Astudent complains that it makes no sense to worry about coliform bacteria in water, since we naturally possess harmless coliforms in our intestines anyway. why do regulatory agencies worry about coliform bacteria in water supplies, then? a. not all coliforms are harmless and symbiotic with human beings and some may carry genes/proteins that can make them dangerous to humans; it is best to keep coliforms out of our drinking water, since it is difficult to identify which ones might be harmless and which ones might be harmful. b. the coliforms in our intestines can sometimes turn harmful, causing intestinal infections; we need to constantly be on guard against this happening; coliforms in water might add to this potential problem. c. regulatory agencies simply need something to do to justify their existence; there is no real danger from coliforms in water supplies. d. regulatory agencies are worried that multiple types of coliforms in water might lead to greater antibiotic resistance in the bacterial populations; they try to keep them out of water to keep antibiotic resistance levels down.

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.

water is a polar molecule. a chemical bond is a force of attraction between atoms or ions. bonds form when atoms share or transfer valence electrons. atoms form chemical bonds to achieve a full outer energy level, which is the most stable arrangement of electrons. so, false

explanation:

in h2o molecule, two water molecules are bonded by a hydrogen bond but the bond between two h - o bonds within a water molecule are covalent. the greater the electronegativity difference, the more ionic the bond is. bonds that are partly ionic are called polar covalent bonds. nonpolar covalent bonds, with equal sharing of the bond electrons, arise when the electronegativities of the two atoms are equal.