When chloroplast pigments absorb light, __________.

• A. carbon dioxide is directly converted into glucose
• B. they immediately release oxygen gas
• C. ATP is synthesized without any intermediate steps
• D. their electrons become excited to a higher energy state

Answer: (D)

Verified step by step guidance

1. Understand the role of chloroplast pigments: Chloroplast pigments, such as chlorophyll, are responsible for capturing light energy during photosynthesis. This energy is used to drive the reactions of photosynthesis.
2. Recognize the process of light absorption: When chloroplast pigments absorb light, the energy from the light excites electrons in the pigment molecules, causing them to move to a higher energy state.
3. Clarify what happens to the excited electrons: These high-energy electrons are transferred to an electron transport chain, where their energy is used to produce ATP and NADPH, which are essential for the Calvin cycle.
4. Eliminate incorrect options: Carbon dioxide is not directly converted into glucose; it requires multiple steps in the Calvin cycle. Oxygen gas is released during the light-dependent reactions, but not immediately upon light absorption. ATP synthesis involves intermediate steps, such as the electron transport chain and chemiosmosis.
5. Conclude the correct answer: The correct explanation is that when chloroplast pigments absorb light, their electrons become excited to a higher energy state, initiating the process of photosynthesis.