A Level Biology Practice Exam

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Master the A Level Biology Exam. Use flashcards and multiple choice questions with hints and explanations to ace your test. Start your journey to excellence!

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What is the primary function of alveoli in respiration?

To filter and clean the air entering the lungs
To absorb nutrients from the air
To perform gas exchange between air and blood
To prevent water loss in the lungs

The correct answer is: To perform gas exchange between air and blood

The primary function of alveoli in respiration is to perform gas exchange between air and blood. Alveoli are tiny, sac-like structures in the lungs that provide a large surface area for efficient gas exchange. They are surrounded by a network of capillaries, where oxygen from the air inside the alveoli diffuses into the bloodstream, and carbon dioxide, a waste product of metabolism, diffuses from the blood into the alveoli to be expelled during exhalation. This process is essential for maintaining the body’s oxygen levels and for getting rid of carbon dioxide, which is vital for homeostasis. The structure of the alveoli, with their thin walls and extensive surface area, maximizes the efficiency of this exchange, making them crucial for respiratory function.