<span>The position of the carbonyl group.
Both aldoses and ketoses are monosaccharides. They are simple sugars with a Carbon chain. The difference is what's in the position of the carbonyl group: aldoses have an aldehyde group while ketoses have aketone group.</span>
The right choice of them is biosphere, community, and organism.
The study of the chemical reactions that take place in all living organisms is called Biochemistry