The cycle of photosynthesis and respiration maintains the balance of carbon dioxide and oxygen on earth. Photosynthesis makes the glucose that is used in cellular respiration to make ATP. The glucose is then turned back into carbon dioxide, which is used in photosynthesis. While water is broken down to form oxygen during photosynthesis, in cellular respiration oxygen is combined with hydrogen to form water. While photosynthesis requires carbon dioxide and releases oxygen, cellular respiration requires oxygen and releases carbon dioxide. It is the released oxygen that is used by us and most other organisms for cellular respiration. We breathe in that oxygen, which is carried through our blood to all our cells. In our cells, oxygen allows cellular respiration to proceed. Cellular respiration works best in the presence of oxygen. Without oxygen, much less ATP would be produced.
Water or other molecules move down their concentration gradient without any energy.........
difference - simple diffusion uses help of transporting protein in the membrane whereas osmosis uses no help.
Es | HIV.gov
There is currently no vaccine available that will prevent HIV infection or treat those who have it. However, scientists are working to develop one.
