Grana are:

Grana are:

• A. Stacks of flattened thylakoids
• B. The fluid inside mitochondria
• C. The site of the Calvin cycle
• D. Pores in the leaf cuticle

Answer: (A)

Grana are stacks of flattened thylakoid membranes inside chloroplasts. This arrangement increases the surface area for the light-dependent reactions of photosynthesis, which occur in the thylakoid membranes and involve chlorophyll, photosystems, and the electron transport chain to produce ATP and NADPH. The fluid surrounding them, the stroma, contains the enzymes for the Calvin cycle. The other options point to different structures: the fluid inside mitochondria is the matrix, not grana; the Calvin cycle happens in the stroma, not in grana; and pores in the leaf cuticle are stomata, not part of chloroplasts.

Grana are stacks of flattened thylakoid membranes inside chloroplasts. This arrangement increases the surface area for the light-dependent reactions of photosynthesis, which occur in the thylakoid membranes and involve chlorophyll, photosystems, and the electron transport chain to produce ATP and NADPH. The fluid surrounding them, the stroma, contains the enzymes for the Calvin cycle. The other options point to different structures: the fluid inside mitochondria is the matrix, not grana; the Calvin cycle happens in the stroma, not in grana; and pores in the leaf cuticle are stomata, not part of chloroplasts.