Certain preparations contain killed or weakened live biological agents that, upon injection into our body, protect the body against those pathogens. what are these preparations called?

Which flexible structure that supports the nerve cord and led to the backbone

Can someone me with this and tell me what’s fracking and what does it have to do with carbon, carbon dioxide, or fossil fuels?

After frida stops exercising, she continues to breathe heavily. what is most likely occurring in her body? heavy breathing during exercise has produced an oxygen surplus in her muscles. this oxygen is being transported to her lungs. this is a result of aerobic respiration. heavy breathing during exercise has produced a carbon dioxide surplus in her muscles. lactate is being transported to her liver. this is a result of aerobic respiration. strenuous exercise has caused her body to be in carbon dioxide debt, and she is breathing hard while lactate is transported to the liver. this is a result of anaerobic respiration. strenuous exercise has caused her body to be in oxygen debt, and she is breathing hard while lactate is transported to the liver. this is a result of anaerobic respiration.