A scientist follows this procedure to test whether plants have been performing photosynthesis.Place Plant X in a dark closet and Plant Y on a sunny windowsill. Wait several days, then remove a leaf from each plant.Boil leaves in alcohol to remove the chlorophyll. Add a chemical indicator that detects sugars. (Dark purple = sugars are present; dark orange = sugars are not present)

Photosynthesis requires light, so Plant Y on the sunny windowsill can make sugars and its leaf should test dark purple. Plant X kept in the dark cannot photosynthesize and will use stored sugars for respiration over several days, so its leaf should test dark orange. Therefore, the expected results are Plant X: dark orange and Plant Y: dark purple.

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