Answer:
Oxygen
Explanation:
When a human breathes in they take in oxygen which they use to stay alive and keep the heart beating when you breathe out you release carbon dioxide. Oxygen is used for cellular respiration which heals you.
Answer:
John: he has naturally acquired active immunity to chicken pox from previous exposure.
Explanation:
Your body naturally has some immunity to things that aren't you, but when you get sick with a specific pathogen, your body begins to make antibodies that specifically recognize that pathogen. Each antibody only recognizes one pathogen, and it floats around waiting to find it again so it can tell your body to kill it before you get sick again. This is why we become immune to chicken pox; after the first time you beat it, your body has the labeled antibodies and it can quickly destroy the pathogen before you get sick again.
Answer:
To compare their hypothesis to the data that they observed
Explanation:
Having both normal, circular red blood cells and sickle shaped red blood cells in his or her circulatory system.
hope this helped :)