biological species are the model used for grouping extinct forms of life.
The biological species is the largest unit of population in which successful
reproduction is possible.
A) I only
B) II only
C) I and III
D) II and III
E) I, II, and III
7. Cephalization is most closely associated with which of the following?
A) sedentary lifestyle
B) concentration of sensory structures at the anterior end
C) predators, but not prey
D) a backbone
E) a sessile existence
8. A number of characteristics are very similar between charophytes and members of the
kingdom Plantae. Of the following, which characteristic does not provide
evidence for a close evolutionary relationship between these two groups?
A) alternation of generations
B) chloroplast structure
C) cell plate formation during cytokinesis
D) sperm cell structure
E) ribosomal RNA nucleotide sequences
9. Which of the following is (are) unique to animals?
A) cells that have mitochondria
B) the structural carbohydrate, chitin
C) nervous conduction and muscular movement
D) heterotrophy
E) both A and C
10. A phylogenetic tree that is "rooted" is one
A) that extends back to the origin of life on Earth.
B) at whose base is located the common ancestor of all taxa depicted on that tree.
C) that illustrates the rampant gene swapping that occurred early in life's history.
D) that indicates our uncertainty about the evolutionary relationships of the taxa
depicted on the tree.
E) with very few branch points
11. Whatever its ultimate cause(s), the Cambrian explosion is a prime example of
A) mass extinction.
B) evolutionary stasis.
C) adaptive radiation.
D) A and B only
E) A, B, and C
12. Which of these is the smallest unit that natural selection can change?
A) a species' gene frequency
B) a population's gene frequency
C) an individual's genome
D) an individual's genotype
E) an individual's phenotype
13. The following are all adaptations to life on land except
A) rosette cellulose-synthesizing complexes.
B) cuticles.
C) tracheids.
D) reduced gametophyte generation.
E) seeds.
14. The correct sequence, from the most to the least comprehensive, of the taxonomic
levels listed here is
A) family, phylum, class, kingdom, order, species, and genus.
B) kingdom, phylum, class, order, family, genus, and species.
C) kingdom, phylum, order, class, family, genus, and species.
D) phylum, kingdom, order, class, species, family, and genus.
E) phylum, family, class, order, kingdom, genus, and species.
15. What is generally true of two very closely related species that have diverged from
each other quite recently?
A) They shared a common ancestor recently in evolutionary time.
B) Genes are unable to pass from one species' gene pool to the other's gene pool.
C) They are unable to produce hybrid offspring upon interbreeding.
D) Their reproductive isolation from each other is complete.
16. The last common ancestor of all animals was probably a
A) unicellular chytrid.
B) unicellular yeast.
C) plant.
D) multicellular fungus.
E) Choanoflagellate
17. Which of these evolutionary agents is most consistent at causing populations to
become better suited to their environments over the course of generations?
A) Mutation
B) Non-random mating
C) Gene flow
D) Natural selection
E) Genetic drift
18. Bryophytes have all of the following characteristics except
A) multicellularity.
B) specialized cells and tissues.
C) lignified vascular tissue.
D) walled spores in sporangia.
E) a reduced, dependent sporophyte
19. If organisms A, B, and C belong to the same class but to different orders and if
organisms D, E, and F belong to the same order but to different families, which of
the following pairs of organisms would be expected to show the greatest degree of
structural homology?
A) A and B
B) A and C
C) B and D
D) C and F
E) D and F
20. A biologist discovers two populations of wolf spiders whose members appear
identical. Members of one population are found in the leaf litter deep within the
woods. Members of the other population are found in the grass at the edge of the
woods. The biologist decides to designate the members of the two populations as
two separate species. Which species concept is this biologist most closely
utilizing?
A) ecological
B) biological
C) morphological
D) phylogenetic
21. The number of legs an insect has, the number of vertebrae in a vertebral column, or
the number of joints in a digit (such as a finger) are all strongly influenced by
A) haploid genomes.
B) introns within genes.
C) heterotic genes.
D) heterogeneous genes.
E) Hox genes
22. Plant spores are produced directly by
A) sporophytes.
B) gametes.
C) gametophytes.
D) gametangia.
E) seeds.
For Questions 23 and 24…
Several closely related frog species of the genus Rana are found in the forests of the
southeastern United States. The species boundaries are maintained by reproductive
barriers. In each case, match the various descriptions of frogs below with the appropriate
reproductive barrier listed.
23. Males of one species sing only when its predators are absent; males of another species
sing only when its predators are present.
A) behavioral
B) gametic
C) habitat
D) temporal
E) mechanical
24. Males of one species are too small to perform amplexus (an action that stimulates
ovulation) with females of all other species.
A) behavioral
B) gametic
C) habitat
D) temporal
E) mechanical
25. The term "homoplasy" is most applicable to which of these features?
A) the legless condition found in various types of extant lizards
B) the 5-digit condition of human hands and bat wings
C) the beta-hemoglobin genes of mice and of humans
D) the fur that covers Australian moles and North American moles
E) the basic skeletal features of dog forelimbs and cat forelimbs
26. Each of the following has a better chance of influencing gene frequencies in small
populations than in large populations, but which one most consistently requires a
small population as a precondition for its occurrence?
A) Mutation
B) Non-random mating
C) Genetic drift
D) Natural selection
E) Gene flow
27. You are trying to identify an organism. It is an animal, but it does not have nerve or
muscle tissue. It is neither diploblastic nor triploblastic. It is probably a
A) flatworm.
B) jelly.
C) comb jelly.
D) sponge.
E) nematode.
28. A trend toward the decrease in the size of plants on the slopes of mountains as
altitudes increase is an example of
A) a cline.
B) a bottleneck.
C) relative fitness.
D) genetic drift.
29. Beginning with the germination of a moss spore, what is the sequence of structures
that develop after germination?
1. embryo
2. gametes
3. sporophyte
4. protonema
5. gametophore
A) 4 1  3  5  2
B) 4  3  5  2  1
C) 4  5  2  1  3
D) 3  4  5  2  1
E) 3  1  4  5  2
30. What distinguishes a coelomate animal from a pseudocoelomate animal is that
coelomates
A) have a body cavity, whereas pseudocoelomates have a solid body.
B) contain tissues derived from mesoderm, whereas pseudocoelomates have no
such tissue.
C) have a body cavity completely lined by mesodermal tissue, whereas
pseudocoelomates do not.
D) have a complete digestive system with mouth and anus, whereas
pseudocoelomates have a digestive tract with only one opening.
E) have a gut that lacks suspension within the body cavity, whereas
pseudocoelomates have mesenteries that hold the digestive system in
place.
31. The best classification system is that which most closely
A) unites organisms that possess similar morphologies.
B) conforms to traditional, Linnaean taxonomic practices.
C) reflects evolutionary history.
D) corroborates the classification scheme in use at the time of Charles Darwin.
E) reflects the basic separation of prokaryotes from eukaryotes
32. A defining characteristic of allopatric speciation is
A) the appearance of new species in the midst of old ones.
B) asexually reproducing populations.
C) geographic isolation.
D) artificial selection.
E) large populations.
33. In which of the following taxa does the mature sporophyte depend completely on the
gametophyte for nutrition?
A) fern
B) bryophyte
C) horsetail (Equisetum)
D) A and C
E) A, B, and C
34. If two genes from one RNA molecule become detached and then, as a unit, get
attached to one end of the other RNA molecule within a single HIV particle,
which of these is true?
A) There are now fewer genes within the viral particle.
B) There are now more genes within the viral particle.
C) A point substitution mutation has occurred in the retroviral genome.
D) The retroviral equivalent of crossing-over has occurred, no doubt resulting in a
heightened positive effect.
E) One of the RNA molecules has experienced gene duplication as the result of
translocation
35. A botanist discovers a new species of plant in a tropical rain forest. After observing
its anatomy and life cycle, the following characteristics are noted: flagellated
sperm, xylem with tracheids, separate gametophyte and sporophyte generations
with the sporophyte dominant, and no seeds. This plant is probably most closely
related to
A) mosses.
B) charophytes.
C) ferns.
D) gymnosperms.
E) flowering plants.
36. A large population of laboratory animals has been allowed to breed randomly for a
number of generations. After several generations, 25% of the animals display a
recessive trait (aa), the same percentage as at the beginning of the breeding
program. The rest of the animals show the dominant phenotype, with
heterozygotes indistinguishable from the homozygous dominants.
What is the estimated frequency of allele A in the gene pool?
A) 0.05
B) 0.25
C) 0.50
D) 0.75
E) 1.00
Use the figure below to answer 37 and 38.
37. A common ancestor for both species C and E could be at position number
A) 1.
B) 2.
C) 3.
D) 4.
E) 5.
38. What pair of species are most closely related?
A) A and B
B) A and E
C) B and C
D) C and D
E) None of the above
39. A hybrid zone is properly defined as
A) an area where two closely related species' ranges overlap.
B) an area where mating occurs between members of two closely related species,
producing viable offspring.
C) a zone that features a gradual change in species composition where two
neighboring ecosystems border each other.
D) a zone that includes the intermediate portion of a cline.
E) an area where members of two closely related species intermingle, but
experience no gene flow.
40. In peas, a gene controls flower color such that R = purple and r = white. In an
isolated pea patch, there are 36 purple-flowering plants and 64 white-flowering
plants. Assuming Hardy-Weinberg equilibrium, what is the value of q for this
population?
A) 0.36
B) 0.60
C) 0.64
D) 0.75
E) 0.80
ESSAY:
Choose and Answer ONLY 3 of the following (10 pts ea.)
1. Describe the life cycle of a moss. Include a diagram showing the stages involved.
(Your entire answer may be a diagram, if complete)
2. Describe the Hardy-Weinberg Equilibrium. What does it mean when a population is
said to be in H-W Eq? What are the five criteria that must be met to be in H-W
Eq? Include equations and variables.
3. Name and describe the eight reproductive barriers (5 pre-zygotic and 3 post-zygotic).
4. Species A-F have the following nucleotide percent differences (divergence) from
outgroup species X. Build a phylogenetic tree that would be a possible
representation of the relatedness among these organisms. Exclude species X but
root the tree.
X
0%
A
12%
B
22%
C
8%
D
31%
E
12%
F
16%
5. Describe the process of gastrulation. Include the beginning and end structures and any
tissue layers derived in the process. You may use diagrams.