Bio 14 Problem Set 2

The ability to taste phenylthiocarbamide (PTC) is a trait controlled by a single gene with two alleles (PTC taster and PTC non-taster). Suppose 36% of a remote mountain village cannot taste PTC and must, therefore, be homozygous recessive (aa) for the PTC non-taster allele. If this population conforms to Hardy-Weinberg expectations for this gene, what percentage of the population must be homozygous (AA) for the PTC taster allele? 48% 40% 16% 32%

16%

If a phenotype is due to an autosomal recessive allele, individuals that display this phenotype must: be heterozygous be homozygous have parents that express the phenotype have one parent that has the recessive allele

be homozygous

Tail fluffiness for the fictitious species Fluffus maximus is controlled by a single gene, where the allele for fluffy tails is dominant to the allele for smooth tails. A litter of 8 babies is born, it contains 2 smooth tailed and 6 fluffy tailed individuals. Assuming these babies are representative, what are the most likely genotypes of the parents? both parents are homozygous smooth one parent is homozygous fluffy, the other is heterozygous both parents are heterozygous one parent is homozygous smooth, the other is homozygous fluffy

both parents are heterozygous

Which of the following is the best null hypothesis for the research question: Does playing music for a dog during a storm decrease its stress response? music affects dog stress during storms by blocking out stressful stimuli music increases dog stress during a storm by magnifying stressful stimuli dogs that listen to music during storms will have the same stress level before and after storms dogs that listen to music during a storm will have the same stress level as those who don't

dogs that listen to music during a storm will have the same stress level as those who don't

The influx of individuals from other populations increases genetic diversity. This is an example of: a bottleneck genetic drift gene flow dispersion

gene flow

The transmission of traits from parents to offspring is called inheritance of acquired characteristics heredity genetics polymorphisms

heredity

Offspring that result from many generations of inbreeding are expected to have heterozygous alleles higher fitness than outcrossed offspring homozygous alleles and lower fitness large genetic variation

homozygous alleles and lower fitness

If a population is diploid and has 2 alleles at one locus, and genotype frequencies like the one below, what can we infer about this population and/or its history? TT = 0.81, Tt = 0.18, tt = 0.01 in relation to locus T, this population has experienced genetic drift in relation to locus T, this population has a long (multiple generations) history of random mating in relation to locus T, this population has high mutation rates in relation to locus T, the parents of this observed generation mated at random

in relation to locus T, the parents of this observed generation mated at random

A mouse with white fur breeds with a mouse with black fur, all of their offspring have a phenotype of gray fur. What does the gene for fur color in these mice appear to be an example of? incomplete dominance codominance complete dominance partial inheritance

incomplete dominance

Which of the following is true about genetic drift? it only happens in small populations it decreases the genetic variability among populations it never results in allele fixation or loss it can cause the prevalence of deleterious alleles to drift up and down

it can cause the prevalence of deleterious alleles to drift up and down

Which of the following is true about inbreeding? it increases the rate by which natural selection removes deleterious alleles from the population it increases the number of heterozygotes in the population it often leads to rapid evolutionary changes on its own it leads directly to changes in allele frequencies

it increases the rate by which natural selection removes deleterious alleles from the population

Which of the following evolutionary mechanisms always increases the prevalence of alleles associated with increased fitness. gene flow natural selection genetic drift mutation

natural selection

Mendel crossed plants with round seeds with plants with wrinkled seeds. F1 offspring all had round seeds. The most likely explanation is... seed wrinkles are not genetically determined wrinkled seeds are dominant round seeds are dominant seed shape is an example of blended inheritance

round seeds are dominant

Individuals of a plant with the genotype Rr have red and white flowers, individuals with RR have red flowers and rr have white flowers. Which of the following is true of the allele(s) that control flower color in this species? R is dominant the alleles display codominance the trait for flower color is likely controlled by several alleles the alleles show incomplete dominance

the alleles display codominance