1. How do scientists use the word “theory,” and how is the word
used in casual conversation? What misconceptions have resulted from
these different uses?

2. How many species of plants provide most of the world’s
calories today? Is the world food supply more secure today than the
food supply pre- Irish potato famine? Be sure to fully justify your
answer.

3. What is the difference between a pathogen and a disease? For
the blight of potatoes, what is the pathogen, and what is the
disease? Why is a parasite not necessarily a pathogen?