Ch. 6 & 7 Test
1. Two similar chromosomes that you inherit from your parents (one from your mother, one from your father) are
called
a. homologous chromosomes.
c. sex chromosomes.
b. sister chromatids.
d. homozygous alleles.
2. Meiosis produces cells with how many chromosomes in humans?
a. 44
b. 22
c. 46
3. Which of the following cell types is diploid?
a. ovum
b. sex cell
c. somatic cell
d. 23
d. gamete
4. A distinguishing characteristic that can be inherited is a(n)
a. cross.
b. allele.
c. gene.
d. trait.
5. Which of the following statements is true of homozygous alleles?
a. They are always inherited together.
b. They are different forms of the same trait.
c. They are identical forms of the same gene.
6. Which law states that organisms inherit two copies of each gene and donate one copy to each of their offspring?
a. law of genetic linkage
c. law of independent assortment
b. law of segregation
d. law of inheritance
7. Which event takes place during anaphase II of meiosis II?
a. Nuclear membrane breaks down.
c. Sister chromatids separate.
b. Spindle fibers disassemble.
d. Cytoplasm divides.
8. Recessive alleles may not be expressed because they are
a. masked by a dominant allele.
b. the least common allele in a population.
c. the most common allele in a population.
d. Not a common allele in a population.
9. Mendel’s second law of genetics, the law of independent assortment, is one explanation of the
a. random fertilization of gametes.
c. greater strength of dominant alleles.
b. genetic variation within species.
d. final stages of gametogenesis.
10. Which of the following events is an important factor in increasing variety among sexually reproducing organisms?
a. testcross
b. gene linkage
c. crossing over
11. Imagine two heterozygous parents. Each has a dominant allele X for brown eyes and a recessive allele x for blue eyes.
The phenotypic ratio for brown:blue eyes in their children is
a. 1:2:1.
b. 3:1.
c. 9:3:3:1.
d. 1:3:1.
12. Which of the following cell types is haploid?
a. liver cell
b. somatic cell c. sperm cell
d. skin cell
13. Which of the following phrases best describes the function of meiosis?
a. conserves chromosome number, produces genetically identical cells
b. conserves chromosome number, produces haploid cells
c. reduces chromosome number by half, produces diploid cells
d. reduces chromosome number by half, produces gametes
14. The fusion of haploid gametes is called
a. gametogenesis.
b. reassortment.
c. meiosis.
15. All of the genetic material that makes up an organism is its
a. gamete.
b. phenotype.
c. genome.
d. fertilization.
d. testcross.
16. In a genotype for plant height, such as Tt, what does each letter represent?
a. one genome b. one allele
c. one gene
d. one gamete
17. When is a recessive allele expressed in offspring?
a. when two copies are present
b. when parents have no dominant alleles
c. when the offspring is heterozygous
18. Crossing over is an important factor in increasing the
a. chances that purebred offspring will inherit desirable traits.
b. likelihood of linkage among genes on sister chromatids.
c. likelihood of linkage among genes on sister chromatids.
d. frequency with which a recessive allele is masked.
19. Two parents have the genotype Gg for a genetic disorder caused by a dominant allele. What is the chance that any of
their children will inherit the disorder?
a. 25%
b. 75%
c. 50%
d. 100%
20. For an XX female to express a recessive sex-linked trait, she must have
a. a Y chromosome.
c. two recessive alleles.
b. an inactivated allele.
d. two dominant alleles.
21. Human height occurs in a continuous range because it is affected by the interaction of several genes, making it a
a. autosomal trait.
b. sex-linked trait.
c. polygenic trait.
d. codominant trait.
22.A female is born with attached earlobes, which is a recessive phenotype. Which of the following genotypes could her
parents have?
a. RR and RR
b. Rr and rr
c. Rr and RR
d. RR and rr
23. Suppose a person is a carrier for a genetic disorder. Which of the following phrases about this person is true?
a. does not have the disorder but can pass it on
b. will develop the disorder only late in life
c. cannot pass the disorder to sons, just daughters
d. the allele is not passed on due to Y chromosome inactivation
24. Phenotype is influenced by many factors, including the chromosome upon which a gene is located, ranges of
dominance, and a. karyotype.
b. pedigree.
c. environment.
d. phenotype.
25. Someone who is heterozygous for a recessive allele that causes a disorder
a. Is not a carrier of the disorder.
b. will not have the disorder.
c. cannot have offspring with the disorder.
d. Will get the disorder late in life.
26. Some members of a family have a recessive sex-linked disorder. Which of the following statements about the family
would be true?
a. All males would have the disorder. b. All females would be carriers.
c. Only males would have the disorder. d. Only females would be carriers.
27. What is the main reason that sex-linked disorders are most often observed in males?
a. The X chromosome only has genes for genetic disorders.
b. The Y chromosome cannot have genes that cause genetic disorders.
c. The Y chromosome cannot mask alleles on the X chromosome.
d. The X chromosome has genes only for sex determination.
28. The Punnett square below shows a cross between two parents who are heterozygous for an autosomal genetic disorder
caused by a recessive allele. People with which genotype will have the disorder?
a. Ss parent
b. Ss offspring c. SS offspring d. ss offspring
29. The wide range of eye color indicates that eye color is
a. sex-linked.
b. recessive.
c. polygenic.
d. epistatic.
30. One parent is homozygous for a recessive allele and one parent is heterozygous for a recessive allele in an autosomal
dominant genetic disorder. What is the chance that a child of those two parents will have the disorder?
a. 25%
b. 75%
c. 50%
d. 100%
31. Suppose a mouse is homozygous for alleles that produce black fur and homozygous for alleles of an epistatic gene that
produces albinism. What color fur will the mouse have?
a. white
b. gray
c. black
d. spotted
32.A female is born with attached earlobes, which is a recessive phenotype. Which of the following statements about her
parents must be true?
a. Neither has the codominant allele.
c. Both parents have the recessive allele.
b. Her father has an inactivated allele.
d. Her mother carries the dominant allele.
33. Suppose a person is homozygous recessive for a recessive genetic disorder. This genotype means that the person
a. is a carrier for the disorder.
c. cannot pass on the gene.
b. has the genetic disorder.
d. is healthy and is not a carrier.
34. Sex-linked disorders appear more often in males because the Y chromosome
a. does not carry sex-linked genes.
b. affects phenotype strongly.
c. has genes only for sex determination.
d. is smaller than the X chromosome.
35. Down syndrome is characterized by having an extra copy of at least a portion of chromosome 21. Which of the
following methods would quickly identify the disorder?
a. pedigree chart
b. meiosis map
c. karyotype
d. linkage map
36. Write the letter that corresponds to the part of the above picture that shows the division of sister chromatids.
37. Write the letter that corresponds to the cells in the diagram that are haploid. How are these cells different from the
cells in part D of the diagram?
38. Describe the process shown in part G of the diagram. How does it contribute to genetic diversity in all sexually
reproducing organisms?
39. What process is shown in diagram 2 of Figure 6.3? How do you know?
40. Identify the process shown in diagram 1. Describe one way the process in diagram 1 is similar to the process in
diagram 2 and one way in which they differ.
41. Write the letter that corresponds to the part of Figure 6.3 that shows the division of homologous chromosomes.
42. At what point in the process shown in diagram 2 might crossing over take place? Explain what would take place and
the effect that this has on genetic diversity.
43. Figure 6.4 shows the results of a cross between a plant with a known genotype and a plant of unknown genotype.
What is the term for this type of cross?
44. In this plant species, the allele for purple flowers is dominant and the allele for white flowers is recessive. Write the
genotype for the offspring that have white flowers.
45. What is the genotype of the offspring that have the dominant trait? What is the phenotypic ratio for the offspring?
46. Suppose the genotype of the unknown parent plant were homozygous dominant. How would this fact affect the
phenotypes of the offspring?
47. Why is it important to use an organism with a recessive phenotype in a cross with an organism of unknown genotype?
48. What is the phenotype of the unlabeled pea plant in the first generation?
49. Which type of interaction or inheritance is shown by the alleles for flower color?
50.
51.
52.
53.
54.
55.
56.
What type of chart is shown in Figure 7.4?
What do the shaded shapes represent?
What method of studying genetic inheritance is shown in the pedigree above?
What do the shaded circles represent?
Is the phenotype in the figure caused by a recessive or a dominant allele? How can you tell?
Do you think the phenotype is caused by a sex-linked gene or an autosomal gene?
Suppose female 5 has children with a male who is heterozygous for the alleles of this trait. What are the possible
genotypes of their offspring? Use a Punnett square in your answer.
57.Make a Punnett square using the parental genotypes. Find all the possible genotypes for the offspring in the F1
generation.
58. The American Curl is a breed of cat that has curly ears. The allele for curly ears is dominant. Suppose a male cat with
the heterozygous genotype is bred to a female cat with the homozygous recessive genotype. Predict the number of kittens
that will have the phenotype for curly ears. In your answer:
 define the word phenotype
 write the genotypes for both parents
 write the phenotypic ratio of the offspring.
 If the cross produces six kittens, predict
how many of them will have the curly ear phenotype.
59. Identify and describe at least three factors that contribute to the genetic diversity of sexually reproducing organisms.
In your answer:
 identify three factors that increase genetic diversity
 describe how one of the factors contributes to the genetic diversity of sexually
reproducing organisms