Question 1

Which of the following best explains why offspring produced by sexual reproduction are genetically different from their parents?

Accepted Answer

Because meiosis and fertilization introduce genetic variation through independent assortment, crossing over, and random fertilization.

Question 2

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 by exchanging DNA between homologous chromosomes.

Question 3

A human cell with 46 chromosomes undergoes meiosis. How many chromosomes will each resulting gamete contain?

Accepted Answer

$$23$$

Question 4

Which of the following events occurs in meiosis but NOT in mitosis?

Accepted Answer

Pairing of homologous chromosomes and crossing over

Question 5

If a diploid organism has a chromosome number of $$2n = 8$$, how many possible combinations of chromosomes can be produced in its gametes due to independent assortment alone?

Accepted Answer

$$2^4 = 16$

Question 6

Which of the following statements about homologous chromosomes is TRUE?

Accepted Answer

They carry the same genes at the same loci but may have different alleles.

Question 7

What is the result of nondisjunction during meiosis?

Accepted Answer

Gametes with an abnormal number of chromosomes, leading to disorders such as Down syndrome

Question 8

Which process restores the diploid chromosome number in sexually reproducing organisms?

Accepted Answer

Fertilization

Question 9

In the human life cycle, what is the chromosome number in a zygote immediately after fertilization?

Accepted Answer

$$2n = 46$$

Question 10

Which of the following best describes the difference between autosomes and sex chromosomes in humans?

Accepted Answer

Autosomes are chromosomes 1-22 and do not determine gender, while sex chromosomes (X and Y) determine biological sex.

Question 11

Which of the following mechanisms does NOT contribute to genetic variation in sexually reproducing organisms?

Accepted Answer

Replication of DNA during interphase

Question 12

A mutation occurs in a gene located on a chromosome. Which of the following statements is TRUE regarding the inheritance of this mutation?

Accepted Answer

The mutation may be passed to offspring if it occurs in a gamete and is involved in fertilization.

Question 13

Which of the following best explains why meiosis is necessary for sexually reproducing organisms?

Accepted Answer

It reduces the chromosome number by half, preventing chromosome doubling in each generation.

Question 14

Which of the following is a direct result of crossing over during meiosis?

Accepted Answer

Formation of recombinant chromosomes with new allele combinations

Question 15

If a plant species has a diploid number of $$2n = 12$$, how many genetically distinct gametes can it produce due to independent assortment alone?

Accepted Answer

$$2^6 = 64$

Question 16

Which of the following scenarios illustrates random fertilization?

Accepted Answer

A single sperm fertilizes an egg, but which sperm and which egg are involved is completely by chance.

Question 17

Which of the following best describes the outcome of meiosis II?

Accepted Answer

Sister chromatids are separated, resulting in four haploid cells.

Question 18

Which of the following is NOT a difference between mitosis and meiosis?

Accepted Answer

Both processes result in the same number of daughter cells.

Question 19

Which of the following best explains why genetic variation is important for evolution?

Accepted Answer

It allows populations to adapt to changing environments through natural selection.

Meiosis and Sexual Life Cycles: Mechanisms and Genetic Variation

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