Choose the best answer.

1		Quantitative traits are probably controlled by single genes.
			A)	True
			B)	False
2		Which of these is an example of a quantitative trait?
			A)	A study compares rats with and without pigment in the irises of their eyes.
			B)	Chinese strains of pigs have larger numbers of piglets per litter than American strains.
			C)	Caterpillars exposed to juvenile hormone mimics are unable to metamorphose into adults.
			D)	All of these are quantitative traits.
			E)	None of these are quantitative traits.
3		In a normal distribution:
			A)	Equal numbers of individuals are found above and below the mean.
			B)	The mean is also the most frequent value.
			C)	68% of individuals are within one standard deviation of the mean.
			D)	All of these.
			E)	None of these.
4		You want to design a study to gauge the extent to which coat color in Irish Setters is similar between parents and offspring. What statistical measure would be most appropriate?
			A)	Variance.
			B)	Covariance.
			C)	Correlation coefficient.
			D)	Regression analysis.
5		Most behavioral traits are affected by many different genetic influences as well as environment. The best descriptor for such traits is:
			A)	Mendelian.
			B)	Polygenic.
			C)	Highly heritable.
			D)	None of these descriptors are accurate.
6		A quantitative trait locus (QTL):
			A)	Contains a known gene which affects a polygenic trait.
			B)	Contains a single gene which affects a polygenic trait.
			C)	Controls all of the variation for a polygenic trait.
			D)	All of the above.
			E)	None of the above.
7		Polygenic traits are traits that are only affected by genetic influences.
			A)	True
			B)	False
8		In a study of rate of weight gain in pigs, scientists crossed two very different breeds of pigs and interbred the offspring for several generations. When they analyzed the F4 offspring, even though all the pigs were raised on the same farm and given the same feed, there were dramatic differences in the rate of weight gain, measured both as pounds of gain per day and number of days to reach market weight. When graphing either statistic for a large number of pigs, a continuous distribution was found. Which of the following statements is the most correct?
			A)	Rate of weight gain in pigs is primarily controlled by environmental factors.
			B)	There are probably only a few genetic factors controlling this trait.
			C)	This trait is controlled by a large number of genetic factors.
			D)	This trait is not affected by environmental factors.
			E)	None of the above statements are accurate.
9		For quantitative traits, two individuals with the same genotype may have different phenotypes.
			A)	True
			B)	False
10		Regarding the Nilsson-Ehle wheat experiment, which of the following statements is true?
			A)	Wheat are heterozygous for three hull color loci.
			B)	Wheat plants can have a range of intensity of hull color.
			C)	Hull color in wheat plants is controlled by a single dominant allele.
			D)	All of the above are true.
			E)	None of the above are true.
11		What color would you expect for the hulls of a wheat plant heterozygous for all three hull color loci?
			A)	Light red
			B)	Intermediate red
			C)	Medium red
			D)	Dark red
			E)	Extra dark red
12		How would you expect an increase in molecular marker density to affect QTL mapping studies?
			A)	Genes affecting quantitative traits can be directly identified.
			B)	Segments of the genome which control quantitative traits can be more quickly identified.
			C)	QTLs will be smaller than those identified in previous studies.
			D)	All of these.
			E)	None of these.
13		Which of these definitions of heritability is most correct?
			A)	The total amount of phenotypic variation in a population.
			B)	The proportion of phenotypic variation in a population that is due to genetic factors.
			C)	The total amount of genetic variation in a population.
			D)	The proportion of phenotypic variation in a population that is due to environmental factors.
			E)	None of these are correct definitions of heritability.
14		High heritability is best demonstrated in which of the following situations?
			A)	Within a wild population of clover plants, there is a very low amount of variation in the number of leaves per stem.
			B)	When studying obesity in a human population, there tends to be less variation within families than across the entire population.
			C)	In a study of adopted children, the children's height is much more similar to that of their biological parents than their adoptive parents.
			D)	The DNR maintains records of deer shot each hunting season. In drought years, the average weight is much lower than in years of sufficient rain.
15		A corn population created by selective breeding over many years shows a very low Vg for number of kernels per ear. Ear size in this strain of corn can probably be increased by further selective breeding.
			A)	True
			B)	False
16		You do a study of heritability of insecticide resistance in European corn borers in Iowa corn crops, and calculate a value of 0.78. This tells you that the trait of insecticide resistance in primarily (78%) influenced by genetic factors, and environment only has a minor impact (22%).
			A)	True
			B)	False
17		Which of these is the best example of the dominance hypothesis?
			A)	Two inbred wheat strains are homozygous for deleterious recessive alleles for different genes, which mildly decrease yield. Hybrids of these two inbred strains are heterozygous for each locus, and display a dramatic increase in yield over either parent.
			B)	Two inbred wheat strains are homozygous for deleterious dominant alleles for different genes, which mildly decrease yield. Hybrids of these two inbred strains are heterozygous for each locus, and display a dramatic increase in yield over either parent.
			C)	Two inbred wheat strains are homozygous for different codominant alleles at a single locus. Hybrids of these two inbred strains are heterozygous for this locus and display an increase in yield over either parent due to an interaction between the gene products of both alleles.
			D)	All of the above illustrate the dominance hypothesis.
			E)	None of the above illustrate the dominance hypothesis.
18		What is the main difference between the dominance and overdominance hypotheses?
			A)	Overdominance requires the presence of recessive alleles for the genes involved.
			B)	Overdominance requires interactions between alleles of different genes.
			C)	Overdominance requires interactions between alleles of the same gene.
			D)	All of these are correct.
			E)	None of these are correct.
19		Dominance can be easily confused with overdominance if QTLs are involved.
			A)	True
			B)	False