Answer:
Oxygen enters the blood stream through the alveoli, which are tiny air sacs in the lungs where gas change is exchanged. Carbon Dioxide goes in through the alveoli and out goes oxygen.
2. air sacs
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By multiplying the rate constant by the substrate concentration (amount) or by determining reaction velocity (V).
Question is unclear, please re word it and i will answer it.
Carbon dioxide enters the leaf through openings usually found on the underside of the leaf called the stomata. Carbon dioxide passes through the stomata through diffusion, a passive process.