Question 1

Which of the following best describes the change in ploidy during meiosis in a diploid organism?

Accepted Answer

The ploidy changes from 2n to n after Meiosis I and remains n after Meiosis II.

Question 2

During which phase of meiosis does crossing over (homologous recombination) occur, and what is its evolutionary significance?

Accepted Answer

Crossing over occurs during Prophase I and increases genetic diversity by creating new allele combinations.

Question 3

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

Accepted Answer

Replication of DNA during S phase

Question 4

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

Accepted Answer

$$23$$

Question 5

Which law explains why alleles for different genes are inherited independently of each other, and during which meiotic phase is this law observed?

Accepted Answer

Law of Independent Assortment; Metaphase I

Question 6

Which of the following best describes the outcome of mitosis in a diploid organism?

Accepted Answer

Two genetically identical diploid cells are produced.

Question 7

If a diploid cell with genotype AaBb undergoes meiosis without crossing over, what is the maximum number of genetically distinct gametes it can produce due to independent assortment?

Accepted Answer

$$4$$

Question 8

Which event marks the transition from diploid (2n) to haploid (n) cells during meiosis?

Accepted Answer

Separation of homologous chromosomes during Anaphase I

Question 9

Which of the following is a direct result of random fertilization in humans?

Accepted Answer

Each zygote has a unique combination of alleles from both parents.

Question 10

Which process is responsible for the separation of sister chromatids?

Accepted Answer

Anaphase of mitosis and Anaphase II of meiosis

Question 11

A mutation occurs in a gene during DNA replication in a germ cell. Which of the following is true about the potential evolutionary impact of this mutation?

Accepted Answer

It can be passed to offspring if the mutated gamete is involved in fertilization.

Question 12

Which of the following best explains why sexual reproduction is advantageous for evolution?

Accepted Answer

It increases genetic diversity through recombination, independent assortment, and random fertilization.

Question 13

Which of the following statements about homologous chromosomes is correct?

Accepted Answer

They carry the same genes but may have different alleles.

Question 14

In a Punnett square for a monohybrid cross (Aa x Aa), what do the letters on the margins represent?

Accepted Answer

Possible alleles in the gametes from each parent

Question 15

Which of the following events occurs only during meiosis and not during mitosis?

Accepted Answer

Pairing and crossing over of homologous chromosomes

Question 16

If a cell has 8 chromosomes at the start of meiosis, how many chromosomes will each gamete have at the end of meiosis?

Accepted Answer

$$4$$

Question 17

Which of the following best describes the difference between somatic cells and gametes in humans?

Accepted Answer

Somatic cells are diploid and gametes are haploid.

Question 18

Which of the following is NOT a phase of meiosis?

Accepted Answer

Anaphase III

Question 19

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

Accepted Answer

Fertilization

Question 20

Which of the following best explains why independent assortment leads to genetic variation?

Accepted Answer

It allows for random combinations of maternal and paternal chromosomes in gametes.

Inheritance and Sources of Genetic Variation: Meiosis, Mitosis, and Mendelian Laws

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