Answer:
4
Explanation:
This is the answer because I have tested it and got it correct. As oxygen-rich (and carbon dioxide-poor) blood travels by a cell the oxygen diffuses through the cell membrane to the area of lower concentration inside the cell. It can do this easily because the oxygen molecule (O2) is very small and has no charge or polarity. The oxygen is used up rapidly by mitochondria.
Answer: i beleive its B
Explanation: the reason i thinkj this is because genes are what make up a humans trates like if your mom and dad have black hair you are very likley to get black hair. And it says there the ALTERNATE version of a TRAIT so that would be your answer :) if im wrong please correct me
