Question

The structure labeled "A" open and close the sites where the gases, carbon dioxide and oxygen, are exchanged during photosynthesis. What is the structure labeled A?

Answer 1

The structure A in the question seems missing but the given answer is based on the description given in the question.

Answer:

The gaseous exchange of carbon dioxide(CO2) and oxygen(O2) occurs through small, regulated openings called stomata during photosynthesis.

Therefore the Structure A is Stomata