Answer:
C. Oxygen concentration decreases as altitude increases
Explanation:
Higher altitudes have lower levels of oxygen and decreased air pressure.
Answer:
Why the red blood cell disc in shape is because that is how blood cells carries oxygen around. This is why blood type is important, and how people with a blood type of AB negative is so rare, this is because the AB negative blood cells doesn't have the shape to carry the oxygen needed for the body.
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I believe that the most contaminated are is the kitchen sink. Researchers say that the sink can contain up to 100,000 times more bacteria than the toilet seat. This is because the sink is where everything is slopped in.The sink should be washed with hot water and disinfected regularly to kill the harmful bacteria.