Why Is Light Needed for Photosynthesis?

Light is essential for photosynthesis because plants need it energy to create glucose, which they store for later use as an energy source for cells. Plants and several other photosynthetic organisms use light energy to change water, carbon dioxide and minerals into oxygen and organic compounds packed with energy.

Light plays a key role in the light stage of photosynthesis, wherein the plant absorbs light energy and triggers electron transfers. This occurs in the plant’s thylakoid membrane, in which light energy is turned into chemical energy. Chlorophyll, beta-carotene and other pigments group together in the membrane and absorb different colors of light. They send the light energy to the primary chlorophyll molecule called a porphyrin ring.

Photosynthesis occurs in the chloroplasts in the leaves of plants and uses the green pigment called chlorophyll. Plants take in and expel gases through the stomates, which are openings in the lower epidermis. Chlorophyll mainly absorbs red and blue light, giving it the green color.

The process of taking away electrons from a molecule is known as oxidation, whereas the process of a molecule obtaining electrons is called reduction. Plants use light energy to propel water oxidation by generating oxygen gas, hydrogen ions and electrons.