CIE iGCSE Co-Ordinated Science B8.3 Transpiration Exam Style Questions Paper 1
▶️ Answer/Explanation
When water evaporates from leaf cells, the cells lose water and become more concentrated (lower water potential). Water then moves into these cells from adjacent cells and ultimately from the xylem by osmosis — the net movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane. Assimilation is the uptake and use of nutrients by cells, egestion is the removal of undigested food, and transpiration is the loss of water vapour itself, not the process that replaces it.
✅ Answer: (C)
✅ Answer: (C)
▶️ Answer/Explanation
A leaf is least likely to wilt when water uptake is greater than, or closest to, water loss.
For leaf D, uptake (15) exceeds loss (10), meaning water is being replaced faster than it is lost.
In leaves A, B and C, water loss exceeds uptake, so they are more likely to wilt.
✅ Answer: (D)
For leaf D, uptake (15) exceeds loss (10), meaning water is being replaced faster than it is lost.
In leaves A, B and C, water loss exceeds uptake, so they are more likely to wilt.
✅ Answer: (D)
▶️ Answer/Explanation
High temperature increases the kinetic energy of water molecules, speeding up evaporation from the leaf surface.
High wind speed removes water vapour from around the leaf quickly, maintaining a steep diffusion gradient.
Both high temperature and high wind speed together give the greatest rate of transpiration.
✅ Answer: (A)
High wind speed removes water vapour from around the leaf quickly, maintaining a steep diffusion gradient.
Both high temperature and high wind speed together give the greatest rate of transpiration.
✅ Answer: (A)
▶️ Answer/Explanation
High temperature increases the kinetic energy of water molecules, increasing the rate of evaporation and hence transpiration.
Low humidity increases the concentration gradient of water vapour between the leaf and the surrounding air, further increasing water loss.
✅ Answer: (B)
Low humidity increases the concentration gradient of water vapour between the leaf and the surrounding air, further increasing water loss.
✅ Answer: (B)
▶️ Answer/Explanation
Water travels up the xylem and moves into the leaf mesophyll cells.
Evaporation itself occurs from the moist surfaces of these mesophyll cells into the internal air spaces of the leaf.
The resulting water vapour then diffuses out of the leaf through the stomata; the stomata are the exit route, not the site of evaporation.
✅ Answer: (C)
Evaporation itself occurs from the moist surfaces of these mesophyll cells into the internal air spaces of the leaf.
The resulting water vapour then diffuses out of the leaf through the stomata; the stomata are the exit route, not the site of evaporation.
✅ Answer: (C)