ICSE 2018
Q. The diagram below represents a process in plants. [5 marks]
The setup was placed in bright sunlight. Answer the following questions:
(i) Name the physiological process depicted in the diagram. Why was oil added to the water?
(ii) When placed in bright sunlight for four hours, what do you observe with regard to the initial and final weight of the plant? Give a suitable reason for your answer.
(iii) What happens to the level of water when this setup is placed in:
1. Humid conditions? 2. Windy conditions?
(iv) Mention any three adaptations found in plants to overcome the process mentioned in (i).
(v) Explain the term ‘Guttation’
Solution:
This 5 marks question based on the diagram of process of Transpiration and was asked by ICSE board in the year 2018 in SECTION-II.
The question tested the knowledge of students on the:
- What is Transpiration?
- Factors affecting Transpiration such as sunlight and wind
- Adaptation by plants to reduce transpiration
- What is Guttation? Explain with examples.
Let's begin with solving the above mentioned questions:
(i) The physiological process depicted in the diagram is Transpiration.
Oil was added to the water to prevent the loss of water due to evaporation.
(ii) When placed in bright sunlight for four hours, the final weight of plant will be less than initial weight of the plant due to loss of water from aerial parts of the plant due to transpiration.
(iii) When the setup is placed in:
a) Humid condition:
Water vapour released during transpiration gets saturated near leaf surface hence transpiration is reduced.
b) Windy condition:
Water vapour released during transpiration is removed faster, hence transpiration increases.
(iv) Three adaptations by plants to overcome Transpiration are:
a) Needle like leaves such as in Cacti
b) Sunken stomata
c) Thick cuticle
(v) Guttation is the process of loss of water as droplets along the margin of leaves through hydathodes in plants such as strawberry and banana.
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