Which of the following is true?
A) The number of species existing at one time has decreased throughout history.
B) Natural selection always favors complexity and a larger body size.
C) Species on Earth today are just a fraction of all species that ever lived.
D) Until recent history, extinctions have always happened gradually and on a small scale.
E) Most organisms present early in Earth's prehistory were more complex than modern organisms.

In which of the following ways is the function of the surface of a microsphere similar to the function of an actual cell membrane? a. both make it possible for the conditions in the interior to be different from the conditions outside. b. both provide a barrier that keeps water from flowing across it so the interior remains dry. c. both separate the rna that forms in the interior from any rna that might form in the environment. d. both can actively move molecules into the interior or out into the surrounding environment.

With regard to enzymes, key is to lock as a) substrate is to activation energy eliminate b) product is to substrate. c) enzyme is to active site. d) substrate is to active site.

Why is a strong sense of taste so important for open ocean predators like oceanic whitetip sharks ?