Key Stage 3 (KS3) Plants Practice Test

Plants primarily obtain carbon dioxide through stomata in their leaves. Stomata are tiny openings located on the surface of leaves that allow for the exchange of gases. When plants undergo photosynthesis, they need carbon dioxide from the atmosphere. The stomata open to let in this carbon dioxide while also allowing oxygen, a byproduct of photosynthesis, to escape.

This process is crucial because it enables plants to convert carbon dioxide and sunlight into glucose and oxygen, fueling their growth and providing energy for various physiological processes. The structure and function of stomata are essential for efficient gas exchange, ensuring that plants can effectively carry out photosynthesis and maintain their metabolic functions.

Other methods, such as obtaining carbon dioxide through roots or from rainwater, do not play a significant role in the gas exchange process, and limiting photosynthesis to only nighttime contradicts the concept that it primarily occurs during daylight when sunlight is available.