Solved 2012 Question Paper ICSE Class 10 Biology — Question 1
Back to all questionsQuestion 2(a)
Given below is an experimental set up to demonstrate a particular process. Study the same and answer the questions that follow:
(i) Name the physiological process being studied.
(ii) Explain the process mentioned above.
(iii) What is the aim of the above experiment ?
(iv) What would you observe in the experimental set-up after an hour? Give a reason to support your answer.
(v) Mention any three adaptations found in plants to overcome the physiological process mentioned in (i) above. [5]
(i) Transpiration.
(ii) Pieces of dry cobalt chloride paper are attached to the two surfaces of the leaf and held in position by two glass slides on either side tied together by elastic bands or held by clips. The leaf remains attached to its own plant. The setup is left for an hour or so.
(iii) The aim of the experiment is to prove that more transpiration occurs from the under surface of a dicot leaf.
(iv) After an hour, the piece of paper which is facing the upper surface of the leaf either does not turn pink or turns pink very slowly in a much longer time than the one on the lower surface which turns pink much faster. This proves that more Transpiration takes place from the lower surface, which is on account of the numerous stomata found on it.
(v) Some plants have developed adaptations to reduce transpiration to cut down loss of water such as:
- Sunken stomata
- Narrow leaves
- Reduced exposed surface by rolling or folding of leaves.