B2 (Cell Division)

Question 1

Chromosomes

Answer 1

• in the nucleus contain genetic material

- 23 pairs from parents

Question 2

Chromosome structure

Answer 2

• coiled up lengths of DNA

- large number of genes for characteristics

Question 3

2 stage of the cell cycle

Answer 3

• growth and DNA replication

- mitosis

Question 4

3 stages of Growth and DNA replication

Answer 4

• cells grows the sub cellular structures like ribosomes and mitochondria
• duplicates DNA so theres an exact copy for each cell
• X shaped chromosomes

Question 5

5 stages of Mitosis

Answer 5

1) Chromosomes line up
2) Cell fibres pull apart, as the arms go to opposite ends of the cell
3) membranes form around the cells and become the nuclei of the two cells
4) cytoplasm and cell membrane divide
5) two new daughter cells with the exact copy of DNA

Question 6

Cell Differentitation

Answer 6

Process when a cell changes to become specialised

Question 7

How does cell differentiation occur?

Answer 7

Develop different sub cellular structures for different types of cells for the functions

Question 8

Differentiation in animals and plants

Answer 8

• animals, differentiation is lost in early stages
• cells in mature animals is for replacing cells
• plants never loose the the ability to differentiate

Question 9

Embryonic Stem Cells

Answer 9

• Undifferentiated cells that can divide

- they are found in early human embryos

Question 10

Adult Stem Cells

Answer 10

• found in bone marrow

- can’t turn into every cell only specific ones (blood cells)

Question 11

3 Advantages of Stem Cells

Answer 11

• cure diseases (replace faulty blood cells)
• cloning to make same genetic information to stop cell rejection
• meristems in plants for growth of more plants that are clones

Question 12

2 Disadvantages of Stem Cells

Answer 12

• can become contaminated

- unethical as destroys potential life