Question 1

A heterozygous tall pea plant (Tt) is crossed with another heterozygous tall pea plant (Tt). What is the expected phenotypic ratio of tall to short offspring?

Accepted Answer

3 tall : 1 short

Question 2

In a dihybrid cross between two heterozygous pea plants (YySs × YySs), where Y = yellow, y = green, S = smooth, s = wrinkled, what is the expected phenotypic ratio among the offspring?

Accepted Answer

$$9:3:3:1$$

Question 3

A child has attached earlobes (a recessive trait), but both parents have free earlobes (dominant trait). What are the most likely genotypes of the parents?

Accepted Answer

Both parents are heterozygous

Question 4

In chickens, black feathers (B) and white feathers (W) show codominance. What is the phenotype of a chicken with genotype BW?

Accepted Answer

Black and white speckled

Question 5

A red flower (RR) is crossed with a white flower (WW), and all offspring are pink (RW). What type of inheritance is this an example of?

Accepted Answer

Incomplete dominance

Question 6

A woman who is a carrier for an X-linked recessive disorder (X$$^NX$^c) $$has children with a man who is not affected (X$$^NY). $$What is the probability that their son will have the disorder?

Accepted Answer

$$50\%$$

Question 7

A woman with blood type A (genotype AO) and a man with blood type B (genotype BO) have a child. Which blood types are possible for their child?

Accepted Answer

A, B, AB, or O

Question 8

Which of the following best describes codominance?

Accepted Answer

Both alleles are fully expressed in the phenotype

Question 9

If a male is affected by an X-linked recessive disorder, which of the following must be true about his genotype?

Accepted Answer

He has one X chromosome with the recessive allele and one Y chromosome

Question 10

A couple has a child with blood type O. The mother is blood type A and the father is blood type B. What are the possible genotypes of the parents?

Accepted Answer

Mother: AO, Father: BO

Question 11

Which of the following is true about dominant and recessive alleles?

Accepted Answer

A dominant allele is expressed if at least one copy is present

Question 12

In a pedigree, how can you identify an X-linked recessive trait?

Accepted Answer

It appears more frequently in males than females

Question 13

A plant with genotype YySs is crossed with a plant with genotype yyss. What proportion of the offspring will have yellow, smooth seeds (Y_S_)?

Accepted Answer

$$1/4$$

Question 14

Which of the following best describes incomplete dominance?

Accepted Answer

The heterozygote has a phenotype intermediate between the two homozygotes

Question 15

A man with blood type AB marries a woman with blood type O. What are the possible blood types of their children?

Accepted Answer

A or B only

Question 16

If a woman with genotype X$$^NX$^n ($$carrier for color blindness) and a man with genotype X$$^NY $$have a daughter, what is the probability that the daughter will be color blind?

Accepted Answer

$$0\% ($$unless the father is color blind)

Question 17

Which of the following crosses would produce a 1:1 phenotypic ratio in the offspring for a monohybrid trait?

Accepted Answer

Tt × tt

Question 18

A man with genotype I$$^AI$^O ($$blood type A) and a woman with genotype I$$^BI$^O ($$blood type B) have a child. What is the probability that the child will have blood type AB?

Accepted Answer

$$1/4$$

Question 19

Which of the following statements about sex-linked traits is correct?

Accepted Answer

They are more likely to affect males than females

Question 20

A woman with genotype I$$^AI$^A ($$blood type A) and a man with genotype I$$^BI$^B ($$blood type B) have a child. What is the blood type of their child?

Accepted Answer

AB

Fundamental Principles of Genetics: Mendelian Inheritance, Blood Types, and Genetic Crosses

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