61 WJEC Biology AS Level - Study And Revision Guide - Neil Roberts (1.6 The Cell Cycle And Cell Division)

Question 1

What does mitosis result in?

Answer 1

Mitosis results in the production of two genetically identical cells.

Question 2

What is the importance of mitosis?

Answer 2

It is important in growth and repair when differentiated cells replicate.

Question 3

What are the stages of mitosis?

Answer 3

It consists of four stages:

1. Prophase
2. Metaphase
3. Anaphase
4. Telophase

Try to remember PMAT:

Prophase (prominent DNA)
Metaphase (middle)
Anaphase (apart)
Telophase (two).

Question 4

What happens during prophase?

Answer 4

1. Chromosomes condense to become shorter and thicker
2. Chromosomes become visible as two sister chromatids attached by a centromere
3. Centrioles move to opposite poles (not higher plants)
4. Nuclear envelope disintegrates
5. Nucleolus disappears

Question 5

What happens during metaphase?

Answer 5

1. Spindle forms
2. Chromosomes align at the equator of the cell attached to spindle microtubules via centromere

Question 6

What happens during anaphase?

Answer 6

1. Spindle fibres shorten
2. Centromeres divide, and chromatids are pulled towards opposite poles

Question 7

What happens during telophase?

Answer 7

1. Chromatids reach poles and become indistinct by uncoiling
2. Nuclear envelope reforms
3. Nucleolus reforms
4. Spindle disintegrates

Question 8

What is important for the exam to know regarding mitosis?

Answer 8

Be prepared to draw or identify chromosomes in any of the four stages of mitosis.

Question 9

Draw a diagram of early prophase?

Answer 9

Question 10

Draw a diagram of late prophase?

Answer 10

Question 11

Draw a diagram of metaphase?

Answer 11

Question 12

Draw a diagram of anaphase?

Answer 12

Question 13

Draw a diagram of telophase?

Answer 13

Question 14

Answer 14