Meiosis

Question 1

What is formed when an egg cell and a sperm cell fuse together during fertilisation?

Answer 1

A zygote.

Question 2

What is a haploid cell?

Answer 2

Cells that have half the number of chromosomes than a normal cell.

Question 3

Where in the body does meiosis occur?

Answer 3

In the reproductive organs

Question 4

How many divisions are involved in meiosis?

Answer 4

2 divisions.

Meiosis l and Meiosis ll

Question 5

What happens in a reduction division?

Answer 5

The chromosome number is halved.

Question 6

What is a homologous pair of chromosomes?

Answer 6

A pair of chromosomes, one that is paternal and one maternal. They are the same size and have the same genes in the same loci.

Question 7

What are alleles?

Answer 7

Different versions of the same gene.

Question 8

What happens in prophase l?

Answer 8

Chromosomes condense.
Chromosomes arrange themselves into homologous pairs and they cross over.
Centrioles move to opposite ends of the cell.
Nuclear envelope condenses.

Question 9

What happens in metaphase l?

Answer 9

Homologous pairs line up along the metaphase plate INDEPENDENTLY and RANDOMLY.
They attach to the spindle by their centromeres.

Question 10

What happens in anaphase l?

Answer 10

Spindles contract separating the homologous pair.

One chromosome goes to each end.

Question 11

What happens in telophase l?

Answer 11

Nuclear envelope forms around each group of chromosomes.

Question 12

What happens in the first cytokinesis?

Answer 12

The cell divides into two, forming 2 haploid daughter cells.

Question 13

What is produced at the end of meiosis?

Answer 13

Gametes (sex cells) for sexual reproduction.

Question 14

What is a bivalent?

Answer 14

When homologous pairs of chromosomes come together and cross over. Bits of the chromatids swap over forming different combinations of alleles.

Question 15

What happens in metaphase ll?

Answer 15

Chromosomes align along the equator.

Question 16

What happens in anaphase ll?

Answer 16

The sister chromatids are separated as the spindles contract.

Question 17

What happens in telophase ll?

Answer 17

Nuclear envelope forms around the chromatids.

Question 18

What happens in the second cytokinesis?

Answer 18

The two cells divide again, forming 4 genetically different haploid daughter cells (gametes).

Question 19

What two events lead to genetic variation in meiosis?

Answer 19

Crossing over and independent assortment.

Question 20

How does crossing over of chromatids lead to genetic variation?

Answer 20

When they cross over, the chromatids in each cell end up with a different set of alleles. So each is different.

Question 21

How does independent assortment lead to genetic variation?

Answer 21

When the chromosomes line up in metaphase l, it is random which way they line up. The final daughter cells will have different combinations of chromosomes to each other.

Question 22

What happens in prophase ll?

Answer 22

The centrioles move to opposite ends.
Spindles form.
Nuclear envelopes break down in both cells.