Question

Which statement about the membrane phospholipids is not true?
A) They associated to form bilayers
B) They have hydrophobic ‘tails’
C) They have hydrophilic ‘heads’
D) They flip readily from one side of the membrane to the other.

Answer 1

Hint:Cell membrane is also called as the plasma membrane. It is the membrane found in all the cells. It separates the interior of the cell from the external environment of the cell. Cell membrane is a semi-permeable membrane which means that it allows the movement of selective molecules or ions across itself.
Complete answer:
Phospholipids : Phospholipids are the class of lipids that are present in the plasma membrane.A phospholipid is a molecule which consists of glycerol, two fatty acids and one phosphate linked head group.They are amphoteric in nature which means that they have a polar or hydrophilic head and a no-polar or hydrophobic tail.Phospholipids arrange themselves in a manner that their hydrophobic tails facing each other and hydrophobic heads facing out.There is a barrier created by this arrangement and give a bilayer structure to the cell membrane. Therefore, it has been clear from the above discussion that statement of option D is not true about the membrane phospholipids.
Hence, option D is the correct answer.
Note: The plasma membrane consists of a lipid bilayer which includes cholesterol between phospholipids which maintain the fluidity of the membrane. The membrane also contains some integral proteins that act as membrane transporters. Plasma membranes perform various functions like osmosis, endocytosis, exocytosis, diffusion, etc.