Evolution of the Influenza Virus Quick Check:

(the answers are surrounded by these stars → ✧✧)

Q1) Why did 40% of the human population evolve to tolerate lactose?

✧ Within cultures that rely on milk-producing animals, individuals who tolerated lactose had a survival advantage. ✧

Q2) What is the difference between genetic drift and natural selection?

✧ Genetic drift is the random increase or decrease of certain genes in a population; natural selection is not random. ✧

Q3) What is an interferon?

✧ An interferon activates the body’s immune system response to a virus. ✧

Q4) Why is there such a wide variety of immune system responses between hosts when they are infected with the same virus?

✧ Slight variations due to mutations in the virus trigger different responses in people. ✧

Q5) Is the following statement true? “Antigenic drift and other mutations to the DNA of viruses are always beneficial for the virus.”

✧ No, because mutated viruses are may be less likely to replicate. ✧