Question

10. Describe the pathway that a molecule will take from the atmosphere until it reaches the

bloodstream. (4)

Answer 1

Molecules travel from the atmosphere to the bloodstream through inhalation, gas exchange in the alveoli, and transport via the bloodstream.

Step-by-step explanation:

The pathway that a molecule takes from the atmosphere until it reaches the bloodstream can be described as follows:

1. Inhalation: The process begins with inhalation, where air containing the molecules enters the respiratory system through the nose or mouth.
2. Gas Exchange: Next, the inhaled air travels through the respiratory system, reaching the alveoli in the lungs. Gas exchange occurs in the alveoli, where oxygen from the inhaled air diffuses into the bloodstream, while carbon dioxide from the bloodstream diffuses into the alveoli to be exhaled.
3. Transport: Once in the bloodstream, oxygen binds to hemoglobin in red blood cells, which carry it to various tissues and organs in the body. Carbon dioxide produced by cellular respiration is transported back to the lungs through the bloodstream to be exhaled during exhalation.

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