Photosynthesis

Photosynthesis is a process that converts light energy, usually from the sun, into chemical energy in the form of glucose.
This process takes place in the green pigment chlorophyll which is found in the chloroplasts of a plant cell.

The Process of Photosynthesis:

Photosynthesis begins when light is absorbed by chlorophyll in the chloroplasts of the plant cell.
Water (H2O) is split by light energy to produce hydrogen and oxygen.
The oxygen is given off as a by-product and exits the plant via stomata, small openings on leaves.
The hydrogen reacts with carbon dioxide (CO2) in a process called the Calvin cycle, resulting in the production of glucose.

The light-dependent reaction occurs in the thylakoid membranes of the chloroplasts.
Light energy is absorbed by chlorophyll and is used to split water molecules into hydrogen ions, electrons, and oxygen.
The oxygen is then released as a by-product into the atmosphere.

Known also as the Calvin cycle or carbon fixation, this stage occurs in the stroma of the chloroplasts.
It does not directly require light, hence termed ‘light-independent’, but it needs the products of the light-dependent reaction: namely ATP (energy) and NADPH (electron carrier).
During the Calvin cycle, CO2 is combined with hydrogen to form glucose.

Photosynthesis is critical for life on Earth as it produces oxygen, an essential component for most organisms’ respiration.
It also forms the basis of food chains, as plants are primary producers that utilize photosynthesis to create the energy-rich compounds other organisms need for survival.

Photosynthesis: The process by which green plants and some other organisms use sunlight to synthesize glucose from carbon dioxide and water.
Chloroplast: A plastid in green plant cells which contains chlorophyll and in which photosynthesis takes place.
Chlorophyll: A green pigment, present in all green plants, responsible for the absorption of light to provide energy for photosynthesis.
Stomata: Tiny openings or pores in plant tissue that allow for gas exchange.
Thylakoid: A flattened sac within a chloroplast where the light-dependent reaction of photosynthesis takes place.
Calvin cycle: The cycle of enzyme-catalysed dark reactions of photosynthesis that convert carbon dioxide and other compounds into glucose.
ATP: Adenosine Triphosphate, a molecule which stores and transfers energy within cells.
NADPH: Nicotinamide Adenine Dinucleotide Phosphate, an electron carrier used during photosynthesis in the light-independent reactions.