Photosynthesis and aerobic respiration are two processes that provide homeostasis to plants and humans, respectively. Because photosynthesis aids in the production of plant products that we consume for energy, and that energy is used to aid in respiration, both these processes are linked to where we derive our energy.
Photosynthesis is one of the most important biological processes that sustain life. It is the process by which autotrophs construct carbohydrates using the equation 6CO2 +6H2O yields C6H12O6 + 6O2. Photosynthesis consists of 2 different stages, the light dependent reactions and the dark dependent reactions. Light dependent reactions occur in the grana of chloroplasts. The photosynthetic pigments absorb light energy that is then used to split a water molecule. The electrons released for the split water molecule are transferred to NADP+ forming NADPH and ATP. The oxygen left over from the split water molecule is released as a byproduct. NADPH and ATP pass to the next stage for photosynthesis, the dark reactions. The dark reactions (also called the Calvin cycle) occur in the stroma of the chloroplast. During this stage carbon dioxide is fixed into glucose molecules using the NADPH and ATP from the light dependent reactions.
Cellular respiration is the process by which cells use the energy stored in glucose to produce ATP. Cellular respiration has 2 pathways: aerobic respiration and alcoholic fermentation. Aerobic respiration requires oxygen and the later does not. Aerobic respiration produces the most ATP per glucose molecule. Alcoholic fermentation produces less ATP and ethanol as a byproduct. The equations/pathways for the 2 are below:
Glucose +water yields 6 Carbon dioxide + 6 water +36ATP
Glucose+water yields 2 ethanol + 2 carbon dioxide + 2 ATP
ATP is key to human metabolic function. It allows our body to perform all of its necessary functions and to exert energy as move and carryout our day. Without photosynthesis and cellular respiration, we would not be able to exist.
Mayer, G. 2008. Biological Principles. Cache House. 167p.