CIE iGCSE Co-Ordinated Science B8.3 Transpiration Exam Style Questions Paper 2
▶️ Answer/Explanation
Transpiration is the evaporation of water from plant leaves; it is fastest when the water vapour concentration gradient between the leaf interior and the surrounding air is greatest.
Warm conditions increase evaporation (more kinetic energy), and dry conditions keep the external humidity low, maintaining a steep diffusion gradient — so warm and dry is the fastest combination.
✅ Answer: (C)
Warm conditions increase evaporation (more kinetic energy), and dry conditions keep the external humidity low, maintaining a steep diffusion gradient — so warm and dry is the fastest combination.
✅ Answer: (C)
▶️ Answer/Explanation
A leaf wilts when water loss (transpiration) exceeds water uptake, causing a net water deficit.
Leaf D is the only one where uptake (15) exceeds loss (10), giving a net water gain.
✅ Answer: (D)
Leaf D is the only one where uptake (15) exceeds loss (10), giving a net water gain.
✅ Answer: (D)
▶️ Answer/Explanation
Water evaporates from the moist surfaces of mesophyll cells inside the leaf, forming water vapour in the air spaces.
This vapour then diffuses out through the stomata (guard cell pores), but it is the mesophyll cells, not the guard cells themselves, where evaporation occurs.
Epidermis and root hair cells are not the sites of this evaporation step in transpiration.
✅ Answer: (C)
This vapour then diffuses out through the stomata (guard cell pores), but it is the mesophyll cells, not the guard cells themselves, where evaporation occurs.
Epidermis and root hair cells are not the sites of this evaporation step in transpiration.
✅ Answer: (C)
▶️ Answer/Explanation
Translocation is the transport of sugars made in the leaf to respiring tissues (and storage organs), and it occurs in the phloem.
Transpiration is the movement of water from the root up to the leaf, and it occurs in the xylem.
Only row C matches both of these correctly (translocation: leaf → respiring tissue via phloem; transpiration: root → leaf via xylem).
✅ Answer: (C)
Transpiration is the movement of water from the root up to the leaf, and it occurs in the xylem.
Only row C matches both of these correctly (translocation: leaf → respiring tissue via phloem; transpiration: root → leaf via xylem).
✅ Answer: (C)
▶️ Answer/Explanation
Water moves from the xylem into the mesophyll cells inside the leaf.
It evaporates from the moist surfaces of these mesophyll cells into the internal air spaces of the leaf.
The water vapour then diffuses out of the leaf through the stomata into the surrounding air, which is the final exit step rather than the evaporation site itself.
✅ Answer: (C)
It evaporates from the moist surfaces of these mesophyll cells into the internal air spaces of the leaf.
The water vapour then diffuses out of the leaf through the stomata into the surrounding air, which is the final exit step rather than the evaporation site itself.
✅ Answer: (C)