The conversion of glucose to starch in plants is a key aspect of the process known as photosynthesis.

Photosynthesis is an essential biochemical process that occurs in plants and certain other organisms. It enables them to transform light energy, primarily from the sun, into chemical energy, which can later be utilized to power various biological activities. This chemical energy is stored in carbohydrate molecules, such as sugars, synthesized from carbon dioxide ($CO_2$) and water ($H_2O$).

The photosynthesis process occurs within chloroplasts, specifically utilizing chlorophyll, the green pigment responsible for light absorption. Photosynthesis is typically divided into two main stages: the light-dependent reactions and the light-independent reactions (also referred to as the Calvin Cycle).

During the light-dependent reactions, which occur in the thylakoid membranes of the chloroplasts, chlorophyll absorbs light energy and converts it into chemical energy in the form of adenosine triphosphate ($ATP$) and nicotinamide adenine dinucleotide phosphate ($NADPH$).

The $ATP$ and $NADPH$ produced in the light-dependent reactions are subsequently used in the light-independent reactions to convert $CO_2$ into glucose. This conversion occurs through a series of biochemical reactions known as the Calvin Cycle, which takes place in the stroma of the chloroplasts.

The glucose generated can be utilized in various ways: it may be used immediately for energy or converted into other substances, such as cellulose, which is a crucial component of the plant’s cell walls. Additionally, when glucose levels are in excess, the plant converts it into starch for storage. This conversion occurs in the chloroplasts and specialized organelles called amyloplasts.

Starch is a polysaccharide, a large molecule composed of numerous glucose units. It serves as an ideal storage molecule because it is insoluble in water, thus not disrupting the plant’s water balance. When the plant requires energy, starch can be rapidly transformed back into glucose.

In summary, the conversion of glucose to starch in plants is an integral part of the photosynthesis process, wherein light energy is transformed into chemical energy and subsequently stored as carbohydrates.