Where are the photoreceptors located inside a human eye?

What are some aquatic organisms that live in cold water temperatures?

Where can a dna be found in a prokaryotic cell

Amino acids contain the elements carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. of the 20 amino acids found in humans, 11 are called "nonessential" because they can be manufactured by the body when needed. which elements in these 11 amino acids are commonly obtained from the metabolism of sugar molecules?