Q: A woman with genotype $$FfEe ($$freckles, free earlobes) and a man with genotype $$ffee (no $$freckles, attached earlobes) have a child. What is the probability that the child will have freckles and free earlobes?

$$P = (\frac{1}{2}) \times (\frac{1}{2}) = \frac{1}{4}$$

Q: In a cross between $$KkLlMm$$ and $$KKLlmm$$, what is the probability of producing an offspring with genotype $$Kkllmm$$? Assume independent assortment.

$$P = (\frac{1}{2}) \times (\frac{1}{4}) \times (\frac{1}{2}) = \frac{1}{16}$$

Question 1

A couple, both heterozygous for the freckles gene ($$Ff$$), are planning to have three children. What is the probability that exactly two of their children will have freckles and one will not? Use the binomial theorem to solve.

Accepted Answer

$$P = \frac{3!}{2!1!} (\frac{3}{4})^2$ (\frac{1}{4})^1$ = \frac{3 	imes 9}{16} = \frac{27}{64}$$

Question 2

Which rule should you use to calculate the probability that a child will have either genotype $$FF or$$ $$Ff$$ for the freckles gene?

Accepted Answer

Sum rule

Question 3

A woman with genotype $$FfEe ($$freckles, free earlobes) and a man with genotype $$ffee (no $$freckles, attached earlobes) have a child. What is the probability that the child will have freckles and free earlobes?

Accepted Answer

$$P = (\frac{1}{2}) 	imes (\frac{1}{2}) = \frac{1}{4}$$

Question 4

In a cross between $$KkLlMm$$ and $$KKLlmm$$, what is the probability of producing an offspring with genotype $$Kkllmm$$? Assume independent assortment.

Accepted Answer

$$P = (\frac{1}{2}) 	imes (\frac{1}{4}) 	imes (\frac{1}{2}) = \frac{1}{16}$$

Question 5

Which of the following pedigree patterns is most consistent with an autosomal dominant trait?

Accepted Answer

Trait appears in every generation and affected individuals have at least one affected parent.

Question 6

A man with genotype $$X^rY ($$red-green color-blind) and a woman with genotype $$X^RX^r ($$carrier) have a son. What is the probability that their son will be color-blind?

Accepted Answer

$$P = \frac{1}{2}$$

Question 7

Which of the following is a key feature of X-linked recessive inheritance?

Accepted Answer

More males than females are affected.

Question 8

A pedigree shows a trait that appears only in males and is passed from father to all sons. What is the most likely mode of inheritance?

Accepted Answer

Y-linked

Question 9

In Drosophila, a reciprocal cross between a red-eyed female and a white-eyed male produces all red-eyed offspring, but the reverse cross produces red-eyed females and white-eyed males. What does this indicate about the white-eye gene?

Accepted Answer

It is X-linked.

Question 10

A pedigree shows a trait that skips generations and appears equally in males and females. What is the most likely mode of inheritance?

Accepted Answer

Autosomal recessive

Question 11

If a woman who is a carrier for hemophilia ($$X^HX^h) $$has children with a normal male ($$X^HY$$), what is the probability that a daughter will have hemophilia?

Accepted Answer

$$P = \frac{1}{4}$$

Question 12

Which of the following is NOT a Mendelian trait?

Accepted Answer

Height in humans

Question 13

A pedigree shows that two unaffected parents have an affected child. What is the most likely mode of inheritance?

Accepted Answer

Autosomal recessive

Question 14

Which formula represents the number of ways to have $$s$$ successes and $$t$$ failures in $$n$$ trials using the binomial theorem?

Accepted Answer

$$\frac{n!}{s!t!}$$

Question 15

Which of the following is a correct application of the product rule in genetics?

Accepted Answer

Calculating the probability of inheriting two independent traits together.

Question 16

A pedigree shows that all sons of an affected mother are affected, but none of her daughters are. What is the most likely mode of inheritance?

Accepted Answer

X-linked recessive

Question 17

Which of the following is true about hemizygosity?

Accepted Answer

It refers to males having only one X chromosome and thus only one allele for X-linked genes.

Question 18

Which of the following diseases is inherited in an autosomal dominant manner?

Accepted Answer

Huntington disease

Question 19

A pedigree shows that an affected father passes a trait to all his daughters but none of his sons. What is the most likely mode of inheritance?

Accepted Answer

X-linked dominant

Mendelian Genetics II & Patterns of Inheritance: Probability, Pedigrees, and Sex-Linkage

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