B2 - Cell Division

Question 1

When and how often do animal and plant cells differentiate?

Answer 1

Animals cells - differentiate at an early stage
Plant cells - differentiate throught life

Question 2

What happens in mitosis?

Answer 2

One set of chromosomes is pulled to each end of the cell.

Question 3

Explain the three phases of the cell cycle.

Answer 3

1st -
- Increases the number of organelles such as ribosomes and mitochondria
- chromosomes replicate
2nd -
- one set of chromosomes are pulled to each end of the celll,
3rd -
- the cytoplasm and the cell membrane divides
- forms 2 genetically identical cells

Question 4

Why does a cell need to undergo mitosis?

Answer 4

• cell devolopment and growth
• replacing damaged cells

Question 5

What is a stem cell?

Answer 5

Undifferentiated cells that can produce specialised cells and more stem cells.

Question 6

Advantages and disadvantages of stem cells obtained from human embryos

Answer 6

• they can be made to differentiate into most types of human cell
• embryos used to obtain stem cells are unwanted ones, which would otherwise be discarded
• if it is not cloned from your embryo it could be rejected by the body
• We are destroying the embryo, which is seen as a human life, when getting the stem cells.

Question 7

Advantages and disadvantages of stem cells obtained from patient’s own marrow.

Answer 7

• stem cells are not rejected
• no ethical problems - no destruction of embryos
• less variety of cells that it can differentiate into

Question 8

Meristem tissue

Answer 8

• produce clones of plants efficiently and economically
  rare species can be cloned can be saved from extinction
  plants with special features such as disease resistance can be cloned at large numbers.

Question 9

What is therauptic cloning?

Answer 9

embryo is produced with the same genes as the patient,
so not rejected by the patient’s body and used for medical treatment