Biology Biomolecules PMC 2020
PMDC Verified Question 107 of 142
Lipids store double amount of energy as compared to carbohydrates because of:
A
High proportion of oxygen
B
Low proportion of carbon
C
High CO ratio
D
High proportion of CH
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: High proportion of CH
Concept:

The thermodynamic potential of a biological fuel depends entirely on its state of reduction (availability of oxidizable hydrogen).

Solution:

  • The vast majority of a lipid's molecular structure is a long aliphatic chain composed purely of carbons bonded to hydrogens.


  • This high proportion of C-H bonds provides an abundance of easily strippable, high-energy electrons that power the electron transport chain to make ATP.


  • Carbohydrates, in contrast, have a much lower C-H proportion because many of their carbons are already bonded to oxygen (hydroxyls), meaning they are "partially burned" fuels.


Why other options are incorrect:

  • High proportion of oxygen / High CO ratio: These represent an oxidized state (lower energy potential), characteristic of carbohydrates, not lipids.


  • Low proportion of carbon: Lipids actually have massive carbon chains.

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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