Exam 11: Mendel and the Gene Idea

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

Marfan syndrome in humans is caused by an abnormality of the connective tissue protein fibrillin. Patients are usually very tall and thin, with long spindly fingers, curvature of the spine, sometimes weakened arterial walls, and sometimes ocular problems, such as lens dislocation. Which of the following would you conclude about Marfan syndrome from this information?

Use the following information to answer the questions below. Tallness (T) in snapdragons is dominant to dwarfness (t), and 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 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?

Which of the following calculations require that you utilize the addition rule?

Hydrangea plants of the same genotype are planted in a large flower garden. Some of the plants produce blue flowers and others pink flowers. This can be best explained by which of the following?

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?

One of two major forms of a human condition called neurofibromatosis (NF 1) is inherited as a dominant gene, although it may range from mildly to very severely expressed. If a young child is the first in her family to be diagnosed, which of the following is the best explanation?

Which of the following differentiates between independent assortment and segregation?

Refer to the following information to answer the questions below. Humanoids on the newly explored planet Brin (in a hypothetical galaxy in ~50 years from the present) have a gene structure similar to our own, but many very different plants and animals. -One species of green plant, with frondlike leaves, a spine-coated stem, and purple cup-shaped flowers, is found to be self-pollinating. Which of the following is true of this species?

Use Figure 11.1 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 11.1, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square. Figure 11.1 -Which of the plants will be true-breeding?

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. -A cross between a true-breeding sharp-spined cactus and a spineless cactus would produce

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

Use the following pedigree (Figure 11.3) 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 11.3 -In each generation of this family after generation I, the age at diagnosis is significantly lower than would be found in nonfamilial (sporadic) cases of this cancer (~63 years). What is the most likely reason?

Which of the following provides an example of epistasis?

Use the following information to answer the questions below. Drosophila (fruit flies) usually have long wings (+), but mutations in two different genes can result in bent wings (bt) or vestigial wings (vg). -If a homozygous bent wing fly is mated with a homozygous vestigial wing fly, which of the following offspring would you expect?

Given the parents AABBCc × AabbCc, assume simple dominance for each trait and independent assortment. What proportion of the progeny will be expected to phenotypically resemble the first parent?

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 trait. -In the F2 generation of the above cross, which of the following phenotypic ratios would be expected?

The following questions refer to the pedigree chart in Figure 11.2 for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle. Figure 11.2 -What is the genotype of individual II-5?

In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white?