Test Bank forChapter 24: Quantitative GeneticsMultiple Choice QuestionsPlant 2: (1a) × (1B) × 1/2c × 1/2d × (1E) = 1/4Test Bank for Chapter 24: Quantitative GeneticsMultiple Choice Questions 1. A QTLa. is one of the genes that influences a trait.b. is a chromosomal region containing genes that influence a quantitative trait.c. will not contain any genes other than the ones influencing a trait.d. is a measure of the phenotypic variation in a quantitative trait.e. is a measure of the genetic variation in a quantitative trait.Answer: bSection: 24.1Comprehension 2. Unlike most examples of this trait, the height characteristic that Mendel studied in pea plants exhibited ____________________ variation.a. continuousb. discontinuousc. meristicd. thresholde. quantitativeAnswer: bSection: 24.1Comprehension 3. ______________ can cause a single genotype to produce a range of potential phenotypes.a. Epistasisb. Genetic variancec. Threshold effectsd. Environmental effectse. HeritabilityAnswer: dSection: 24.1Comprehension 4. Two highly inbred tobacco plants are crossed. One has dark green leaves. The other has yellow leaves. The F1 have light green leaves. Five hundred progeny from F1  F1 crosses areanalyzed. Their leaves show continuous variation in color, but none has dark green or yellow leaves. What do these data suggest about the number of genes determining this trait?a. There are two genes that determine this trait.b. There are three genes that determine this trait.c. There are four genes that determine this trait.d. There are more than four genes that determine this trait.e. There is not enough information to estimate the number of genes.Answer: dSection: 24.1Comprehension 5. A series of experiments shows that oil content in a diploid grain is influenced by five genes (a through e) with additive alleles. The highest producing strain is 20% oil content; the lowest has close to 0%. A plant of unknown genotype has an oil content of 12%. What is a possible genotype for this plant? (+ = additive alleles)a. a+a+b+b+c+c+d+de+e b. a+a+b+b+ ccddeec. a+a+b+bccddeed. aab+bc+cd+d+e+e+e. a+a+b+b+c+c+d+dee Answer: dSection: 24.1Application 6. Flower diameter in sunflowers is a quantitative trait. A plant with 6-cm flowers, from a highly inbred strain, is crossed to a plant with 30-cm flowers, also from a highly inbred strain. The F1 have 18-cm flowers. F1  F1 crosses yield F2 plants with flowers ranging from 6 to 30 cm in diameter, in approximately 4-cm intervals (6, 10, 14, 18, 22, 26, 30). The number of different genes influencing flower diameter in this plant is a. 3.b. 4.c. 5.d. 6.e. 7.Answer: aSection: 24.1Application 7. Flower diameter in sunflowers is a quantitative trait. A plant with 6-cm flowers, from a highly inbred strain, is crossed to a plant with 30-cm flowers, also from a highly inbredstrain. The F1 have 18-cm flowers. F1  F1 crosses yield F2 plants with flowers ranging from 6 to 30 cm in diameter, in approximately 4-cm intervals (6, 10, 14, 18, 22, 26, 30). An 18-cm F1 plant is crossed to a 6-cm plant. What is the probability of an offspring with oneadditive allele, if all genes that influence this trait are unlinked?a. 1/3b. 1/4c. 1/6d. 3/8e. 1/16Answer: dSection: 24.1Application 8. ______________________ is measured in terms of the original units squared.a. Meanb. Standard deviationc. Variance d. Correlation coefficiente. Narrow sense heritabilityAnswer: cSection: 24.2Comprehension 9. Distributions A and B in the figure below havea. the same mean and the same variance.ABfrequencyunitsb. different means and different variances.c. the same mean but different variances.d. different means but the same variance.e. different means but are correlated.Answer: bSection: 24.2Comprehension10. In a normal distribution, 99% of the measurements fall withina. 1% of the mean.b. 5% of the mean.c. plus or minus one standard deviation of the mean.d. plus or minus two standard deviations of the mean.e. plus or minus three standard deviations of the mean.Answer: eSection 24.2Comprehension 11. Quantitative characters often exhibit a ______________ distribution.a. skewed b. normalc. bimodal d. covariancee. tangentialAnswer: bSection: 24.2Comprehension 12. ______________ is a way to measure the strength of the association between two variables.a. Regression b. Covariancec. Correlation d. Variancee. Standard deviationAnswer: cSection: 24.2Comprehension13. Phenotypic variation in a trait is often represented as a ___________, which graphs the number of each phenotypic class in a sample.a. bimodal distributionb. frequency distribution c. regression lined. correlatione. variance plotAnswer: bSection: 24.2Comprehension 14. The _____________ is the statistic that measures the spread of a distribution around the mean.a. covariance b. correlation coefficientc. regression coefficientd. variancee. averageAnswer: dSection: 24.2Comprehension 15. Since the entire population is too large to work with, a sample is often used to characterize the population. This sample should a. be at most 5% of the population size to minimize the computational efforts.b. be randomly selected so that it represents the entire population.c. include individuals that are selected to fully represent the extreme values in the distribution. d. be small enough to mitigate against chance events skewing the distribution of the sample.e. include all of the features mentioned above.Answer: bSection: 24.2Comprehension 16. A _______________ allows us to predict the value of one variable from the value of a correlated variable. a. regression b. covariancec. correlationd. variancee. standard deviationAnswer: aSection: 24.2Comprehension 17. When _____________________ is high for a particular trait, offspring tend to resemble their parents for that trait.a. phenotypic variance b. the number of genes controlling a traitc. narrow-sense heritability d. genetic-environment interactione. environmental varianceAnswer: cSection: 24.3Comprehension 18. Heritability indicates thea. degree to which a characteristic is genetically determined.b. proportion of phenotypic variation in a trait that is due to genetic differences. c. degree to which a characteristic is environmentally determined.d. proportion of phenotypic variation in a trait that is due to the environment.e. extent to which identical twins are phenotypically similar.Answer: bSection: 24.3Comprehension19. Knowing the __________ of a trait has great practical importance because it allows