B and T cells become activated and divide to produce identical cells when _____
a. activated by an antigen
b. major histocompatibility genes are expressed
c. activated by the presence of cancerous cells
d. plasma cells begin to produce and secrete antibodies
e. killer T cells bind to any pathogen
a
You might also like to view...
When a young, vigorously growing culture of bacteria is transferred to fresh medium of different composition, the lag phase is usually short or absent.
Answer the following statement true (T) or false (F)
The microscopic air sacs or alveoli are the sites where blood
(a) picks up oxygen. (b) gives up carbon dioxide. (c) gives up oxygen. (d) both a and b.
What is the best description of a nerve?
a. A bundle of sensory, motor, or both types of nerve fibers outside the central nervous system b. A single extension of a neuron c. The same as a neuron but found only within the central nervous system d. A collection of nerve cell bodies outside the central nervous system e. A set of sensory cells only found in the autonomic nervous system
Biomagnification results in an increased concentration of bioaccumulated chemicals as one moves from upper to lower trophic levels.
Answer the following statement true (T) or false (F)