sentence: Most leaves have stomata, which open and close.
sentences_before: A 'leaf' is an above-ground plant organ. Its main functions are photosynthesis and gas exchange. A leaf is often flat, so it absorbs the most light, and thin, so that the sunlight can get to the chloroplasts in the cells.
sentences_after: They regulate carbon dioxide, oxygen, and water vapour exchange with the atmosphere.
concept_name: leaf
headings: Leaf
categories: Basic English 850 words Plant anatomy