BIOL110 Exam 3 Mastering Bio Questions (answered)

BIOL110 Exam 3 Mastering Bio Questions (answered) A gene that affects the expression of a second gene is an example of __________________. A. pleiotropy B. codominance C. epistasis D. polygenic inheritance E. incomplete dominance C. epistasis __________ is an example of a character that is controlled by more than one gene (a quantitative character) and demonstrates a continuum of phenotypes. A. Pleiotropy B. Polygenic inheritance C. Epistasis D. Codominance E. Incomplete dominance B. Polygenic inheritance The gene controlling ear color in an organism known as a gizmo has two alleles that exhibit incomplete dominance: CR, which codes for red ears; and CY, which codes for yellow ears. Individuals that are homozygous for the CR allele have red ears, whereas the heterozygous genotype produces orange ears. Those that are homozygous for the CY allele have yellow ears. If two individuals with orange ears are crossed, what ratio of phenotypes should be expected in the offspring? A. 9:3:1, red:yellow:orange ears B. 3:1, red:yellow ears C. 1:2:1, red:orange:yellow ears D. 1:2:1, red:yellow:orange ears E. 1:3, red:yellow ears C. 1:2:1, red:orange:yellow ears Mice with the genotypes BBCc and bbcc are crossed. The alleles for brown coat (b) and no pigment (c) are recessive, and black coat (B) is dominant. What color of mice would NOT be produced by this mating? A. brown B. white C. black A. brown An individual that is heterozygous for an allele and that exhibits a phenotype intermediate between that of the two homozygous alternatives is an example of _____. a.) polygenic inheritance b.) pleiotropy c.) codominance d.) incomplete dominance e.) epistasis d.) incomplete dominance What possible blood types could offspring have if their two parents have the blood types A and AB, respectively? A. AB only B .A, B, AB, and O C. A and O only D. A and B only E. A, B, and AB only E. A, B, and AB only In water snakes, body color is controlled by two alleles that display incomplete dominance. Snakes with the BB genotype are brown, those with the Bb genotype are gray, and individuals with the bb genotype are green. If a brown snake and a gray snake are crossed, what ratio of phenotypes should be expected in the offspring? A. 1:1, gray:green B. 1:2:1, brown:gray:green C. 1:1, brown:gray D.1:1:1, brown:gray:green1:1, brown:green C. 1:1, brown:gray You are examining a trait which shows three distinct phenotypes, with the phenotype of heterozygotes expressing both alleles seen in the homozygotes. This is an example of: A. Codominance. B. Complete dominance. C. Incomplete dominance. D. Pleiotrophy. A. Codominance. Pedigrees reveal that a trait shows a dominant pattern of inheritance if that trait generally _______. A. skipped generations B. was lethal C. did not skip generations D. was only inherited by males C. did not skip generations ________________________ is an example of a recessive inherited trait. A. Huntington's disease B.Cystic fibrosis C. Brachydactyly. D. The AB blood type B.Cystic fibrosis If one parent who has Huntington's disease is heterozygous for the trait and the other parent is not affected, what are the chances of their offspring inheriting the trait? A. 50% B. 100% C. 0 D. 25% A. 50% If both parents are carriers of an recessive inherited trait, what are the chances that their child will express that trait? A. 50% B. 25% C. 0 D. 100% ... The effects of ______________________ can be almost completely overcome by regulating the diet of the individual from infancy. A. cystic fibrosis B. sickle-cell disease C. phenylketonuria (PKU) D. Huntington's disease C. phenylketonuria (PKU) The following question refer to the pedigree chart in the figure below for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle. What is the genotype of individual II-5? ww What is the likelihood that the progeny of IV-3 and IV-4 will have the trait? 50% What is the probability that individual III-1 is Ww? 1 The figure below shows the pedigree for a family. 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. Males are represented by squares, females by circles. From this pedigree, this trait seems to be inherited _____. A. as a result of epistasis B. as an autosomal dominant C. as an autosomal recessive D. from mothers B. as an autosomal dominant In rabbits, the homozygous genotype LCLC has normal legs, LCLc results in deformed legs, and LcLc results in very short legs. The genotype FBFB produces black fur, FBFb brown fur, and FbFb white fur. If a cross is made between brown rabbits with deformed legs and white rabbits with deformed legs, what percentage of the offspring would be expected to have deformed legs and white fur? A. 25% B. 100% C. 50% D. 33% A. 25% Gene S controls the sharpness of spines in a type of cactus. Cacti with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cacti have dull spines. At the same time, a second gene, N, determines whether or not cacti have spines. Homozygous recessive nn cacti have no spines at all. The relationship between genes S and N is an example of which of the following inheritance patterns? A. codominance B. pleiotropy C. incomplete dominance D. epistasis D. epistasis Skin color in a certain species of fish is inherited via a single gene with four different alleles. One fish of this type has alleles 1 and 3 (S1S3) and its mate has alleles 2 and 4 (S2S4). If each allele confers a unit of color darkness such that S1 has one unit, S2 has two units, and so on, then what proportion of their offspring would be expected to have five units of color? A. 1/2 B. 1/8 C. 0 D. 1/4 A. 1/2 In mice, agouti fur is a dominant trait resulting in individual hairs having a light band of pigment on an otherwise dark hair shaft. A mouse with agouti fur is shown here, along with a mouse with solid color fur, which is the recessive phenotype (A = agouti; a = solid color). A separate gene, which is not linked to the agouti gene, can result in either a dominant black pigment or a recessive brown pigment (B = black; b = brown). A litter of mice from the mating of two agouti black parents includes offspring with the following fur colors:solid color, blacksolid color, brown (sometimes called chocolate)agouti blackagouti brown (sometimes called cinnamon) What would be the expected frequency of agouti brown offspring in the litter? A. 9/16 B. 1/2 C. 1/8 D. 3/16 E. 1/4 F. not enough information given D. 3/16 Because the two traits are determined by unlinked genes, they assort independently. As a result, you need to use the multiplication rule to calculate the probability of agouti brown offspring (A_ bb) from AaBb parents. The probability of A_offspring is 3/4, and the probability of bb offspring is 1/4. The combined probability is therefore 3/4 x 1/4 = 3/16. In addition to A and a, the “agouti” gene has a third allele, AY . Here is some information about the inheritance of the AY allele. The AY allele is dominant to both A and a. The homozygous genotype (AYAY ) results in lethality before birth. The heterozygous genotypes (AYA or AYa) result in yellow fur color, regardless of which alleles are present for the B/b gene. (This effect exhibited by the AY allele is known as epistasis--when the expression of one gene masks the expression of a second gene.) Suppose you mate two mice with the genotypes AYaBb x AYaBb . Considering only the live-born offspring, what would be the expected frequency of mice with yellow fur? 2/3 Because the presence of the AY allele is epistatic to (masks expression of) the B/b gene, the B/b gene does not need to be taken into consideration in this problem. For the AYa x AYa cross, 1/4 of the offspring would have the AYAY genotype, which is lethal before birth. For the live-born offspring, 2/3 would be AYa, and thus have yellow fur. In the same mouse species, a third unlinked gene (gene C/c) also has an epistatic effect on fur color. The presence of the dominant allele C (for color), allows the A/a and B/b genes to be expressed normally. The presence of two recessive alleles (cc), on the other hand, prevents any pigment from being formed, resulting in an albino (white) mouse. Match the phenotypes on the labels at left to the genotypes listed below. Labels can be used once, more than once, or not at all. Because the C/c gene is epistatic to both the A/a and B/b genes, any offspring with the cc allele combination will be albino. Otherwise, the A/a and B/b genes are expressed normally. In the same mouse species, a fourth unlinked gene (gene P/p) also affects fur color. For mice that are either homozygous dominant (PP) or heterozygous (Pp), the organism’s fur color is dictated by the other three genes (A/a, B/b, and C/c). For mice that are homozygous recessive (pp), large patches of the organism’s fur are white. This condition is called piebaldism. In a cross between two mice that are heterozygous for agouti, black, color, and piebaldism, what is the probability that offspring will have solid black fur along with large patches of white fur? 9/256 Because each gene segregates independently, you need to determine the probability of each genotype independently and then multiply the four probabilities together. The probability of offspring with solid color (aa) is 1/4; the probability of offspring with black fur (BBor Bb) is 3/4; the probability of colored fur (CCor Cc) is 3/4; and the probability of piebald, or white patches (pp), is 1/4. The combined probability is1/4 x 3/4 x 3/4 x 1/4 = 9/256. Which of the following statements about independent assortment and segregation is correct? A. The law of segregation is accounted for by anaphase of mitosis. B. The law of independent assortment requires describing two or more genes relative to one another. C. The law of segregation requires describing two or more genes relative to one another. D. The law of independent assortment is accounted for by observations of prophase I. B. The law of independent assortment requires describing two or more genes relative to one another. 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,