B2 Cell Division

Question 1

In body cells, what are chromosomes found in

Answer 1

Pairs

Question 2

Body cells divide in a series of stages called?

Answer 2

The cell cycle

Question 3

What are the three stages of the cell cycle

Answer 3

Interphase, mitosis and cytokinesis

Question 4

Interphase

Answer 4

Chromosomes in the nucleus duplicate

Question 5

Mitosis

Answer 5

Nucleus doubles itself and separates

Question 6

Cytokinesis

Answer 6

The cell membrane and cytoplasm separate, making two identical daughter cells.

Question 7

Where does mitosis take place in plant cells

Answer 7

Throughout life in the meristems found in the shoot snd root tips

Question 8

What are stem cells

Answer 8

Undifferentiated cells that can turn into a wide range of specialised cells

Question 9

Benefit of stem cells

Answer 9

Could save lives, treat untreatable deseases and is useful for medical research

Question 10

Downsides of stem cells

Answer 10

Hard to grow the correct cell needed, embryonic stem cells have potential risks and some have religious / ethnical objections

Question 11

Name the molecule that makes up chromosomes

Answer 11

DNA

Question 12

Why is mitosis important to organisms

Answer 12

• for growth
• for repair of cells / tissues
• development
• asexual reproduction

Question 13

Explain how a leaf can grow even though there is no trace left of the original leaf

Answer 13

• stem cells are
undifferentiated
• stem / meristematic cells can differentiate into any type of cell / leaf cells
• meristem contains stem cells

Question 14

Unlike the plant, most animals cannot grow back parts of their body after they have been cut off. Explain why this is

Answer 14

many plant cells retain the ability to differentiate throughout life

most animal cells can only differentiate at an early stage

Question 15

Pros and cons of stem cells

Answer 15

any six from: pros:
• many cells could be produced
• cells / tissues of any type could be produced
• stem cells would not be rejected by the patient
• stem cells would be produced that could be used for research
• sexual reproduction / fertilisation not involved
• would reduce waiting time for organ
transplants cons:
• shortage of donor eggs
• egg donation / collection
painful
• poor success rate to
produce viable eggs
• embryo is destroyed
• could lead to cloning of
humans in the future
• justified conclusion