20
Describe one reason why the garden pea was an excellent model system for studying inheritance.
  1. The garden pea has flowers that close tightly to promote cross-fertilization.
  2. The garden pea has flowers that close tightly to prevent cross-fertilization.
  3. The garden pea does not mature in one season and is a perennial plant.
  4. Male and female reproductive parts attain maturity at different times, promoting self-fertilization.
21
How would you perform a reciprocal cross to test stem height in the garden pea?
  1. First cross is performed by transferring the pollen of a heterozygous tall plant to the stigma of a true breeding dwarf plant. Second cross is performed by transferring the pollen of a heterozygous dwarf plant to the stigma of a true breeding tall plant.
  2. First cross is performed by transferring the pollen of a true breeding tall plant to the stigma of a true breeding dwarf plant. Second cross is performed by transferring the pollen of a true breeding dwarf plant to the stigma of a true breeding tall plant.
  3. First cross is performed by transferring the pollen of a true breeding tall plant to the stigma of a heterozygous dwarf plant. Second cross is performed by transferring the pollen of a heterozygous dwarf plant to the stigma of a true breeding tall plant.
  4. First cross is performed by transferring the pollen of a heterozygous tall plant to the stigma of a heterozygous dwarf plant. Second cross is performed by transferring the pollen of a heterozygous tall plant to the stigma of a heterozygous dwarf plant.
22
Flower position in pea plants is determined by a gene with axial and terminal alleles. Given that axial is dominant to terminal, list all of the possible F1 and F2 genotypes and phenotypes from a cross involving parents that are homozygous for each trait. Express genotypes with conventional genetic abbreviations.
  1. F1: All AA-axial; F2: AA-Axial and aa-terminal.
  2. F1: All aa-terminal; F2: AA-Axial and Aa-terminal.
  3. F1: AA-axial and Aa-terminal; F2: All AA-axial.
  4. F1: All Aa-axial; F2: AA-Axial, Aa-Axial, and aa-terminal.
23
Use a Punnett square to predict the offspring in a cross between a dwarf pea plant (homozygous recessive) and a tall pea plant (heterozygous). What is the phenotypic ratio of the offspring?
  1. 1 Tall : 1 dwarf
  2. 1 tall : 2 dwarf
  3. 3 tall : 1 dwarf
  4. 1 dwarf : 4 tall
24
Can a human male be a carrier of red-green color blindness?
  1. Yes, males can be the carriers of red-green color blindness, as color blindness is autosomal dominant.
  2. No, males cannot be the carriers of red-green color blindness, as color blindness is X-linked.
  3. No, males cannot be the carriers of red-green color blindness, as color blindness is Y-linked.
  4. Yes, males can be the carriers of red-green color blindness, as color blindness is autosomal recessive.
25
Use the probability method to calculate the genotypes and genotypic proportions of a cross between AABBCc and Aabbcc parents.
  1. Possible genotypes are AABBcc, AaBbCc, AaBbcc and the ratio 1:2:1.
  2. Possible genotypes are AABbcc, AaBbCc, AaBbcc and the ratio 1:3:1.
  3. Possible genotypes are AABbCc, AABbcc, AaBbCc, AaBbcc and the ratio 1:1:1:1.
  4. Possible genotypes are AABbcc, AaBbCC, AaBbcc and the ratio 1:1:1.
26
How does the segregation of traits result in different combinations of gametes at the end of meiosis?
  1. The chromosomes randomly align during metaphase I at the equator, and separation of homologous chromosomes occurs during anaphase I. Similarly separation of sister chromatids occurs at anaphase II of meiosis II. At the end of meiosis II, four different gametic combinations are produced, each containing a haploid set of chromosomes.
  2. The chromosomes randomly align during anaphase I at the equator. Separation of bivalent chromosomes occur during metaphase I of meiosis I. Similarly, separation of sister chromatids occurs at metaphase II of meiosis II. At the end of meiosis II, four different gametic combinations are produced, each containing a haploid set of chromosomes.
  3. The chromosomes randomly align during prophase I at the equator, and separation of sister chromatids occurs during metaphase I of meiosis I. Similarly separation of bivalent chromosomes occur at metaphase II of meiosis II. At the end of meiosis II, four different gametic combinations are produced, each containing a diploid set of chromosomes.
  4. The chromosomes randomly align during prophase I at the equator, and separation of bivalent chromosomes occur during anaphase I of meiosis I. Similarly, separation of homologous chromosomes occurs at metaphase II of meiosis II. At the end of meiosis II, four different gametic combinations are produced, each containing a diploid set of chromosomes.
27
In Section 12.3, “Laws of Inheritance,” an example of epistasis was given for summer squash. Cross white WwYy heterozygotes to demonstrate the phenotypic ratio of 12 white : 3 yellow : 1 green that was given in the text.
  1. 12 offspring are white, as the W gene is epistatic to the Y gene. Three offspring are yellow, because w is not epistatic. Green offspring is obtained when the recessive form of both genes (wwyy) are present.
  2. 12 offspring are white as W gene is hypostatic to Y gene. Three offspring are yellow because Y is epistatic to w. Green offspring is obtained when the dominant form of both the genes (WWYY) is present.
  3. 12 offspring are white as W gene is dominant. Three offspring are yellow because Y is dominant and w is recessive. Green offspring is obtained when the recessive form of both the genes (wwyy) is present, showing codominance.
  4. 12 offspring are white as W is epistatic to Y gene. Three offspring are yellow because Y is hypostatic to w. Green offspring is obtained when the recessive form of both the genes (wwyy) are present, showing codominance.