Exam 1
BIOL 221
1. Which of the following sequences represents the hierarchy of biological organization from the least to the most complex level?
A) organelle, tissue, biosphere, ecosystem, population, organism
B) cell, community, population, organ system, molecule, organelle
C) organism, community, biosphere, molecule, tissue, organ
D) ecosystem, cell, population, tissue, organism, organ system
E) molecule, cell, organ system, population, ecosystem, biosphere
2. A cross between homozygous purple-flowered and homozygous white-flowered pea plants results in offspring with purple flowers. This demonstrates
A) the blending model of genetics.
B) true-breeding.
C) dominance.
D) a dihybrid cross.
3. Which of the following is true of a species that has a chromosome number of 2n = 16?
A) The species is diploid with 32 chromosomes per cell.
B) The species has 16 sets of chromosomes per cell.
C) Each cell has 8 homologous pairs.
D) During the S phase of the cell cycle there will be 32 separate chromosomes.
E) A gamete from this species has 4 chromosomes
4. Which of the following descriptions best fits the class of molecules known as nucleotides?
A) a nitrogenous base and a phosphate group
B) a nitrogenous base and a pentose sugar
C) a nitrogenous base, a phosphate group, and a pentose sugar
D) a phosphate group and an adenine or uracil
E) a pentose sugar and a purine or pyrimidine
5. What is a chromatid?
A) a chromosome in G1 of the cell cycle
B) a replicate of a chromosome
C) a chromosome found outside the nucleus
D) a special region that holds two centromeres together
6. When Thomas Hunt Morgan crossed his red-eyed F1 generation flies to each other, the F2 generation included both red- and white-eyed flies. Remarkably, all the white- eyed flies were male. What was the explanation for this result?
A) The gene involved is on the X chromosome.
B) The gene involved is on the Y chromosome.
C) The gene involved is on an autosome.
D) Other male-specific factors influence eye color in flies.
E) Other female-specific factors influence eye color in flies
7. Males are more often affected by sex-linked traits than females because
A) males are hemizygous for the X chromosome.
B) male hormones such as testosterone often alter the effects of mutations on the X chromosome.
C) female hormones such as estrogen often compensate for the effects of mutations on the X.
D) X chromosomes in males generally have more mutations than X chromosomes in females.
E) mutations on the Y chromosome often worsen the effects of X-linked mutations
8. Which of the following statements about the 5' end of a polynucleotide strand of DNA is correct?
A) The 5' end has a hydroxyl group attached to the number 5 carbon of ribose.
B) The 5' end has a phosphate group attached to the number 5 carbon of ribose.
C) The 5' end has thymine attached to the number 5 carbon of ribose.
D) The 5' end has a carboxyl group attached to the number 5 carbon of ribose.
E) The 5' end is the fifth position on one of the nitrogenous bases.
9. What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants?
A) There is considerable genetic variation in garden peas.
B) Traits are inherited in discrete units, and are not the results of "blending."
C) Recessive genes occur more frequently in the F1 than do dominant ones.
D) Genes are composed of DNA.
E) An organism that is homozygous for many recessive traits is at a disadvantage.
10. How do the daughter cells at the end of mitosis and cytokinesis compare with their parent cell when it was in G1 of the cell cycle?
A) The daughter cells have half the amount of cytoplasm and half the amount of DNA.
B) The daughter cells have half the number of chromosomes and half the amount of DNA.
C) The daughter cells have the same number of chromosomes and half the amount of DNA.
D) The daughter cells have the same number of chromosomes and the same amount of DNA.
E) The daughter cells have the same number of chromosomes and twice the amount of DNA.
11. After telophase I of meiosis, the chromosomal makeup of each daughter cell is
A) diploid, and the chromosomes are each composed of a single chromatid.
B) diploid, and the chromosomes are each composed of two chromatids.
C) haploid, and the chromosomes are each composed of a single chromatid.
D) haploid, and the chromosomes are each composed of two chromatids.
E) tetraploid, and the chromosomes are each composed of two chromatids.
12. Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. This suggests
A) that the parents were true-breeding for contrasting traits.
B) incomplete dominance.
C) that a blending of traits has occurred.
D) that the parents were both heterozygous.
E) that each offspring has the same alleles
For the following questions, match the key event of meiosis with the stages listed below.
I.ProphaseIV.Prophase II
II.Metaphase IVI.Metaphase II
III.Anaphase IVII.Anaphase II
IV.Telophase IVIII.Telophase II
13. Tetrads of chromosomes are aligned at the equator of the spindle; alignment determines independent assortment.
A) I
B) II
C) IV
D) VII
E) VIII
14. Synapsis of homologous pairs occurs; crossing over may occur.
A) I
B) II
C) IV
D) VI
E) VII
15. Centromeres of sister chromatids disjoin and chromatids separate.
A) II
B) III
C) IV
D) V
E) VII
16. If a DNA sample were composed of 10% thymine, what would be the percentage of guanine?
A) 10
B) 20
C) 40
D) 80
E) impossible to tell from the information given
17. A localized group of organisms that belong to the same species is called a
A) biosystem.
B) community.
C) population.
D) ecosystem.
E) family.
18. Which term describes centromeres uncoupling, sister chromatids separating, and the two new chromosomes moving to opposite poles of the cell?
A) telophase
B) anaphase
C) prometaphase
D) metaphase
E) prophase
19. SRY is best described in which of the following ways?
A) A gene region present on the Y chromosome that triggers male development
B) A gene present on the X chromosome that triggers female development
C) An autosomal gene that is required for the expression of genes on the Y chromosome
D) An autosomal gene that is required for the expression of genes on the X chromosome
E) Required for development, and males or females lacking the gene do not survive past early childhood
20. When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive phenotype?
A) 0%
B) 25%
C) 50%
D) 75%
E) 100%
21. If cells in the process of dividing are subjected to colchicine, a drug that interferes with the functioning of the spindle apparatus and causes a failure at the M check- point, at which stage will mitosis be arrested?
A) anaphase
B) prophase
C) telophase
D) metaphase
E) interphase
22. In cats, black fur color is caused by an X-linked allele; the other allele at this locus causes orange color. The heterozygote is calico (tortoiseshell). What kinds of offspring would you expect from the cross of a black female and an orange male?
A) Calico females; calico males
B) Black females; orange males
C) Orange females; orange males
D) Calico females; black males
E) Orange females; black males
23. Which of the following types of cells utilize deoxyribonucleic acid (DNA) as their genetic material but do not have their DNA encased within a nuclear envelope?
A) animal
B) plant
C) archaea
D) fungi
E) protests
24. If there are 20 chromatids in a cell at metaphase, how many chromosomes are there in each daughter cell following cytokinesis?
A) 10
B) 20
C) 30
D) 40
E) 80
25. Red-green color blindness is a sex-linked recessive trait in humans. Two people with normal color vision have a color-blind son. What are the genotypes of the parents?
A) XcXc and XcY
B) XcXc and XCY
C) XCXC and XcY
D) XCXC and XCY
E) XCXc and XCY
26. The fact that all seven of the pea plant traits studied by Mendel obeyed the principle of independent assortment most probably indicates which of the following?
A) None of the traits obeyed the law of segregation.
B) The diploid number of chromosomes in the pea plants was 7.
C) All of the genes controlling the traits were located on the same chromosome.
D) All of the genes controlling the traits behaved as if they were on different chromosomes.
E) The formation of gametes in plants occurs by mitosis only.
27. The difference between the sugar in DNA and the sugar in RNA is that the sugar in DNA
A) is a six-carbon sugar and the sugar in RNA is a five-carbon sugar.
B) can form a double-stranded molecule.
C) has a six-membered ring of carbon and nitrogen atoms.
D) can attach to a phosphate.
E) contains one less oxygen atom
28. In order to understand the chemical basis of inheritance, one must understand the molecular structure of DNA. This is an example of the application of ______to the study of biology.
A) evolution
B) emergent properties
C) reductionism
D) the cell theory
E) feedback regulation
29. Mendel's second law of independent assortment has its basis in which of the following events of meiosis I?
A) Synapsis of homologous chromosomes
B) Crossing over
C) Alignment of tetrads at the equator
D) Separation of homologs at anaphase
E) Separation of cells at telophase
30. Prokaryotes are classified as belonging to two different domains. What are the domains?
A) Bacteria and Eukarya
B) Archaea and Monera
C) Eukarya and Monera
D) Bacteria and Protista
E) Bacteria and Archaea
31. If one strand of a DNA molecule has the sequence of bases 5'ATTGCA3', the other complementary strand would have the sequence
A) 5'TAACGT3'.
B) 3'TAACGT5'.
C) 5'UAACGU3'.
D) 3'UAACGU5'.
E) 5'UGCAAU3'.
32. In birds, sex is determined by a ZW chromosome scheme. Males are ZZ and females are ZW. A recessive lethal allele that causes death of the embryo is sometimes present on the Z chromosome in pigeons. What would be the sex ratio in the offspring of a cross between a male that is heterozygous for the lethal allele and a normal female?
A) 2:1 male to female
B) 1:2 male to female
C) 1:1 male to female
D) 4:3 male to female
E) 3:1 male to female
33. Which of the following occurs in meiosis but not in mitosis?
A) Chromosome replication
B) Synapsis of chromosomes
C) Production of daughter cells
D) Alignment of chromosomes at the equator
E) Condensation of chromatin
34. Where do the microtubules of the spindle originate during mitosis in animal cells?
A) centromere
B) centrosome
C) centriole
D) chromatid
E) kinetochore
35. For most ecosystems ______is (are) the ultimate source of energy, and energy leaves the ecosystem in the form of ______.
A) sunlight; heat
B) heat; light
C) plants; animals
D) plants; heat
E) producers; consumers
36. A new organism is discovered in the forests of Costa Rica. Scientists there determine that the polypeptide sequence of hemoglobin from the new organism has 72 amino acid differences from humans, 65 differences from a gibbon, 49 differences from a rat, and 5 differences from a frog. These data suggest that the new organism
A) is more closely related to humans than to frogs.
B) is more closely related to frogs than to humans.
C) may have evolved from gibbons but not rats.
D) is more closely related to humans than to rats.
E) may have evolved from rats but not from humans and gibbons
37. Regarding mitosis and cytokinesis, one difference between higher plants and animals is that in plants
A) the spindles contain microfibrils in addition to microtubules, whereas animal spindles do not contain microfibrils.
B) sister chromatids are identical, but they differ from one another in animals.
C) a cell plate begins to form at telophase, whereas in animals a cleavage furrow is initiated at that stage.
D) chromosomes become attached to the spindle at prophase, whereas in animals chromosomes do not become attached until anaphase.
E) spindle poles contain centrioles, whereas spindle poles in animals do not.
38. Chiasmata are what we see under a microscope that let us know which of the following is occurring?
A) Asexual reproduction
B) Meiosis II
C) Anaphase II
D) Crossing over
E) Separation of homologs
39. Cinnabar eyes is a sex-linked recessive characteristic in fruit flies. If a female having cinnabar eyes is crossed with a wild-type male, what percentage of the F1 males will have cinnabar eyes?
A) 0%
B) 25%
C) 50%
D) 75%
E) 100%
40. The lowest level of biological organization that can perform all the activities required for life is the
A) organelle–for example, a chloroplast.
B) cell–for example, a skin cell.
C) tissue–for example, nervous tissue.
D) organ system–for example, the reproductive system.
E) organism–for example, an amoeba, dog, human, or maple tree
41. What best describes daughter strands in the semi-conserved model of DNA replication?
A) Both daughter strands consist completely of parental strand DNA
B) Both daughter strands consist completely of newly formed DNA
C) One daughter strand consists completely of parental strand DNA, the other is completely newly formed DNA
D) Both daughter strands consist of half parental strand DNA and half newly formed DNA
E) None of the above
42. Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of the cross BbTt × BBtt will have black fur and long tails?
A) 1/16
B) 3/16
C) 3/8
D) 1/2
E) 9/16
43. Chromosomes first become visible during which phase of mitosis?
A) prometaphase
B) telophase
C) prophase
D) metaphase
E) anaphase
Refer to the following information to answer the questions below.
A man who is an achondroplastic dwarf with normal vision marries a color-blind woman of normal height. The man's father was six feet tall, and both the woman's parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X-linked recessive.
44. How many of their daughters might be expected to be color-blind dwarfs?
A) All
B) None
C) Half
D) One out of four
E) Three out of four
45. What proportion of their sons would be color-blind and of normal height?
A) All
B) None
C) Half
D) One out of four
E) Three out of four
46. Which of the following statements concerning prokaryotic and eukaryotic cells is not correct?
A) Prokaryotic cells lack a membrane-bound nucleus.
B) Prokaryotic cells contain small membrane-enclosed organelles.
C) Eukaryotic cells contain a membrane-bound nucleus.
D) DNA, or deoxyribonucleic acid, is present in both prokaryotic cells and eukaryotic cells.
E) DNA or deoxyribonucleic acid is present in the nucleus of eukaryotic cells.
47. How does the sexual life cycle increase the genetic variation in a species?
A) By allowing independent assortment of chromosomes
B) By allowing fertilization
C) By increasing gene stability
D) By conserving chromosomal gene order
E) By decreasing mutation frequency
48. In snapdragons, heterozygotes for one of the genes have pink flowers, whereas homozygotes have red or white flowers. When plants with red flowers are crossed with plants with white flowers, what proportion of the offspring will have pink flowers?
A) 0%
B) 25%
C) 50%
D) 75%
E) 100%
49. What type of inheritance is seen in #48 above?
A) Standard dominant/recessive
B) Codominance
C) Incomplete dominance
D) X-linked inheritance
50. Which of the following is reflective of the phrase "the whole is greater than the sum of its parts"?
A) high-throughput technology
B) emergent properties
C) natural selection
D) reductionism
E) feedback regulations
51. Movement of the chromosomes during anaphase would be most affected by a drug that
A) reduces cyclin concentrations.
B) increases cyclin concentrations.
C) prevents elongation of microtubules.
D) prevents shortening of microtubules.
E) prevents attachment of the microtubules to the kinetochore
52. When pairs of homologous chromosomes separate during anaphase I,
A) the maternal chromosomes all move to the same daughter cell.
B) the sister chromatids remain attached to one another.
C) recombination is not yet complete.
D) the synaptonemal complex is visible under the light microscope
53. Which of the following best describes the flow of information in eukaryotic cells?
A) DNA → RNA → proteins
B) RNA → proteins → DNA
C) proteins → DNA → RNA
D) RNA → DNA → proteins
E) DNA → proteins → RNA
Refer to the following to answer the questions below.
Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cactuses have dull spines. At the same time, a second gene, N, determines whether cactuses have spines. Homozygous recessive nn cactuses have no spines at all.
54. The relationship between genes S and N is an example of
A) incomplete dominance.
B) epistasis.
C) complete dominance.
D) pleiotropy.
E) codominance.
55. A cross between a true-breeding sharp-spined cactus and a spineless cactus would produce
A) all sharp-spined progeny.
B) 50% sharp-spined, 50% dull-spined progeny.
C) 25% sharp-spined, 50% dull-spined, 25% spineless progeny
D) all spineless progeny.
E) It is impossible to determine the phenotypes of the progeny
The following is a map of four genes on a chromosome:
56. Between which two genes would you expect the highest frequency of recombination?
A) A and W
B) W and E
C) E and G
D) A and E
E) A and G
57. What is the reason that linked genes are inherited together?
A) They are located close together on the same chromosome.
B) The number of genes in a cell is greater than the number of chromosomes.
C) Chromosomes are unbreakable.
D) Alleles are paired together during meiosis.
E) Genes align that way during metaphase I of meiosis
58. Cells that are in a nondividing state are in which phase?
A) G0
B) G2
C) G1
D) S
E) M
59. Meiosis II is similar to mitosis in that
A) the daughter cells are diploid.
B) DNA replicates before the division.
C) sister chromatids separate during anaphase.
D) homologous chromosomes synapse.
E) the chromosome number is reduced
60. If nondisjunction occurs in meiosis II during gametogenesis, what will be the result at the completion of meiosis?
A) All the gametes will be diploid.
B) Half of the gametes will be n + 1, and half will be n - 1.
C) 1/4 of the gametes will be n + 1, one will be n - 1, and two will be n.
D) There will be three extra gametes.
E) Two of the four gametes will be haploid, and two will be diploid.
ESSAY:
(5 pts ea.)
1. Using a Punnett square, complete the following tri-hybrid cross. Provide the outcome of genotypic ratios, phenotypic ratios, and the probability of an offspring with the genotype AABBCC.