The purple sulfur and green sulfur bacteria a. both use hydrogen sulfide as a source of electrons. b. generate oxygen. c. preferentially use organic molecules as an electron source. d. both lack gas vesicles.

A. both use hydrogen sulfide as a source of electrons

Explanation:

Both purple and green sulfur bacteria exhibit anoxygenic photosynthesis and do not produce water as a by-product of the process. During the process, they use any organic or inorganic compound as a source of the electron but do not use water molecules for the same purpose.

Both of these bacteria preferentially use H2S (hydrogen sulfide) as an electron donor and oxidize it into elemental sulfur or sulfates.

white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.

cuz he's blad

explanation: