Exchange

Question 1

Environment around cells of multicellular organisms

Answer 1

Tissue Fluid

Question 2

Explain how the cuticle reduces water loss in plants

Answer 2

waxy → impermeable to water
(waterproof)

Question 3

How does the hairs help prevent water loss in Marram grass?

Answer 3

→ Reduces air movement

→ Traps water vapour
- reduces the diffusion gradient (water potential gradient)

Question 4

How can stomata reduce water loss from a plant?

Answer 4

stoma can close;

reduces area for evaporation or transpiration;

Question 5

Describe what happens to the diaphragm to bring about the change in its shape (2 marks)

Answer 5

1. Flatten / moves down;
2. (Diaphragm muscle) contracts;

Question 6

Air moves into the lungs during inhalation. Explain how the diaphragm causes this. (3 marks)

Answer 6

1. Diaphragm contracts / moves down / flattens;
   Ignore refs to rib movement
2. Increases volume (of thorax) and decrease in pressure;
   (Accept pressure lower than atmospheric pressure)
   3.Air moves from high to lower pressure / down pressure gradient;

Question 7

Explain what causes the oxygen concentration in the tracheae to fall when the spiracles are closed. (2 marks)

Answer 7

(oxygen is used in) respiration therefore diffuses (from tracheae) to tissues;

oxygen unable to enter organism;

Question 8

There are large numbers of mitochondria in the small intestine epithelial cells. Explain how these organelles help the cell to absorb the products of digestion. (2 marks)

Answer 8

(Site of aerobic) respiration / ATP production / energy release;
Q Reject: anaerobic respiration
Q Reject: energy produced

Active transport / transport against the concentration gradient;
Accept: energy produced in the form of ATP