Apentix/AP Biology/Unit 2: Cell Structure and Function/Question
AP Biologymediummcq1 pt

Inside a chloroplast, thylakoid membranes are arranged in stacked disks called grana. How does this stacked architecture benefit a photosynthetic cell?

A.It concentrates photosystems and electron carriers on a large membrane area, increasing light-capture capacity
B.It stores digestive enzymes that recycle worn pigment molecules
C.It provides an acidic pocket where the Calvin cycle fixes carbon fastest
D.It manufactures the phospholipids used to build cellular membranes

Explanation

Core Concept

Grana multiply the membrane surface available for chlorophyll-containing photosystems and their carriers. More packed membrane means more photons can be absorbed per chloroplast volume, raising the output of the light reactions. The architecture ties internal structure directly to photosynthetic efficiency.

Correct Answer

AIt concentrates photosystems and electron carriers on a large membrane area, increasing light-capture capacity

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