Why do plants need sunlight?

Too lengthy; did not read: Photosynthesis is the process by which plants convert light energy into electrons in the chloroplast, which powers the synthesis of energy. Glucose is a simple sugar that plants use for energy-related activities.

The chloroplast, an organelle is a small structure within a cell that performs specific cellular functions; inside the chloroplast are many pancake-like discs called thylakoids, which are arranged in stacks called granum. Each disc contains a pigment called chlorophyll (there are other pigments as well), which is what gives an object its color, such as green in plants, and also absorbs certain wavelengths of light.

The light enters the cell and passes through the chloroplast, where it is absorbed by the chlorophyll and excites an electron in a stage called Photosystem II. This excited electron is full of energy and travels around with lots of energy, passing through this stage and providing energy for a few different functions (I won't go into detail), and then into Photosystem I (Photosystem II comes first, but Photosystem I was discovered first).

I've already talked about the oxygen that results from the splitting of water, but I haven't talked about the hydrogen that is left to float around while it waits. When the time comes, hydrogen is pumped out of the cell through a protein called ATP Synthase, which converts the hydrogen that has passed through it into ATP (I won't go into detail about this protein either). ATP stands for adenosine triphosphate, which is important for the next step in photosynthesis.

In addition to ATP, another energy source called NADP+ is also generated, or recycled, at the same time. An internal hydrogen atom is joined to this NADP+ to create NADPH, which is then transferred outside the thylakoid into the Calvin Cycle, the subsequent stage of photosynthesis.

The plant converts this glucose into usable energy (ATP) by respiration, which is the opposite of photosynthesis.

Photosynthesis is the process by which plants change carbon dioxide and water into glucose and oxygen. Photosynthesis requires sunlight because it provides the energy required to drive this chemical reaction, which enables plants to make their own food and survive. Sunlight is also necessary for the regulation of several physiological processes in plants, such as growth, flowering, and fruit development.