19. Changing nitrogen gas into a more reactive form (so organisms can use it) is called:
A. Denitrification
B. Nitrogen fixation
C. Nitrification
D. Decomposition

Cancer cells spread to other parts of the body by entering the bloodstream. which of the following organs could prevent a cancer cell in the bloodstream from spreading, and why? a. the spleen, because it releases lymphocytes into the blood b. the peyer's patches, because they release lymphocytes into the blood c. the lymph nodes, because they release lymph into the blood d. the thymus, because it releases lymph into the blood