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11 Dec 2019

Consider a hypothetical quantitative weight trait affected by five loci. Assume complete dominance at all loci, and no epistasis. The independent effect of each dominant allele is +8 lb and the independent effect of each recessive allele is -2 lb. The population mean for the trait is 500 lb.

a. If an animal is heterozygous at all loci, and the environmental effect is -12 lb, what are the values for the animal’s breeding value, genotypic value, gene combination value, and phenotypic value?

b. If an animal is homozygous dominant at three loci and homozygous recessive at the other two, and the environmental effect is +10, what are the values for the animal’s breeding value, genotypic value, gene combination value, and phenotypic value?

c. Which animal would produce the heaviest offspring, on average? Why?

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Deanna HettingerLv2
13 Dec 2019
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Related questions

The seed color in a species of flowering plant can be either green or white, with the trait determined by two independently assorting loci. At one locus, the G allele produces green color and is dominant to the recessive g allele for white. At the other locus the dominant, C, allele code for color production and its recessive counterpart, c, codes for colorless or white seeds. A pure-breeding green seeded plant is crossed with a white- seeded plant homozygous for both loci.

a) Identify all possible genotype(s) for the white-seeded parent and the F1 genotype(s) that each would produce when crossed with the true-breeding green seeded plant.

b) Assume that the genotype of the original white-seeded parent is gg,cc,F1 plants from the cross described in a. are crossed to produce the F2. Identify the F2 phenotypes and their expected ratio.

c) What would be the probability of producing a white-seeded plant in a cross between two F2 plants of the genotypes Ggcc and ggCc.

Part A

In humans, individuals may or may not have a widow’s peak. This trait is controlled by genes at a single locus, with the allele for having a widow’s peak dominant to the allele for not having one. A population of humans is sampled; 59 have a widow’s peak and 44 do not. 25 of the people with a widow’s peak are homozygous dominant. What are the frequencies of the dominant and recessive alleles observed in this sample?

p = _____

q = _____

Part B

In a species of corn, individuals have either narrow or wide corn cobs. This trait is controlled by genes at a single locus, with the narrow cob allele dominant to the wide cob allele. A farmer counts 74 narrow cob and 113 wide cob plants in a field. Of the narrow cob plants, 28 are homozygous dominant. What are the frequencies of the dominant and recessive alleles observed in this sample?

p = _____

q = _____

Part C

In a population of peas, the frequency of the dominant allele for a purple flower is 0.61 and the frequency of the recessive allele for a white flower is 0.39. What would the genotypic frequencies be if the population is in equilibrium?

_____ = Frequency of homozygous dominant individuals

_____ = Frequency of heterozygous individuals

_____ = Frequency of homozygous recessive individuals

How many individuals would you expect of each genotype in a population of 500 peas?

_____ = Number of homozygous dominant individuals

_____ = Number of heterozygous individuals

_____ = Number of homozygous recessive individuals

Part D

In mice, a mahogany coat color allele is dominant over the tan coat color allele. In a population of mice, the frequency of the allele for mahogany coat color is 0.19 and the frequency of the allele for tan coat color is 0.81. What would the genotypic frequencies be if the population is in equilibrium?

_____ = Frequency of homozygous dominant individuals

_____ = Frequency of heterozygous individuals

_____ = Frequency of homozygous recessive individuals

How many individuals would you expect of each genotype in a population of 100 mice?

_____ = Number of homozygous dominant individuals

_____ = Number of heterozygous individuals

_____ = Number of homozygous recessive individuals

Part E

In humans, the free earlobe allele is dominant over the attached ear lobe allele. In a population of humans, the frequency of the allele for free earlobes is 0.42 and the frequency of the allele for attached earlobes is 0.58. What would the genotypic frequencies be if the population is in equilibrium?

_____ = Frequency of homozygous dominant individuals

_____ = Frequency of heterozygous individuals

_____ = Frequency of homozygous recessive individuals

How many individuals would you expect of each genotype in a population of 25 humans?

_____ = Number of homozygous dominant individuals

_____ = Number of heterozygous individuals

_____ = Number of homozygous recessive individuals

QUESTION 1

Jim is blood type A, his brother John is type O and his sister Jane is type AB. What are the genotypes of their parents?
A.
IAi and IBi
B.
IAIA and IBIB
C.
IAi and IBIB
D.
IAIB and ii
E.
IAIA and IBi

QUESTION 2

Which of the following is true for alleles that show incomplete dominance?
A.
Heterozygotes have a genotype like the dominant allele.
B.
Homozygotes have a genotype like the recessive allele.
C.
Heterozygotes have a phenotype intermediate between the dominant and recessive alleles.
D.
Homozygotes have the same phenotype as the heterozygotes.
QUESTION 3

Which principle of inheritance concluded that when games are formed in meiosis, the two alleles of each gene separate from one another, and each gamete receives only one allele?
A.
independent assortment
B.
heterozygosity
C.
segregation
D.
dominance
QUESTION 4

Which term best describes a condition in which alleles at one locus can alter the expression of alleles at another locus?
A.
polygenic inheritance
B.
codominance
C.
multiple alleles
D.
pleiotropy
E.
epistasis
QUESTION 5

A single unit of genetic information located on a chromosome defines:
A.
a trait
B.
an allele
C.
a chromosome
D.
a locus
E.
a gene
QUESTION 6

The physical expression (appearance or function) of an organism's genes defines:
A.
genotype
B.
a single characteristic
C.
physiology
D.
mutation
E.
phenotype
QUESTION 7

Palomino horses (golden color with a blond mane) are an incompletely dominant trait produced by the combination of the chestnut color allele and the cream color allele. If you wanted to produce as many palominos as possible, which mating strategy below would be the best choice?
A.
Chestnut x Cream
B.
Palomino x Cream
C.
Palomino x Chestnut
D.
Palomino x Palomino
QUESTION 8

Which term best describes the effect of a single gene on multiple aspects of the phenotype?
A.
epistasis
B.
pleiotropy
C.
multiple alleles
D.
codominance
E.
polygenic inheritance
QUESTION 9

Which term best describes the separate expression of both alleles for a single trait in the same cell?
A.
multiple alleles
B.
codominance
C.
pleiotropy
D.
epistasis
E.
polygenic inheritance
QUESTION 10

One form of a gene found on a single chromosome defines:
A.
an allele
B.
a locus
C.
a chromosome
D.
a trait
E.
a gene
QUESTION 11

A chocolate lab (whose mother was a yellow lab) is mated with a black lab whose genotype is BbEe. What fraction of the offspring would be expected to be yellow labs?
A.
1/4
B.
none
C.
1/2
D.
3/16
E.
1/8
QUESTION 12

What type of allele is always expressed regardless of whether the individual is homozygous or heterozygous for it?
A.
Both the dominant and recessive alleles
B.
Recessive allele
C.
Allosteric allele
D.
Lethal allele
E.
Dominant allele
QUESTION 13

Given the parents AABBGgHhrr × AabbGgHhRr, assume simple dominance and independent assortment. What proportion of the progeny will be expected to have the genotype AaBbggHHrr?
A.
1/256
B.
1/64
C.
1/16
D.
1/32
E.
1/128
QUESTION 14

___________________ is defined as having two of the same type of allele for a particular trait.
A.
Homozygous
B.
Dominance
C.
Incomplete dominance
D.
Heterozygous
E.
Genotype

QUESTION 15

The physical position of an allele on a single chromosome defines:
A.
an allele
B.
a chromosome
C.
a gene
D.
a locus
E.
a trait
QUESTION 16

Which term best describes two or more genes affecting the phenotype in an additive fashion?
A.
codominance
B.
polygenic inheritance
C.
multiple alleles
D.
pleiotropy
E.
epistasis

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