▶️ Answer/Explanation
The image displays the lower epidermis of a leaf, characterized by specialized structures for gas exchange. The label $X$ points specifically to one of the bean-shaped cells that flank a small opening or pore. These are guard cells, which control the opening and closing of the stoma (the pore itself). Unlike regular epidermal cells, guard cells contain chloroplasts, which are visible as small grains in the photomicrograph. Options B and C are located in the internal layers of the leaf, and option D is a transport tissue found within vascular bundles, not on the surface.
✅ Answer: (A)
▶️ Answer/Explanation
The palisade mesophyll layer is located just below the upper epidermis (A) and is characterized by tall, cylindrical, closely packed cells. Structure B represents a palisade cell, which is specialized for photosynthesis as it contains a high density of chloroplasts and is positioned to receive maximum sunlight. In contrast, C points to the vascular bundle (xylem/phloem), and D indicates a guard cell surrounding a stoma on the lower epidermis. Because B is the elongated cell layer optimized for light absorption, it is the correct identification.
✅ Answer: (B)
✅ Answer: (B)
▶️ Answer/Explanation
The cell labelled $X$ is located directly beneath the upper epidermis. These cells are characteristically columnar (tall and narrow) and arranged closely together in a regular layer to maximize light absorption. This specific tissue layer is known as the palisade mesophyll. Unlike the spongy mesophyll below it, which has large air spaces, the palisade layer contains a high density of chloroplasts, making it the primary site for photosynthesis in the leaf. The epidermis consists of the outer protective layers, and guard cells are found surrounding the stomata on the leaf surface.
✅ Answer: (C) palisade mesophyll
✅ Answer: (C) palisade mesophyll