If chloroplasts are isolated from a plant cell and exposed to light, they release ______.

• A. nitrogen (\(N_2\))
• B. carbon dioxide (\(CO_2\))
• C. glucose (\(C_6H_{12}O_6\))
• D. oxygen (\(O_2\))

Answer: (D)

Verified step by step guidance

1. Understand the role of chloroplasts: Chloroplasts are organelles in plant cells responsible for photosynthesis, a process that converts light energy into chemical energy stored in glucose while releasing oxygen as a byproduct.
2. Recall the photosynthesis equation: The general equation for photosynthesis is: $6_{\mathrm{CO}}+6_H{2}_O\to C_{6_H}$. This shows that oxygen (\(O_2\)) is released during photosynthesis.
3. Focus on the light-dependent reactions: In the presence of light, chloroplasts carry out the light-dependent reactions of photosynthesis, where water (\(H_2O\)) is split into oxygen (\(O_2\)), protons, and electrons through a process called photolysis.
4. Identify the byproduct of photolysis: During photolysis, oxygen (\(O_2\)) is released as a byproduct, which is why isolated chloroplasts exposed to light release oxygen.
5. Conclude the reasoning: Based on the photosynthesis process and the role of chloroplasts, the correct answer is oxygen (\(O_2\)), as it is the byproduct of the light-dependent reactions when chloroplasts are exposed to light.