Biology Biomolecules NUMS 2024
PMDC Verified Question 11 of 142
Sucrose is used as a transport carbohydrate instead of glucose because:
A
It is disaccharide
B
It is non-reducing sugar
C
It is soluble in water
D
It does not change osmotic potential of water
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: It is non-reducing sugar
Concept:

Plants must transport energy vast distances through the phloem without the sugar reacting with surrounding cellular structures along the way.

Solution:

  • Glucose contains a free, highly reactive aldehyde group (it is a reducing sugar). If plants pumped pure glucose through their veins, it would indiscriminately react with and damage transport proteins along the route.


  • To solve this, plants bond glucose to fructose, locking both reactive ends together to form Sucrose.


  • Because Sucrose is a completely stable, non-reducing sugar, it acts as a chemically inert "safe" cargo, traveling unharmed through the phloem until it reaches the root sinks where enzymes finally break it apart for use.


Why other options are incorrect:

  • Soluble in water: Both glucose and sucrose are highly soluble.


  • Osmotic potential: All soluble sugars massively alter osmotic potential (which is actually how phloem sap physically flows).


  • Is a disaccharide: Maltose is also a disaccharide, but it is highly reactive (reducing), so it is not used for transport. The key is being non-reducing.

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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