This will leave the plant through the leaves or be used by the plant for respiration. In photosystem I, the electron comes from the chloroplast electron transport chain. The light stage needs light so it is called the light-dependent stage. Stacks of thylakoids called grana form a third membrane layer. Unlike the light stage, the dark stage is controlled by enzymes and therefore affected by temperature.
This will leave the plant through the leaves or be used by the plant for respiration. Updated April 26, By Dr. The two stages of photosynthesis: Photosynthesis takes place in two stages: light-dependent reactions and the Calvin cycle light-independent reactions.
The light phase of photosynthesis takes place on the thylakoid membrane.
Cyanobacteria and planktonic algae can grow over enormous areas in water, at times completely covering the surface. Light-Independent Reactions In the light-independent reactions or Calvin cycle, the energized electrons from the light-dependent reactions provide the energy to form carbohydrates from carbon dioxide molecules. Chloroplasts contain disc-shaped structures called thylakoids, which contain the pigment chlorophyll.
Photosynthesis and the Leaf In plants, photosynthesis generally takes place in leaves, which consist of several layers of cells.
Photoactivation of chlorophyll a results in the splitting of water molecules and the transfer of energy to ATP and reduced nicotinamide adenine dinucleotide phosphate NADP.
The two photosystems oxidize different sources of the low-energy electron supply, deliver their energized electrons to different places, and respond to different wavelengths of light. Pigments in the light-harvesting complex pass light energy to two special chlorophyll a molecules in the reaction center. Accessory pigments absorb energy that chlorophyll a does not absorb.
In reality, the process includes many steps involving intermediate reactants and products.
The ecosystem surrounding the vents has a diverse array of animals, such as tubeworms, crustaceans, and octopi that derive energy from the bacteria.
The light-independent reactions are sometimes called the Calvin cycle because of the cyclical nature of the process. The dark stage is called the light-independent stage. The material within the chloroplast is called the stroma. The light-dependent reactions take place in the thylakoid membranes in the granum stack of thylakoids , within the chloroplast. Six molecules of carbon dioxide enter the cycle, which in turn produces one molecule of glucose or sugar.
Oxygen gas is produced as a by-product. Embedded in the thylakoid membrane is chlorophyll, a pigment that absorbs certain portions of the visible spectrum and captures energy from sunlight. Plants use these compounds in all of their metabolic processes; plants do not need to consume other organisms for food because they build all the molecules they need. The light stage needs light so it is called the light-dependent stage. Key Terms photosystem: Either of two biochemical systems active in chloroplasts that are part of photosynthesis. The two stages of photosynthesis: Photosynthesis takes place in two stages: light-dependent reactions and the Calvin cycle light-independent reactions.
The light-independent reactions are sometimes called the Calvin cycle because of the cyclical nature of the process.