I believe the answer is D. A reactant that is catalyze a by an enzyme.
Answer:
A
Explanation:
She already got it I was just adding an anwser for someone if anybody didnt see her comment on the question.
GOOD LUCK ON THE TEST!!
Adenine forms two hydrogen bonds with thymine in DNA while three hydrogen bonds are formed between guanine and cytosine.
Thymine and cytosine are pyrimidines because they have a single ring structure. Adenine and guanine are purines because they have a double ring structure.
OK so basically the ice age had occurred during the Pleistocene it was about 2.6 billion years ago
Answer:2
Explanation: Sperm cells in plants are found inside the pollen grain. When the pollen grains fall on the stigma, the pollen raptures and forms a pollen tube then the sperm cells pass through the pollen tube to the ovary.