Question 1

Which of the following best describes the difference between homologous chromosomes and sister chromatids?

Accepted Answer

Homologous chromosomes are inherited from each parent and carry the same genes but may have different alleles; sister chromatids are identical copies formed after DNA replication.

Question 2

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

Accepted Answer

Crossing over occurs during prophase I and results in genetic recombination, increasing genetic variation.

Question 3

If a human somatic cell contains 46 chromosomes, how many chromosomes are present in a human gamete after meiosis?

Accepted Answer

23

Question 4

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

Accepted Answer

Synapsis and crossing over between homologous chromosomes

Question 5

A diploid cell ($$2n) $$undergoes meiosis. How many haploid ($$n) $$cells are produced, and how does this process contribute to genetic diversity?

Accepted Answer

Four haploid cells are produced, and genetic diversity is increased by independent assortment and crossing over.

Question 6

Which formula correctly calculates the number of possible chromosome combinations due to independent assortment in gametes, where $$n is $$the haploid number?

Accepted Answer

$$2^n$$

Question 7

In humans, what is the approximate number of possible chromosome combinations in gametes due to independent assortment alone?

Accepted Answer

About 8.4 million

Question 8

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

Accepted Answer

Replication of chromosomes during interphase

Question 9

A mutation occurs in a gene located on a chromosome. What is the term for the specific location of this gene on the chromosome?

Accepted Answer

Locus

Question 10

Which statement best explains why offspring produced by sexual reproduction are not identical to their parents?

Accepted Answer

Genetic variation arises from mutations, independent assortment, crossing over, and random fertilization.

Question 11

During which stage of meiosis do homologous chromosomes separate, and what is the result?

Accepted Answer

Anaphase I; homologous chromosomes are separated, reducing chromosome number by half

Question 12

Which of the following is TRUE regarding the alternation of generations in plants and some algae?

Accepted Answer

Both diploid (sporophyte) and haploid (gametophyte) multicellular stages are present.

Question 13

Which process restores the diploid number of chromosomes in sexually reproducing organisms?

Accepted Answer

Fertilization

Question 14

A zygote is formed by the fusion of two gametes. If each gamete contains $$n$$ chromosomes, how many chromosomes does the zygote have?

Accepted Answer

$$2n$$

Question 15

Which of the following best describes the role of cohesin proteins during meiosis?

Accepted Answer

Cohesins hold sister chromatids together until they are separated during anaphase II.

Question 16

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

Accepted Answer

Production of recombinant chromosomes containing DNA from both parents

Question 17

If a mutation creates a new allele in a population, what is the evolutionary significance of this event?

Accepted Answer

It provides a new version of a gene that can be acted upon by natural selection.

Question 18

Which of the following statements about karyotypes is correct?

Accepted Answer

A karyotype displays the number, size, and shape of chromosomes in a cell.

Question 19

Which of the following best explains why only diploid cells can undergo meiosis?

Accepted Answer

Diploid cells have two sets of chromosomes, allowing homologous pairs to form and separate.

Question 20

A scientist observes a cell with chromosomes aligned at the metaphase plate, but each chromosome consists of two genetically distinct sister chromatids. Which phase of meiosis is being observed?

Accepted Answer

Metaphase II

Meiosis and Sexual Life Cycles – Study Notes (Campbell Biology, Ch. 13)

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