The cells in the palisade layer of a leaf contain many organelles that carry out photosynthesis. Suggest why the cells here contain more of these organelles than the cells in the mesophyll.

• A. They are farther from the light
• B. They are older
• C. Usually closer to the light
• D. They are less metabolically active

Answer: (C)

Light intensity is highest near the leaf’s upper surface, so the palisade layer sits where it can capture the most light. The cells in this layer are tall and packed with chloroplasts, maximizing light absorption to drive photosynthesis. The deeper mesophyll receives less light and is more geared toward gas exchange, so it has fewer chloroplasts. That's why these palisade cells contain more organelles that carry out photosynthesis—they’re positioned to get the most light.