Question 1

A man has a rare dominant autosomal trait.There is a _______ probability that one of his children will have the disease.

Accepted Answer

The answer of A man has a rare dominant autosomal...

Question 2

The cross AaBb × AaBb is an example of a _______ cross, and the results of such crosses led Mendel to propose what we now call the law of _______.
A) self; segregation of genes
B) dihybrid; segregation of genes
C) dihybrid; independent assortment
D) test; segregation of genes
E) test; independent assortment

Accepted Answer

The cross AaBb × AaBb is a dihybrid cross because it involves two traits (A/a and B/b), and the results of such crosses led Mendel to propose the law of independent assortment, which states that alleles for different genes segregate independently of each other during meiosis.

Question 3

A scientist works with a particular strain of bacteria.Sometime after a cross-contamination event in the lab, she finds that her bacteria have now acquired antibiotic resistance.She concludes that the strains have undergone _______.

Accepted Answer

The answer of A scientist works with a particular strain...

Question 4

You have discovered a new species of rodent in a remote forest.You manage to trap a handful of the animals and bring them back to your lab to establish a breeding program for study.All of the rodents have smooth cup-shaped ears, but as you breed successive generations, you also notice individuals with notched ears, ones with serrated ears, and ones with long floppy ears.Genetic tests establish that there is only one gene involved, so you infer that the genetic phenomenon responsible is _______.

Accepted Answer

The answer of You have discovered a new species of...

Question 5

For a typical situation of incomplete dominance in which one parent is BB and the other is bb, _______ percent of the offspring would be expected to display the heterozygous phenotype in the F₂ generation.

Accepted Answer

The answer of For a typical situation of incomplete dominance...

Question 6

A woman has B blood type of the ABO system.Her mother is type O.From this, we can infer that her father
A) has AB blood type.
B) could not have AB blood type.
C) could not have B blood type.
D) could not have O blood type.
E) could be any blood type.

Accepted Answer

The answer of A woman has B blood type of...

Question 7

Assume that blending inheritance, not particulate Mendelian inheritance, is operating in a life form.An individual with a tail that is 10 centimeters long is crossed with an individual that has a tail 2 cm long.What would the expected tail length be in the F₂ progeny? A) All individuals would have tails that are 10 cm long. B) All individuals would have tails that are 6 cm long. C) 9/16 would have tails that are 10 cm long, 6/16 would have tails that are 6 cm long, and 1/16 would have tails that are 2 cm long. D) 1/4 would have tails that are 10 cm long, 1/2 would have tails that are 6 cm long, and 1/4 would have tails that are 2 cm long. E) 3/4 would have tails that are 10 cm long, and 1/4 would have tails that are 2 cm long.

Accepted Answer

In blending inheritance, the traits of the parents blend together and are not expressed as discrete units. Therefore, the expected tail length in the F₂ progeny would be the average of the parent tail lengths, which is (10 cm + 2 cm)/2 = 6 cm.

Question 8

Coat color in mice involves the effects of multiple gene interactions.If a mouse has two recessive alleles (aa) for coat color, it will always be albino no matter what the genotype of other genes involved in coat color.This is an example of
A) pleiotropy.
B) incomplete dominance.
C) codominance.
D) heterosis.
E) epistasis.

Accepted Answer

This is an example of epistasis, where one gene (the gene for albinism in this case) masks or suppresses the expression of another gene at a different locus, determining the coat color regardless of the other genes' configurations.

Question 9

If both parents have AB blood type, _______ percent of their children would be expected to have type AB blood.

Accepted Answer

The answer of If both parents have AB blood type,...

Question 10

A test cross of a pea plant with round and yellow seeds yields half round, yellow seeds and half round, green seeds.You conclude that the plant was homozygous for the shape gene and _______ for the color gene.

Accepted Answer

The answer of A test cross of a pea plant...

Question 11

What is the probability that a cross between a true-breeding pea plant with spherical seeds and a true-breeding pea plant with wrinkled seeds will produce F₁ progeny with spherical seeds? A) ½ B) ¼ C) 0 D) 1/8 E) 1

Accepted Answer

In Mendelian genetics, a cross between a true-breeding (homozygous) plant with spherical seeds (SS) and a true-breeding plant with wrinkled seeds (ss) will produce F1 progeny that are all heterozygous (Ss) for the seed shape trait. Since the spherical seed trait (S) is dominant over the wrinkled seed trait (s), all F1 progeny (Ss) will exhibit spherical seeds. Therefore, the probability is 1 (100%).

Question 12

You are crossing different varieties of snapdragons to get different colored flowers.After crossing one of your red-flowered plants to one of your white-flowered plants, you get pink-flowered plants.This pattern of inheritance shows _______.

Accepted Answer

The answer of You are crossing different varieties of snapdragons...

Question 13

What fraction of offspring of the cross AaBb × AaBb would be homozygous for both the dominant alleles, assuming that they are on different chromosomes?
A) 1/4
B) 1/8
C) 1/16
D) 1/32
E) 1/64

Accepted Answer

When crossing two individuals heterozygous for two different genes (AaBb x AaBb), the probability of producing offspring that are homozygous for both dominant alleles is 1/16, or 6.25%. This is because there are four possible gamete combinations that can be made by each parent (AB, Ab, aB, ab) and therefore 16 possible offspring genotypes. Of these 16 possible genotypes, only one is homozygous dominant for both traits (AABB).

Question 14

You have chosen to study the genetics of snapdragon flower color.True-breeding red-flowered plants crossed with true-breeding white-flowered plants generate all pink-flowered F₁ offspring.When the F₁ offspring are crossed, you get the following numbers of F₂ offspring: 24 red, 54 pink, and 22 white.You interpret this inheritance pattern as A) incomplete dominance. B) codominance. C) epistasis. D) blending. E) pleiotropy.

Accepted Answer

The inheritance pattern seen in this scenario is consistent with incomplete dominance. When true-breeding red-flowered snapdragons are crossed with true-breeding white-flowered snapdragons, the resulting F1 generation consists of all pink-flowered plants. This suggests that the red and white flower color alleles are not completely dominant over each other, resulting in a blending of the two colors to create pink. When the F1 generation is crossed, the resulting F2 generation shows a ratio of 1 red : 2 pink : 1 white, which is consistent with incomplete dominance. In codominance, both alleles are fully expressed and would result in a different ratio of offspring. Epistasis involves one gene affecting the expression of another gene, which is not seen in this scenario. Blending and pleiotropy are not possible explanations for this inheritance pattern.

Question 15

A man has a rare dominant autosomal trait.There is a _______ probability that one of his grandchildren will have the disease.

Accepted Answer

The answer of A man has a rare dominant autosomal...

Question 16

You are researching the effects of a dominant mutation that causes a particular rare phenotype.Your pedigree studies show you that not everyone who has the allele shows the phenotype.You conclude that the allele has low _______.

Accepted Answer

The answer of You are researching the effects of a...

Question 17

If both parents have AB blood type, _______ percent of their children would be expected to have type O blood.

Accepted Answer

The answer of If both parents have AB blood type,...

Question 18

Whether a pea seed is round or wrinkled is due to a single Mendelian gene, with round seeds being dominant to wrinkled seeds.In the progeny of a test cross, _______ of 80 seeds should be round if the unknown round-seeded individual being tested is heterozygous.
A) 0
B) 20
C) 40
D) 60
E) 80

Accepted Answer

If the unknown round-seeded individual being tested is heterozygous, then it can be represented as Rr (where R represents round seed allele and r represents wrinkled seed allele). In a test cross, the individual is crossed with a homozygous recessive individual (rr). The possible gametes for Rr individual are R and r, while for the rr individual it is only r. Therefore, the possible offspring will be Rr and rr in a 1:1 ratio. Since round seeds are dominant, only individuals with at least one R allele will have round seeds. Therefore, out of the 80 possible offspring, 40 will have round seeds (Rr) and 40 will have wrinkled seeds (rr). Thus, the answer is (C) 40.

Question 19

Unattached earlobes are a dominant trait in humans.Finn and Maggie both have unattached earlobes but their daughter, Celia, does not.If Finn and Maggie have a second child, what is the probability that this child will have attached earlobes?
A) 1/4
B) 1/2
C) 3/4
D) 1
E) 1/8

Accepted Answer

Since both Finn and Maggie have unattached earlobes but their daughter has attached earlobes, it means both parents must be heterozygous (having one allele for unattached earlobes and one for attached). The Punnett square for two heterozygous parents (Uu x Uu, where U = unattached, u = attached) shows that there is a 1/4 chance of having a child with attached earlobes (uu).

Question 20

Incomplete dominance
A) involves the distinct expression of both alleles, as in the ABO blood group system.
B) is far less common than complete dominance.
C) is the same as codominance.
D) results in a phenotypic ratio of 1:2:1 in a monohybrid cross.
E) occurs only in X-linked genes.

Accepted Answer

Incomplete dominance results in a 1:2:1 phenotypic ratio in a monohybrid cross, where the heterozygote shows an intermediate phenotype between the two homozygotes.

Quiz 12: Inheritance, Genes, and Chromosomes

A man has a rare dominant autosomal trait.There is a _______ probability that one of his children will have the disease.

The cross AaBb × AaBb is an example of a _ cross, and the results of such crosses led Mendel to propose what we now call the law of _.

A scientist works with a particular strain of bacteria.Sometime after a cross-contamination event in the lab, she finds that her bacteria have now acquired antibiotic resistance.She concludes that the strains have undergone _______.

For a typical situation of incomplete dominance in which one parent is BB and the other is bb, _______ percent of the offspring would be expected to display the heterozygous phenotype in the F₂ generation.

A woman has B blood type of the ABO system.Her mother is type O.From this, we can infer that her father

Assume that blending inheritance, not particulate Mendelian inheritance, is operating in a life form.An individual with a tail that is 10 centimeters long is crossed with an individual that has a tail 2 cm long.What would the expected tail length be in the F₂ progeny?

Coat color in mice involves the effects of multiple gene interactions.If a mouse has two recessive alleles (aa) for coat color, it will always be albino no matter what the genotype of other genes involved in coat color.This is an example of

If both parents have AB blood type, _______ percent of their children would be expected to have type AB blood.

A test cross of a pea plant with round and yellow seeds yields half round, yellow seeds and half round, green seeds.You conclude that the plant was homozygous for the shape gene and _______ for the color gene.

What is the probability that a cross between a true-breeding pea plant with spherical seeds and a true-breeding pea plant with wrinkled seeds will produce F₁ progeny with spherical seeds?

You are crossing different varieties of snapdragons to get different colored flowers.After crossing one of your red-flowered plants to one of your white-flowered plants, you get pink-flowered plants.This pattern of inheritance shows _______.

What fraction of offspring of the cross AaBb × AaBb would be homozygous for both the dominant alleles, assuming that they are on different chromosomes?

A man has a rare dominant autosomal trait.There is a _______ probability that one of his grandchildren will have the disease.

You are researching the effects of a dominant mutation that causes a particular rare phenotype.Your pedigree studies show you that not everyone who has the allele shows the phenotype.You conclude that the allele has low _______.

If both parents have AB blood type, _______ percent of their children would be expected to have type O blood.

Whether a pea seed is round or wrinkled is due to a single Mendelian gene, with round seeds being dominant to wrinkled seeds.In the progeny of a test cross, _______ of 80 seeds should be round if the unknown round-seeded individual being tested is heterozygous.

Unattached earlobes are a dominant trait in humans.Finn and Maggie both have unattached earlobes but their daughter, Celia, does not.If Finn and Maggie have a second child, what is the probability that this child will have attached earlobes?

Incomplete dominance

Quiz 12: Inheritance, Genes, and Chromosomes

A man has a rare dominant autosomal trait.There is a _______ probability that one of his children will have the disease.

The cross AaBb × AaBb is an example of a _______ cross, and the results of such crosses led Mendel to propose what we now call the law of _______.

A scientist works with a particular strain of bacteria.Sometime after a cross-contamination event in the lab, she finds that her bacteria have now acquired antibiotic resistance.She concludes that the strains have undergone _______.

For a typical situation of incomplete dominance in which one parent is BB and the other is bb, _______ percent of the offspring would be expected to display the heterozygous phenotype in the F2 generation.

A woman has B blood type of the ABO system.Her mother is type O.From this, we can infer that her father

Assume that blending inheritance, not particulate Mendelian inheritance, is operating in a life form.An individual with a tail that is 10 centimeters long is crossed with an individual that has a tail 2 cm long.What would the expected tail length be in the F2 progeny?

Coat color in mice involves the effects of multiple gene interactions.If a mouse has two recessive alleles (aa) for coat color, it will always be albino no matter what the genotype of other genes involved in coat color.This is an example of

If both parents have AB blood type, _______ percent of their children would be expected to have type AB blood.

A test cross of a pea plant with round and yellow seeds yields half round, yellow seeds and half round, green seeds.You conclude that the plant was homozygous for the shape gene and _______ for the color gene.

What is the probability that a cross between a true-breeding pea plant with spherical seeds and a true-breeding pea plant with wrinkled seeds will produce F1 progeny with spherical seeds?

You are crossing different varieties of snapdragons to get different colored flowers.After crossing one of your red-flowered plants to one of your white-flowered plants, you get pink-flowered plants.This pattern of inheritance shows _______.

What fraction of offspring of the cross AaBb × AaBb would be homozygous for both the dominant alleles, assuming that they are on different chromosomes?

A man has a rare dominant autosomal trait.There is a _______ probability that one of his grandchildren will have the disease.

You are researching the effects of a dominant mutation that causes a particular rare phenotype.Your pedigree studies show you that not everyone who has the allele shows the phenotype.You conclude that the allele has low _______.

If both parents have AB blood type, _______ percent of their children would be expected to have type O blood.

Whether a pea seed is round or wrinkled is due to a single Mendelian gene, with round seeds being dominant to wrinkled seeds.In the progeny of a test cross, _______ of 80 seeds should be round if the unknown round-seeded individual being tested is heterozygous.

Unattached earlobes are a dominant trait in humans.Finn and Maggie both have unattached earlobes but their daughter, Celia, does not.If Finn and Maggie have a second child, what is the probability that this child will have attached earlobes?

Incomplete dominance

The cross AaBb × AaBb is an example of a _ cross, and the results of such crosses led Mendel to propose what we now call the law of _.

For a typical situation of incomplete dominance in which one parent is BB and the other is bb, _______ percent of the offspring would be expected to display the heterozygous phenotype in the F₂ generation.

Assume that blending inheritance, not particulate Mendelian inheritance, is operating in a life form.An individual with a tail that is 10 centimeters long is crossed with an individual that has a tail 2 cm long.What would the expected tail length be in the F₂ progeny?

What is the probability that a cross between a true-breeding pea plant with spherical seeds and a true-breeding pea plant with wrinkled seeds will produce F₁ progeny with spherical seeds?