Q: If $$p = 0.6$$ and $$q = 0.4 in a $$population, what is the expected frequency of heterozygotes under Hardy-Weinberg equilibrium?

$$2pq = 2 \times 0.6 \times 0.4 = 0.48$$

Question 1

Which of the following best describes the difference between the blending theory of inheritance and Mendel’s particulate theory of inheritance?

Accepted Answer

Blending theory suggests that offspring are a mix of parental traits, while Mendel’s particulate theory states that traits are inherited as discrete units (genes) that remain unchanged across generations.

Question 2

A woman with type AB blood and a man with type O blood have a child. Which blood types are possible for their child, considering the multiple alleles for the ABO blood group?

Accepted Answer

Type A or Type B

Question 3

In a population of 200 individuals, 18 show the recessive phenotype for a trait controlled by a single gene with two alleles. Assuming Hardy-Weinberg equilibrium, what is the frequency of the dominant allele? (Show your calculation steps.)

Accepted Answer

First, $$q^2$$ = \frac{18}{200} = 0.09$$, so q$$ = \sqrt{0.09} = 0.3$$. Then p = 1 - 0.3 = 0.7$.

Question 4

Which of the following scenarios best illustrates the founder effect in population genetics?

Accepted Answer

A small group of birds colonizes a new island, and their descendants show different allele frequencies compared to the original population.

Question 5

A man with genotype $$X^A Y$$ and a woman with genotype $$X^A X^a$$ for an X-linked recessive trait have children. What is the probability that their son will express the recessive phenotype?

Accepted Answer

$$0.5 (50$$%)

Question 6

Which of the following is NOT a requirement for Hardy-Weinberg genetic equilibrium?

Accepted Answer

High mutation rate

Question 7

In a certain species of flower, red and white alleles show incomplete dominance. If a red-flowered plant ($$RR) is $$crossed with a white-flowered plant ($$WW$$), what will be the phenotype of the $$F_1$$ generation?

Accepted Answer

All pink flowers

Question 8

Which of the following best explains why sexual reproduction increases genetic variation in a population?

Accepted Answer

It shuffles existing alleles through independent assortment, crossing over, and random fertilization.

Question 9

A pedigree shows a trait that appears in every generation and affects both males and females equally. Which inheritance pattern is most likely?

Accepted Answer

Autosomal dominant

Question 10

Which of the following is an example of directional selection?

Accepted Answer

After a volcanic eruption darkens the landscape, dark-colored mice become more common because they are less visible to predators.

Question 11

If $$p = 0.6$$ and $$q = 0.4 in a $$population, what is the expected frequency of heterozygotes under Hardy-Weinberg equilibrium?

Accepted Answer

$$2pq = 2 	imes 0.6 	imes 0.4 = 0.48$$

Question 12

Which of the following statements about codominance is correct?

Accepted Answer

Both alleles are fully expressed in the phenotype of heterozygotes.

Question 13

A geneticist observes that a certain mitochondrial disorder is passed from mothers to all their children, but never from fathers. What is the most likely explanation?

Accepted Answer

The disorder is inherited through mitochondrial DNA, which is transmitted only by mothers.

Question 14

Which of the following events during meiosis explains Mendel’s law of independent assortment?

Accepted Answer

Random alignment of homologous chromosome pairs during metaphase I

Question 15

A population of 1000 individuals has 360 individuals with the homozygous recessive genotype ($$aa). $$Assuming Hardy-Weinberg equilibrium, what is the frequency of the dominant allele ($$A$$)?

Accepted Answer

First, $$q^2$$ = \frac{360}{1000} = 0.36$$, so q = 0.6$. Then p = 1 - 0.6 = 0.4$.

Question 16

Which of the following is a consequence of nondisjunction during meiosis?

Accepted Answer

Gametes with abnormal numbers of chromosomes, leading to conditions such as Down syndrome.

Question 17

Which of the following best describes genetic drift?

Accepted Answer

Random changes in allele frequencies, especially in small populations.

Question 18

A pedigree shows a trait that skips generations and is more common in males. Which inheritance pattern is most likely?

Accepted Answer

X-linked recessive

Question 19

Which of the following is a real-world example of stabilizing selection?

Accepted Answer

Human birth weights are most commonly in the intermediate range, with very low and very high weights having higher mortality.

Question 20

Which of the following best explains why the Hardy-Weinberg equation is useful in studying microevolution?

Accepted Answer

It provides a baseline to detect changes in allele frequencies, indicating that evolution is occurring.

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