Q: Which equation correctly represents the probability of two heterozygous parents (Aa x Aa) producing a homozygous recessive offspring?

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

Question 1

Which of the following best describes the purpose of pedigree analysis in human genetics?

Accepted Answer

To trace inheritance patterns of traits and predict the probability of genetic disorders in families.

Question 2

In a pedigree, a shaded square represents which of the following?

Accepted Answer

A male expressing the trait.

Question 3

If two parents are both heterozygous for a recessive genetic disorder (Aa), what is the probability that their child will inherit the disorder?

Accepted Answer

25%

Question 4

Which equation correctly represents the probability of two heterozygous parents (Aa x Aa) producing a homozygous recessive offspring?

Accepted Answer

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

Question 5

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

Accepted Answer

Autosomal recessive

Question 6

Which of the following statements about sickle-cell disease is correct?

Accepted Answer

It provides a selective advantage against malaria in heterozygotes.

Question 7

A child is born with albinism, a recessive trait. Both parents have normal pigmentation. What are the genotypes of the parents?

Accepted Answer

Both are heterozygous carriers.

Question 8

Which of the following best explains why harmful recessive alleles can persist in a population?

Accepted Answer

They are masked in heterozygous carriers who do not show symptoms.

Question 9

In a family pedigree, if a trait is present in every generation and affected individuals have at least one affected parent, what is the most likely inheritance pattern?

Accepted Answer

Autosomal dominant

Question 10

Which of the following is a real-world consequence of inbreeding in human populations?

Accepted Answer

Increased expression of harmful recessive traits.

Question 11

A couple, both carriers for cystic fibrosis (a recessive disorder), want to know the probability that their child will be a carrier but not affected. What is the correct probability?

Accepted Answer

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

Question 12

Which of the following is NOT a characteristic of autosomal dominant inheritance?

Accepted Answer

Trait can skip generations.

Question 13

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

Accepted Answer

Y-linked

Question 14

Which of the following equations represents the probability that two heterozygous parents (Aa x Aa) will have a child who is a carrier (heterozygous) for a recessive trait?

Accepted Answer

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

Question 15

Which of the following best explains why sickle-cell disease remains prevalent in certain populations?

Accepted Answer

Heterozygotes have increased resistance to malaria.

Question 16

A pedigree shows that a child has a genetic disorder, but both parents are unaffected. What is the most likely explanation?

Accepted Answer

Both parents are carriers of a recessive allele.

Question 17

Which of the following is a potential consequence of a lethal dominant allele in a population?

Accepted Answer

It usually results in death before reproductive age, reducing its frequency.

Question 18

Which of the following disorders is caused by a defect in the transport of chloride ions across cell membranes?

Accepted Answer

Cystic fibrosis

Question 19

A pedigree shows that a trait is present in both males and females, but only males pass it to their sons. What is the most likely inheritance pattern?

Accepted Answer

Y-linked

Question 20

Which of the following best describes the inheritance pattern of Huntington's disease?

Accepted Answer

Autosomal dominant

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