Answer the following scenarios:

1. Luis has a very painful coldsore on his upper lip. Earlier that semester he had used a topical cream containing polymyxin to treat an infected cut on his hand. At that time, he had read in
his microbiology textbook that polymyxin is an antibiotic that disrupts cell membranes. He applied some polymyxin cream to his coldsore daily, but obtained no relief. Why did this treatment fail?
Explain it in 200 words.

2. During the early stages of development of the Earth’s atmosphere, the planet was exposed to a greater amount of ultraviolet radiation than it is today. What do you suppose were the effects
of this radiation on the longevity of individual organisms and on the rate of evolution of life forms? Discuss it in 200 words.

3. Infectious disease mortality decreased significantly in the 20th century compare to all the time proceeding this period. This recent success in treating infectious diseases has led us to
believe that eradication of disease is possible. However, between 1980 and 1992 the rate increased 58%. What factors have changed in modern times that make this goal harder to achieve? Explain your
answer in 200 words.
EXPLAIN YOUR ANSWER IN EACH SCENARIO IN 200 WORDS