Tag: botany

The light reaction takes place in the grana of the chloroplast. This is also known as the cyclic and non-cyclic form of photophosphorylation in which the ATP and NADPH + H$^+$ are produced. In the non-cyclic photophosphorylation, there is splitting of the water molecules which results in the production of oxygen molecule. 

Photophosphorylation refers to the use of light energy from photosynthesis to ultimately provide the energy to convert ADP to ATP, thus replenishing the universal energy currency in living things. Light generally provides energy to form the bonds. It is an endothermic reaction.

In light-dependent reactions, the energy from sunlight is absorbed by chlorophyll and converted into chemical energy in the form of electron carrier molecules like ATP and NADPH.

Light phase is also known as a photochemical phase because it is a light dependent phase. During this phase, the formation of high-energy chemical intermediates ATP and NADPH$ _{2}$ takes place. ATP and NADPH$ _{2}$ are the assimilatory power of photosynthesis. Light phase also includes light absorption, water splitting and release of oxygen. Two photosynthetic units called Photosystem I and Photosystem II are also involved in light phase. Light phase consists of two photochemical reactions, i.e. non-cyclic photophosphorylation and cyclic photophosphorylation.

In photosynthesis, the light-dependent reactions take place on the thylakoid membranes. The light-independent reactions take place in the stroma. The thylakoid membrane contains some integral membrane protein complexes that catalyze the light reactions. There are four major protein complexes in the thylakoid membrane Photosystem II (PSII), Cytochrome b6f complex, Photosystem I (PSI), and ATP synthase. These four complexes work together to ultimately create the products ATP and NADPH.

Light reactions of photosynthesis which takes place in thylakoids membranes of chloroplast utilize sunlight and water to produce oxygen, ATP and NADPH.

Photosynthesis is a process in which phosphorylation occurs. Phosphorylation is a process in which phosphate group is added, and in the case of photosynthesis it happens in the presence of light, thus called as 'photophosphorylation'. ADP is converted to ATP, the energy currency as the main product of this process. In photosynthesis, cyclic and non-cyclic photophosphorylation takes place in the light phase and generate ATP and NADPH.

Photoluminescence is the phenomenon of light emission after absorption of photons in the form of electromagnetic radiation. Chemiluminescence is the phenomenon of emission of light from a chemical reaction. Phosphorescence is a type of photoluminescence which is related to fluorescence. It does not re-irradiate the absorbed light immediately like fluorescence. Fluorescence is the phenomenon of re-irradiation of light absorbed light or electromagnetic radiation.

A) ADP and ${ H } _{ 2 }O$ are required in addition to NADP.