Cells that require more energy like muscle cells or wings of bees would probably contain more of which of the following organelles?

As a small change in a person's dna can cause a genetic disorder

What was the land like over 500 million years ago? what was under the sea?

The concept of keystone species is controversial among ecologists because most organisms are highly interdependent. if each of the trophic levels is dependant on all others how can we say one is most important