Where does the energy come from to make sugar during photosynthesis? d. Minerals from the soil c. Water b. Sunlight a. Respiration
The correct answer and explanation is:
The correct answer is b. Sunlight.
Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy stored in sugars. The main source of energy for this process is sunlight.
During photosynthesis, plants capture sunlight using a pigment called chlorophyll found in chloroplasts. The energy from sunlight excites electrons in chlorophyll molecules, initiating a series of reactions known as the light-dependent reactions. These reactions split water molecules into oxygen, protons, and electrons, releasing oxygen as a byproduct. The light energy is converted into chemical energy in the form of two molecules: ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate).
The ATP and NADPH produced in the light-dependent reactions then power the light-independent reactions, also called the Calvin cycle. In this cycle, carbon dioxide from the air is fixed and combined with other molecules to eventually produce glucose (a type of sugar). This glucose stores chemical energy that the plant can use for growth, reproduction, and other metabolic activities.
While water is necessary as a raw material in photosynthesis and minerals from the soil are important for plant nutrition and enzyme functions, they do not provide the energy for sugar production. Respiration is a process where organisms break down sugars to release energy, which is the opposite direction of energy flow compared to photosynthesis.
In summary, sunlight is the essential energy source that drives the entire photosynthesis process, enabling plants to transform carbon dioxide and water into sugars and oxygen. This energy conversion sustains life on Earth by providing food and oxygen to many living organisms.