Meiosis

Question 1

Why is meiosis important

Answer 1

• Meiosis halves the number of chromosomes in the nucleus and produces haploid daughter cells that then act as gametes in sexual reproduction.
• Gametes need to be haploid as they fuse during fertilisation to form zygote in order to preserve original chromosome number in zygote.

Question 2

What are the names of the steps in meiosis

Answer 2

Meiosis I: 
1. Prophase I. 
2. Metaphase I. 
3. Anaphase I. 
4. Telophase I. 
Meiosis II: 
5. Prophase II. 
6. Metaphase II. 
7. Anaphase II. 
8. Telophase II.

Question 3

What type of cell division is meiosis known as

Answer 3

Reduction division

Question 4

What does meiosis produce

Answer 4

Gametes

Question 5

Describe prophase 1

Answer 5

Chromatin condenses and undergoes super-coiling, resulting in it
becoming shorter, thicker and visible under a light microscope.
 The chromosomes now come together to form homologous pairs

Question 6

Describe metaphase 1

Answer 6

Spindle fibres are completely formed and attach to the centromeres of the homologous chromosomes.
The chromosomes line up down the middle of the spindles along with their homologous pair.

Question 7

Describe anaphase 1

Answer 7

The spindle fibers start to pull on the chromosomes and each homologous chromosome heads towards a different pole.

Question 8

Describe telophase 1

Answer 8

Chromosomes are now at the pole, nuclear membranes start to form around the chromosomes, and the chromosomes start to unwind back into chromatin. Cytokinesis occurs and the two cells split. These two cells are still diploid at this point. The next 4 phases occur to each of these cells

Question 9

Describe prophase 2

Answer 9

The chromosomes reorganize and the nuclear membranes start to dissolve again. Sister chromatids are again joined by a centromere. Spindles start to reform between centrosomes.

Question 10

Describe metaphase 2

Answer 10

Spindles are fully formed again and attach to the centromeres. The chromosomes line up down the middle of the spindles.

Question 11

Describe anaphase 2

Answer 11

The spindles pull the sister chromatids apart. Each goes towards a different pole

Question 12

Describe telophase 2

Answer 12

Nuclear membranes start to form around the chromosomes again. A cleavage forms. Cytokinesis occurs and the two diploid cells have now divided into 4 haploid cells.

Question 13

Define tetrad

Answer 13

A paired set of homologous chromosomes, each composed of two sister chromatids

Question 14

Describe interphase

Answer 14

DNA is in its chromatin form and the DNA replicates.

Question 15

Define homologous chromosomes

Answer 15

Chromosomes that have the same sequence of genes, that have the same structure, and that pair during meiosis

Question 16

Define crossing over

Answer 16

Process in which homologous chromosomes exchange portions of their chromatids during meiosis. This increases genetic variation.

Question 17

Define haploid

Answer 17

A cell that contains only one set of chromosomes instead of the normal pair. Gametes, which are sex cells like sperm and eggs, are haploid cells.

Question 18

Define diploid

Answer 18

A cell that contains two sets of chromosomes; one inherited from the mother and one inherited from the father. Most body cells (nerve, brain, muscle, skin, etc.) are considered diploid cell.