There would be 40 units of energy left, because 10% is lost each time.
Answer: b. They can live away from water
Explanation:
The frogs are the amphibian organisms, which are capable of survival both in water as well as land. In frogs external fertilization is used as a mode of sexual reproduction. The females lay their eggs in water in the same time the males also secrete their sperms in the water. The eggs are fertilized by the sperms in water. For reproduction the frogs are dependent on water. But with the evolution of frogs, which allows them to fertilize the eggs on the land. The frogs can live away from water.
I would say that B) single events or several causes working together to produce extinction in a short period is referred to as mass extinction, but I am not 100% sure.
A macromolecule is a very large molecule, such as protein, commonly created by polymerization of smaller subunits (monomers). They are typically composed of thousands of atoms or more. The most common macromolecules in biochemistry are biopolymers and large non-polymeric molecules. :D