Meiosis

Question 1

What is the correct sequence of the development of a mature sperm cell?

Answer 1

Spermatogonium –> 1 spermatocyte –> 2 spermatocyte –> spermatid –> spermatozoan

Question 2

What happens to the egg cells from the time of birth until shortly before ovulation?

Answer 2

All egg cells are arrested at the prophase stage of meiosis 1. These are known as primary oocytes.

Question 3

What happens to egg cells during the process of ovulation?

Answer 3

The egg cells have completed meiosis 1 and are now arrested in the metaphase ll as a haploid cell called a secondary oocyte.

Question 4

What is required for the secondary oocyte to become a mature ovum?

Answer 4

A sperm must penetrate the outer layers of the secondary oocyte.

Question 5

What is the last point in the meiotic cycle in which the cell has a diploid number of chromosomes?

Answer 5

During telophase l.

Question 6

What happens during anaphase l?

Answer 6

The first meiotic division (reductional division) separate homologous chromosomes to opposite poles of the cell.

Question 7

What happens during telophase l?

Answer 7

Cytokinesis occurs and results in two haploid daughter cells.

Question 8

What are ways that can contribute to genetic variability?

Answer 8

1. Random fertilization of an egg by a sperm.
2. Random segregation of homologous chromosomes.
3. Crossing over between homologous chromosomes during meiosis.

Question 9

What happens during the S stage?

Answer 9

DNA is replicated precisely, without error, to where there is NO genetic variability. Both strands of DNA should be identical.

Question 10

What is a key difference between meiosis and mitosis?

Answer 10

During metaphase of mitosis, centromeres are present directly on the metaphase plate; during metaphase of meiosis l, there are NO centromeres on the metaphase plate.

Question 11

What is another key difference between meiosis and mitosis?

Answer 11

Synapsis and crossing over during prophase l, and homologous chromosomes are separated during meiosis l. This is different compared to mitosis where there are sister chromatids instead.

Question 12

Define nondisjunction.

Answer 12

It refers to the incorrect segregation of homologous chromosomes during anaphase l or of sister chromatids during anaphase ll.

Question 13

What is the genotype of a woman with Turner syndrome?

Answer 13

45,X