GENETICS WORKSHEET

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University of New Orleans *

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3453

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Biology

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Dec 6, 2023

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pdf

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GENETICS WORKSHEET Due Sunday 7/12 Name 1) Albinism is an autosomal recessive trait. A man and woman who both have normal pigmentation have one child out of three who has albinism (without melanin pigmentation). What are the genotypes of this child's parents? A) One parent must be homozygous for the recessive allele; the other parent can be homozygous dominant, homozygous recessive, or heterozygous. B) One parent must be heterozygous; the other parent can be homozygous dominant, homozygous recessive, or heterozygous. C) Both parents must be heterozygous. D) One parent must be homozygous dominant; the other parent must be heterozygous. 2) In pea plants, the tall phenotype is dominant to the dwarf phenotype. If a heterozygous pea plant is crossed with a homozygous tall pea plant, what is the probability that the offspring will be dwarf in size? A) 1 B) 1/2 C) 1/4 D) 0 3) A man has extra digits (six fingers on each hand and six toes on each foot). His wife and their daughter have the normal number of digits (five fingers on each hand and five toes on each foot.) Having extra digits is a dominant trait. The couple's second child has extra digits. What is the probability that their next (third) child will have extra digits? A) 1/2 B) 1/16 C) 1/8 D) 3/4 4) A black guinea pig crossed with an albino guinea pig produced twelve black offspring. When the albino was crossed with a second black animal, six blacks and six albinos were obtained. What is the best explanation for this genetic situation? A) Albino is recessive; black is dominant. B) Albino is dominant; black is incompletely dominant. C) Albino and black are codominant. D) Albino is recessive; black is codominant. 5) Mendel crossed yellow-seeded and green-seeded pea plants and then allowed the offspring to self-pollinate to produce an F2 generation. The results were as follows: 6022 yellow and 2001 green (8023 total). The allele for green seeds has what relationship to the allele for yellow seeds?

A) dominant B) incomplete dominant C) recessive D) codominant Use the figure below to answer the question. 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 the figure, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square. 6) Which of the boxes marked 1-4 correspond to plants with a heterozygous genotype? 2 & 3 7) Which of the boxes marked 1-4 correspond to plants that would have dark green leaves? 1,2, 3 8) Which of the boxes marked 1-4 correspond to plants that would have light green leaves? 4 9) A woman who has blood type A has a daughter who is type O and a son who is type B. Which of the following is a possible phenotype for the father? A) A B) O C) B D) AB 10) Red-green color blindness is a sex-linked recessive trait in humans. Two people with normal color vision have a color-blind son. What are the genotypes of the parents? (Use this notation: X N is the dominant normal color vision allele; X n is the recessive color blind allele.) X^n X^n X^nY

11) When Thomas Hunt Morgan crossed his red-eyed F1 generation flies to each other, the F2 generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result? A) The gene involved is located on the Y chromosome. B) The gene involved is located on the X chromosome. C) The gene involved is located on an autosome, but only in males. D) Other male-specific factors influence eye color in flies. 12) In cats, black fur color is determined by an X-linked allele; the other allele at this locus determines orange color. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male? A) tortoiseshell females; tortoiseshell males B) black females; orange males C) tortoiseshell females; black males D) orange females; black males 11) Duchenne muscular dystrophy is a serious condition caused by a recessive allele of a gene on the human X chromosome. The patients have muscles that weaken over time because they have absent or decreased dystrophin, a muscle protein. They rarely live past their twenties. How likely is it for a woman to have this condition? A) Women can never have this condition. B) One-fourth of the daughters of an affected man would have this condition. C) One-half of the daughters of an affected father and a carrier mother could have this condition. D) Only if a woman is XXX could she have this condition. 12) A recessive allele on the X chromosome is responsible for red-green color blindness in humans. A woman with normal vision whose father is color blind marries a color-blind male. What is the probability that this couple's first son will be color blind? 1/2 13) Glucose-6-phosphate dehydrogenase deficiency (G6PD) is inherited as a recessive allele of an X-linked gene in humans. A woman whose father suffered from G6PD marries a normal man. (a) What proportion of their sons is expected to be G6PD? 1/2 (b) If the husband was not normal but was G6PD deficient, would you change your answer in part (a)? It wouldn’t since the sons get x chromosome from mother

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