Question

Why is it inefficient for humans to get their energy directly from the sun as plants do.

Answer 1

The energy of the sun sent to the earth in the form of the photons that is called light energy. These photons absorb by some biomolecules, they become excited and vibrating to producing chemical energy. This type of biomolecules is packed in the plant cell organ called the chloroplast. Chloroplast show similarity with cyanobacteria, famous for inventing photosynthesis on the Earth and historically cyanobacteria free-living and independent from the plants. According to endosymbiotic theory, cyanobacteria and plant make endosymbiosis relationship. Therefore, plant cell enables to do photosynthesis by the help of chloroplast. Chloroplast absent in animal cell; hence animal cannot do photosynthesis. Photosynthesis is a process in which inorganic compounds convert organic compounds in the presence of chlorophyll and sunlight. It means sunlight trap by the chlorophyll molecules and uses it to produce sugar by combining carbon dioxide and water. Therefore, plant and cyanobacteria are the only organisms that convert light energy into chemical energy in the presence of a chloroplast organ, whenever an animal cell cannot use sunlight in the absence of chloroplast.