Biology Biomolecules ETEA 2022
PMDC Verified Question 94 of 142
The most common protein in nature is ____.
A
Collagen
B
Rubisco
C
DNAase
D
Keratin
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: Rubisco
Concept:

Biological abundance is determined by evaluating the total biomass of organisms on Earth, which is overwhelmingly dominated by photosynthetic life.

Solution:

  • Rubisco (Ribulose-1,5-bisphosphate carboxylase-oxygenase) is the primary enzyme responsible for carbon fixation in the Calvin cycle of photosynthesis.


  • Because it is present in massive quantities in the chloroplasts of almost every single plant and photosynthetic algae across the globe, it is unequivocally recognized as the most abundant protein in the world.


Why other options are incorrect:

  • Collagen: The most abundant protein in the animal kingdom (roughly 25-35% of mammalian protein mass), but animals represent a tiny fraction of global biomass compared to plants.


  • Keratin & DNAase: Abundant in specific tissues, but dwarfed globally by Rubisco.

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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