Dicot Leaf Mesophyll Thickness Ratio

Steps:

• Recall dicot leaf structure: palisade mesophyll (upper, for photosynthesis) is denser and thicker than spongy mesophyll (lower, for gas exchange).
• Note the given ratio: palisade layer ≈ 2x thicker than spongy layer.
• Examine diagrams for vertical cross-section showing palisade above spongy with correct thickness proportion.
• Select diagram matching this ratio.

Why C is correct:

• Diagram C shows palisade mesophyll layer approximately twice the thickness of the spongy layer, aligning with standard dicot leaf anatomy.

Why the others are wrong:

• A: Palisade and spongy layers shown equal in thickness, violating the 2:1 ratio.
• B: Spongy layer depicted thicker than palisade, reversing the typical structure.
• D: Palisade layer shown less than twice as thick as spongy, underrepresenting the ratio.

Final answer: C