front 1 A complex trait is a trait that is influenced by ______. | back 1 several genes and the environment |
front 2 A trait that can be described numerically, such as height or weight, is defined as a(n) ______ trait. | back 2 quantitative |
front 3 Which field of genetics studies the inheritance of complex traits? | back 3 Quantitative genetics |
front 4 The length of an ear of corn is an example of a(n) _____ trait. | back 4 quantitative |
front 5 A trait that does not fall into discrete categories are called ____. | back 5 continuous e.g. height and weight |
front 6 A meristic trait is a trait that ______. | back 6 can be counted and expressed in whole numbers |
front 7 A quantitative trait is defined as a trait that ______. | back 7 can be described numerically |
front 8 A trait that is influenced by many genes and is inherited quantitatively is defined as a(n) ______ trait. | back 8 threshold |
front 9 A frequency distribution is a graph that shows the ______. | back 9 number of individuals in various phenotypic categories |
front 10 Which of the following are examples of quantitative traits? | back 10 Speed of flight in birds Blood pressure in humans Number of bristles in Drosophila |
front 11 A continuous trait is a trait that ______. | back 11 does not fall into discrete categories |
front 12 A frequency distribution in which a trait varies in a symmetrical way around an average value is called a(n) ____ distribution and produces a(n) ____ -shaped curve. | back 12 normal; bell |
front 13 A trait that can be counted and expressed in whole numbers is called a(n) ______ trait. | back 13 meristic |
front 14 Which field of genetics involves the statistical study of biological traits? | back 14 Biometrics |
front 15 What is a threshold trait? | back 15 A trait inherited quantitatively due to contributions of many genes |
front 16 In a group of ten dairy cows, the following amounts of milk production per day were observed (measured in liters per day): 15, 16, 18, 18, 20, 20, 20, 21, 21, 22. What is the mean milk production per day in this group of cows? | back 16 19.1 liters per day |
front 17 A graph that presents phenotypic categories on the x-axis and the number of individuals that fall into a category on the y-axis is called a(n) ____ distribution. | back 17 frequency |
front 18 Which of the following formulas is the correct equation for calculation of the mean? In these equations, X� is the mean, ΣX is the sum of all values in the group, and N is the number of individuals in the group. Multiple choice question. X� = X with a line over it. | back 18 ![]() X�= ΣXN Reason: The sum of all of the values of a parameter within a group divided by the number of individuals in the group is defined as the mean. |
front 19 The length of an ear of corn is an example of a(n) _____ trait. | back 19 quantitative |
front 20 In a sample with N individuals, variance is calculated as the _____. | back 20 ![]() sum of the squared deviations from the mean divided by N - 1 |
front 21 What is a normal distribution? | back 21 A frequency distribution that varies in a symmetrical way around an average value |
front 22 ![]() In a group of fruit flies, the mean number of abdominal bristles was 16.4 bristles. The data are presented in the table. What is the variance of bristle number in this group of fruit flies? | back 22 6.0 bristles2 |
front 23 What is the focus of the biometric field of genetics? | back 23 The statistical study of biological traits |
front 24 In a sample of corn growing in a field, the mean percentage of oil content is 12.0%. The variance of oil content is 4.0%2. 100 ears of corn were analyzed to determine these values. What is the standard deviation of oil content for this sample of corn? | back 24 2.0% Reason: Take the square root of the variance. 4√ = 2 |
front 25 In a group of eight fruit flies, individuals with the following numbers of abdominal bristles were observed: 10, 10, 11, 8, 11, 12, 10, 11. What is the mean number of abdominal bristles in this group of fruit flies? | back 25 10.4 bristles |
front 26 The square root of the variance is equal to the ____ ____ of a data set. | back 26 standard deviation (SD) |
front 27 The sum of all of the values of a parameter within a group divided by the number of individuals in the group is defined as the ______. | back 27 mean |
front 28 In a normal distribution, what percentage of all individuals have phenotypic values within one standard deviation of the mean? | back 28 68% |
front 29 Variance is a statistical measure of the ______. | back 29 variation of a trait around the mean |
front 30 True or false: When a chi-square test shows that the correlation coefficient for two variables is statistically significant, it means that there is a cause-and-effect relationship between the variables. | back 30 False Reason: A significant correlation coefficient does not necessarily imply a cause-and-effect relationship. It simply shows that there is a true association between the two variables. |
front 31 ![]() A farmer measured the weight of eight newborn cattle. The data are presented in the table provided. The mean weight of the cattle in this group is 603 kg. What is the variance? | back 31 140 kg2 |
front 32 ![]() The following data were collected from a sample of corn ears. The length and weight of each ear were measured. What is the covariance of ear length and ear weight? | back 32 18.8 |
front 33 In a bushel of corn, the mean length of the corn ears is 16.0 cm. The variance of the ear length in this bushel of corn is 2.0 cm2. In this bushel, 20 ears of corn were measured to determine these values. What is the standard deviation of ear length in this sample? | back 33 1.4 cm Reason: SD = Vx√ = 2.0√ = 1.4 cm |
front 34 The standard deviation of a data set is equal to the square root of the ______. | back 34 variance |
front 35 ![]() Covariance is a measure of the relationship between ______. | back 35 two different variables |
front 36 If a population fits a normal distribution, then what percentage of individuals have phenotypic values within two standard deviations above or below the mean? | back 36 95% |
front 37 For a population of mice, the mean weight is 25.0 grams, and the standard deviation of weight is 0.3 grams. The mean length from the nose to the base of the tail is 8.0 cm, and the standard deviation of body length is 0.4 cm. The covariance of these two variables is 0.07. What is the correlation coefficient between these two variables? | back 37 0.58 Reason: (0.07) / (0.3)(0.4) = 0.58 |
front 38 If a correlation coefficient is found to be statistically significant, it means that ______. | back 38 there is a true association between the two variables Reason: A strong correlation does not necessarily imply a cause and effect relationship. Reason: A negative relationship between variables can also lead to a statistically significant correlation coefficient. |
front 39 The strength of the association between two variables can be reported as a value that ranges between -1 and +1. This value is called the ____ coefficient. | back 39 correlation |
front 40 ![]() The data table shown here presents information about stem length and number of flowers per plant in a certain type of plant. What is the covariance between stem length and flower number? | back 40 -3.5 |
front 41 If a correlation coefficient of two traits is negative, it means that _____. | back 41 as one trait increases, the other decreases |
front 42 A correlation coefficient is considered significant if ______. | back 42 statistical analysis results in a probability value greater than 0.05 |
front 43 Which of the following statistical values is a measure of the relationship between two variables? | back 43 Covariance |
front 44 In order to analyze the significance of a(n) ____ coefficient, the sampling of the population must be unbiased, the values of both variables must follow a normal distribution, and the relationship between the two variables must be linear. | back 44 correlation |
front 45 In a group of twenty ten-year-old girls, the mean height is 150 cm, and the mean weight is 30 kg. The standard deviation of height is 5 cm, and the standard deviation of weight is 2 kg. The covariance between height and weight is 8.0. What is the correlation coefficient between these two variables? | back 45 0.8 Reason: 8 / (5)(2) = 0.8 |
front 46 ![]() Suppose the correlation coefficient between birth weights of 22 infants and pre-pregnancy weights of their mothers is 0.338. Based on this calculation, you can conclude that the two variables show ______. | back 46 no true association |
front 47 ![]() The correlation coefficient is a measure of the ______. | back 47 strength of the relationship between two variables |
front 48 ![]() Suppose that leaf number and plant height for 32 tomato plants shows a linear relationship with a correlation coefficient of 0.642. In this case you would ____ the null hypothesis that the size of the correlation coefficient is due to random sampling error. | back 48 reject |
front 49 If there is no relationship between two variables, the correlation coefficient will be ______. | back 49 zero |
front 50 Quantitative traits are ______. | back 50 controlled by multiple genes |
front 51 The significance of a correlation coefficient can be evaluated by ______. | back 51 determining its probability by statistical analysis Reason: The r value is compared to tabulated values at 5% and 1% significance. |
front 52 What assumptions must be met in order for a correlation coefficient to be valid? | back 52 The relationship between the values of the two variables is linear. The sampling of the entire population being studied is unbiased. The values of both variables follow a normal distribution. |
front 53 Polygenic inheritance is the transmission of a trait that is determined by ______. | back 53 two or more different genes |
front 54 ![]() A study of mineral accumulation in 52 rice plants showed a linear relationship between iron content and zinc content with a correlation coefficient of 0.765. Based on this calculation, you can conclude that the two variables show ______. Answer Choices: a true association a cause and effect relationship no association | back 54 a true association |
front 55 Suppose that milk volume and body weight for 27 Guernsey cows shows a linear relationship with a correlation coefficient of 0.187. In this case you cannot ____ the null hypothesis that the size of the correlation coefficient is due to random sampling error. | back 55 reject |
front 56 Quantitative traits tend to show a continuum of variation because they are usually ____, meaning that they are controlled by multiple genes. | back 56 polygenic |
front 57 Transmission of a trait determined by two or more different genes is referred to as ____ inheritance. | back 57 polygenic |
front 58 How many genes control hull color in bread wheat? | back 58 Two |
front 59 In bread wheat, hull color is determined by two genes. For the first gene, the R1 allele produces red color, and the r1 allele produces white color. Similarly, the R2 allele results in red pigment, and the r2 allele does not. The effects of the red alleles are additive. In a self-cross of a strain with genotype R1r1R2r2, what phenotypic ratio is expected in the offspring? | back 59 1:4:6:4:1 Reason: Polygenic traits do not exhibit expected Mendelian ratios. |
front 60 ![]() The graph shows a hypothetical situation in which seed weight is controlled by three genes, each with light (w) and heavy (W) alleles, and a low environmental effect. If the environmental effect were high, ______. | back 60 the overlaps between genotypes increases |
front 61 What is a quantitative trait locus? | back 61 The chromosomal location of one or more genes that affect the phenotype of a quantitative trait |
front 62 In QTL mapping, researchers try to identify the association between ______. | back 62 molecular markers and the phenotypes of quantitative traits Reason: QTL mapping seeks to determine relationships between phenotypes and molecular markers. |
front 63 In bread wheat, the color of the hull can be dark red, white, or various intermediate shades of red. Genetic analysis of this trait has demonstrated that it is controlled by ______. | back 63 two loci with additive effects on hull color |
front 64 Click and drag on elements in order Place the steps in QTL mapping in order, with the first step at the top. | back 64 ![]() Answer in the picture. |
front 65 In a certain type of plant, the stem is always at least 20 centimeters long. Two genes (A and B) with additive alleles influence the stem length. For these two genes, each dominant allele adds an additional 2 cm to the length of the stem; the recessive alleles do not change the length of the stem. If a plant with the genotype AaBb is allowed to self-cross, what proportion of the offspring will be 22 cm tall? | back 65 4/16 Reason: Polygenic traits do not exhibit expected Mendelian ratios. |
front 66 ![]() The graphs show the relationship between seed weight and genotype for a single gene that influences seed weight. Which statement describes the difference between the two graphs? | back 66 Graph A shows a low environmental effect on seed weight, whereas Graph B shows a high environmental effect |
front 67 When a quantitative trait is analyzed, its phenotypic variance can be partitioned into ____ variance, ____ variance, and the interactions and associations between them. | back 67 genetic; environmental |
front 68 The chromosomal location of one or more genes that influence a quantitative trait is called a quantitative trait | back 68 locus or loci |
front 69 When phenotypic variance is determined solely by genotypic and environmental variance, and genetic and environmental factors are independent of one another, then total phenotypic variance is equal to genetic variance ____ environmental variance. | back 69 plus, +, or and |
front 70 The purpose of QTL mapping is to ______. | back 70 identify the chromosomal locations of genes that influence a quantitative trait Reason: The basis of QTL mapping is the association between genetically determined phenotypes for quantitative traits and molecular markers. |
front 71 In which situation does genetics play a greater role than the environment in promoting phenotypic variation within a group? | back 71 When V G is high and V E is low Reason: If V G is very high and V E is very low, genetics plays a greater role in promoting phenotypic variation. |
front 72 In a QTL mapping experiment, the two strains that are selected for breeding must ______. | back 72 differ with respect to a quantitative trait be highly inbred |
front 73 Mating between close relatives, such as brothers and sisters, is referred to as | back 73 inbreeding |
front 74 The phenotypic variance of a quantitative trait can be partitioned into several components. Match each component of variation to the correct description. | back 74 ![]() Answer in the picture. |
front 75 In inbred strains of mice, all phenotypic variance is due to ______. | back 75 environmental variance Reason: VG equals 0 for inbred strains of mice. |
front 76 When genetic and environmental factors are independent of one another, and genetic variance (V G) and environmental variance (V E) are the only factors that determine phenotypic variance (V P), then V P is equal to the ______. | back 76 sum of V G and V E. |
front 77 A population in which all members of the population are homozygous for the same allele of a given gene is referred to as ______. | back 77 monomorphic |
front 78 When the genetic variance for a trait is low and the environmental variance is high, most of the phenotypic variation within a group can be attributed to ______ factors. | back 78 environmental Reason: With low genetic variance, environmental factors play a greater role in variation. |
front 79 In a group of genetically homogeneous mice, the phenotypic variance for weight is 10 g2. In a group of genetically heterogeneous mice, the phenotypic variance for weight is 25 g2. Based on this information, what are the genetic, environmental, and phenotypic variances for this trait in the heterogeneous mice? | back 79 V G = 15 g2, V E = 10 g2, and V P = 25 g2 Reason: V E = variance for the homogenous mice. V G = difference in variance between heterogenous and homogenous mice. V p = total phenotypic variance. Reason: V E = variance for the homogenous mice. V p = total phenotypic variance. Reason: V E = variance for the homogenous mice. V G = difference in variance between heterogenous and homogenous mice. Reason: V E = variance for the homogenous mice. V G = difference in variance between heterogenous and homogenous mice. V p = total phenotypic variance. |
front 80 In QTL mapping, after two inbred strains are crossed with one another, the F1 offspring are backcrossed to both parental strains. Researchers next analyze the association between ______. | back 80 the phenotype being studied and molecular markers on the chromosomes |
front 81 Genotype-environmental interaction (represented by V G x E ) is ______. | back 81 variance attributed to interactions between genetic and environmental factors |
front 82 What is inbreeding? | back 82 Mating between close relatives |
front 83 ![]() The data table shown here presents the longevity of two different strains of fruit flies at three different temperatures. The variation in longevity reported here is best described as ______. | back 83 a genotype-environment interaction |
front 84 In an inbred strain of mice, the genetic variance for a quantitative trait is equal to ______. | back 84 0 Reason: Monomorphic members of a population are all homozygous for the same allele of a given gene. Within such an inbred strain of mice, the VG equals zero. |
front 85 The tendency of certain genotypes to be found preferentially in particular environments is called a genotype-environment ____. | back 85 association |
front 86 Monomorphic members of a population ______. | back 86 are homozygous for the same allele of a given gene |
front 87 In a genetically homogeneous group of fruit flies, the phenotypic variance for abdominal bristles is 4 bristles2. In a genetically heterogeneous group of fruit flies, the phenotypic variance for abdominal bristles is 12 bristles2. What are the genetic, environmental, and phenotypic variances for this trait in heterogeneous flies? | back 87 V G = 8 bristles2, V E = 4 bristles2, and V P = 12 bristles2 Reason: VP = VG + VE; where VP is the total phenotypic variance; VG is the relative amount of variance due to genetic variation; VE is the relative amount of variance due to environmental variation. |
front 88 A genotype-environmental interaction exists when _______. | back 88 the environmental effects on phenotype differ according to genotype |
front 89 In studies of human genetics, the effects of genotype-environment associations can be minimized by studying _______. | back 89 siblings adopted at birth by different parents |
front 90 ![]() This figure depicts the varying effects of environmental factors on plants with three different genotypes. The variation represented here is best described as ______. | back 90 a genotype-environment interaction |
front 91 A genotype-environment association is ______. | back 91 the increased likelihood of finding certain genotypes in a particular environment |
front 92 A population in which all members of the population are homozygous for the same allele of a given gene is referred to as ______. | back 92 monomorphic |
front 93 Heritability is a measurement of the ______. | back 93 proportion of phenotypic variance due to genetic variance |
front 94 Genetic studies that compare quantitative traits in identical versus fraternal twins can be used to evaluate how a quantitative trait is affected by _______. | back 94 genotype-environment associations |
front 95 If all of the phenotypic variation for a trait is due to environmental effects, not to genetic variation in the population, then the heritability of the trait will be equal to ______. | back 95 0 Reason: If the phenotypic variance is due to genetic variance, the heritability would have a value of 1. |
front 96 In a population of dairy cows, the phenotypic variance for daily milk production is 5.0 L2. The genetic variance is 2.0 L2, and the environmental variance is 3.0 L2. What is the broad-sense heritability for daily milk production in this group of cattle? | back 96 0.40 Reason: Divide the genetic variance by the total phenotypic variance. (2.0/5.0 = 0.40) |
front 97 The tendency of certain genotypes to be found preferentially in particular environments is called a genotype-environment ____. | back 97 association |
front 98 Which component of genetic variance is attributed to alleles that have additive effects? | back 98 V A |
front 99 For a particular population in a particular environment, the fraction of phenotypic variance that is due to genetic variance is called ____. | back 99 heritability |
front 100 Which one fits the situation where the narrow-sense heritability will be similar to the broad-sense heritability for a quantitative trait? | back 100 V A is large compared to V D and V I |
front 101 In a population of chickens, the phenotypic variance for egg weight is 20 g2. VE = 8 g2, VG = 12 g2, and VA = 5 g2. What is the narrow-sense heritability of egg weight in this population of chickens? | back 101 0.25 Reason: Divide VA by VT, where VT is the phenotypic variance. |
front 102 If the heritability value of a trait is equal to 1, it means that ______. | back 102 all of the phenotypic variation in the population is due to genetic variance Reason: If the heritability value of a trait is equal to 1, it means that none of the genetic variation is due to environmental effects. All of the phenotypic variation in the population is due to genetic variance. |
front 103 If the observed phenotypic correlation coefficient between related individuals is 0.20 and the expected correlation coefficient based on the known genetic relationship is 0.50, then the narrow-sense heritability for the trait is ______. | back 103 0.40 Reason: Divide the observed value by the expected value. (0,20 / 0.50 = 0.40) |
front 104 In a group of mice, the total phenotypic variance for body weight is 12.0 g2. The genetic variance is 9.0 g2, and the environmental variance is 3.0 g2. What is the broad-sense heritability for this trait? | back 104 0.75 Reason: Divide the genetic variance by the total phenotypic variance. (9/12 = 0.75) |
front 105 True or false: In order to calculate narrow-sense heritability from correlation coefficients, it is necessary to assume that genetics and the environment are independent variables. | back 105 True Reason: This assumption must be made in order to calculate narrow-sense heritability based on correlation coefficients. |
front 106 Genetic variance can be partitioned into three distinct categories. Match each type of variance with the correct description. | back 106 ![]() VA: variance due to the additive effects of alleles |
front 107 To study the heritability of human fingerprints, the ______. fingerprints categorized as to whether they contain mostly arches, loops, or whorls most unique finger is selected as a representative and the total length of the ridges is determined lengths of all fingerprint ridges for all 10 fingers are added number of ridges that cross a line is counted for all 10 fingers | back 107 number of ridges that cross a line is counted for all 10 fingers |
front 108 If VA is very large in comparison to VD and VI, then narrow-sense heritability will be ______ broad-sense heritability. | back 108 approximately the same as |
front 109 ![]() The table shown here presents data collected about fingerprint patterns. Based on the information in this table, which of the following conclusions is supported? | back 109 Most of the variability in fingerprint patterns can be explained by genetic variation among individuals. |
front 110 In a certain type of plant, the phenotypic variance for height is 10 cm2. VE = 6 cm2, VG = 4 cm2, and VA = 2 cm2. What is the narrow-sense heritability for this trait? | back 110 0.2 Reason: Divide VA by VT, where VT is the phenotypic variance. |
front 111 ![]() As shown in the table, the correlation coefficient for fingerprint patterns between identical twin pairs is ______ than for pairs of fraternal twins, showing that the phenotypic variance is due to almost entirely to ______ variance. | back 111 higher; genetic |
front 112 For a certain trait, the expected correlation coefficient for an aunt-niece relationship is 0.25. In a group of aunts and nieces, the observed correlation coefficient is found to be 0.20. What is the narrow-sense heritability for this trait? | back 112 0.80 Reason: Divide the observed value by the expected value. (0,20 / 0.25 = 0.80) |
front 113 When narrow-sense heritability is calculated from correlation coefficients, an assumption that is inherent in the computation is that ______. | back 113 genetics and the environment are independent variables Reason: When narrow-sense heritability is calculated from correlation coefficients, an assumption that is inherent in the computation is that genetics and the environment are independent variables. |
front 114 The goal of selective breeding is to ______. | back 114 modify phenotypes in economically important plants and animals |
front 115 Kristine Bonnevie developed a method to study fingerprints by drawing a line from a triradius to the center of the fingerprint and counting the number of ____ that cross the line. | back 115 ridges |
front 116 The heritability of fingerprint pattern is 0.97. This means that ______. | back 116 97% of the phenotypic variance in fingerprint pattern is due to genetic variance Reason: High heritability values indicate that nearly all of the phenotypic variance is due to genetic variance. |
front 117 Selective breeding of plants and animals can result in ______. | back 117 artificial selection |
front 118 ![]() Comparing the correlation coefficients between fingerprint patterns in identical and fraternal twin pairs as shown in the table, you can conclude that the phenotypic variance in patterns is ______. | back 118 mostly due to genetic variance |
front 119 What is the difference between natural selection and artificial selection? | back 119 Natural selection favors reproductive success, while artificial selection favors traits that are desirable to humans. |
front 120 If the observed phenotypic correlation coefficient between related individuals is 0.20 and the expected correlation coefficient based on the known genetic relationship is 0.50, then the narrow-sense heritability for the trait is ______. | back 120 0.40 Reason: Divide the observed value by the expected value. (0,20 / 0.50 = 0.40) |
front 121 A certain allele of the insulin-like growth factor 1 gene is very common in small dogs but is almost absent from large breeds of dogs. The differences in the prevalence of this allele in different types of dogs can be attributed to ______. | back 121 selective breeding |
front 122 A breeding strategy designed to modify phenotypes in an economically important plant or animal is called breeding. | back 122 selective |
front 123 True or false: In order for selective breeding to be successful in modifying a quantitative trait, there must be genetic differences among individuals in a group. | back 123 True Reason: Genetic differences among individuals are essential in order for selective breeding to be successful. |
front 124 To study the heritability of human fingerprints, the ______. | back 124 number of ridges that cross a line is counted for all 10 fingers |
front 125 The modification of phenotypes of economically important plants and animals through selective breeding is referred to as ____ selection. | back 125 artificial or truncation |
front 126 In the figure, the outcome of selective breeding of corn with high or low oil content over 77 generations is shown. The results demonstrate that selective breeding can modify a(n) ______ in a directive manner. | back 126 quantitative trait |
front 127 When a breeder chooses individuals with desirable traits to be parents, the result is ____ selection. When environmental factors favor traits that enhance reproductive success, the result is ____ selection. | back 127 artificial; natural |
front 128 In an unselected population, a quantitative trait is most likely to be at a(n) ______ value. | back 128 intermediate |
front 129 Kale, broccoli, Brussels sprouts, cabbage, and kohlrabi have all been derived from the wild mustard plant by ____ breeding. | back 129 selective |
front 130 The success of selective breeding in modifying quantitative traits can be attributed to ____ variation among individuals. | back 130 genetic, allelic, or allele |
front 131 What is a selection limit? | back 131 A plateau for the value of a trait where artificial selection is no longer effective |
front 132 After many generations of selective breeding, a selection limit may be reached because ______. | back 132 the population is monomorphic for most of the alleles that affect the trait of interest Reason: Repeated selective breeding may result in a monomorphic population. |
front 133 ![]() The figure shows that selective breeding for 77 generations produced corn strains of differing oil content, one with over ____% oil content and another with less than ____% oil content. | back 133 18; 1 |
front 134 In a group of plants that has not been subjected to selective breeding for height, plant height is most likely to be ______ in value. | back 134 intermediate |
front 135 What is realized heritability? | back 135 Narrow-sense heritability that is estimated based on the response to artificial selection Reason: Realized heritability equates with narrow-sense heritability measured with artificial selection experiments. |
front 136 A certain allele of the insulin-like growth factor 1 gene is very common in small dogs but is almost absent from large breeds of dogs. The differences in the prevalence of this allele in different types of dogs can be attributed to ______. | back 136 selective breeding |
front 137 After the use of selective breeding for many generations, a trait will often reach a plateau where artificial selection is no longer effective. This plateau is called a selection ____. | back 137 limit |
front 138 A farmer is interested in increasing the length of the ears of corn in his field. He begins with corn with an average ear length of 15.0 cm. From his starting population, he selectively breeds plants with an average ear length of 20.0 cm. In the next generation, the average ear length is 18.0 cm. What is the realized heritability? | back 138 0.60 Reason: Divide the response in the offspring to selection by the selection differential in the parents. |
front 139 True or false: Selective breeding may result in a selection limit due to the accumulation of alleles that have a negative effect on fitness. | back 139 True Reason: Artificial selection for one trait can result in the accumulation of alleles that have a negative impact on overall fitness. This can result in a selection limit. |
front 140 When narrow-sense heritability is estimated based on the response to artificial selection, it is referred to as heritability. | back 140 realized |
front 141 To calculate realized heritability based on the results of selective breeding, it is necessary to know the value of R, which represents the ____ to selection observed in the offspring, and also the value of S, which represents the ____ differential of the parents. | back 141 response; selection |
front 142 Narrow-sense heritability can be used to predict ______. | back 142 the expected change in the population mean for a trait that can be achieved through artificial selection |
front 143 In a population of mice, the average tail length is 8.0 cm. A researcher who wants to breed mice to have longer tails selects parents from this group of mice with an average tail length of 10.0 cm. The offspring of this cross have an average tail length of 8.5 cm. What is the realized heritability? | back 143 0.25 Reason: Divide the response in the offspring to selection by the selection differential in the parents. |
front 144 In a certain plant, the mean plant height is 30 cm. From this population of plants, a breeder selects individuals with a mean height of 36 cm and uses them for selective breeding. If narrow-sense heritability for height is 0.8, then what is the expected mean height of the plants in the next generation? | back 144 34.8 cm Reason: The next generation will be 4.8 cm taller than the mean starting population. [0.8 (36-30) = 4.8] Thus, 30 + 4.8 = 34.8 cm. |
front 145 Inbreeding may promote homozygosity for deleterious alleles. This phenomenon is referred to as inbreeding | back 145 depression |
front 146 Match each variable involved in the calculation of realized heritability with the correct description. | back 146 ![]() Answer in the picture. |
front 147 The proportion of phenotypic variance that can be used to predict changes in the population mean through artificial selection is the ____-sense heritability. | back 147 narrow |
front 148 What is heterosis? | back 148 The increased vigor observed in the offspring of a cross between two different inbred lines |
front 149 A cattle breeder wants to increase the average birth weight of calves in his herd. In his original herd, the average birth weight is 580 kg. From this population, he selects breeders whose average birth weight was 630 kg. If the narrow-sense heritability of birth weight is 0.75, then what average birth weight is expected in the next generation? | back 149 617.5 kg Reason: 0.75 (630 kg-580 kg) = 37.5kg ; 580kg + 37.5 kg = 617.5 kg |
front 150 What is inbreeding depression? | back 150 The tendency for inbreeding to promote homozygosity for deleterious alleles |
front 151 Charles Davenport proposed that hybrid vigor is due to ______. | back 151 the favorable effects of dominant alleles in a hybrid |
front 152 When two different inbred strains are bred with one another, their offspring are often larger and/or longer-lived than either of the inbred parental strains. This phenomenon is called hybrid vigor, or ____. | back 152 heterosis |
front 153 According to the overdominance hypothesis, which of the following individuals would have the greatest fitness? | back 153 A heterozygote |
front 154 Hybrid vigor is most likely due to the fact that when highly inbred strains are crossed with one another, their offspring are ______ for deleterious recessive alleles carried by each of the two strains. | back 154 homozygous recessive Reason: In the homozygous state, recessive alleles may be deleterious. |
front 155 When neither of two alleles is recessive and the heterozygote is more vigorous than either homozygote, a phenomenon called has occurred. | back 155 overdominance |