Describe a living system that is not an organ system or an ecosystem.

Hydrosphere is the correct answer

The basic building blocks of dna and rna are nucleotides

Well,what i learned was that unlike many other  endothermic  reactions,  photosynthesis  does not absorb energy as heat. instead, during plants absorb energy from sunlight to turn carbon dioxide and water into oxygen and glucose, which is a type of sugar molecule. the energy is stored in the glucose molecules, ready to be used when needed.