Pepsin, a common enzyme found in the stomach, is most active at ph values between 0.5 and 2.5. it works slowly between ph values of 2.6 and 3.4. beyond a ph of about 3.5, it becomes completely inactive. why does this happen?
a) the enzyme inactivates because it melts into a liquid when it is not at the right ph.
b) the protein chain in the enzyme is denatured, permanently inactivating it as the ph approaches 7.
c) the enzymes slow down, because changing the ph changes the temperature as well, and affects the reaction.
d) the enzyme's active site contracts into the wrong shape, but this is always reversible if the right ph is restored.

answer; i believe that the correct answer is (light);

hey, i believe your answer would be d. sugar ribose and the base uracil. i believe this is the answer, because rna consists of sugar ribose, adenine, guanine, cytosine, and uracil.

your first option is incorrect, because that's dna. where it consists of sugar deoxyribose, adenine, guanine, cytosine and thymine.

your second option is also incorrect, this is because sugar deoxyribose is in dna, and uracil is in rna. these two do not make sense together.

your third option being incorrect, because sugar ribose is in rna, but not the base of thymine. rna consists of uracil, not thymine.

lastly your fourth option being correct! this answer is correct, because both sugar ribose, and the base uracil are in rna! ~

answer is d. sugar ribose and the base uracil.