Question

which of the following structures is an opening on the underside of a leaf that is necessary for gas exchange?
stoma
cuticle
epidermis
shoot

Explanation:

To solve this, we analyze each option:

• Stoma: Small openings (stomata, plural) on leaf undersides for gas exchange (O₂, CO₂, H₂O vapor).
• Cuticle: Waxy layer on leaf surface to reduce water loss, not an opening.
• Epidermis: Outer tissue layer of leaves, not a gas - exchange opening.
• Shoot: Plant structure (stem, leaves, etc.), not a leaf - specific gas - exchange opening.

Only “stoma” matches the description of a leaf - underside opening for gas exchange.

Answer:

A. stoma