Biology Biomolecules UHS 2024
PMDC Verified Question 27 of 142
The hydrophilic end of phospholipid molecule is polar because of the presence of:
A
Glycerol
B
Amine group
C
Fatty Acid
D
Phosphate group
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Phosphate group
Concept:

Amphipathic molecules possess severely contrasting regions of electrical charge.

Solution:

  • A phospholipid consists of a non-polar glycerol backbone attached to two incredibly non-polar fatty acid tails.


  • However, the third binding site on the glycerol is occupied by a massive Phosphate group (\(PO_4^{3-}\)).


  • This phosphate group carries a strong, permanent negative electrical charge. Because water is highly polar, it intensely targets and forms hydrogen bonds with this charged region, making the entire 'head' of the molecule highly polar and hydrophilic (water-loving).


Why other options are incorrect:

  • Fatty Acid: These are the intensely non-polar, hydrophobic "tails" that aggressively repel water.


  • Glycerol: Its polar \(-OH\) groups are destroyed during ester bond formation, rendering the central backbone relatively neutral.


  • Amine group: While some specific head groups (like choline) have nitrogen, the fundamental universal cause of polarity in all phospholipids is the negatively charged phosphate base.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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