- A Palisade and spongy mesophyll are sometimes mistakenly thought to be structurally and functionally identical leaf tissue layers with little real distinction
- B Palisade = columnar cells, densely packed, upper layer, more chloroplasts (primary photosynthesis); spongy = irregular cells, loose with air spaces (gas exchange)
- C Palisade mesophyll is sometimes mistakenly thought to be positioned directly beneath the lower epidermis; spongy mesophyll beneath the upper epidermis
- D Spongy mesophyll is sometimes mistakenly thought to contain substantially more chloroplasts than the palisade layer positioned directly above it
Correct answer: B. Palisade = columnar cells, densely packed, upper layer, more chloroplasts (primary photosynthesis); spongy = irregular cells, loose with air spaces (gas exchange)
Explanation: Palisade mesophyll: columnar cells, densely packed, many chloroplasts, upper layer - primary site of photosynthesis. Spongy mesophyll: irregular cells, loose arrangement with large air spaces - facilitates CO2 diffusion and gas exchange. Both found between upper and lower epidermis.
Concept context
Internal tissue organisation: meristems, permanent tissues (xylem, phloem, parenchyma), and secondary growth. Frequently tested in NEET.