Cell Structure

Question 1

Define cell differentiation

Answer 1

The process involving the development of newly formed cells into more specialised and distinct cells as they mature.

Question 2

Define a differentiated cell in terms of genes.

Answer 2

a cell that expresses only genes that produce the proteins characteristic for that type of cell.

Question 3

Why are differentiated cells important in a multicellular organism?

Answer 3

They are able to perform a specialised function in the body.

Question 4

What is a disadvantage of cells becoming specialised?

Answer 4

They often lose the ability to make new copies of themselves.

Question 5

Define a stem cell.

Answer 5

Stem cells are cells that have not undergone cell differentiation.

Question 6

Name the two main types of stem cells.

Answer 6

Adult stem cells

Embryonic stem cells

Question 7

Describe an embryonic stem cells

Answer 7

An embryo develops from a fertilised egg, and cells at the early stages of its development are stem cells. If these cells are removed from the embryo, they will differentiate into any cell type.

Question 8

Describe adult stem cells.

Answer 8

Adult stem cells are found in limited numbers at certain locations in the body. These can differentiated into related cell types only.

Question 9

Give 3 examples of where adult stem cells are stored.

Answer 9

Brain
Bone marrow
Heart

Question 10

What name is given to the region of a plant where cell division occurs?

Answer 10

Meristems

Question 11

Where are the main meristems in a plant found?

Answer 11

Close to the tip of the shoot and the tip of the root.

Question 12

Give 4 advantages of using stem cells.

Answer 12

• treating patients with currently untreatable conditions
• growing organs for transplants
• medical research.
• replacing cells that have been damaged or destroyed (eg spinal cord/brain injuries)

Question 13

Give three clinical disadvantages of using stem cells

Answer 13

• no guarantee of the success of stem cell therapies
• difficulty in obtaining and storing embryonic stem cells
• cultured stem cells could be contaminated with viruses which could infect the recipient.

Question 14

Give three ethical disadvantages of using stem cells

Answer 14

• for therapeutic cloning, is it right to create embryos for therapy and destroy them in the process?
• at what stage of its development should an embryo be regarded/treated as a person?
• a source of embryonic stem cells is unused embryos produced by IVF

Question 15

Describe the function of the cell membrane.

Answer 15

Controls the movement of substances in and out of the cell.

Question 16

Describe the function of the cytoplasm

Answer 16

Where most of the chemical reactions happen

Question 17

Describe the function of the mitochondria

Answer 17

Where most energy is released in respiration

Question 18

Describe the function of the ribosome

Answer 18

Site of protein synthesis

Question 19

Describe the function of the nucleus

Answer 19

Contains genetic material (DNA) which controls the cell’s activities

Question 20

Describe the function of a vacuole in a plant cell.

Answer 20

Filled with cell sap to keep the cell turgid.

Question 21

Function of chloroplasts

Answer 21

Absorb light energy for photosynthesis.

Question 22

Function of the cell wall.

Answer 22

Strengthens the cell and supports the plant.

Question 23

Differences between an animal and a plant cell.

Answer 23

Plant cells contain:

• chloroplasts
• cell wall
• permanent vacuole