Question 1

Which of the following best explains why offspring produced by sexual reproduction are genetically different from their parents?

Accepted Answer

Because meiosis and fertilization introduce genetic variation through independent assortment, crossing over, and random fertilization.

Question 2

A human skin cell is classified as a somatic cell. Which of the following statements about somatic and germ cells is correct?

Accepted Answer

Somatic cells are diploid and divide by mitosis, while germ cells can undergo meiosis to produce haploid gametes.

Question 3

Which of the following best describes the genetic relationship between two sister chromatids?

Accepted Answer

They are genetically identical, having been produced by DNA replication.

Question 4

In humans, which of the following cells is haploid?

Accepted Answer

Sperm cell

Question 5

Which of the following statements about autosomes and sex chromosomes is correct?

Accepted Answer

Autosomes are chromosomes that do not determine sex, while sex chromosomes are involved in determining the sex of an individual.

Question 6

Why must fertilization and meiosis alternate in all sexual life cycles?

Accepted Answer

To ensure that the chromosome number remains constant across generations.

Question 7

Which of the following organisms exhibits a life cycle in which the multicellular haploid stage is dominant?

Accepted Answer

Moss

Question 8

During which phase of meiosis do homologous chromosomes separate, leading to a reduction in chromosome number?

Accepted Answer

Anaphase I

Question 9

A cell is observed under a microscope with chromosomes aligned in pairs along the metaphase plate. Which process is most likely occurring?

Accepted Answer

Meiosis I metaphase

Question 10

Which of the following is a key difference between mitosis and meiosis?

Accepted Answer

Mitosis involves one cell division, while meiosis involves two consecutive cell divisions.

Question 11

If an organism has a diploid number of 8 ($$2n = 8$$), how many possible combinations of chromosomes can be produced in its gametes by independent assortment alone?

Accepted Answer

$$2^4 = 16$

Question 12

Which event during meiosis is primarily responsible for generating new combinations of alleles on a single chromosome?

Accepted Answer

Crossing over between non-sister chromatids during prophase I

Question 13

A geneticist is studying a cell in which homologous chromosomes are paired and exchanging genetic material. Which stage of meiosis is being observed?

Accepted Answer

Prophase I

Question 14

Which of the following best explains why the segregation of homologous chromosomes in meiosis I leads to a reduction in ploidy?

Accepted Answer

Because homologous chromosomes, each consisting of two chromatids, are separated into different cells, halving the chromosome number.

Question 15

Which of the following scenarios best illustrates the concept of random fertilization contributing to genetic variation?

Accepted Answer

A single sperm fertilizes an egg, and the resulting zygote has a unique combination of alleles due to the random selection of gametes.

Question 16

Which of the following best describes the arrangement of chromosomes during metaphase of mitosis compared to metaphase I of meiosis?

Accepted Answer

In mitosis, chromosomes align singly at the metaphase plate; in meiosis I, homologous pairs align together at the metaphase plate.

Question 17

A plant species has a diploid number of 10 ($$2n = 10). If $$crossing over occurs at least once per homologous pair, which of the following best describes the potential for genetic variation in its gametes?

Accepted Answer

There are $$2^5 = 32$ possible combinations from independent assortment, and crossing over further increases variation.

Question 18

Which of the following is NOT a source of genetic variation in sexually reproducing organisms?

Accepted Answer

Replication of DNA during S phase

Question 19

A biologist observes a cell with chromosomes consisting of two chromatids each, but the homologous chromosomes are no longer paired. Which stage of meiosis is this cell most likely in?

Accepted Answer

Metaphase II

Question 20

Which of the following best explains why a child can inherit a genetic disorder that neither parent visibly exhibits?

Accepted Answer

Because independent assortment and random fertilization can bring together two recessive alleles from carrier parents.

Meiosis and Sexual Life Cycles: Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard