Question 1

Which of the following best describes the difference between asexual and sexual reproduction in terms of genetic variation?

Accepted Answer

Asexual reproduction produces genetically identical offspring, while sexual reproduction results in genetic variation among offspring.

Question 2

In humans, how many chromosomes are found in a somatic cell, and what is the term for this chromosome number?

Accepted Answer

46 chromosomes; diploid

Question 3

During meiosis, what is the significance of crossing over, and in which phase does it occur?

Accepted Answer

Crossing over increases genetic variation and occurs during prophase I.

Question 4

If a human gamete contains 23 chromosomes, what is the chromosome number of the zygote after fertilization?

Accepted Answer

$$2n = 46$$

Question 5

Which of the following statements about homologous chromosomes is correct?

Accepted Answer

Homologous chromosomes carry genes controlling the same inherited characters.

Question 6

What is the formula for the number of possible combinations of chromosomes due to independent assortment in gametes, and what is the value for humans?

Accepted Answer

The formula is $$2^n$$; for humans, it is $$2^{23}$$ \approx 8,400,000$$.

Question 7

Which event is unique to meiosis and does NOT occur in mitosis?

Accepted Answer

Synapsis and crossing over of homologous chromosomes

Question 8

In plants, what is the name of the diploid multicellular stage that produces haploid spores by meiosis?

Accepted Answer

Sporophyte

Question 9

Which mechanism contributes to genetic variation by combining DNA from two parents into a single chromosome?

Accepted Answer

Crossing over

Question 10

A mutation occurs in a gene that codes for a protein involved in DNA repair. Which of the following best describes the potential evolutionary significance of this mutation?

Accepted Answer

It may create a new allele that could be favored by natural selection if it increases fitness.

Question 11

During meiosis I, what is the outcome of the separation of homologous chromosomes?

Accepted Answer

Each daughter cell receives one member of each homologous pair, resulting in haploid cells with duplicated chromosomes.

Question 12

Which of the following best explains why siblings from the same parents are not genetically identical?

Accepted Answer

Independent assortment, crossing over, and random fertilization create unique combinations of alleles in each offspring.

Question 13

In most fungi and some protists, which stage is the only diploid stage in the life cycle?

Accepted Answer

Single-celled zygote

Question 14

Which of the following is TRUE regarding the behavior of chromosomes during fertilization and meiosis?

Accepted Answer

Meiosis halves the chromosome number, while fertilization restores it.

Question 15

A karyotype is used in medical genetics to diagnose chromosomal abnormalities. Which of the following best describes what a karyotype shows?

Accepted Answer

An ordered display of the pairs of chromosomes from a cell

Question 16

Which of the following equations correctly represents the relationship between diploid and haploid chromosome numbers in humans?

Accepted Answer

$$2n = 46$$

Question 17

During which phase of meiosis are cohesins cleaved along the chromosome arms, allowing homologs to separate?

Accepted Answer

Anaphase I

Question 18

Which of the following mechanisms is responsible for the creation of recombinant chromosomes?

Accepted Answer

Crossing over during prophase I

Question 19

A bdelloid rotifer is able to increase genetic diversity by incorporating foreign DNA from the environment. What type of reproduction does this organism primarily use?

Accepted Answer

Asexual reproduction

Question 20

Which of the following best describes the evolutionary significance of genetic variation produced by sexual reproduction?

Accepted Answer

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

Meiosis and Sexual Life Cycles: Mechanisms and Evolutionary Significance

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