A1. Dryness of the air makes a virus easy to fly in the air.
Somebody who has a cold coughs or sneezes. Droplets holding viruses spread in the air.
If the humidity is high like in summer, the droplets are caught by water droplets in the air and drop on the ground.
On the other hand, In the winter, because the air is dry, the droplets holding viruses are not hit by the water droplets so they float in the air. It means there are more viruses in the air in the winter.
a. 500 b. 10 thousands c. 1 million
A2. 1 million
Q3. Where does a common cold virus invade to induce cold symptoms?
a. Cells in the throat
b. Cells in the stomach
A3. Cells in the throat. Cold symptoms occur when common cold virus multiplies in the cells. There are cilia on the surface of the throat, which are microscopic, hair-like structure extending from a cell.
If the cilia are covered by mucus, the intruded viruses are caught and wrapped by mucus, and pushed back as phlegm.
If the air is dry, the throat becomes dry and the mucus evaporates, causing viruses to invade into the cells and multiply. As a result, we catch a cold.
Some people cough out phlegm, but some people swallow the phlegm. In that case, the virus is digested by stomach acid so people taking a medication to control stomach acid need to be careful.
Cilia don't work very much without mucus so it is important to keep the throat wet.