Question

How do plants capture light energy for use in photosynthesis?

Answer 1

Chloroplasts are the double-membraned organs- found in all green plants and green algae that contain the photosynthetic pigment chlorophyll and other carotenoid pigments. They create glucose or sugar molecules through the process of photosynthesis.

Complete answer:
Photosynthesis is the phenomenon of conversion of light energy to chemical energy. The chemical energy is stored in the form of sugars in the organisms. Sunlight functions as the main source of light energy, while carbon dioxide and water are the main reactants. In the presence of sunlight, carbon dioxide and water react to form sugar molecules. It is a redox mechanism where carbon dioxide is reduced to form sugar molecules, and water molecules are oxidized to form oxygen molecules. The molecular oxygen is released as a byproduct.

Plants capture light energy through the chlorophyll pigments- present inside their green leaves. Chlorophylls are the green pigments that are located in the thylakoid membrane of the chloroplast. The chloroplast is a double-membranous organ that is either oval, round or disc-shaped. They are plastids that are green in color due to the presence of chlorophyll a and chlorophyll b pigment. The inner compartmentalization of the chloroplasts is done by- the thylakoid membrane. The chloroplasts can be divided into- two parts structurally- Grana and the Stroma. The Grana consist of thylakoids and is the functional unit of the organ. The stroma is the matrix of the cell and contains necessary enzymes.

The chlorophyll-a pigment present in the chloroplasts absorbs light or solar energy. The absorption of light occurs according to their wavelength. The chlorophyll pigments absorb red and blue light and reflect green light. Thus, providing green color to the leaves. These chlorophyll pigments are closely bound with the reaction center, which creates a charge separation in the leaves by donating the excited electron to the quinone molecule. The oxidation of water in the process of photosynthesis is the result of the charged chlorophyll molecules. The energy captured is used to generate high- energy electrons that have high reduction potential.
The non-green plants do not perform photosynthesis due to the absence of the chlorophyll pigment.
The light energy absorbed by these chlorophyll pigments is converted into chemical energy by the- production of ATP and NADPH molecules.

Note: In eukaryotic organisms, the chlorophyll pigments are present inside the- chloroplast of the cells. The prokaryotic cells lack membrane-bound organelles. They perform photosynthesis by the infoldings of their plasma membrane. The chlorophyll pigments are attached to the thylakoid membrane.