The systematic examination of a phenomenon using measurements based on careful observation is called:

The release of histamine during an allergic reaction causes:

A. reduced vascular permeability. B. systemic vasodilation. C. reduced cardiovascular function. D. smooth muscle relaxation.

If the photon frequency of electromagnetic radiation is increased tenfold, then the

a. velocity will increase times 10. b. velocity will decrease to 10. c. wavelength will increase times 10. d. wavelength will decrease to 1/10.