Is photosynthesis anabolic or catabolic? Is photosynthesis endergonic or exergonic? Explain.
The correct answer and explanation is :
Photosynthesis is an anabolic and endergonic process.
Anabolic Process
Anabolism refers to the building of complex molecules from simpler ones, which requires energy input. Photosynthesis is anabolic because it involves the production of glucose (a complex molecule) from simpler molecules like carbon dioxide (CO₂) and water (H₂O). During photosynthesis, light energy is absorbed by chlorophyll in plant cells and used to drive the conversion of CO₂ and H₂O into glucose (C₆H₁₂O₆) and oxygen (O₂). This synthesis of glucose from simple compounds is an example of an anabolic process, where smaller molecules are joined together to form a more complex one, storing energy in the chemical bonds of glucose.
Endergonic Process
Endergonic reactions are those that require an input of energy to proceed. Photosynthesis is endergonic because it requires energy from sunlight to convert carbon dioxide and water into glucose and oxygen. This energy is absorbed by the plant’s chlorophyll during the light-dependent reactions of photosynthesis. The energy from the sun is stored in the chemical bonds of the glucose molecules produced during the process. In contrast, an exergonic reaction releases energy, but photosynthesis stores energy in glucose, making it endergonic.
Explanation
In photosynthesis, light energy is absorbed by pigments in the chloroplasts, primarily chlorophyll. This energy is used in the light-dependent reactions to generate ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate), which are energy carriers. The ATP and NADPH produced in the light reactions are then used in the Calvin cycle, a series of reactions that fix carbon dioxide into glucose, a stable energy storage molecule. The process requires energy because it is building a high-energy molecule (glucose) from lower-energy molecules (CO₂ and H₂O). Therefore, photosynthesis is both anabolic (building complex molecules) and endergonic (requiring energy input).