Chapter 11 Mastering Biology

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 crosses BbTt × BBtt will be expected to have black fur and long tails? A. 3/8 B. 1/2 C. 1/16 D. 9/16 E. 3/16

1/2

Two true-breeding stocks of pea plants are crossed. One parent has red, axial flowers and the other has white, terminal flowers; all F1 individuals have red, axial flowers. The genes for flower color and location assort independently. If 1,000 F2 offspring resulted from the cross, approximately how many of them would you expect to have red, terminal flowers? A. 190 B. 565 C. 65 D. 250 E. 750

190

Use the following information to answer the questions below. Two true-breeding stocks of pea plants are crossed. One parent has red, axial flowers and the other has white, terminal flowers; all F1 individuals have red, axial flowers. The genes for flower color and location assort independently. Among the F2 offspring, what is the probability of plants with white axial flowers? A. 1/4 B. 9/16 C. 1/8 D. 1/16 E. 3/16

3/16

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%

50%

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE? A. 4 B. 8 C. 16 D. 64

8

What do we mean when we use the term monohybrid cross? A. A monohybrid cross involves a single parent. B. A monohybrid cross results in a 9:3:3:1 phenotype ratio in the F2 offspring. C. A monohybrid cross is performed for one generation. D. A monohybrid cross produces a single offspring. E. A monohybrid cross involves organisms that are heterozygous for one character.

A monohybrid cross involves organisms that are heterozygous for one character.

A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism? A. HhTt B. HT C. T D. tt E. Hh

HT

Why did the F1 offspring of Mendel's classic pea cross always look like one of the two parental varieties? A. Phenotype was not dependent on genotype. B. Each allele affected phenotypic expression. C. One allele was dominant. D. The traits blended together during fertilization. E. No genes interacted to produce the parental phenotype.

One allele was dominant.

Which of the following statements describes one difference between the law of independent assortment and the law of segregation? A. The law of segregation is accounted for by anaphase of mitosis. B. The law of segregation explains the segregation of two or more genes relative to one another. C. The law of segregation requires having two or more generations to describe. D. The law of independent assortment explains the segregation of two or more genes relative to one another.

The law of independent assortment explains the segregation of two or more genes relative to one another.

What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants? A. Genes are composed of DNA. B. Recessive genes occur more frequently in the F1 generation than do dominant ones. C. There is considerable genetic variation in garden peas. D. An organism that is homozygous for many recessive traits is at a disadvantage. E. Traits are inherited in discrete units, and are not the results of the "blending" of traits.

Traits are inherited in discrete units, and are not the results of the "blending" of traits.

Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. What does this suggest? A. that the parents were true-breeding for contrasting traits B. that the trait shows incomplete dominance C. that the parents were both heterozygous for a single trait D. that each offspring has the same alleles for each of two traits E. that a blending of traits has occurred

that the parents were both heterozygous for a single trait

Mendel accounted for the observation that traits that had disappeared in the F1 generation reappeared in the F2 generation by proposing that A. the traits were lost in the F1 due to dominance of the parental traits. B. new mutations were frequently generated in the F2 progeny, "reinventing" traits that had been lost in the F1. C. members of the F1 generation had only one allele for each trait, but members of the F2 had two alleles for each trait. D. traits can be dominant or recessive, and the recessive traits were "hidden" by the dominant ones in the F1. E. the mechanism controlling the appearance of traits was different between the F1 and the F2 plants.

traits can be dominant or recessive, and the recessive traits were "hidden" by the dominant ones in the F1.