Biology Biomolecules ETEA 2022
PMDC Verified Question 83 of 142
Ribose is a pentose sugar (5-carbon) that contains:
A
Ketone group
B
Carboxyl group
C
Aldehyde group
D
Ester group
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Aldehyde group
Concept:

Monosaccharides are classified structurally as either aldoses (having an aldehyde group at Carbon-1) or ketoses (having a ketone group at Carbon-2).

Solution:

  • Ribose is an aldo-pentose. It possesses a terminal aldehyde group (-CHO) at carbon-1.


  • Its structural isomer, Ribulose, is the ketose version possessing a ketone group.


Why other options are incorrect:

  • Ketone group: Found in Ribulose and Fructose.


  • Carboxyl / Ester groups: These characterize organic acids and lipids, not standard sugar molecules.

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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