14.    Evolutionarychange of a trait in a population under the effect of selection canoccur only when

         a) VE > 0 b) h2> 0 c) h2 = 0 d) VE = 0

15.    You examine bodyweight in a laboratory population of mice. You find thatindividuals fall into five discrete weight classes with meanweights of 15 grams, 20 gr., 25 gr., 30 gr., and 35 gr. Thevariance of weight within each class is very low, and thedistribution of weights in the different weight classes do notoverlap. Based on these observations you would conclude that inthis population and environment

a) body weight is a quantitative traitb) body weight is a qualitative trait   c) body weight isaffected by many different genes d) body weight is affected only byenvironment e) a & d.

16.    In sage plants,height is affected by only one gene, T. One hundred seeds ofgenotype TT are grown in a field. After one month the plants aremeasured and are found to exhibit a continuous normal distributionof heights ranging from 4 to 12 inches. What can you conclude aboutthis phenotypic variation? a) it must be due to genetic variationalone b) it must be due to environmental variation alone c) it isdue to a combination of genetic and environmental variation d) youcannot tell the source of the variation.

17.    You bring asample of flies from a natural population into the laboratory andbegin selecting for high body weight by using the heaviest 20% ofthe population as parents each generation for five generations.If mean body weight remains the same in eachgeneration

         a) phenotypicvariation is due only to effects of the environment b) phenotypicvariation is due only to genetic variation among individuals c) VG> 0 d) VE = 0

18.    Given theobservations described in the previous question you would concludethat for body weight

         a) heritability iszero b) heritability is greater than zero but less than 1 c)heritability is 1 d) heritability is greater than 1

19.    Theheritability of body weight in cows a) can bemeasured on a single individual b) is the proportion of VG which isdue to VE  c) is the proportion of VP which is due toVG   d) is the proportion of VE transmitted to offspringe) all of the above.