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Chlorophyll and Starch Formation
The plant was left uncovered in the light for 48 hours. After 48 hours the student tested a leaf from the plant for starch. Figure 6 shows the green and white parts of the leaf before the test.
Explain the results you gave in Question 07.2.
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Marking points
- 1 Contrasts chlorophyll presence in the green part with its absence in the white part.
- 2 Links chlorophyll/light absorption to photosynthesis and starch formation in the green part, or gives the valid converse for white.
Full-mark answer
The green region contains chlorophyll, which absorbs light, so that region can photosynthesise and make glucose that is stored as starch. The white region lacks chlorophyll, so it cannot absorb the light needed for photosynthesis and does not form starch.
Why this answer loses marks
The green part changed colour because it was already green.
Leaf colour does not explain the starch result; link chlorophyll to light absorption, photosynthesis and starch formation.