The diagram above illustrates a leaf before and after an experiment stated below. The leaf shown in diagram I was detached from a potted plant which had been exposed to sunlight for 4-5 hours while diagram ll shows the same leaf after the test for starch.
(7) (a) Name the type of leaf used for this experiment (b) Why is this type of leaf most suitable for the experiment? (c) State one precaution that should be taken in carrying out this experiment (d) What would be the colours of the parts labelled X and Y after the test for starch? (e) Suggest the aim of this experiment.
Explanation
7. (a) Variegated leaf (b) This is because chlorophyll is only present in the green patches, and not in other patches that have white, yellow or pink colours (c) The leaves must be exposed to sunlight for photosynthesis to take place (d) (i) x will only retain the brown colour of iodine (i) y will be blue-black in colour (e) Aim: To show that chlorophyll is essential for photosynthesis.