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Multiple Choice
Which of the following best describes the overall energy change in photosynthesis?
A
Photosynthesis is an exothermic process because it releases energy as heat.
B
Photosynthesis is an endothermic process because it absorbs energy from sunlight.
C
Photosynthesis is neither endothermic nor exothermic.
D
Photosynthesis alternates between endothermic and exothermic reactions.
Verified step by step guidance
1
Understand the key terms: An endothermic process absorbs energy (e.g., sunlight), while an exothermic process releases energy (e.g., heat). Photosynthesis involves the absorption of sunlight to drive the synthesis of glucose.
Recall the overall equation for photosynthesis: . This equation shows that light energy is required to convert carbon dioxide and water into glucose and oxygen.
Analyze the energy flow: During photosynthesis, light energy is absorbed by chlorophyll and other pigments in the chloroplasts. This energy is used to drive the light-dependent reactions, which produce ATP and NADPH, and the light-independent reactions (Calvin cycle), which synthesize glucose.
Determine the classification: Since photosynthesis requires the absorption of energy (sunlight) to proceed, it is classified as an endothermic process.
Conclude: The correct description is 'Photosynthesis is an endothermic process because it absorbs energy from sunlight.' This aligns with the energy absorption required for the process to occur.