Ch28 Complex and Quantitative Traits – Test Bank | 7e

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1) What is true concerning a quantitative trait?

A) Individuals fall into distinct classes for comparison
B) The phenotypic variation for the trait is continuous
C) The phenotypic variation for the trait falls into two to three classes
D) The frequency distribution of the trait will have an asymmetrical shape

2) The square root of the variance is called the __________.

A) mean
B) standard deviation
C) standard error
D) covariance

3) When analyzing two variables, the strength of the association between the variables is called the __________.

A) covariance
B) standard deviation
C) correlation coefficient
D) variance

4) In calculations of the degrees of freedom for a correlation coefficient, what value does the degrees of freedom take?

A) (n - 1)
B) (n - 2)
C) (n - 1)/2
D) 2(n - 1)

5) After calculating a correlation coefficient you discover that the value is not significant at the 5% level. What can be done to produce a significant difference?

A) Increase the sample size
B) Decrease the sample size
C) Nothing, the value will remain the same regardless of sample size

6) What is a typical characteristic of a quantitative trait?

A) No environmental influence on the trait
B) Polygenic basis
C) Discontinuous distribution of phenotypic trait
D) Usually the graph of trait versus frequency has two distinct peaks

7) QTL mapping can rely on the relationship between genes for quantitative traits and which of the following?

A) The centromere
B) Transposon sites
C) Structural genes
D) Molecular markers such as RFLPs

8) In QTL mapping, the parental strains are crossed and the F 1 generation backcrossed to which of the following?

A) The F 2 generation
B) The parental generation
C) A strain that is homozygous recessive for all markers
D) A wild-type organism

9) A heritability value of 0.997 indicates which of the following?

A) The majority of the phenotypic variation has a genetic basis.
B) The majority of the phenotypic variation has an environmental basis.
C) The trait is polygenic.
D) There is a significant difference between the two strains.

10) For a quantitative trait, the total variance of the population is due to which of the following?

A) The amount of variance due to genetic factors only
B) The amount of variance due to environmental factors only
C) The difference between the variance attributed to genetic and environmental factors
D) The sum of the genetic and environmental variances

11) Inbreeding reduces which of the following variances to near zero?

A) Genetic variance
B) Environmental variance
C) Both variances
D) Neither variance

12) Heritability may be calculated as which of the following?

A) The total variance minus environmental variance
B) Total variance minus genetic variance
C) Genetic variance divided by environmental variance
D) Genetic variance divided by total variance

13) The first step inthebackcross mating strategy for QTL mapping is that __________.

A) two inbred parental strains that differ in a quantitative trait are crossed to produce an F1
B) the F1 offspring are crossed with each other
C) the F2 offspring must contain chromosomes that are recombinant between the markers and the genes involved in the trait
D) each parent should contain the same alleles at each QTL

14) After several generations of artificial selective breeding, a plateau is reached where artificial selection is no longer effective. This is called the __________.

A) realized limit
B) realizedheritability
C) selectioncoefficient
D) selection limit

15) Heterosis is __________.

A) the combination of lethal alleles due to inbreeding
B) an increased vigor of hybrids resulting from the crossing of inbred strains
C) a measurement of the variance due to environmental factors
D) the result of homozygosity of multiple, dominant, detrimental alleles

16) It is possible for a genetically homozygous plant population to show a bell-shapedheight distribution because __________.

A) of environmental factors
B) the trait isdiscrete
C) of genetic variation

17) Polygenic inheritance may result in a continuum of phenotypes because __________.

A) as the number of genes controlling a trait increases and the influence of environment variation becomes greater, there is a blurring of discreteness <!--Markup Copied from Habitat-->
B) the alleles for each gene are either completely dominant or recessive
C) additive genes mean the characters are meristic
D) correlations among various traits are always positive

18) The equation that describes the relationship between phenotypic variance, genetic variance and environmental variance is __________.

A) VP = VG + VE
B) 1 = VG + VE + VP
C) VE = VG + VP
D) VG = VP + VE

19) The best definition for genotype-environment interactions is __________.

A) environmental effects on the phenotype differ with genotype
B) environment does not affect phenotype
C) phenotypes will always be affected by the environment no matter what the genotype
D) genotypes and phenotypes do not change with environmental conditions

20) Calculate the narrow-sense heritability of height between aunts and nieces if the observed phenotypic correlation coefficient is 0.1.

A) 0.4
B) 2.5
C) 4
D) 0.25

21) A selective breeding program is trying to develop an agricultural plant with decreased stem length to aid in mechanical harvesting. The mean stem height of the population is 36 cm while the mean stem height of the parents is 30 cm and the mean stem height of the offspring is 33 cm. What is the realized heritability for stem height in this crop?

A) 0.5
B) 1
C) .33
D) 0

22) Hybrids resulting from matings of inbred strains often show heterosis, explained by two different hypotheses, overdominance and dominance. Which statement is correct regardingthese hypotheses?

A) The overdominance hypothesis relies on dominant/recessive alleles.
B) The dominance hypothesis relies on the fact that in the F1s, the deleterious effects of recessive alleles are masked by dominant ones.

23) If in breeding selection the difference between the mean of the offspring and the mean of the starting population is 3.8 and the difference between the mean of the parents and the mean of the starting population is 5.3 then the realized heritability is approximately __________.

A) 0.72
B) 1.4
C) 1.5
D) 20.3

24) The heights of mothers and their female children are measured (in inches) with the following results

24.1) What is the mean height for the mothers and daughters?

A) Mothers: 66.75 inDaughters: 67.63 in
B) Mothers: 65.75 inDaughters: 67.63 in
C) Mothers: 66.75 inDaughters: 66.52 in
D) Mothers: 65.67 inDaughters: 66.45 in

24.2) What is the variance for the mother's and daughter's heights?

A) Mothers: 42.21 in2Daughters: 24.27 in2
B) Mothers: 41.32 in2Daughters: 23.71 in2
C) Mothers: 43.78 in2Daughters: 24.27 in2
D) Mothers: 42.21 in2Daughters 23.78 in2

24.3) What is the standard deviation for the mother's and daughter's heights?

A) Mothers: 6.50 inDaughters: 4.93 in
B) Mothers: 1781.68 inDaughters: 589.03 in
C) Mothers: 42.21 inDaughters: 24.27 in
D) Mothers: 5.50 inDaughters: 5.93 in

25) Heritability is the amount of genetic variation in a particular population and a particular environment.

⊚ true
⊚ false

26) Heritability values can be compared between populations if there is variation in the environmental conditions.

⊚ true
⊚ false

27) Traits that fall into discrete categories are called continuous traits.

⊚ true
⊚ false

28) The sum of all of the values for a trait, divided by the total number of individuals, is called the standard deviation.

⊚ true
⊚ false

29) QTL stands for quantitative trait loci and is an example of monogenic inheritance.

⊚ true
⊚ false

30) The amount of phenotypic variation in a group that is due to genetic variation is called heritability.

⊚ true
⊚ false

31) Many organisms used in modern agriculture are a result of artificial selection.

⊚ true
⊚ false

32) The process of mating between genetically unrelated individuals is called inbreeding.

⊚ true
⊚ false

33) Realized heritability may be determined from artificial selection experiments.

⊚ true
⊚ false