Sam came home from school with a cold caused by a virus and his sister, ana, caught it from him. sam got well and went back to school. a few days before ana got well, sam came down with a cold again. their mother said that ana had given the cold back to sam. how likely is it that their mother is correct, and what does it mean for ana's chances of getting sick again?

What do heterotrophic cells need to survive?

The hypothesis of continental drift states that earth's continents, which are located on tectonic plates, move relative to each other. which of the following is true of the movement of the tectonic plates? a. tectonic plates only move once every million years. b. they move at a rate of approximately 5 centimeters per year. c. tectonic plates never move, only the continents located on them do. d. their movements are very rapid and occur at random times.

What are some characteristics of a free enterprise economy?