Photosynthesis

Step 1: Understand the process of energy conversion in biological systems.
Living organisms require energy, and this energy often originates from external sources. The question asks about the conversion of radiant energy (light energy) into chemical energy. Step 2: Define the given options.
(1) Photosynthesis: This is the process used by green plants, algae, and some bacteria to convert light energy into chemical energy, in the form of glucose and other organic compounds. This process uses carbon dioxide and water.
(2) Chemical Synthesis (or Chemosynthesis): This is the biological conversion of one or more carbon molecules (usually carbon dioxide or methane) and nutrients into organic matter using the oxidation of inorganic molecules (e.g., hydrogen gas, hydrogen sulfide) or methane as a source of energy, rather than sunlight. It does not involve radiant energy.
(3) Respiration: This is the process where organisms break down glucose and other food molecules to release chemical energy (ATP) for cellular activities. It involves the conversion of chemical energy (stored in food) into other forms of chemical energy (ATP), often with the release of heat, but it does not convert radiant energy into chemical energy.
(4) Transpiration: This is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems, and flowers. It is a physical process related to water transport, not energy conversion. Step 3: Relate the given description to the definitions.
The description "The change of radiant energy into chemical energy" directly corresponds to the definition of photosynthesis. Step 4: Conclude the correct term.
Photosynthesis is the process by which radiant energy is converted into chemical energy. (1) Photosynthesis