Taxis

(plural taxes) the movement of a cell or organism in response to a stimulus in environment. This stimulus may be temperature (thermotaxis), light (phototaxis), gravity (geotaxis) or chemical (CHEMOTAXIS).

Taken from Dictionary of Science

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A taxis (plural taxes, pronounced /ˈtæksiːz/) is an innate behavioral response by an organism to a directional stimulus or gradient of stimulus intensity. A taxis differs from a tropism (turning response, often growth towards or away from a stimulus) in that the organism has motility and demonstrates guided movement towards or away from the stimulus source. It is sometimes distinguished from a kinesis, a non-directional change in activity in response to a stimulus that results in the migration toward or away from a stimulus.

Taken from Wikipedia

Vaccine

a modified preparation of a VIRUS or BACTERIA that is no longer dangerous but can produce an immune response. It therefore gives immunity against infection with the actual disease. Vaccines can be administered by mouth or by a hypodermic syringe and are not effective immediately as it takes time for the recipient's IMMUNE SYSTEM to develop a memory for the modified virus or bacterium by producing specific ANTIBODIES.

Taken from Dictionary of Science