Question 1

In a cross between two individuals heterozygous for a single gene exhibiting complete dominance (

Aa 	imes Aa

), what are the expected genotypic and phenotypic ratios of the offspring, respectively?

Accepted Answer

Genotypic ratio 1:2:1; Phenotypic ratio 3:1

Answer

Genotypic ratio 1:1; Phenotypic ratio 1:1

Answer

Genotypic ratio 3:1; Phenotypic ratio 1:2:1

Answer

Genotypic ratio 9:3:3:1; Phenotypic ratio 3:1

Question 2

In a dihybrid cross between two individuals heterozygous for two independently assorting traits (

Aa 	imes Aa

), what is the expected phenotypic ratio of the offspring if both genes follow the principles of Mendelian complete dominance?

Accepted Answer

9:3:3:1

Answer

1:2:1:2:4:2:1:2:1

Answer

1:1:1:1

Answer

3:1

Question 3

In a cross between two snapdragon plants with pink flowers (

Aa 	imes Aa

), which exhibit incomplete dominance, what are the expected genotypic and phenotypic ratios of the offspring?

Accepted Answer

Genotypic ratio 1:2:1; Phenotypic ratio 1:2:1

Answer

Genotypic ratio 1:1; Phenotypic ratio 1:1

Answer

Genotypic ratio 1:2:1; Phenotypic ratio 3:1

Answer

Genotypic ratio 3:1; Phenotypic ratio 1:2:1

Question 4

A testcross is performed by crossing an individual with a dominant phenotype but unknown genotype with a homozygous recessive individual (

Aa 	imes Aa

). If the resulting offspring show a 1:1 phenotypic ratio, what can be concluded about the unknown parent's genotype and the genotypic ratio of the offspring?

Accepted Answer

The parent is

Aa 	imes Aa

; Genotypic ratio 1:1

Answer

The parent is

Aa 	imes Aa

; Genotypic ratio 1:1

Answer

The parent is

Aa 	imes Aa

; Genotypic ratio 1:2:1

Answer

The parent is

Aa 	imes Aa

; Genotypic ratio 3:1

Question 5

In a cross involving two genes that are perfectly linked (zero recombination), what would be the expected phenotypic ratio of the offspring if two individuals heterozygous in coupling (cis) phase (

Aa 	imes Aa

) are crossed, assuming complete dominance for both traits?

Accepted Answer

3:1

Answer

9:3:3:1

Answer

1:2:1

Answer

1:1:1:1

Question 6

In a cross between an individual with blood type

Aa 	imes Aa

(

I^AI^B

) and an individual with blood type

O

(

ii

), what are the expected genotypic and phenotypic ratios of the offspring?

Accepted Answer

Genotypic ratio 1:1; Phenotypic ratio 1:1

Answer

Genotypic ratio 1:1; Phenotypic ratio 3:1

Answer

Genotypic ratio 1:2:1; Phenotypic ratio 3:1

Answer

Genotypic ratio 1:2:1; Phenotypic ratio 1:2:1

Question 7

In a cross between two fruit flies that are heterozygous for a lethal recessive allele that causes death in the homozygous state early in development (

Aa 	imes Aa

), what is the expected phenotypic ratio among the surviving adult offspring?

Accepted Answer

2:1

Answer

3:1

Answer

1:1

Answer

1:2:1

Question 8

In a cross between two cats that both have the genotype

Aa 	imes Aa

for fur length (where

I^AI^B

is short hair and

O

is long hair), what is the probability that an offspring will have the same phenotype as the parents and what is the probability it will have the same genotype as the parents, respectively?

Accepted Answer

Answer

Answer

Answer

Question 9

In a case of recessive epistasis, such as coat color in Labrador retrievers where the 'ee' genotype masks the expression of the B/b alleles, what is the expected phenotypic ratio of offspring from a dihybrid cross (

Aa 	imes Aa

)?

Accepted Answer

9:3:4

Answer

12:3:1

Answer

15:1

Answer

9:3:3:1

Question 10

In a cross between two pea plants that are both heterozygous for seed shape (

Aa 	imes Aa

), where round (

I^AI^B

) is completely dominant to wrinkled (

O

), what is the probability that a round-seeded offspring is a carrier of the recessive allele?

Accepted Answer

Answer

Answer

Answer

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