Which of the following correctly identifies the two main stages of photosynthesis?

• A. Glycolysis and Krebs cycle
• B. Light-dependent reactions and Calvin cycle
• C. Oxidative phosphorylation and photolysis
• D. Electron transport chain and fermentation

Answer: (B)

Verified step by step guidance

1. Understand the process of photosynthesis: Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy stored in glucose. It occurs in two main stages: the light-dependent reactions and the Calvin cycle.
2. Step 1: Light-dependent reactions: These occur in the thylakoid membranes of chloroplasts. During this stage, light energy is absorbed by chlorophyll and other pigments, which drives the production of ATP and NADPH. Water is split (photolysis) to release oxygen as a byproduct.
3. Step 2: Calvin cycle (light-independent reactions): This occurs in the stroma of the chloroplast. ATP and NADPH produced in the light-dependent reactions are used to convert carbon dioxide into glucose through a series of enzyme-mediated steps.
4. Compare the options provided: Glycolysis and Krebs cycle are part of cellular respiration, not photosynthesis. Oxidative phosphorylation and photolysis are processes related to energy production but do not describe the two main stages of photosynthesis. Electron transport chain and fermentation are unrelated to photosynthesis.
5. Conclude that the correct answer is 'Light-dependent reactions and Calvin cycle,' as these are the two main stages of photosynthesis.