Which of these correctly describes how organic catalysts operate in biological reactions?

Out of the following given choices;

a. they are used up in the reactions
b. they lower the overall energy of the reactions
c. they lower the activation energy of the reactions
d. they keep the temperature of the reactions constant

The answer is C. A catalyst provides an different route for a reaction, mostly bypassing some transitional states hence lowering the reaction energy. The catalyst is not consumed in the reaction.  

a neutral ph of 7 and normal organism temperature is needed for a certain enzyme to be effective.  

what would happen to the enzyme if the ph and/or temperature fluctuate greatly from the norm?  

a.the enzyme’s hydrogen bonds will break.  

b.the activation energy will increase.  

c.more product will be formed.

d.the ideal temperature and ph for the enzyme function will decrease.  

i think the miocene epoch spans the time from 23 million to 12 million years ago.