C. an endangered species is one that is at risk of dying out, while an extinct species is one that no longer exists.
B positive patients can receive blood from B positive, B negative, O positive and O negative donors.
Approximately one billion oxygen molecules. that is because there are about 250 million molecules of haemoglobin in each cell, and each haemoglobin molecule binds to 4 oxygen molecules
Mutations are disruptions in the human body