The correct answer is: " enzymes " .
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Note that "enzymes" are "biological catalysts" .
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"Catalysts" are agents that 'increase the rate of' , or 'speed up' , a 'chemical reaction' , when added to the reactants; and by definition, catalysts do so within affecting the reaction itself.
As aforementioned, "enzymes" can function as "biological catalysts" — which means that enzymes within the cell membrane can 'speed up' , or 'increase the rate of' , biological reactions (i.e. biochemical reactions) — without affecting the biological reaction (i.e. biochemical reaction) itself.
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Hope this helps you!
Wishing you well in your academic pursuits —
and within the "Brainly" community, as well!
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