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, and what is this condition called?

Accepted Answer

Each gamete will have 23 chromosomes; this is called the haploid condition.

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 non-disjunction event occurs during meiosis I in a human female, which of the following could be a possible outcome in her offspring?

Accepted Answer

The offspring could have trisomy 21, resulting in Down syndrome.

Question 5

Which of the following statements about homologous chromosomes is correct?

Accepted Answer

Homologous chromosomes carry the same genes at the same loci, but may have different alleles.

Question 6

A plant has a diploid number $$(2n) of 8. $$After meiosis, how many chromosomes will each gamete have, and how many genetically unique gametes can be produced by independent assortment alone (ignore crossing over)?

Accepted Answer

Each gamete will have 4 chromosomes; $$2^4 = 16$ unique gametes.

Question 7

Which of the following best describes the difference between meiosis I and meiosis II?

Accepted Answer

Meiosis I separates homologous chromosomes, while meiosis II separates sister chromatids.

Question 8

A child is born with only one X chromosome (XO). Which meiotic error most likely led to this condition, and what is the name of the syndrome?

Accepted Answer

Non-disjunction during meiosis; Turner syndrome.

Question 9

Which of the following is a key advantage of sexual reproduction over asexual reproduction?

Accepted Answer

Sexual reproduction produces offspring with greater genetic variation, increasing adaptability to changing environments.

Question 10

During metaphase I of meiosis, what is the arrangement of chromosomes at the metaphase plate, and why is this important?

Accepted Answer

Homologous pairs align randomly at the metaphase plate, leading to independent assortment and genetic variation.

Question 11

Which of the following best explains why individuals with different combinations of alleles at a gene locus may have different traits?

Accepted Answer

Alleles are different versions of a gene that can result in different phenotypes.

Question 12

Which of the following events does NOT occur during meiosis but does occur during mitosis?

Accepted Answer

Separation of sister chromatids during the first division.

Question 13

A geneticist is studying a trait controlled by multiple genes (polygenic inheritance). Which of the following best explains why siblings can have a wide range of phenotypes for this trait?

Accepted Answer

Multiple loci and alleles combine in different ways during meiosis, resulting in a broad spectrum of phenotypes.

Question 14

Which of the following is a direct result of independent assortment during meiosis?

Accepted Answer

Gametes receive random combinations of maternal and paternal chromosomes.

Question 15

In a certain animal, the diploid number $$(2n) is 12. $$How many chromosomes will be present in each cell at the end of meiosis II?

Accepted Answer

Each cell will have 6 chromosomes.

Question 16

Which of the following best describes the outcome of meiosis in terms of genetic diversity?

Accepted Answer

Meiosis produces four genetically unique haploid cells due to crossing over and independent assortment.

Question 17

A mutation occurs that prevents crossing over during meiosis. Which of the following would most likely be observed in the offspring?

Accepted Answer

Reduced genetic variation among offspring.

Question 18

Which of the following is true regarding the centromere during meiosis I and mitosis?

Accepted Answer

The centromere survives anaphase I in meiosis but dissolves during anaphase in mitosis.

Question 19

Which of the following best explains why asexual reproduction results in less genetic variation compared to sexual reproduction?

Accepted Answer

Asexual reproduction relies solely on mutations for genetic variation, while sexual reproduction combines alleles from two parents and includes crossing over and independent assortment.

Meiosis, Chromosome Behavior, and Genetic Variation: Study Notes for General Biology

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