Which process is primarily responsible for the conversion of solar energy into chemical energy in plants?

Photosynthesis is the process that primarily converts solar energy into chemical energy in plants. During this process, chlorophyll, the green pigment found in plant cells, absorbs sunlight. This energy is then utilized to convert carbon dioxide from the atmosphere and water from the soil into glucose, a type of sugar that serves as an energy source for the plant. Oxygen is released as a byproduct of this reaction.

This process is vital for life on Earth, as it forms the base of the food chain; plants, being autotrophs, produce their own food and serve as a primary energy source for herbivores, which in turn support carnivores. The glucose produced during photosynthesis not only fuels the plant's growth and development but can also be stored for later use or converted into other organic compounds that the plant requires.

The other processes listed—cell respiration, fermentation, and transpiration—do not primarily involve the conversion of solar energy into chemical energy. Instead, cell respiration is the process whereby plants and animals break down glucose to release energy. Fermentation is an anaerobic process that also breaks down glucose to extract energy, typically occurring in the absence of oxygen. Transpiration is the process through which plants lose water vapor from their leaves, playing a