Where does carbon dioxide enter the leaf?

Where does carbon dioxide enter the leaf?

• A. Stomata
• B. Phloem
• C. Xylem
• D. Epidermis

Answer: (A)

Gas exchange in leaves happens mainly through stomata, the tiny pores on the leaf surface that are surrounded by guard cells. Carbon dioxide from the air diffuses into the leaf through these openings and travels to the photosynthetic cells in the mesophyll. The stomata also let oxygen exit as a byproduct of photosynthesis, and their opening is regulated to balance CO2 intake with water loss. Phloem and xylem are the plant’s transport tissues, carrying sugars and water/minerals, not routes for gas entry. The epidermis is the outer protective cell layer, while the stomatal pores within it are the actual entry points for CO2.

Gas exchange in leaves happens mainly through stomata, the tiny pores on the leaf surface that are surrounded by guard cells. Carbon dioxide from the air diffuses into the leaf through these openings and travels to the photosynthetic cells in the mesophyll. The stomata also let oxygen exit as a byproduct of photosynthesis, and their opening is regulated to balance CO2 intake with water loss.

Phloem and xylem are the plant’s transport tissues, carrying sugars and water/minerals, not routes for gas entry. The epidermis is the outer protective cell layer, while the stomatal pores within it are the actual entry points for CO2.