Question 1

Which of the following best explains why meiosis is necessary for sexual reproduction in humans?

Accepted Answer

Meiosis reduces the chromosome number by half, preventing chromosome doubling in each generation after fertilization.

Question 2

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

Accepted Answer

$$23$$

Question 3

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

Accepted Answer

Crossing over occurs during prophase I and increases genetic variation among gametes.

Question 4

If a mistake occurs during meiosis resulting in a gamete with an extra chromosome 21, what condition may result after fertilization?

Accepted Answer

Down syndrome (trisomy 21)

Question 5

Which of the following statements about homologous chromosomes is correct?

Accepted Answer

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

Question 6

A cell is described as heterozygous at a particular gene locus. What does this mean?

Accepted Answer

It has two different alleles for that gene.

Question 7

Which process is responsible for the independent assortment of chromosomes, and how does it contribute to genetic diversity?

Accepted Answer

Independent assortment occurs during metaphase I, allowing random orientation of homologous pairs, which increases genetic diversity in gametes.

Question 8

Which of the following best distinguishes meiosis from mitosis?

Accepted Answer

Meiosis results in four genetically unique haploid cells, while mitosis results in two genetically identical diploid cells.

Question 9

A woman with genotype $$Pp$$ for flower color (where $$P is $$dominant for purple and $$p is $$recessive for white) produces gametes. What proportion of her gametes will carry the $$p$$ allele?

Accepted Answer

$$50\%$$

Question 10

Which of the following events does NOT occur during meiosis I?

Accepted Answer

Sister chromatids separate at the centromere.

Question 11

A geneticist is studying a population where asexual reproduction is the only mode of reproduction. Which of the following is the primary source of genetic variation in this population?

Accepted Answer

Random mutations during DNA replication

Question 12

In a certain plant species, the diploid number ($$2n) is$$ $$8. $$After meiosis, how many chromosomes will each gamete contain?

Accepted Answer

$$4$$

Question 13

Which of the following best describes the outcome if DNA replication occurred between meiosis I and meiosis II?

Accepted Answer

Gametes would have double the normal amount of DNA, leading to polyploidy.

Question 14

Which of the following is a direct result of the process of synapsis during prophase I of meiosis?

Accepted Answer

Formation of tetrads (bivalents) allowing for crossing over.

Question 15

A male child is born with an XYY karyotype. Which meiotic error most likely led to this condition?

Accepted Answer

Nondisjunction of the Y chromosome during meiosis II in the father.

Question 16

Which of the following best explains why genetic variation is advantageous for a population?

Accepted Answer

It increases the likelihood that some individuals possess traits that allow survival in changing environments.

Question 17

During which stage of meiosis do homologous chromosomes align at the metaphase plate, and what is the significance of their arrangement?

Accepted Answer

Metaphase I; their random alignment leads to independent assortment and increased genetic diversity.

Question 18

Which of the following is true regarding the difference between the products of meiosis and mitosis?

Accepted Answer

Meiosis produces four haploid cells, each genetically unique; mitosis produces two diploid cells, each genetically identical.

Question 19

A zygote is formed by the fusion of two gametes. If one gamete is missing a sex chromosome (O) and the other is a normal X, what is the likely outcome?

Accepted Answer

The zygote will develop into a female with Turner syndrome.

Question 20

Which of the following best describes the role of alleles in genetic inheritance?

Accepted Answer

Alleles are different forms of a gene found at the same locus on homologous chromosomes.

Molecular Biology of the Gene: Meiosis, Chromosome Behavior, and Genetic Variation

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