Answer:
Oral poliovirus vaccine or Sabin vaccine, named for its inventor American physician and microbiologist Albert Sabin, was developed. OPV contains live attenuated (weakened) virus and is given orally.
Answer: A. Heat within the Earth
Explanation: the earth’s crust floats on liquid rock. The convection currents caused by the Earth’s rotation cause movement at the surface.
Answer:
The first clear recognition of enzymes came in 1833 when scientists discovered that an alcohol precipitate of malt extract contained a thermolabile substance that converted starch into sugar. They called the substance diastase. We now know that this was an enzyme that we call amylase.
Explanation:
C. Oxygen and nutrients taken in by the respiratory system are transported to the circulatory system for transport around the entire body.
Also, B and D cannot be correct, as carbon dioxide is not wanted in the body (it's a waste product of respiration of the body cells)
