Exam 14: Mendel and the Gene Idea

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 a small birdlike animal has an extremely variable tail length, which is a highly polymorphic trait. Geneticists have come to realize that there are eight separate genes for tail length per haploid genome, with each gene having two alleles. One allele for each gene (a, b, and so on)increases the length by 1 cm, whereas the other allele (a₂, b₂, and so on)increases it by 0.5 cm. One bird was analyzed and found to have the following genotype: A₁a₁b₂b₂c₁c₂d₁d₂e₂e₂f₁f₂g₁g₁h₁h₂ What is the length of its tail?

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

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?

Which of the following is the best statement of the use of the addition rule of probability?

Mendel was able to draw his ideas of segregation and independent assortment because of the influence of 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?

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 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 boxes correspond to plants with a heterozygous genotype?

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?

The frequency of heterozygosity for the sickle-cell anemia allele is unusually high, presumably because this reduces the frequency of malaria. Such a relationship is related to which of the following?

What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants?

If the environmental parameters, such as temperature, humidity, atmosphere, sunlight, and so on, are mostly Earthlike, which of the following do you expect of its types of leaves, stems, and flowers?

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 flies that are heterozygous for both the bent wing gene and the vestigial wing gene are mated, what is the probability of offspring with bent wings only?

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 likelihood that the progeny of IV-3 and IV-4 will have the trait?

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 probability that individual III-1 is Ww?

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 boxes marked 1-4 correspond to plants with dark leaves?

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 -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?

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE?

An ideal procedure for fetal testing in humans would have which of the following features?

Phenylketonuria (PKU)is a recessive human disorder in which an individual cannot appropriately metabolize a particular amino acid. The amino acid is not otherwise produced by humans. Therefore, the most efficient and effective treatment is which of the following?