Exam 14: Mendel and the Gene Idea

Use Figure 14.1 and the following description to answer the questions below. In a particular plant, leaf color is controlled by gene locus D. Plants with at least one allele D have dark green leaves, and plants with the homozygous recessive dd genotype have light green leaves. A true-breeding dark-leaved plant is crossed with a light-leaved one, and the F₁ offspring is allowed to self-pollinate. The predicted outcome of the F₂ is diagrammed in the Punnett square shown in Figure 14.1, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square. Figure 14.1 -Which of the plants will be true-breeding?

Use the following information to answer the questions below. Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant characteristic. -If true-breeding red long radishes are crossed with true-breeding white oval radishes, the F₁ will be expected to be which of the following?

Mendel's observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division?

An obstetrician knows that one of her patients is a pregnant woman whose fetus is at risk for a serious disorder that is detectable biochemically in fetal cells. The obstetrician would most reasonably offer which of the following procedures to her patient?

Mendel's second law of independent assortment has its basis in which of the following events of meiosis I?

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. -If 1,000 F₂ offspring resulted from the cross, approximately how many of them would you expect to have red, terminal flowers?

A scientist discovers a DNA-based test for one allele of a particular gene. This and only this allele, if homozygous, produces an effect that results in death at or about the time of birth. Of the following, which is the best use of this discovery?

The following questions refer to the pedigree chart in Figure 14.2 for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle. Figure 14.2 -What is the genotype of individual II-5?

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?

Use the following information to answer the questions below. Skin color in a certain species of fish is inherited via a single gene with four different alleles. -How many different types of gametes would be possible in this system?

Refer to the following information 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 or not cactuses have spines. Homozygous recessive nn cactuses have no spines at all. -If doubly heterozygous SsNn cactuses were allowed to self-pollinate, the F₂ would segregate in which of the following ratios?

Use the following pedigree (Figure 14.3) for a family in which dark-shaded symbols represent individuals with one of the two major types of colon cancer. Numbers under the symbols are the individual's age at the time of diagnosis. Figure 14.3 -What is the genotype of the deceased individual in generation II?

Use the following information to answer the questions below. Tallness (T) in snapdragons is dominant to dwarfness (t), while red (R) flower color is dominant to white (r). The heterozygous condition results in pink (Rr) flower color. -A dwarf, red snapdragon is crossed with a plant homozygous for tallness and white flowers. What are the genotype and phenotype of the F₁ individuals?

Use the following pedigree (Figure 14.3) for a family in which dark-shaded symbols represent individuals with one of the two major types of colon cancer. Numbers under the symbols are the individual's age at the time of diagnosis. Figure 14.3 -From this pedigree, how does this trait seem to be inherited?

In the cross AaBbCc × AaBbCc, what is the probability of producing the genotype AABBCC?

Use the information given here to answer the following questions. Feather color in budgies is determined by two different genes, Y and B, one for pigment on the outside and one for the inside of the feather. YYBB, YyBB, or YYBb is green; yyBB or yyBb is blue; YYbb or Yybb is yellow; and yybb is white. -A blue budgie is crossed with a white budgie. Which of the following results is not possible?

Which of the following describes the ability of a single gene to have multiple phenotypic effects?

Cystic fibrosis affects the lungs, the pancreas, the digestive system, and other organs, resulting in symptoms ranging from breathing difficulties to recurrent infections. Which of the following terms best describes this?

The individual with genotype AaBbCCDdEE can make many kinds of gametes. Which of the following is the major reason?

Which of the following provides an example of epistasis?