Biology
The given figure represents an experiment:
(a) Leaf A was coated with grease on both the surfaces.
(b) Leaf B was coated with grease on the lower surface.
(c) Leaf C was coated with grease on the upper surface.
(d) Leaf D was left without any application of grease.
All the four leaves A, B, C and D were left in a room for about 24 hours.
(i) Which leaf dries first? Give reason.
(ii) Which leaf dries last? Give reason.
Transpiration
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Answer
(i) Leaf D — The leaf with no greasing on either surfaces would dry first because it would lose water from both surfaces i.e. it would lose maximum quantity of water.
(ii) Leaf A — It was coated with grease on both the surfaces. Hence, it would dry last because greasing prevents evaporation of water and transpiration occurs through stomata which are present more on the lower surface of the leaf.
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Related Questions
Distinguish between Transpiration and Evaporation
Give reason/suitable explanation for each :
(a) Nerium loses less amount of water during transpiration.
(b) More transpiration occurs from the under surface of a dicot leaf.
(c) Transpiration increases with the velocity of wind.
(d) Leaves of some plants wilt during midday and recover in the evening.
(e) Guttation normally occurs during early mornings or late nights.
(f) Forests tend to bring more rains.
Given below is the diagram of an apparatus used to study a particular phenomenon in plants:
(a) Name the apparatus.
(b) What is it used for?
(c) What is the role played by the air-bubble in this experiment?
(d) What is the use of the reservoir?
(e) What happens to the movement of the air-bubble if the apparatus is kept:
- In the dark
- In sunlight
- In front of a fan
Give a reason in each case.
Given ahead is the diagram of an experimental set up to study the process of transpiration in plants. Study the same and then answer the questions that follow:
(a) Name the colour of dry cobalt chloride paper.
(b) Is the experimental leaf a monocot or a dicot? Give a reason to support your answer.
(c) Why are glass slides placed over the dry cobalt chloride papers?
(d) After about half an hour what change, if any, would you expect to find in the cobalt chloride paper placed on the dorsal and ventral sides of the leaf? Give a reason to support your answer.