Question

Why does photosynthesis need light?

Answer 1

Photosynthesis is the conversion of light energy into chemical energy by green plants and other organisms. Light energy is captured and used by green plants during photosynthesis to convert water, carbon dioxide, and minerals into oxygen and energy-rich organic compounds.

Complete answer:
During photosynthesis, light provides energy for the synthesis of glucose from carbon dioxide and water. Photosynthesis is a photochemical reaction that consists of two main steps: the Light reaction (also known as Hill's reaction) and the Dark reaction (also known as Blackman's reaction).
In the presence of light, a light reaction occurs. The dark reaction can occur in the absence of light, but it is dependent on the light reaction's end product. As a result, the light reaction must come first. The chlorophyll entraps light during the light reaction, and the solar energy is converted into chemical energy in the form of ATP molecules. Because light energy is used to split water, this can happen. This reaction produces oxygen (yay for us heterotrophs!) and hydrogen ions as byproducts. The hydrogen ions are used to make ATP, as previously stated.
During the dark reaction of photosynthesis, ATP molecules provide energy for the synthetic reactions and are converted into ADP molecules. As a result, during the dark reaction, ADP molecules are formed, which are then converted into ATP molecules during the light reaction. As a result, light is required for photosynthesis to provide energy for synthetic reactions. Photo-phosphorylation is the process of synthesizing ATP molecules in the presence of light.
So, during photosynthesis, light provides energy for the synthesis of glucose from carbon dioxide and water. Thus, photosynthesis needs light.

Note:
Photosynthesis in plants stops at night or when there is no light, and respiration takes over. For growth and other metabolic processes, the plant uses energy from the glucose it produces. When the sun sets, photosynthesis ceases. Most plants switch from photosynthesis to respiration, a process in which carbon dioxide and water are produced rather than consumed, during the night.