When phospholipids are mixed with water their interact with water and their are repelled, forming a lipid bilayer. hydrophilic heads; hydrophobic tails hydrophobic tails; hydrophilic heads hydrophobic heads; hydrophilic tails hydrophilic tails; hydrophobic heads?

The answer is;  hydrophilic heads; hydrophobic tails

The hydrophilic heads of a phospholipid are composed of a phosphate and glycerol molecule. Since the phosphate has a charge, the head are able to interact with water molecules through hydrogen bonds (Remember water is a polar molecule).  The hydrophobic tails are composed of hydrocarbon chains that are uncharged hence do not interact with water. When phospholipids are immersed in water, they form a bilipid layer - with the hydrophobic  tails clumped up together in the center and the hydrophilic heads on the outside.

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.

a scenario where a cell may be needed to perform a form of endocytosis is when transporting large molecules. a scenario where a cell may be needed to perform a form of exocytosis is when releasing the large molecule from the cell.