In most plants, photosynthesis primarily occurs in which structure?

• A. Phloem sieve-tube elements in the leaf veins
• B. Chloroplasts within mesophyll cells of the leaf
• C. Mitochondria within root cortex cells
• D. Xylem vessels in the stem

Answer: (B)

Verified step by step guidance

1. Understand that photosynthesis is the process by which plants convert light energy into chemical energy, primarily producing glucose and oxygen.
2. Recall that photosynthesis occurs in specialized organelles called chloroplasts, which contain the pigment chlorophyll responsible for capturing light energy.
3. Identify the location of chloroplasts within the plant: they are most abundant in the mesophyll cells of the leaf, which are the primary sites for photosynthesis.
4. Recognize that other structures listed, such as phloem sieve-tube elements, mitochondria in root cortex cells, and xylem vessels, have different functions unrelated to the main site of photosynthesis.
5. Conclude that the correct structure where photosynthesis primarily occurs is the chloroplasts within mesophyll cells of the leaf.