A student testing the hypothesis that carbon
dioxide is an indispensable factor for
photosynthesis, places a pelargonium plant
under a jar where air is enriched with carbon
dioxide and he covers the jar with an opaque
cover. Ten hours later, when the leaves are
treated in hot alcohol and iodine water, they
show yellow coloration.
a. What does this coloration indicate? What
conclusion can be drawn?
b. The student does not expect this result.
Help him find the error that he has
committed while experimenting.
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