Question 1

Which of the following statements correctly differentiates between somatic cells and gametes in humans?

Accepted Answer

Somatic cells are diploid ($$2n$$), containing two sets of chromosomes, while gametes are haploid ($$n$$), containing one set.

Question 2

A pea plant with genotype $$Tt ($$where $$T is $$tall and $$t is $$short) is crossed with another $$Tt$$ plant. What is the expected genotype ratio among the offspring?

Accepted Answer

$$1	ext{:}2	ext{:}1 (TT$$:Tt:tt)

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 describes the law of independent assortment?

Accepted Answer

Each pair of alleles segregates independently of other pairs during gamete formation.

Question 5

A woman who is a carrier for an X-linked recessive disorder ($$X^NX^n) $$and a man who is unaffected ($$X^NY) $$have a child. What is the probability that their son will have the disorder?

Accepted Answer

$$0.5 or$$ $$50\%$$

Question 6

Which of the following is an example of incomplete dominance?

Accepted Answer

A pink-flowered plant results from crossing a red-flowered plant with a white-flowered plant.

Question 7

What is nondisjunction, and what is a possible result in humans?

Accepted Answer

Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate during meiosis, possibly resulting in conditions like Down syndrome ($$2n+1).$$

Question 8

Which mutation involves a segment of one chromosome breaking off and attaching to a nonhomologous chromosome?

Accepted Answer

Translocation

Question 9

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

Accepted Answer

A phosphate group, a deoxyribose sugar, and a nitrogenous base

Question 10

What is meant by the antiparallel nature of DNA strands?

Accepted Answer

One strand runs from $$5' to$$ $$3'$$, and 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 parental 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, what is the main difference between the leading and lagging strands?

Accepted Answer

The leading strand is synthesized continuously, while the lagging strand is synthesized in short fragments called Okazaki fragments.

Question 14

A man with genotype $$AaBb$$ produces sperm. According to the law of independent assortment, what is the probability that a sperm will carry the $$ab$$ combination?

Accepted Answer

$$0.25$$

Question 15

Which of the following best describes a homozygous recessive genotype?

Accepted Answer

An individual with two recessive alleles for a gene (e.g., $$aa)$$

Question 16

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

Accepted Answer

Ligase

Question 17

A woman with blood type $$IAi$$ and a man with blood type $$IBi$$ have a child. What is the probability that their child will have type AB blood?

Accepted Answer

$$0.25 or$$ $$25\%$$

Question 18

Which of the following scenarios best illustrates codominance?

Accepted Answer

A white cow and a red cow produce offspring with both red and white hairs.

Question 19

Which enzyme synthesizes short RNA primers needed for DNA polymerase to begin replication?

Accepted Answer

Primase

Question 20

If a mutation causes a segment of a chromosome to be reversed end to end, what type of chromosomal mutation has occurred?

Accepted Answer

Inversion

Exam Review Guidance: Genetics, Cell Division, and DNA Structure

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