Question 1

Which of the following best describes the difference between somatic cells and gametes in humans?

Accepted Answer

Somatic cells are diploid ($$2n$$), while gametes are haploid ($$n).$$

Question 2

A cell with genotype $$Aa is $$crossed with a cell with genotype $$aa. $$What is the expected genotype ratio in the offspring?

Accepted Answer

$$1:1$$ ($$Aa:aa)$$

Question 3

During which stage of meiosis does crossing over occur, and what is its significance?

Accepted Answer

Crossing over occurs during prophase I and increases genetic variation.

Question 4

Which of the following best illustrates the law of independent assortment?

Accepted Answer

Alleles for different genes segregate independently during gamete formation.

Question 5

In a dihybrid cross between two heterozygous individuals ($$AaBb 	imes AaBb$$), what is the expected phenotypic ratio if both traits exhibit complete dominance?

Accepted Answer

$$9:3:3:1$$

Question 6

Which scenario best exemplifies incomplete dominance?

Accepted Answer

A red flower ($$RR) $$crossed with a white flower ($$rr) $$produces pink flowers ($$Rr).$$

Question 7

Which of the following best describes nondisjunction and its result?

Accepted Answer

Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate during meiosis, resulting in gametes with abnormal chromosome numbers.

Question 8

Which chromosomal mutation involves a segment of one chromosome attaching to a non-homologous chromosome?

Accepted Answer

Translocation

Question 9

Which of the following correctly identifies the parts of a nucleotide?

Accepted Answer

A nucleotide consists of a phosphate group, a five-carbon sugar, and a nitrogenous base.

Question 10

Which statement best describes the antiparallel nature of DNA strands?

Accepted Answer

One strand runs from $$5' to$$ $$3'$$, while the other runs from $$3' to$$ $$5'.$$

Question 11

Why is DNA replication described as semiconservative?

Accepted Answer

Each new DNA molecule consists of one original strand and one newly synthesized strand.

Question 12

Which enzyme is responsible for unwinding the DNA double helix during replication?

Accepted Answer

Helicase

Question 13

During DNA replication, which strand is synthesized continuously and which is synthesized in fragments?

Accepted Answer

The leading strand is synthesized continuously, while the lagging strand is synthesized in fragments (Okazaki fragments).

Question 14

A woman who is heterozygous for an X-linked gene ($$X^A X^a) $$has children with a man who is homozygous for the dominant allele ($$X^A Y). $$What is the probability that a son will inherit the recessive allele?

Accepted Answer

$$0.5$$

Question 15

Which enzyme joins Okazaki fragments on the lagging strand during DNA replication?

Accepted Answer

Ligase

Question 16

If a parent is homozygous dominant ($$AA) $$and the other is homozygous recessive ($$aa$$), what will be the phenotype of their offspring assuming complete dominance?

Accepted Answer

All offspring will display the dominant phenotype.

Question 17

Which of the following best describes the law of segregation?

Accepted Answer

Each individual has two alleles for each gene, and these alleles separate during gamete formation.

Question 18

Which of the following is an example of codominance?

Accepted Answer

A person with blood type AB expresses both A and B antigens equally.

Question 19

Which enzyme synthesizes the RNA primer required for DNA polymerase to begin replication?

Accepted Answer

Primase

Question 20

A chromosome undergoes a mutation where a segment is reversed end to end. What type of mutation is this?

Accepted Answer

Inversion

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