Q: In a population, the frequency of allele A is $$p = 0.7$$ and allele a is $$q = 0.3. $$According to the Hardy-Weinberg equation, what is the expected frequency of heterozygotes?

$$2pq = 2 \times 0.7 \times 0.3 = 0.42$$

Question 1

Which of the following best explains why males are more likely than females to express recessive X-linked genetic disorders, such as hemophilia?

Accepted Answer

Males have only one X chromosome, so a single recessive allele will be expressed.

Question 2

A woman who is heterozygous for an X-linked trait (X	extsuperscript{A}X	extsuperscript{a}) and a man who does not carry the trait (X	extsuperscript{A}Y) have a child. What is the probability that their son will express the recessive trait?

Accepted Answer

$$\frac{1}{2}$$

Question 3

Which chromosomal mutation is most likely to result in a gene being present in two copies on the same chromosome, potentially leading to overexpression?

Accepted Answer

Duplication

Question 4

During DNA replication, which enzyme is responsible for joining Okazaki fragments on the lagging strand?

Accepted Answer

Ligase

Question 5

A scientist observes that after several rounds of DNA replication, each DNA molecule consists of one old and one new strand. Which model of replication does this observation support?

Accepted Answer

Semi-conservative replication

Question 6

Which of the following best describes the difference between DNA and RNA?

Accepted Answer

DNA is usually double-stranded, while RNA is usually single-stranded.

Question 7

A mutation changes a codon from UAU (tyrosine) to UAA (stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 8

Which process occurs in the nucleus and results in the production of a molecule that carries genetic information to the ribosome?

Accepted Answer

Transcription

Question 9

Which of the following is NOT a step in eukaryotic mRNA processing?

Accepted Answer

Attachment of Okazaki fragments

Question 10

Which of the following provides evidence for Darwin’s theory of evolution by natural selection?

Accepted Answer

The presence of homologous structures in different species

Question 11

A population of beetles is exposed to a pesticide. Over several generations, most beetles are resistant to the pesticide. Which mechanism best explains this change?

Accepted Answer

Natural selection

Question 12

Which of the following statements about evolution is correct?

Accepted Answer

Evolution acts on existing variation within populations.

Question 13

In a population, the frequency of allele A is $$p = 0.7$$ and allele a is $$q = 0.3. $$According to the Hardy-Weinberg equation, what is the expected frequency of heterozygotes?

Accepted Answer

$$2pq = 2 	imes 0.7 	imes 0.3 = 0.42$$

Question 14

Which of the following is NOT a condition required for Hardy-Weinberg equilibrium?

Accepted Answer

Natural selection favoring one allele

Question 15

A small group of finches colonizes a new island, and their allele frequencies differ from the original population. This is an example of:

Accepted Answer

Founder effect

Question 16

Which type of natural selection favors individuals with intermediate phenotypes and reduces variation in a population?

Accepted Answer

Stabilizing selection

Question 17

A patient’s cells are found to have abnormally short telomeres. Which cellular process is most likely to be affected as a result?

Accepted Answer

DNA replication

Question 18

A gene is translocated from chromosome 1 to chromosome 15. Which chromosomal mutation does this represent?

Accepted Answer

Translocation

Question 19

Which of the following best describes the relationship between codons and anticodons during translation?

Accepted Answer

Codons are on mRNA and are complementary to anticodons on tRNA.

Question 20

A frameshift mutation occurs in a gene. Which of the following is the most likely result?

Accepted Answer

The reading frame is altered, potentially changing every amino acid after the mutation.

Key Concepts in Chromosomal Inheritance, DNA Replication, Gene Expression, and Evolution

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