defence cell in blood are called white blood cells
A primary reason for needing a new vaccine for influenza each year is that there could be mutation of surface proteins leading to a new outbreak
<h3>What is antigenic drift?</h3>
Antigenic drift is a phenomenon that causes small changes or mutations in the genes of influenza viruses leading to changes in their surface proteins of the virus, which are HA (hemagglutinin) and NA (neuraminidase).
For this reason, new influenza vaccines are produced yearly to alter the effects that may emerge as a result.
Thus, a primary reason for needing a new vaccine for influenza each year is that there could be mutation of surface proteins leading to a new outbreak
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Answer: slightly cooler than
Explanation:
The testes are the male gonads. These are found in a loose pouch which is called as the scrotum behind the penis. The testes are responsible for production and storage of sperms which are the male gametes, and fluids which makes up the composition of the semen in males. The testes being the sperm factor functions efficiently when the temperature of the scrotum is slightly cooler than the rest of the body.
