▶️ Answer/Explanation
Detailed solution
(a)
Water evaporates from the surfaces of the mesophyll cells into the air spaces.
Water vapour moves out of the leaves through the stomata by the process of diffusion.
Explanation: The syllabus states that water evaporates from the surfaces of mesophyll cells into air spaces and then diffuses out of the leaves through stomata as water vapour. This process is driven by the random movement of molecules.
(b)(i)
(15) (mm per minute)
Explanation: The rate is calculated by dividing the distance moved by the time taken. At (25^\circ\text{C}), the distance is (45) mm over (3) minutes.
(b)(ii)
The correct conclusions are:
- As temperature increases, the rate of transpiration increases and then remains constant.
(The rate increases from (6) to (23) mm/min as temperature goes from (20^\circ\text{C}) to (40^\circ\text{C}), then stays at (23) mm/min at (45^\circ\text{C}).) - From (20^\circ\text{C}) to (30^\circ\text{C}), the rate of transpiration triples.
(At (20^\circ\text{C}) rate is (6). At (30^\circ\text{C}) rate is (18). (6 \times 3 = 18).) - From (20^\circ\text{C}) to (45^\circ\text{C}), the rate of transpiration increases by (17) mm per minute.
(Rate at (45^\circ\text{C}) is (23). Rate at (20^\circ\text{C}) is (6). Difference: (23 – 6 = 17).)