Biology Support & Movement ETEA 2023
PMDC Verified Question 36 of 75
A sarcomere is the region of a myofibril between two successive:
A
I-lines
B
A-lines
C
Z-line
D
M-lines
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Z-line
Concept:

Anatomical boundaries of the contractile unit.

Formula:

N/A (Conceptual)

Solution:

  • A myofibril consists of repeating sub-units called sarcomeres.


  • The distinct, zig-zag structural proteins that physically anchor the thin actin filaments mark the outer boundaries of these units.


  • The space situated strictly between two adjacent Z-lines (or Z-discs) defines exactly one functional sarcomere.


Why other options are incorrect:

M-lines anchor myosin in the exact center of the sarcomere. A-bands and I-bands represent wide regions of overlapping or isolated proteins, not boundary lines.

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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