Answer:
I believe it is lipids.
Explanation:
Lipids are waterproofing molecules.
Prokaryotic Microorganism's
Answer:
Four innovations are central nervous system, eyes, bilateral and hermaphrodites.
Explanation:
Innovations found in an ancient flatworm were the presence of central nervous system means head and a brain. The head had eyes which is the first in the animal world. Their body is bilateral means equally divided into two parts. They are also hermaphrodites means having male and female on a single organism which was not present at that time of animals.
Unlike arteries, veins contain valves that ensure blood flows in only one direction. (Arteries don't require valves because pressure from the heart is so strong that blood is only able to flow in one direction.) Valves also help blood travel back to the heart against the force of gravity.
