Biology Chemical Coordination SZABMU 2024 Reconduct
PMDC Verified Question 2 of 50
Which pathway will be followed by water soluble hormone for crossing plasma membrane?
A
Receptor \(\rightarrow\) 2nd messenger \(\rightarrow\) Activation of energy
B
2nd messenger \(\rightarrow\) Receptor \(\rightarrow\) Activation of energy
C
Activation of energy \(\rightarrow\) Receptor \(\rightarrow\) 2nd messenger
D
Receptor \(\rightarrow\) Activation of energy \(\rightarrow\) 2nd messenger
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Receptor \(\rightarrow\) 2nd messenger \(\rightarrow\) Activation of energy
Concept:

Hormone signaling mechanisms depend entirely on whether the hormone is lipid-soluble (can penetrate membranes) or water-soluble (cannot penetrate).

Solution:

  • Because water-soluble (peptide) hormones cannot push through the hydrophobic lipid bilayer, they must bind to a surface Receptor.


  • This binding activates an intracellular 2nd messenger molecule (like cyclic AMP).


  • The 2nd messenger then cascades through the cytoplasm, resulting in the Activation of cellular enzymes/energy to alter the cell's function.


Why other options are incorrect:

The order is strictly chronological: outside receptor first, inside messenger second, physiological change last.

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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