QUESTION 49 (4 marks)
A water molecule enters a plant through its roots. Some of this water is later released from the leaves; some is used in photosynthesis.
a) Name the process by which water vapour leaves the plant and explain how it connects plants with atmospheric water. [2 marks]
b) Describe two processes in the pathway by which atmospheric water returns to soil or a water body. [2 marks]
Practice marking scheme
Answer
a) Transpiration; liquid water taken up by plants is released as vapour to the atmosphere. b) Condensation forms droplets, followed by precipitation reaching the surface.
Working
Water is absorbed from soil, transported through the plant and released as water vapour, chiefly through stomata. Condensation converts atmospheric water vapour into liquid droplets or ice; precipitation transfers water from clouds to the Earth’s surface. The distinction between transformation of state and transfer between reservoirs should be clear.
Marking criteria
- Names transpiration. [1 mark]
- Links plant water uptake to release of water vapour into the atmosphere. [1 mark]
- Describes condensation. [1 mark]
- Describes precipitation reaching soil or surface water. [1 mark]
Practice question aligned to the current QCAA syllabus; review the worked solution and marking criteria.
View the QCAA syllabusCompare your working with the guide above.