Multiple Choice Answers


1. Which of the following statements about the relationship between DNA molecules and chromatids is correct?
a.  Each chromatid contains a single linear DNA molecule.
b.  Each chromatid contains a large number of circular DNA molecules.
c.  The number of DNA molecules per chromatid varies between one and two depending on the time in the cell cycle.
d.  The number of DNA molecules per chromatid is described by the term ploidy.  Thus, diploid cells contain two, tetraploid four, etc.
e.  Each gene is a DNA molecule, and chromosomes contain many genes, therefore each chromatid contains a large number of linear DNA molecules.

2. Which of the following terms refers to structures with similar, but not identical, DNA molecules?
a. diploids
b. homologous chromosomes
c. sister chromatids
d. homologs
e. choices b and d are both correct

3. How many chromosomes and how many chromatids are present in a haploid cell during metaphase if a diploid cell from the organism has 48 chromosomes during G1?
a) 24 and 24;
b) 24 and 48;
c) 48 and 48;
d) 48 and 96;
e) 96 and 96.

4. Which of the following statements about meiosis is correct?
a.  One purpose of meiosis is to assure that sexual reproduction does not double the amount of DNA per cell each generation.
b.  One purpose of meiosis is to assure that daughter cells are essentially identical.
c.  One purpose of meiosis is to provide a large amount of variation within a population.
d.  Choices a and c are both correct.
e.  Choices a, b, and c are all correct.

5. What is a major difference between Prophase of Meiosis I and Prophase of Meiosis II?
a.  DNA synthesis occurs in Prophase I, but not in Prophase II.
b.  Recombination occurs in Prophase I, but not in Prophase II.
c.  The spindle forms in Prophase II, but not Prophase I.
d.  Chromosomes line up in the center of the cell in Prophase I.  Chromosomes do not line up in Prophase II.
e.  Choices b and c are both correct.

6. A diploid brain cell from a female mouse has 22 chromosomes in Metaphase.  How many chromosomes and how many chromatids are present in prophase of meiosis II in this mouse?
a.  11 chromosomes and 11 chromatids
b.  11 chromosomes and 22 chromatids
c.  22 chromosomes and 11 chromatids
d.  22 chromosomes and 22 chromatids
e.  22 chromosomes and 44 chromatids

7. A Drosophila melanogaster  sperm cell has four chromosomes.  How many DNA molecules, how many chromatids, and how many chromosomes are present in a Drosophila  cell nucleus during metaphase
of Meiosis I?
a.  4 DNA Molecules, 4 chromatids, and 4 chromosomes
b. 8 DNA Molecules, 8 chromatids, and 4 chromosomes
c. 8 DNA Molecules, 8 chromatids, and 8 chromosomes
d. 16 DNA Molecules, 8 chromatids, and 8 chromosomes
e. 16 DNA Molecules, 16 chromatids, and 8 chromosomes

8. A tetraploid marigold cell has 48 chromosomes in its nucleus during the G1 portion of the mitotic cell cycle.  How many chromosomes are  present in a cell from the same plant which is in the metaphase of meiosis II?
a. 96
b. 48
c. 24
d. 12
e. 6

9. The transmission of traits from one generation to another is called:
a.) genetic recombination.
b.) meiosis.
c.) gene transmission.
d.) inheritance.

10.          Chromosomes in a pair that have the same length, staining pattern, and centromere position are known as_________________.
a.) homolougues.
b.) sister chromatids
c.) somatic chromosomes.
d.) none of the above.

11.          Gametes are produced by ____________ which takes place in the _____________ part of the life cycle.
a.) mitosis, haploid.
b.) mitosis, diploid.
c.) meiosis, diploid.
d.) meiosis, haploid.

12.          Which of the following is not true about alleles?
a.) Alleles are another name for sister chromatids.
b.) Alleles are alternate versions of genes.
c.) Alleles account for the variation in inherited characters.
d.) All of the above are true.

13. What are the resulting probabilities of a cross between QQ and Qq?
a.) 25% QQ: 50% Qq: 25% qq
b.) 50% QQ: 25 Qq: 25% qq
c.) 50% QQ: 50% Qq
d.) 75% QQ: 25% Qq

14. Cyctic Fibrosis is an example of __________________.?
a.) plieotrophy
b.) multiple alleles
c.) epistasis
d.) incomplete dominance

15. Trisomy 21 is an example of_________________.
a.) Polyploidy
b.) Aneuploidy
c.) monosomy
d.) none of the above.

16. Darwin coined the term________________.
a.) evolution
b.) gradualism
c.) natural selection
d.) uniformitarianism.

17. What is the differential success in reproduction that results from the interaction between individuals that vary in heritable traits and their environments?
a.) survival of the fittest.
b.) natural selection
c.) evolution
d.) inheritance

18. What is the smallest unit that can evolve?
a.) family
b.) an individual
c.) population
d.) species

19. A localized group of individuals capable of interbreeding and producing fertile offspring is a__________________.
a.) species
b.) family
c.) pack
d.) population.

20. New genes and alleles originate only by
a.) mutations
b.) genetic drift
c.) natural selection
d.) gene flow

21. Which of the following is not a condition for Hardy-Weinberg Equilbirum?
a.) Extremely large population size
b.) No gene flow
c.) Mutations must occur
d.) No Natural Selection can occur.

22. If a typical somatic cell has 24 chromosomes, how many chromosomes are expected in a normal gamete?
a. 48
b. 24
c. 12
d. 6
e. The information given is insufficient to answer the question

23. In New Zealand, a new species of animal is found.  There are three feather colors that
occur frequently in the population: black, white, and grey with black seeming to be dominant.  Which is a reasonable explanation, assuming that feather color is controlled by a single gene?
a. Pleiotropy
b. Incomplete dominance
c. Polygenic Inheritance
d. The grey feather color is the result of a mutation

24. Green leaves are dominant to yellow leaves and blue berries are dominant to purple berries.  You find a green leafed, blue berried plant.  What must you do to determine this plant’s genotype?
a. Cross it to a pure breeding green leafed, blue berry plant
b. Cross it to a pure breeding green leafed, purple berry plant
c. Cross it to a pure breeding yellow leafed, blue berry plant
d. Cross it to a pure breeding yellow leafed, purple berry plant

25. A man with type B blood fathers children with a woman who also has type B blood.  What is/are the possible blood type/s of their offspring?
a. B only
b. A or B
c. A, B, or O
d. O only
e. B  or O

26. Homologous chromosomes
a. Line up on the metaphase plate of Metaphase I
b. Carry the same genetic loci
c. Segregate during meiosis
d. All of the above

27. When does crossing over occur?
a. Mitosis
b. Metaphase I
c. Metaphase II
d. Prophase I
e. S phase

28. Mendel’s Law of Independent Assortment is fulfilled by movement of the chromosomes in which stage of cell division?
a. Metaphase of mitosis
b. Anaphase of meiosis I
c. Anaphase of meiosis II
d. Metaphase of meiosis I
e. Cytokinesis in animal cells

29. Crossing over occurs between:
a. Sister chromatids of a homologous pair
b. Non-sister chromatids of a homologous pair
c. Any two chromosomes that happen to line up next to each other at metaphase
d. The sex chromosomes only
e. More than one of the above is true about crossing over

30. Which of the following observations did not lead Darwin to propose the Theory of Evolution?
a. The existence of variation within natural populations
b. Relatively stable size of natural populations
c. Presence of different fossil species in different strata
d. Stable (constant) environmental conditions through time
e. All of the above lead Darwin to propose the Theory of Evolution

31. What is are homologous characters?
a. Traits derived from adaptation to similar environments
b. Traits derived from a shared common ancestor
c. Adaptations that perform the same function in different species
d. Adaptations that perform different functions in different species
e. None of the above

32. Which of the following provide evidence that supports the Theory of Evolution?
a. Presence of vestigial organs
b. “Transition” fossil species
c. Homologous genes
d. Similar features in Embryonic development among chordates
e. Some but not all of the above
f. All of the above

33. True or False.  An individual can evolve.
a. True
b. False

34. True or False.  Natural selection influences the rate at which favorable mutations occur.
a. True
b. False

35. True or False.  The mechanism of evolution is natural selection.
a. True
b. False

36. Which of the following are examples of evolution that can be observed in human life times?
a. Insect species becoming pesticide-resistant
b. Infectious disease gaining antibiotic resistance
c. The transition from wild wolves to domestic dogs
d. A & B only
e. All of the above

37. Which of the following is a false statement about linked genes?
a. Are located on the same chromosome
b. Do not separate independently in gamete formation
c. Separate independently in gamete formation
d. Tend to be inherited together
e. C & D

38. Which statement accurately describes recombination frequency?
a. The more frequently recombination happens between two genes, the closer together the loci are
b. The more frequently recombination happens between two genes, the farther apart the loci are
c. The frequency of recombination has nothing to do with the distance between two genes on a chromosome
d. None of the above

39. Mendel proposed the Law of Segregation without any knowledge of the existence of chromosomes.  Which of the following supports Mendel’s Law?
a. Independent assortment in Meiosis
b. Formation of identical cells in Mitosis
c. Some genes are linked
d. All of the above
e. None of the above

40. A woman with AB blood has children with a man who has type O blood.  What are the possible blood types of their children?
a. Type A only
b. Type B only
c. Type A and Type B
d. Type A, Type B, Type AB
e. Type A, Type B, Type AB, and Type O

41. In a certain species of frog, yellow eyes are dominant to grey eyes and brown spots are dominant to purple spots.  If a two frogs that are each heterozygous for both traits mate, what proportion of the offspring will have yellow-eyes and purple-spots?
a. 1/2
b. ¼
c. 5/16
d. 3/16
e. none of the above

42. Upon arriving on Pluto, you discover a new race of aliens.  You observe that Plutonions range from having no orange spots at all to being almost completely covered in orange spots, with a whole spectrum of orange-spottedness in between.  Assuming the Plutonions are a sexually reproducing diploid species, which of the following is a reasonable guess concerning the inheritance pattern of the orange spot trait?
f. Incomplete Dominance
g. Pleiotropy
h. Polygenetic Inheritance
i. Multiple alleles
j. All of the above are reasonable guesses

43.  A human cell containing 22 autosomes and a Y chromosome is:
a. a somatic cell of a male
b. a zygote
c. a somatic cell of a female
d. a sperm

44.Homologous chromosomes move toward opposite poles of a dividing cell during:
a. mitosis
b. meiosis I
c. meiosis II
d. fertilization
e. binary fission

45. Crossing over usually contributes to genetic variation by exchanging chromosomal segments between:
a. sister chromatids of a chromosome
b. chromatids of nonhomologous chromosomes
c. non sister chromatids of homologues
d nonhomologous loci of the genome

46. Meiosis II is similar to mitosis in that:
a. homologous chromosomes synaps
b. DNA replicates before the division
c. the daughter cells are diploid
d. sister chromatids separate during anaphase

47. A heterozygous individual is crossed with a homozygous dominant individual. The probablility of getting a heterozygote is:
a. 0
b. .25
c. .50
d. .75

48. In mice, grey coat color is( mix of black and white hairs) occurs in the heterozygous individuals (Gg). When two grey mice are crossed, the phenotypes of the progeny are 1black:2grey:1white. Which of the following of the crosses would produce the highest percentage of grey mice?
a. Grey X Grey
b. Grey X Black
c. White X Black
d. White X Grey

49. There is good evidence for linkage when:
a. multiple alleles are found
b. a gene is recessive to a dominant allele
c. two genes work together to control a specific characteristic
d. genes do not segregate independently during meiosis
e. blending inheritance occurs

50. A recessive allele in the X chromosome is responsible for hemophilia in humans. A woman with normal blood clotting whose mother was a hemophiliac marries a man who has normal blood clotting. Which of the following is possible:
a. They may have daughters with hemophilia
b. They may have hemophilic sons
c. none of their children could have hemophilia
d. none of the above
e. all of the above

51. The ABO blood types in humans is an example of:
a. multiple alleles
b. epistasis
d. polygenic inheritance
d. codominance
e. all of the above
f. more than one of above

52. ___________ occurs when a gene at one locus alters the expression of a gene at a second locus. ____________ is an additive effect of two or more genes on a single phenotypic character.
a. pleiotrophy; epistasis
b. epistasis; polygenic inheritance
c. polygenic inheritance: epistasis
d. epistasis; pleiotrophy

53. Crossing over is important because:
a. it causes segregation
b. it aligns the chromosomes at metaphase II of meiosis
c. it creates new combinations of alleles on homologous chromosomes
d. it causes mutations

54. A geneticist mixed together many different kinds of fruit flies- some with long wings, some with short wings, some with long legs, and some with short legs. He allowed the flies to feed, mate randomly, and reproduce by the thousands. After many generations, most of the flies in the population had medium length wings and medium length legs, and most of the extreme types disappeared. This illustrates:
a. stabilizing selection
b. diversifying selection
c. fitness
d. genetic drift

55. In a population that is in Hardy-Weinberg equilibrium, the frequency of a recessive allele in the gene pool is 0.7. The frequency of organisms in this population with the homozygous dominant genotype will be:
a. 49%
c. 21%
d. %9
e. 7%

56. A bottleneck event is a non-adaptive feature that:
a. shows a fluctuation in allele frequencies
b. results in a large population  crash
c. results in crossing over
d. all of the above
e. none of the above

57.  Down Syndrome is caused by _____ of chromosome 21.
a. deletion
b. translocation
c. nondisjunction
d. insertion

58.  Meiosis results in ______.
a. two identical cells
b. two non-identical cells
c. four identical cells
d.four non-identical cells

59.  AaBb is ______ at two loci.
a. epistatic
b. homozygous
c. linked
d. heterozygous

60.  Mating red flowers with yellow flowers makes all orange flowers.
This is an example of ______.
a. codominance
b. incomplete dominance
c. complete dominance
d. dominant and recessive

61.  The recombination frequencies are as follows: A to B is 14%, B to C is 5%, and C to A is 9%. What is the order of genes on the chromosome?
a. ACB
b. ABA
c. CAB
d. ABC

62.  A human gamete contains _____ chromosomes.
a. 13
b. 46
c. 23
d. 92

63.  Plants are commonly _______, having multiple sets of chromosomes.
a. haploid
b. monoploid
c. anueploid
d. polyploid

64.  In fruit flies, red eyes (W) are dominant over white eyes (w). You cross an unknown genotype with a fly that is homozygous recessive and end up with all red-eyed flies. What was the genotype of the unknown?
a. ww
b. Ww
c. WW
d. not enough information

65. According to Mendel’s law of segregation,
a. There is a 50% probability that a gamete will get a dominant allele
b. Gene pairs segregate independently of other genes in gamete formation
c. Allele pairs separate in gamete formation
d. The laws of probability determine gamete formation
e. There is a 3:1 ratio in the F2 generation

66. A 1:1 phenotypic ration in a testcross indicates that
a. The alleles are dominant
b. One parent must have been homozygous recessive
c. The dominant phenotype parent was a heterozygote
d. The alleles segregate independently
e. The alleles are co-dominant

67. If both parents are carriers of a lethal recessive gene, the probability that their child will inherit and express the disorder is
a. 1/8
b. ¼
c. ½
d. ¾
e. 0

68. In a dihybrid cross of heterozygote, what proportion of the offspring will be phenotypically dominant for both traits?
a. 1/16
b. 3/16
c. ¼
d. 9/16
e. ¾
69. You think that two alleles for coat color in mice show incomplete dominance.  What is the best and simplest cross to perform in order to support your hypothesis?
a. A testcross of a homozygous recessive mouse with a mouse of unknown genotype
b. A cross of F1 mice to look for a 1:2:1 ration the offspring
c. A cross between two true-breeding mice of different colors to look for an intermediate phenotype in the F1
d. A cross of F1 mice to look for a 9:3:4 ratio in the offspring

70. Which of the following is not a source of genetic variation in sexually reproducing organisms?
a. Crossing over
b. Replication of DNA during S phase before Meiosis I
c. Independent assortment of chromosomes
d. Random fertilization of games
e. Mutations

71. Meiosis II is similar to mitosis because
a. Sister chromatids separate
b. Homologous chromosomes separate
c. DNA replication precedes the division
d. They both take the same amount of time
e. Haploid cells are produced

72. Homologous chromosomes
a. Have identical genes
b. Have genes for the same traits at the same loci
c. Are found in gametes
d. Separate in Meiosis II
e. Have all of the above characteristics

73. If a populations has the following genotype frequencies, AA = .42; Aa = .46; aa = .12; what are the allele frequencies?
a. A = .42; a  = .12
b. A = .6; a = .4
c. A = .65; a = .35
d. A = .76; a = .24
e. A = .88; a = .12

74. In a population with two alleles, B and b, the allele frequency of b is .4.  What would the frequency of heterozygotes be if the population was in Hardy-Weinberg equilibrium?
a. 16
b. 24
c. 48
d. 6
e. You cannot tell from this information

75. Darwinian fitness is a measure of
a. Survival
b. Number of matings
c. Adaptation to the environment
d. Successful competition for resources
e. Number of viable offspring

76. In a study of a population of field mice, you find that 48% of mice have a coat color that indicates that they are heterozygous for long tails.  What would be the frequency of the dominant allele in the population?
a. 24
b. 48
c. 50
d. 60
e. You cannot estimate allele frequency from this information