Inheritance Patterns

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AP Biology › Inheritance Patterns

Questions 1 - 10
1

According to the law of independent assortment, what is the possible number of combinations that chromosomes can assort to independently in the gamete?

8,388,608

70,368,744,177,664

2,048

4,194,304

16,777,216

Explanation

According to the law of independent assortment, there are 2n combinations where chromosomes can assort into different gametes. So where n is the haploid number, you get 223=8,388,608. There are 8,388,608 possible combinations of chromosomes when assorting into gametes.

2

According to the law of independent assortment, what is the possible number of combinations that chromosomes can assort to independently in the gamete?

8,388,608

70,368,744,177,664

2,048

4,194,304

16,777,216

Explanation

According to the law of independent assortment, there are 2n combinations where chromosomes can assort into different gametes. So where n is the haploid number, you get 223=8,388,608. There are 8,388,608 possible combinations of chromosomes when assorting into gametes.

3

According to the law of independent assortment, what is the possible number of combinations that chromosomes can assort to independently in the gamete?

8,388,608

70,368,744,177,664

2,048

4,194,304

16,777,216

Explanation

According to the law of independent assortment, there are 2n combinations where chromosomes can assort into different gametes. So where n is the haploid number, you get 223=8,388,608. There are 8,388,608 possible combinations of chromosomes when assorting into gametes.

4

Each person can have one of four possible blood types: A, B, AB, or O. Blood type A means that the "A" antigen is present on the red blood cell surface. Blood type B means that the "B" antigen is present on red blood cells' surfaces. Blood type "AB" means that both the "A" antigen and the "B" antigen are present on the red blood cells' surfaces. Blood type "O" means that no antigens are present on the red blood cells' surfaces.

A mother with blood type A and the genotype "A/O" and a father with blood type B and genotype "B/B" have a child with blood type AB. This is an example of what type of inheritance pattern?

Codominance

Incomplete dominance

X-linked autosomal dominance

Complete autosomal dominance

Autosomal recessive

Explanation

The child is blood type AB, meaning that the child has both the "A" antigen and the "B" antigen on his or her red blood cells. The child is able to express the products of both genes simultaneously. The A antigen was inherited from mom, and the B antigen was inherited from dad. The "A" and "B" alleles are codominant because they can both be expressed in the same person at the same time if the person inherits both alleles, as is the case in this example.

5

What is the phenotypic ratio for a cross between a plant with blue flowers BB and a plant with white flowers bb?

All blue

All white

Half blue, half white

75% blue, 25% white

25% blue, 75% white

Explanation

The phenotypic ratio is the ratio of one phenotype to another (phenotype is the trait expressed, in this case color, while genotype is the allele combination (BB, bb, Bb, or bB) that produces that phenotype. The capital letters BB signify that the blue allele (B) is dominant to the white allele (b). As such, the only genotype that will produce white plants is bb. All other combinations (BB, Bb, bB) will produce a blue plant. If you cross a homozygous (both dominant or both recessive) dominant plant with a homozygous recessive plant, the dominant allele will be present in all of the offspring, as every possible allele the blue plant could contribute will be dominant to every possible allele the white plant could contribute, making all of the offspring blue.

6

In mammals, which type of phenotypic expression will show recessive traits more frequently in males than females?

X-linked

Incomplete dominance

Complete dominance

Co-dominance

Mitochondrial

Explanation

The correct answer is "X-linked." Mammalian females have two X chromosomes, with recessive alleles often not apparent unless there are two copies. Mammalian males have only one X chromosome, so any recessive alleles on it will be expressed.

7

What is the phenotypic ratio for a cross between a plant with blue flowers BB and a plant with white flowers bb?

All blue

All white

Half blue, half white

75% blue, 25% white

25% blue, 75% white

Explanation

The phenotypic ratio is the ratio of one phenotype to another (phenotype is the trait expressed, in this case color, while genotype is the allele combination (BB, bb, Bb, or bB) that produces that phenotype. The capital letters BB signify that the blue allele (B) is dominant to the white allele (b). As such, the only genotype that will produce white plants is bb. All other combinations (BB, Bb, bB) will produce a blue plant. If you cross a homozygous (both dominant or both recessive) dominant plant with a homozygous recessive plant, the dominant allele will be present in all of the offspring, as every possible allele the blue plant could contribute will be dominant to every possible allele the white plant could contribute, making all of the offspring blue.

8

Each person can have one of four possible blood types: A, B, AB, or O. Blood type A means that the "A" antigen is present on the red blood cell surface. Blood type B means that the "B" antigen is present on red blood cells' surfaces. Blood type "AB" means that both the "A" antigen and the "B" antigen are present on the red blood cells' surfaces. Blood type "O" means that no antigens are present on the red blood cells' surfaces.

A mother with blood type A and the genotype "A/O" and a father with blood type B and genotype "B/B" have a child with blood type AB. This is an example of what type of inheritance pattern?

Codominance

Incomplete dominance

X-linked autosomal dominance

Complete autosomal dominance

Autosomal recessive

Explanation

The child is blood type AB, meaning that the child has both the "A" antigen and the "B" antigen on his or her red blood cells. The child is able to express the products of both genes simultaneously. The A antigen was inherited from mom, and the B antigen was inherited from dad. The "A" and "B" alleles are codominant because they can both be expressed in the same person at the same time if the person inherits both alleles, as is the case in this example.

9

Your neighbor has a flower garden in which there are red flowers and white flowers. These flowers are diploid organisms, and flower color is an autosomal trait. The gene for red flowers (R) is dominant, while the gene for white flowers (r) is recessive.

Which of the following is the genotype of a white flower?

rr

Rr

RR

r

R

Explanation

The correct answer is "rr". In order to express the recessive phenotype (white flowers), the organism must have only the recessive allele. When the question stem says that the organism is "diploid," it means that each flower has two copies of each chromosome. This means that the flower must have two alleles, so there must be two letters, not just one, in the correct answer.

10

In mammals, which type of phenotypic expression will show recessive traits more frequently in males than females?

X-linked

Incomplete dominance

Complete dominance

Co-dominance

Mitochondrial

Explanation

The correct answer is "X-linked." Mammalian females have two X chromosomes, with recessive alleles often not apparent unless there are two copies. Mammalian males have only one X chromosome, so any recessive alleles on it will be expressed.

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