Question 1

What is the probability that an individual is Aa or AA if his or her parents are both heterozygous for the trait? A)¹/₄ B)¹/₂ C)³/₄ D)1

Accepted Answer

When both parents are heterozygous, their genotypes would be Aa. Using a Punnett square, we can determine the possible genotypes of their offspring: A a A AA Aa a Aa aa As can be seen, there is a 25% chance of the offspring being AA (homozygous dominant) and a 50% chance of being Aa (heterozygous). Therefore, the probability of an individual being Aa or AA is 75% (25% for AA and 50% for Aa). Choice C (³/₄) reflects this probability.

Question 2

Nondisjunction results in gametes that violate which of the following principles?
A)dominance
B)segregation
C)independent assortment
D)epistasis

Accepted Answer

Nondisjunction results in gametes that violate the principle of segregation, which states that two alleles for each trait separate during gamete formation and end up in different gametes. Nondisjunction occurs when homologous chromosomes or sister chromatids fail to separate properly during meiosis, resulting in gametes with an abnormal number of chromosomes. This violates the principle of segregation because the gametes do not have the expected number of each chromosome, including the alleles that are supposed to segregate during meiosis.

Question 3

The phenotype ratio of the progeny of a cross between two individuals with a trait that displays incomplete dominance is:
A)1:3.
B)1:1:1.
C)1:2.
D)1:2:1.

Accepted Answer

In incomplete dominance, a heterozygous genotype (Aa) displays an intermediate phenotype between the two homozygous genotypes (AA and aa). Therefore, the progeny ratio of a cross between two individuals with incomplete dominance is 1:2:1, with one homozygous dominant (AA), two heterozygous (Aa), and one homozygous recessive (aa) offspring.

Question 4

The bands observed in a gel for a VNTR (variable number of tandem repeats) polymorphism in a father (F) and mother (M) are shown in the accompanying diagram. What possible patterns of bands are expected among their offspring? 
A)(1, 2), (1, 3), (2, 3), (3, 4)
B)(1, 2), (1, 4), (2, 3), (3, 4)
C)(1, 3), (1, 4), (2, 3), (2, 4)
D)(1, 3), (2, 3), (1, 4), (3, 4)

Accepted Answer

The answer of The bands observed in a gel for...

Question 5

Segregation of alleles corresponds to the separation of:
A)genes.
B)genotypes.
C)chromosomes.
D)phenotypes.

Accepted Answer

Segregation of alleles refers to the separation of chromosomes during meiosis, which ultimately results in the separation of genes and alleles. Therefore, the most accurate answer is C, chromosomes. The segregation of alleles leads to different combinations of alleles in offspring and thus generates different genotypes and phenotypes, but these terms do not directly correspond to the segregation of alleles.

Question 6

A woman and a man are both heterozygous for a recessive allele for a rare genetic disease. If they have one child, what is the probability that he or she will be affected? If they have two children, what is the probability that at least one of them will be affected?
A)7/16, 1/4
B)1/4, 3/4
C)3/4, 1/4
D)3/4, 7/16
E)1/4, 7/16

Accepted Answer

The probability that one child will be affected is 1/4. The probability that at least one of two children will be affected is 7/16.

Question 7

If the phenotype of pea pod color is determined by incomplete dominance and the combination of an allele for yellow seeds and an allele for green seeds yields blue seeds, you would expect the F₂ generation from an original cross of true-breeding green stock with true-breeding yellow stock to be: A)25% yellow, 50% blue, 25% green. B)67% green, 33% yellow. C)67% blue, 33% yellow. D)100% green. E)100% blue.

Accepted Answer

In incomplete dominance, the F1 generation from a cross of true-breeding green and yellow would all be blue. The F2 generation would then show a 1:2:1 ratio: 25% yellow, 50% blue, and 25% green.

Question 8

A testcross of an organism of unknown genotype is done when the organism is crossed with an organism that is:
A)a heterozygote.
B)a dominant homozygote.
C)a recessive homozygote.
D)All of these choices are correct.

Accepted Answer

A testcross is done to determine the genotype of an organism, typically one that displays a dominant phenotype. The organism is crossed with a homozygous recessive organism to determine whether the unknown organism is heterozygous or homozygous dominant. Therefore, the correct choice is C, a recessive homozygote. Choices A and B are incorrect because a heterozygote or dominant homozygote would not provide information on the unknown organism's genotype.

Question 9

The addition rule requires which of the following?
A)More than one outcome (such as two different genotypes resulting in black fur)can occur simultaneously in an organism.
B)Two outcomes (such as having the genotype BB or Bb)are mutually exclusive in an organism.

Accepted Answer

The addition rule in probability is used when two outcomes cannot occur at the same time, meaning they are mutually exclusive. For example, an organism cannot have both the genotype BB and Bb simultaneously; it must have one or the other.

Question 10

In the F₂ generation of a homozygous round (AA) × homozygous wrinkled (aa) cross in peas, two seeds are chosen at random. What is the probability that one is AA and the other aa? A)(1/4)² B)(3/4)(1/4) C)2(3/4)(1/4) D)(3/4)²

Accepted Answer

The first generation (F1) from a cross between homozygous round (AA) and homozygous wrinkled (aa) peas will all be heterozygous (Aa), producing gametes that are either A or a. When these F1 individuals self-pollinate, the offspring (F2) will have a genotype ratio of 1AA:2Aa:1aa, or a phenotype ratio of 3 round (AA or Aa) to 1 wrinkled (aa). The probability of selecting one AA and one aa seed is calculated by considering the combinations of picking AA first then aa, or aa first then AA. The probability of picking an AA seed is 1/4, and the probability of picking an aa seed is also 1/4. Since there are two ways this can happen (AA then aa, or aa then AA), we multiply the probability of one event by 2. The probability of picking a round seed (either AA or Aa) is 3/4. Thus, the correct calculation is 2 times the probability of picking an AA seed (1/4) times the probability of picking an aa seed (1/4) after picking a round seed, which is 2(3/4)(1/4).

Question 11

The F₁ generation of a cross between two individuals, one that is homozygous dominant for a trait and the other that is homozygous recessive for the trait, will yield progeny with the same phenotype.

Accepted Answer

When a homozygous dominant individual is crossed with a homozygous recessive individual, all of the offspring in the F1 generation will have the same phenotype, which will be that of the dominant allele. In this case, since the homozygous dominant individual has two dominant alleles and the homozygous recessive individual has two recessive alleles, all of the offspring will inherit one dominant allele from the homozygous dominant parent and one recessive allele from the homozygous recessive parent. This will result in all offspring having the dominant phenotype, even though they are heterozygous for the trait.

Question 12

A testcross involves crossing with a(n) _____ individual and is used to determine the _____ of the tested parent. A)homozygous dominant; phenotype B)homozygous recessive; phenotype C)homozygous dominant; genotype D)homozygous recessive; genotype E)F₂ offspring; parental genotype

Accepted Answer

A testcross involves crossing an individual with an unknown genotype with a homozygous recessive individual to determine the genotype of the tested parent.

Question 13

Which of the following represents the expected genotypes of an F₂ generation consisting of 8 individuals from an initial cross of a true-breeding black (BB) rabbit and a true-breeding white (bb) rabbit? A)8 progeny: 8 BB, 0 bb, 0 Bb B)8 progeny: 4 BB, 4 bb, 0 Bb C)8 progeny: 2 BB, 2 bb, 4 Bb D)8 progeny: 0 BB, 0 bb, 8 Bb

Accepted Answer

The F1 generation from a BB x bb cross would all be Bb. Crossing two Bb individuals in the F2 generation would result in a 1:2:1 ratio of BB:Bb:bb, which translates to 2 BB, 4 Bb, and 2 bb for 8 individuals.

Question 14

Mendel's principle of segregation corresponds to what part of meiosis?
A)condensation of chromosomes in prophase I
B)alignment of homologs in metaphase I
C)separation of homologs in anaphase I
D)alignment of chromosomes in metaphase II
E)separation of daughter chromatids in anaphase II

Accepted Answer

Mendel's principle of segregation refers to the separation of homologous chromosomes during meiosis, which occurs during anaphase I.

Question 15

A recessive trait is expressed when the genotype is:
A)homozygous dominant or heterozygous.
B)homozygous recessive or heterozygous.
C)heterozygous only.
D)homozygous dominant only.
E)homozygous recessive only.

Accepted Answer

A recessive trait is expressed in the phenotype only when the individual has two copies of the recessive allele, meaning they are homozygous recessive.

Question 16

In genetic crosses, the symbols AA and Aa refer respectively to:
A)heterozygous and homozygous phenotypes.
B)heterozygous and homozygous genotypes.
C)homozygous and heterozygous phenotypes.
D)homozygous and heterozygous genotypes.
E)homozygous and heterozygous morphotypes.

Accepted Answer

In genetic crosses, the symbols AA and Aa refer respectively to homozygous and heterozygous genotypes. "Homozygous" means that two alleles of a gene are the same (in this case, both are "A"), while "heterozygous" means that two alleles of a gene are different (in this case, one is "A" and one is something else, probably "a"). The terms "phenotype" and "morphotype" refer to physical traits or characteristics, not to the genetic makeup of an organism.

Question 17

A true-breeding black rabbit is crossed with a true-breeding white rabbit. If the black color trait is dominant, which of the following represents the expected phenotype of an F₂ generation consisting of 8 individuals? A)8 black rabbits, 0 white rabbits, 0 grey rabbits B)2 black rabbits, 2 white rabbits, 4 grey rabbits C)0 black rabbits, 0 white rabbits, 8 grey rabbits D)4 black rabbits, 2 white rabbits, 2 grey rabbits E)6 black rabbits, 2 white rabbits, 0 grey rabbits

Accepted Answer

In the F2 generation, the expected phenotypic ratio for a monohybrid cross with complete dominance is 3:1. Therefore, out of 8 rabbits, 6 would be black (dominant) and 2 would be white (recessive).

Question 18

In the story of the Personal Genome Case, Claudia Gilmore had a 50-50 chance of inheriting the mutation in the BRCA1 gene because she is equally likely to inherit either of her father's BRCA1 alleles, and one of these is the mutant risk factor.

Accepted Answer

This is stated in the story: "Because Claudia inherited one copy of the BRCA1 gene from each parent, she has a 50-50 chance of inheriting the mutation in the BRCA1 gene."

Question 19

Animals that sexually reproduce are _____ and produce _____ gametes.
A)haploid; diploid
B)diploid; haploid
C)diploid; diploid
D)haploid; haploid

Accepted Answer

Animals that sexually reproduce are diploid and they undergo meiosis to produce haploid gametes. These haploid gametes from the male and female combine during fertilization to form a diploid zygote which eventually develops into an organism.

Question 20

The use of the multiplication rule requires which of the following?
A)The events being considered are associated.
B)The events being considered occur independently.

Accepted Answer

The multiplication rule can only be applied when the events being considered are independent of each other. If the events are associated or dependent, a different method must be used to calculate their combined probability.

Quiz 16: Mendelian Inheritance

What is the probability that an individual is Aa or AA if his or her parents are both heterozygous for the trait?

Nondisjunction results in gametes that violate which of the following principles?

The phenotype ratio of the progeny of a cross between two individuals with a trait that displays incomplete dominance is:

The bands observed in a gel for a VNTR (variable number of tandem repeats) polymorphism in a father (F) and mother (M) are shown in the accompanying diagram. What possible patterns of bands are expected among their offspring?

Segregation of alleles corresponds to the separation of:

A woman and a man are both heterozygous for a recessive allele for a rare genetic disease. If they have one child, what is the probability that he or she will be affected? If they have two children, what is the probability that at least one of them will be affected?

If the phenotype of pea pod color is determined by incomplete dominance and the combination of an allele for yellow seeds and an allele for green seeds yields blue seeds, you would expect the F₂ generation from an original cross of true-breeding green stock with true-breeding yellow stock to be:

A testcross of an organism of unknown genotype is done when the organism is crossed with an organism that is:

The addition rule requires which of the following?

In the F₂ generation of a homozygous round (AA) × homozygous wrinkled (aa) cross in peas, two seeds are chosen at random. What is the probability that one is AA and the other aa?

The F₁ generation of a cross between two individuals, one that is homozygous dominant for a trait and the other that is homozygous recessive for the trait, will yield progeny with the same phenotype.

A testcross involves crossing with a(n) _ individual and is used to determine the _ of the tested parent.

Which of the following represents the expected genotypes of an F₂ generation consisting of 8 individuals from an initial cross of a true-breeding black (BB) rabbit and a true-breeding white (bb) rabbit?

Mendel's principle of segregation corresponds to what part of meiosis?

A recessive trait is expressed when the genotype is:

In genetic crosses, the symbols AA and Aa refer respectively to:

A true-breeding black rabbit is crossed with a true-breeding white rabbit. If the black color trait is dominant, which of the following represents the expected phenotype of an F₂ generation consisting of 8 individuals?

In the story of the Personal Genome Case, Claudia Gilmore had a 50-50 chance of inheriting the mutation in the BRCA1 gene because she is equally likely to inherit either of her father's BRCA1 alleles, and one of these is the mutant risk factor.

Animals that sexually reproduce are _ and produce _ gametes.

The use of the multiplication rule requires which of the following?

Quiz 16: Mendelian Inheritance

What is the probability that an individual is Aa or AA if his or her parents are both heterozygous for the trait?

Nondisjunction results in gametes that violate which of the following principles?

The phenotype ratio of the progeny of a cross between two individuals with a trait that displays incomplete dominance is:

The bands observed in a gel for a VNTR (variable number of tandem repeats) polymorphism in a father (F) and mother (M) are shown in the accompanying diagram. What possible patterns of bands are expected among their offspring?

Segregation of alleles corresponds to the separation of:

A woman and a man are both heterozygous for a recessive allele for a rare genetic disease. If they have one child, what is the probability that he or she will be affected? If they have two children, what is the probability that at least one of them will be affected?

If the phenotype of pea pod color is determined by incomplete dominance and the combination of an allele for yellow seeds and an allele for green seeds yields blue seeds, you would expect the F2 generation from an original cross of true-breeding green stock with true-breeding yellow stock to be:

A testcross of an organism of unknown genotype is done when the organism is crossed with an organism that is:

The addition rule requires which of the following?

In the F2 generation of a homozygous round (AA) × homozygous wrinkled (aa) cross in peas, two seeds are chosen at random. What is the probability that one is AA and the other aa?

The F1 generation of a cross between two individuals, one that is homozygous dominant for a trait and the other that is homozygous recessive for the trait, will yield progeny with the same phenotype.

A testcross involves crossing with a(n) _____ individual and is used to determine the _____ of the tested parent.

Which of the following represents the expected genotypes of an F2 generation consisting of 8 individuals from an initial cross of a true-breeding black (BB) rabbit and a true-breeding white (bb) rabbit?

Mendel's principle of segregation corresponds to what part of meiosis?

A recessive trait is expressed when the genotype is:

In genetic crosses, the symbols AA and Aa refer respectively to:

A true-breeding black rabbit is crossed with a true-breeding white rabbit. If the black color trait is dominant, which of the following represents the expected phenotype of an F2 generation consisting of 8 individuals?

In the story of the Personal Genome Case, Claudia Gilmore had a 50-50 chance of inheriting the mutation in the BRCA1 gene because she is equally likely to inherit either of her father's BRCA1 alleles, and one of these is the mutant risk factor.

Animals that sexually reproduce are _____ and produce _____ gametes.

The use of the multiplication rule requires which of the following?

If the phenotype of pea pod color is determined by incomplete dominance and the combination of an allele for yellow seeds and an allele for green seeds yields blue seeds, you would expect the F₂ generation from an original cross of true-breeding green stock with true-breeding yellow stock to be:

In the F₂ generation of a homozygous round (AA) × homozygous wrinkled (aa) cross in peas, two seeds are chosen at random. What is the probability that one is AA and the other aa?

The F₁ generation of a cross between two individuals, one that is homozygous dominant for a trait and the other that is homozygous recessive for the trait, will yield progeny with the same phenotype.

A testcross involves crossing with a(n) _ individual and is used to determine the _ of the tested parent.

Which of the following represents the expected genotypes of an F₂ generation consisting of 8 individuals from an initial cross of a true-breeding black (BB) rabbit and a true-breeding white (bb) rabbit?

A true-breeding black rabbit is crossed with a true-breeding white rabbit. If the black color trait is dominant, which of the following represents the expected phenotype of an F₂ generation consisting of 8 individuals?

Animals that sexually reproduce are _ and produce _ gametes.