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Biology, 8e (Campbell) Chapter 14 Mendel and the Gene IdeaMultiple-Choice Questions1) Pea plants were particularly well suited for use in Mendel's breeding experiments for all of the following reasons except that A) peas show easily observed variations in a number of characters, such as pea shape and flower color. B)it is possible to control matings between different pea plants. C)it is possible to obtain large numbers of progeny from any given cross. D) peas have an unusually long generation time. E)many of the observable characters that vary in pea plants are controlled by single genes. Answer: D Topic: Concept 14.1 Skill: Knowledge/Comprehension2) What is the difference between a monohybrid cross and a dihybrid cross? A) A monohybrid cross involves a single parent, whereas a dihybrid cross involves two parents. B)A monohybrid cross produces a single progeny, whereas a dihybrid cross produces two progeny. C)A dihybrid cross involves organisms that are heterozygous for two characters and a monohybrid only one. D) A monohybrid cross is performed for one generation, whereas a dihybrid cross is performed for two generations. 1E)A monohybrid cross results in a 9:3:3:1 ratio whereas a dihybrid cross gives a 3:1 ratio. Answer: C Topic: Concept 14.1 Skill: Knowledge/Comprehension3) A cross between homozygous purple-flowered and homozygous white-flowered pea plants results in offspring with purple flowers. This demonstrates A) the blending model of genetics. B)true-breeding. C)dominance. D) a dihybrid cross. E)the mistakes made by Mendel. Answer: C Topic: Concept 14.1 Skill: Knowledge/Comprehension24) The F1 offspring of Mendel's classic pea cross always looked like one of the two parental varieties becauseA) one phenotype was completely dominant over another. B)each allele affected phenotypic expression. C)the traits blended together during fertilization. D) no genes interacted to produce the parental phenotype. E)different genes interacted to produce the parental phenotype. Answer: A Topic: Concept 14.1 Skill: Knowledge/Comprehension 5) What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants? A) There is considerable genetic variation in garden peas. B)Traits are inherited in discrete units, and are not the results of "blending." C)Recessive genes occur more frequently in the F1 than do dominant ones. D) Genes are composed of DNA. E)An organism that is homozygous for many recessive traits is at a disadvantage. Answer: B Topic: 3Concept 14.1 Skill: Knowledge/Comprehension6) How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE? A) 4 B)8 C)16 D) 32 E)64 Answer: B Topic: Concept 14.1 Skill: Application/Analysis7) Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. This suggests A) that the parents were true-breeding for contrasting traits. B)incomplete dominance. C)that a blending of traits has occurred. D) that the parents were both heterozygous. E)that each offspring has the same alleles. Answer: 4D Topic: Concept 14.1 Skill: Knowledge/Comprehension58) Two characters that appear in a 9:3:3:1 ratio in the F2 generation should have which of the following properties? A) Each of the traits is controlled by single genes. B)The genes controlling the characters obey the law of independent assortment. C)Each of the genes controlling the characters has two alleles. D) Four genes are involved. E)Sixteen different phenotypes are possible. Answer: B Topic: Concept 14.1 Skill: Knowledge/Comprehension 9) 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? A) HT B)Hh C)HhTt D) T E)tt Answer: A Topic: 6Concept 14.1 Skill: Application/Analysis10) It was important that Mendel examined not just the F1 generation in his breeding experiments, but the F2 generation as well, because A) he obtained very few F1 progeny, making statistical analysis difficult. B)parental traits that were not observed in the F1 reappeared in the F2. C)analysis of the F1 progeny would have allowed him to discover the law of segregation, but not the law of independent assortment. D) the dominant phenotypes were visible in the F2 generation, but not in the F1. E)many of the F1 progeny died. Answer: B Topic: Concept 14.1 Skill: Synthesis/Evaluation11) 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? A) 0% B)25% C) 50% D) 75% E)7100% Answer: C Topic: Concept 14.1 Skill: Application/Analysis 8Use 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 12) Which of the boxes marked 1-4 correspond to plants with dark leaves? A) 1 only B)1 and 2 C)2 and 3 D) 4 only E)1, 2, and 3 Answer: E Topic: Concept 14.1 Skill: Application/Analysis13) Which of the boxes correspond to plants with a heterozygous genotype? A) 1 B)91 and 2 C)1, 2, and 3 D) 2 and 3 E)2, 3, and 4 Answer: D Topic: Concept 14.1 Skill: Application/Analysis14) Which of the plants will be true-breeding? A) 1 and 4 B)2 and 3 C)1—4 D) 1 only E)None Answer: A Topic: Concept 14.1 Skill: Application/Analysis 1015) Mendel accounted for the observation that traits which had disappeared in the F1 generation reappeared in the F2 generation by proposing that A) new mutations were frequently generated in the F2 progeny, "reinventing" traits that had been lost in the F1. B)the mechanism controlling the appearance of traits was different between the F1 and the F2 plants. C) traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in theF1. D) the traits were lost in the F1 due to blending of the parental traits. E)members of the F1 generation had only one allele for each character, but members of the F2


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UMD BSCI 107 - Mendel and the Gene Idea

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