2b Cell Structure

Question 1

What is a zygote? (1)

Answer 1

The single cell formed after fertilisation occurs.

Question 2

How is a 16 cell embryo formed? (2)

Answer 2

• By mitosis (cell division)

- 1 cell > 2 cells > 4 cells > 8 cells > 16 cells

Question 3

What is differentiation? (1)

Answer 3

• The process whereby cells become specialised, e.g. nerve cells.

Question 4

What is a stem cell? (1)

Answer 4

• A cell which has the potential to divide many times while remaining undifferentiated/unspecialised.

Question 5

What are the two types of stem cell? (2)

Answer 5

• Embryonic

- Adult

Question 6

What are embryonic stem cells? (2)

Answer 6

• Found in early stage development of embryos.

- Can differentiate into any type of cell.

Question 7

What are adult stem cells? (3)

Answer 7

• Found in particular tissues
• such as bone marrow, lining of small intestine and skin,
• which are unable to differentiate into any type of cell.

Question 8

What is stem cell therapy? (2)

Answer 8

• Use of stem cells to treat disease

- E.g. bone marrow transplants

Question 9

Describe the use of stem cell therapy in the treatment of leukaemia (3)

Answer 9

• Leukemia is a type of blood cancer.
• Chemotherapy destroys both healthy and cancerous cells.
• Stem cell therapy supplies stem cells that can divide and differentiate and therefore replace cells lost in chemotherapy.

Question 10

What are the advantages and disadvantages of embryonic stem cell therapy? (3)

Answer 10

• Ability to differentiate into any type of cell; Not limited.
• Could be used to treat Parkinson’s disease, diabetes etc
• Ethical issues with use as they come from unborn foetuses.