Photosynthesis is the procedure by which plants use sunlight, water, and carbon dioxide to produce oxygen and also energy in the form of sugar.

You are watching: What is water’s role in the light reaction of photosynthesis?


Green Tree Leaves

The plant leaves are green since that shade is the component of sunshine reflected by a colors in the leaves dubbed chlorophyll.

Photograph courtesy the Shutterstock


Most life on earth depends top top photosynthesis.The procedure is carried out by plants, algae, and some species of bacteria, which capture energy from sunshine to produce oxygen (O2) and also chemical energy stored in glucose (a sugar). Herbivores then achieve this energy by eat plants, and carnivores attain it by eat herbivores.

The process

During photosynthesis, plants take in carbon dioxide (CO2) and water (H2O) from the air and soil. Within the tree cell, the water is oxidized, meaning it loser electrons, while the carbon dioxide is reduced, meaning it gains electrons. This transforms the water into oxygen and the carbon dioxide into glucose. The plant then releases the oxygen ago into the air, and stores energy within the glucose molecules.


Inside the plant cell are tiny organelles dubbed chloroplasts, which store the energy of sunlight. Within the thylakoid membranes the the chloroplastic is a light-absorbing pigment called chlorophyll, i beg your pardon is responsible for giving the plant its green color. During photosynthesis, chlorophyll absorbs power from blue- and red-light waves, and also reflects green-light waves, making the plant appear green.

Light-dependent reaction vs. Light-independent reactions

While there are many steps behind the process of photosynthesis, it can be broken down right into two significant stages: light-dependent reactions and also light-independent reactions. The light-dependent reaction takes place within the thylakoid membrane and also requires a secure stream of sunlight, therefore the name light-dependent reaction. The chlorophyll absorbs energy from the irradiate waves, which is converted right into chemical power in the form of the molecule ATP and NADPH. The light-independent stage, additionally known together the Calvin Cycle, takes ar in the stroma, the room between the thylakoid membranes and also the chloroplastic membranes, and does not require light, thus the surname light-independent reaction. During this stage, power from the ATP and also NADPH molecules is offered to rally carbohydrate molecules, favor glucose, from carbon dioxide.

See more: Which Gas Is Most Important For Understanding Atmospheric Processes

C3 and also C4 photosynthesis

Not all develops of photosynthesis are produced equal, however. There are different types of photosynthesis, consisting of C3 photosynthesis and also C4 photosynthesis. C3 photosynthesis is offered by the bulk of plants. It involves developing a three-carbon compound called 3-phosphoglyceric acid throughout the Calvin Cycle, which walk on to come to be glucose. C4 photosynthesis, ~ above the various other hand, produces a four-carbon intermediate compound, which splits right into carbon dioxide and a three-carbon compound during the Calvin Cycle. A benefit of C4 photosynthesis is the by producing higher levels that carbon, it enables plants to flourish in atmospheres without much light or water.