In order to survive plants must trap sunlight and turn it into energy. They do this by way of a process known as photosynthesis. In photosynthesis, plants convert carbon dioxide to carbohydrates by way of a complex set of reactions. Additionally, photosynthesis allows for the release of oxygen and the survival of all life forms.
The process of photosynthesis is necessary for the survival of all life forms. The organisms created by photosynthesis provide energy and food sources that sustain practically all life on the planet. Without photosynthesis, life on earth would not exist.
Photosynthesis is a process by which plants trap and use energy. Starr describes photosynthesis “as an ancient pathway that evolved in distinct ways in different organisms.” In weed and leafy plants photosynthesis occurs in two stages. Energy is absorbed through the light-dependent reactions and converted to ATP energy.
In the first stage water molecules are split and the NADP coenzyme picks up the freed hydrogen and electrons and transforms them into NADPH. In the light-independent stage ATP provides energy to sites where glucose is created from combined carbon, hydrogen, and oxygen. The carbon and oxygen are provided by carbon dioxide and the hydrogen is derived from water. In scientific form the process of photosynthesis is: 12H20 + 6C02 ® 602 + C6H1206 + 6H20.
The light-dependent stage and the light-independent stage occur at different sites inside each chloroplast. The chloroplast has two outer membranes that are wrapped around the stroma, which is the fluid interior. Within the stroma is an interior membrane. The first stage of photosynthesis takes place at the thylakoid membrane system. In the thylakoid membrane are channels of interconnected disks called grana. The purpose of the channels and disks is to collect the hydrogen ions utilized in ATP production. The second stage, which involves the assimilation of sugars, takes place in the stroma.
Within thylakoid membranes are photosystems, or light-trapping clusters. A membrane may have several thousand photosystems. Additionally, each photosystem includes two hundred to three hundred molecules. The purpose of the pigments is to harvest energy. Chlorophylls absorb violet-to-blue and red light wavelengths and reflect green wavelengths while carotenoids capture violet and blue wavelengths and transmit red, yellow, and orange wavelengths.