You a given a plant tissue in lab and asked to determine if the tissue is a source or a sink. Microscopic analysis reveals an abundance of colorless parenchyma cells with plastids. Only one biochemical test reacts positively with your sample. In the presence of iodine, the plastids turn a dark purplish color. Based on this information you determine your sample is
A. a sink because your sample is rich in carbohydrates.
B. a source because your sample is rich in carbohydrates.
C. a source because your sample contains plastids.
D. both a source and sink because it contains both plastids and carbohydrates.
Answer: A
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