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______________ can cause a single genotype to produce a range of potential phenotypes.

Environmental effects

Knowing the __________ of a trait has great practical importance because it allows statistical predictions regarding the phenotypes of offspring to be made on the basis of the parents' phenotypes.

heritability

The estimated broad-sense heritability for milk production in a herd of dairy cattle is high. Which is a valid inference?

Little of the variation in milk production is due to environmental variation within the herd.

Suppose that researchers estimate that broad-sense heritability of IQ in Sweden is 0.8. Which of the following conclusions is (are) valid, assuming that the estimate is accurate?

Most variance for IQ in Sweden is due to total genetic variance.

Which model best explains inheritance of complex traits such as height, weight, and IQ?

control of the traits by more than one gene plus environmental effects

Total phenotypic variance can be decomposed into all but one of these components:

heritability.

QTL mapping requires all of the following except:
a. genetic markers.

an estimate of homozygosity in the population.

A series of experiments shows that oil content in a diploid grain is influenced by five genes (a through e) with additive alleles. The highest producing strain is 20% oil content; the lowest has close to 0%. A plant of unknown genotype has an oil content of 12%. What is a possible genotype for this plant? (+ = additive alleles)

aab+bc+cd+d+e+e+

Flower diameter in sunflowers is a quantitative trait. A plant with 6-cm flowers, from a highly inbred strain, is crossed to a plant with 30-cm flowers, also from a highly inbred strain. The F1 have 18-cm flowers. F1  F1 crosses yield F2 plants with flowers ranging from 6 to 30 cm in diameter, in approximately 4-cm intervals (6, 10, 14, 18, 22, 26, 30).

19. The number of different genes influencing flower diameter in this plant is:

3

An 18-cm F1 plant is crossed to a 6-cm plant. What is the probability of an offspring with one additive allele, if all genes that influence this trait are unlinked?

3/8

Two highly inbred tobacco plants are crossed. One has dark green leaves. The other has yellow leaves. The F1 have light green leaves. Five hundred progeny from F1  F1 crosses are analyzed. Their leaves show continuous variation in color, but none has dark green or yellow leaves. What do these data suggest about the number of genes determining this trait?

There are more than 4 genes that determine this trait.

Distributions A and B in the figure below have

different means and different variances.

The graph below shows how yield in two varieties of corn respond to different environmental conditions.

Under tested conditions, variety 2 is more sensitive to environment quality than variety 1.

If broad-sense heritability for a trait is very high and narrow-sense heritability is very low, which of the following must be true?

Dominance variance must be high relative to total phenotypic variance.

In a normal distribution, 99% of the measurements fall within:

plus or minus three standard deviations of the mean.

The probability that two alleles are identical by descent is the ____________.

inbreeding coefficient

Rapid changes in allelic frequencies by __________ take place in populations that are small.

genetic drift

Which agent of evolution tends to reduce genetic variation between populations and increase genetic variation within each population?

migration

A Mendelian population is defined by individuals:

interbreeding

Which of the following evolutionary forces does NOT normally change allele frequencies?

nonrandom mating

Which agent of evolution is most likely responsible for the decrease in the frequency of a recessive allele as shown in the graph below?

selection

Which of the following does NOT bring about evolution in a population?

random mating

DNA typing is used to compare evidence DNA (E) left at a crime scene to two suspects (S1 and S2). Suspect 1 is excluded by the evidence, but suspect 2 remains included. What is the frequency of suspect 2's genotype if the allele frequencies in the population are f(A1) = 0.1, f(A2) = 0.2, and f(A3) = 0.7 and the population is at Hardy-Weinberg equilibrium?

0.04

Suppose that in a population the frequency of a particular recessive condition is 1/400. Assume the presence of only a dominant allele (A) and a recessive allele (a) in the population and that the population is at Hardy-Weinberg equilibrium. What is the frequency of the recessive allele that causes the condition?

1/20

Suppose that in a population the frequency of a particular recessive condition is 1/400. Assume the presence of only a dominant allele (A) and a recessive allele (a) in the population and that the population is at Hardy-Weinberg equilibrium. What is the frequency of heterozygotes in the population?

38/400

. If there are two alleles, A and a, in a population and the population is at Hardy-Weinberg equilibrium, which frequency of A would produce the greatest frequency of heterozygotes?

0.5

If there is random mating in a population and no evolutionary forces are acting on the population, what will be the expected outcome?

Both the genotype distribution and the allele frequencies will remain the same.

Any change in a population from Hardy-Weinberg equilibrium can be defined as ______.

. evolution

__________ speciation arises in the absence of any geographic barrier to gene flow.

Sympatric

A phylogenetic tree for three species, A, B, and C, is shown below.
A particular DNA region that is shared by all three species is cloned from each species and sequenced. There are about 100 nucleotide substitutions between A and C and between B and C. There are only 20 differences between A and B. The fossil record indicates that the ancestor to A and B diverged from the ancestor to C around 10 million years ago. What is the best estimate of the divergence between A and B based on this information, assuming a constant rate of mutation and the same rate of mutation on all branches?

500,000 years ago

______ is the splitting of one lineage into two.

Cladogenesis

. ______ is best known for developing the concept of biological species.

Mayr

The observation that some genes are mosaics of other genes can be explained by ______.

exon shuffling

. ______ are sets of genes that are similar in sequence but encode different products.

Multigene families

Which region of a gene should have the highest rates of substitution?

third position of a codon

Which of the following markers is not used to investigate genetic variation in natural populations?

isotope

______ characteristics evolved from the same character in a common ancestor.

Homologous

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