NEET 2016 · Class 11

Locomotion and Movement

Name the ion responsible for unmasking of active sites for myosin for cross-bridge activity during muscle contraction.

  1. (A)Calcium
  2. (B)Magnesium
  3. (C)Sodium
  4. (D)Potassium

The NCERT line that answers it

Verbatim line

Increase in $\text{Ca}^{++}$ level leads to the binding of calcium with a subunit of troponin on actin filaments and thereby remove the masking of active sites for myosin.

Chapter
Locomotion and Movement
Section
17.2.2 Mechanism of Muscle Contraction
Page
5
Words matched
25 of 28

The answer appears as a continuous sentence in NCERT. This is that sentence.

How this line gives the answer

0, emb=1.0, combined=1.0). Verified: high — The span explicitly states that increased calcium ions bind to troponin and remove the masking of active sites for myosin, which directly answers the question about the ion responsible for unmasking active sites for cross-bridge activity.

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