Active transport occurs in cells, for example, when the na-k pump is at work. any process that involves active transport most often involves the a. movement of molecules without any predictable pattern. b. movement of molecules from a lower concentration to a higher concentration. c. movement of molecules from a higher concentration to a lower concentration. d. movement of molecules from a lower to higher concentration and then back to the point of origin.

Which of the following observation darwin shape his concept of descent with modification? a) species diversity declines farther from the equator. b) fewer species live on islands than on the nearest continents. c) birds live on islands located farther from the mainland than the bird's maximum nonstop flight distance. d) south american temperate plants are more similar to the tropical plants of south america than to the temperate plants of europe. e) earthquakes reshape life by causing mass extinctions.