Unit 2 - Cell Division

Question 1

Name the two types of cell division

Answer 1

Mitosis and Meiosis

Question 2

What is cell division needed for?

Answer 2

Growth and repair of damaged cells and for producing new offspring

Question 3

What is Mitosis?

Answer 3

Normal cell division, it produces clones of the origional adult cell

Question 4

What happens during mitosis?

Answer 4

1. The normal body cell has 46 chromosomes in 23 pairs
2. As cell division starts, each chromosome makes a copy of itself
3. The chromosomes **line up **in the centre of the cell
4. The chromosomes are split evenly between the 2 new cells, each cell is a **genetically identical clone of the parent cell **(daughter cells)

Question 5

Where does mitosis happen

Answer 5

In all your body cells

Question 6

What is meiosis

Answer 6

A special type of cell division which takes place in the ovaries and **testes **to produce gametes (sex cells)

Question 7

What happens during meiosis?

Answer 7

• An adult cell in the testes or ovary has 46 chromosomes in 23 pairs
• A copy of each chromosomes is made
• The cells divide and one copy of each pair of chromosomes ends up in each new cell (this halfs the number of chormosomes)
• A second cell division takes place and one copy of each cell ends up in 4 daughter cells

The 4 cells are gametes as they contain half the genetic information of the origional plant cell

Question 8

Why do 2 gametes fuse together during fertilisation?

Answer 8

To restore the chromosome number

Question 9

Why is reproduction via meiosis important?

Answer 9

It introduces variation

Question 10

What are stem cells?

Answer 10

Undifferenciaed cells, they don’t have a specific job but can divide to become any type of cell.

Question 11

What are the 2 sources of stem cells?

Answer 11

Embryonic stem cells and adult stem cells

Question 12

What is a pro and a con of embryonic stem cells?

Answer 12

+ They can be used to create any type of cell

• They need to be collected from embryos (this damages them - therefore catalyses ‘right to life’ belief)

Question 13

What are 2 pro’s and 3 cons of adult stem cells

Answer 13

+ Adults can give permission for removal

+ Using a persons stem cells allows identical cells to be created for that person

• Difficult to remove (as they are in bone marrow)
• They can’t become any type of cell (only a few)
• May cause cancer (by growing out of control)

Question 14

Name the 4 ways in which we can use stem cells

Answer 14

1. Grow new nervous tissue eg for spinal damage
2. Grow replacement organs that won’t be rejected if the persons own stem cells are used
3. **Treat diseases **of the brain
4. Grow new skin for burn victims