Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?

Photosynthesis converts light energy to chemical energy. which molecules are the end product of this transformation of energy in this reaction?

What percentage of light hits earth's surface directly?

Which of the following matches the organisms described with the correct domain? a. archaea--multicellular, eukaryotic organisms that do not have cell walls b. eukarya--single-celled and multicellular organisms, with a defined nucleus and a variety of nutritional sources c. bacteria--unicellular, eukaryotic organisms with cell walls that do not contain peptidoglycan d. bacteria--unicellular, eukaryotic organisms that always lack cell walls