View the animation below, then complete the quiz to test your knowledge of the concept.

1	Foreign substances that elicit an immune response are termed
	A)	aliens.
	B)	antigens.
	C)	antibodies.
	D)	viruses.
	E)	bacteria.
2	Macrophages secrete ________ which then activates ________ .
	A)	antibodies ; helper T cells
	B)	interleukin-1 ; cytotoxic T cells
	C)	interleukin-1 ; helper T cells
	D)	interleukin-2 ; cytotoxic T cells
	E)	interleukin-2 ; helper T cells
3	The human body makes
	A)	only one type of cytotoxic T cell.
	B)	tens of different types of cytotoxic T cells.
	C)	hundreds of different types of cytotoxic T cells.
	D)	thousands of different types of cytotoxic T cells.
	E)	millions of different types of cytotoxic T cells.
4	Helper T cells can stimulate the proliferation of cytotoxic T cells but not that of B cells.
	A)	True
	B)	False
5	The secondary immune response to a previously encountered pathogen is swifter and stronger than the primary immune response.
	A)	True
	B)	False