What role do glucose and oxygen play in cellular respiration? They are reactants because they are present before the reaction.
They are reactants because they are present after the reaction.
They are products because they are present before the reaction.
They are products because they are present after the reaction.

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They are reactants because they are present before the reaction

answer:   option a) glucagon was secreted by his pancreas before he ate the cookies because blood glucose was low. insulin was secreted after he ate the cookies because his blood glucose was high.

explanation:

d. organisms have cells with different shapes and functions.