Biology Support & Movement UHS 2023
PMDC Verified Question 38 of 75
During sliding of actin filaments, ATP is used for?
A
Cross bridge formation
B
Cross bridge breaking
C
Dragging filaments
D
Shortening of filaments
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: Cross bridge breaking
Concept:

The role of ATP in the cross-bridge cycle.

Formula:

N/A (Conceptual)

Solution:

  • Counterintuitively, myosin physically binds to actin spontaneously when calcium exposes the binding sites; this initial attachment does not require new ATP.


  • The 'power stroke' (dragging) is powered by the release of stored ADP and Phosphate.


  • However, for the myosin head to physically detach and let go of the actin filament, a fresh molecule of ATP must physically bind to it. Thus, ATP is strictly required for cross bridge breaking.


Why other options are incorrect:

Without ATP, cross bridges lock permanently (causing Rigor Mortis). Filaments themselves never shorten; they only slide.

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.

Previous Question All Support & Movement MCQs Next Question

Want to solve full-length papers under timed exam conditions?

Practice with zero-scroll lockdown sprints, dynamic latency zone timers, live peer selection telemetry, and the automated Amber mistake recovery loop.

Enter Arena Sprint iOS App Android App