Download b. The smallest cell (B) has the greatest surface area to volume ratio

b. The smallest cell (B) has the greatest surface area to volume ratio for diffusion;
surface area to volume ratio is also increased by the cell having a flat shape as in C.
c. Oxygen; carbon dioxide
2 a. Pleural membranes
b. Squamous
c. Goblet
d. Macrophage
e. Expiratory reserve volume
3. a. Large surface area; thin walls
b. Photosynthesis in palisade/spongy mesophyll cells; produces oxygen/uses up carbon
dioxide; maintains diffusion gradient of oxygen out of leaf/carbon dioxide into leaf.
c. Leaf/epidermis covered in waxy cuticle; which reduces permeability/is impermeable
to water vapour; gas exchange is via stomata; which can close (to restrict water loss).
4. Ventilation rate = 0.36 × 18;
= 6.48 dm3 min–1
b .Vital capacity
c .10 breaths per minute
d. Oxygen consumption = 3.5 – 2.7 = 0.8 dm3
6 .a. A = ciliated epithelial cell/ciliated epithelium
B = goblet cell/mucus-secreting cell
C = air space
D = cartilage
E = elastic fibres
b. Goblet cell (B) secretes mucus; which traps dust/bacteria; cilia on epithelium beat/move;
moving mucus out of bronchus.
7. a. Not under conscious control.
b .Contracts; to alter diameter of bronchioles; can increase diameter during exercise.
c. Pollen/dust/allergens/other causes; muscle contracts; narrows airways; causing difficulty in
breathing