What are the 3 processe of photosynthesis?
Answers
The Photosynthesis Process:
Stage 1: Harvesting Radiant Energy
When a beam of sunlight hits a green, leafy plant, the process of photosynthesis is set in motion. The first step of photosynthesis occurs in the chloroplasts of plant cells. Light photons are absorbed by a pigment called chlorophyll, which is abundant in the thylakoid membrane of each chloroplast. Chlorophyll appears green to the eye because it does not absorb green waves on the light spectrum. It reflects them instead, so that's the color you see.
Plants take in carbon dioxide through their stomata (microscopic openings in tissue) for use in photosynthesis. Plants transpire and replenish oxygen in the air and ocean.
Stage 2: Converting Radiant Energy
After radiant energy from sunlight is absorbed, the plant converts light energy into a usable form of chemical energy to fuel the plant’s cells. In light-dependent reactions occurring during the second stage of the process of photosynthesis, electrons get excited and split off from water molecules, leaving oxygen as a by-product. The hydrogen electrons of the water molecule then move to a reaction center in the chlorophyll molecule.
In the reaction center, the electron passes along a transport chain, aided by the enzyme ATP synthase. Energy is lost as the excited electron drops to lower energy levels. Energy from electrons is transferred to adenosine triphosphate (ATP) and reduced nicotinamide adenine dinucleotide phosphate (NADPH), commonly referred to as “energy currency” of cells.
Stage 3: Storing Radiant Energy
The last stage of the photosynthesis process is known as the Calvin-Benson cycle, in which the plant uses atmospheric carbon dioxide and water from soil to convert ATP and NADPH. The chemical reactions that make up the Calvin-Benson cycle occur in the stroma of the chloroplast. This stage of the process of photosynthesis is light-independent and can happen even at night.
ATP and NADPH have a short shelf life and must be converted and stored by the plant. Energy from ATP and NADPH molecules enables the cell to use or “fix” atmospheric carbon dioxide, resulting in the production of sugar, fatty acid and glycerol in the third stage of photosynthesis. Energy that the plant doesn’t need immediately is stored for later use.