Question

which statement best describes what a thylakoid does during photosynthesis?
○ surrounds the grana and keeps them moist
○ enables the light-dependent reactions to occur
○ combines carbon dioxide and water to make sugar
○ helps the light-independent reactions to occur

Explanation:

To solve this, we analyze each option:

• Option 1: Thylakoids are part of grana (stacks of thylakoids), so they don't "surround" grana. Eliminate.
• Option 2: Thylakoid membranes contain chlorophyll and are the site of light - dependent reactions in photosynthesis. This matches their function.
• Option 3: Combining \(CO_2\) and \(H_2O\) to make sugar is the light - independent (Calvin cycle) which occurs in the stroma, not thylakoids. Eliminate.
• Option 4: Light - independent reactions occur in the stroma, not thylakoids. Eliminate.

Answer:

B. enables the light - dependent reactions to occur