In most vascular plants, where does the majority of photosynthesis occur?

• A. In the phloem sieve tube elements of leaves, where sugars are synthesized for transport
• B. In chloroplasts within mesophyll cells of leaves, especially the palisade mesophyll
• C. In xylem vessels of stems, where water is converted into sugars
• D. In mitochondria within root cells, where cellular respiration produces glucose

Answer: (B)

Verified step by step guidance

1. Understand that photosynthesis is the process by which plants convert light energy into chemical energy stored in glucose.
2. Recall that photosynthesis primarily occurs in cells containing chloroplasts, the organelles responsible for capturing light energy.
3. Identify the location of chloroplasts in vascular plants, which is mainly within the mesophyll cells of leaves.
4. Recognize that the mesophyll is divided into two layers: the palisade mesophyll (tightly packed cells rich in chloroplasts) and the spongy mesophyll (loosely packed cells). The palisade mesophyll is the primary site of photosynthesis due to its high chloroplast density.
5. Conclude that the majority of photosynthesis occurs in chloroplasts within mesophyll cells of leaves, especially the palisade mesophyll, rather than in phloem, xylem, or root cells.