Answer: restriction enzymes serve the purpose of defense against invading viruses.
Explanation:
Answer: A
Explanation:
Oxygen makes up another 20 to 21 percent of our atmosphere. It's essential for life on Earth, and interestingly enough, it is poisonous when highly concentrated. Our concentration of 20 to 21 percent seems just right.
Epithelial tissue <span>covers the body surface and forms the lining for most internal cavities. </span>
I believe that would be estrogen.