Genetics MCAS Review

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In fruit flies, the gene for eye color is on the X chromosome. The allele for red eyes is dominant to the allele for white eyes. A researcher crosses a heterozygous red-eyed female fly (XRXr) with a red-eyed male fly (XRY).Which of the following statements describes the expected outcome of the cross?

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The feather color of Andalusian chickens is controlled by a single gene with two alleles. A cross between a true-breeding, white-feathered Andalusian hen and a true-breeding, black-feathered Andalusian rooster results in 100% blue-feathered Andalusian offspring. Which of the following describes the inheritance pattern for feather color in these chickens?

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Scientists studying human diseases often use animal models. For example, fruit flies have been used to study Alzheimer’s disease. Scientists insert certain human genes found in patients with Alzheimer’s disease into fruit flies and observe how these genes affect the fruit flies.Where must the human gene be inserted for a fruit fly to produce offspring with this gene?

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Mice with the same parents can have different traits. Which of the following best explains how most of these differences occur?

Use the information below to answer #5 to 6

When exposed to bright sunlight, some people involuntarily sneeze. This reaction is known as a photic response. It is controlled by a single gene with two alleles, H and h. A man and a woman who sneeze when exposed to bright sunlight are both heterozygous for the photic response trait.ygo

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Identify the most likely inheritance pattern for this trait

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Draw a Punnett square using the allele symbols H and h to show the expected genotypes of the man and woman’s biological children. Identify all possible phenotypes of the offspring and their expected percentages.

Use the information below to answer #7 and 8

Corn kernels can be high in starch (starchy) or high in sugar (sweet). The allele for starchy kernels (H) is dominant to the allele for sweet kernels (h). Each kernel on an ear of corn represents an individual offspring. A particular ear of corn has 92 starchy kernels and 88 sweet kernels.

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What are the most likely genotypes of the parent corn plants that produced this particular ear of corn?

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Identify the genotypes for two corn plants that, when crossed, will produce plants with 100% starchy kernels.

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In flowers, white petals (H) are dominant to yellow (h). A heterozygous white flower and a yellow flower are crossed. What percent of the offspring will be yellow?

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In four o’clock plants, the allele for red flower color is incompletely dominant to the allele for white flower color. As a result, plants that are heterozygous for flower color have pink flowers. If two plants with pink flowers are crossed, what are the expected percentages of phenotypes in the offspring?

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Fur color in some cats is partially determined by the TYR gene, which has four alleles (C, cb, cs, c). Expression trends for the TYR alleles are summarized in the table below.

A male cat with albino fur color is crossed with a female cat with Siamese fur color. Considering only the effect of the TYR gene, which of the following is expected to be observed in the offspring?

In cattle, the allele for no horns (P) is dominant to the allele for horns (p). The allele for cloven hooves (C) is dominant to the allele for mule feet (c). Cattle that are heterozygous for these traits are crossed. The Punnett square for this cross is shown below.

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What is the probability that an offspring will have the same phenotype as the parents?

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Cattle normally have two separate toes on each foot. In a condition called mulefoot, a recessive allele causes the toes to fuse, resembling the foot of a mule.Two cattle, each with normal, separate toes, have a calf with mulefoot. What is the probability that the next calf born to these parent cattle will also have mulefoot?

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In betta fish, alleles for color are incompletely dominant. Green fish have genotype GG, dark blue fish have genotype gg, and royal blue fish have genotype Gg.Two royal blue betta fish are crossed. What percentage of the offspring is expected to be green?

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Mice with the same parents can have different traits. Which of the following best explains how most of these differences occur?

Use the information below to answer #5 to 6

Identify the most likely inheritance pattern for this trait

Draw a Punnett square using the allele symbols H and h to show the expected genotypes of the man and woman’s biological children. Identify all possible phenotypes of the offspring and their expected percentages.

Use the information below to answer #7 and 8

What are the most likely genotypes of the parent corn plants that produced this particular ear of corn?

Identify the genotypes for two corn plants that, when crossed, will produce plants with 100% starchy kernels.

In flowers, white petals (H) are dominant to yellow (h). A heterozygous white flower and a yellow flower are crossed. What percent of the offspring will be yellow?

What is the probability that an offspring will have the same phenotype as the parents?

In betta fish, alleles for color are incompletely dominant. Green fish have genotype GG, dark blue fish have genotype gg, and royal blue fish have genotype Gg.Two royal blue betta fish are crossed. What percentage of the offspring is expected to be green?

For a new liver cell to form, DNA replication is necessary because it ensures that the newly formed cell has which of the following?