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Earn 100

During contraction of skeletal muscle, which of the following does not occur?
(a)The length of isotropic band shortens.
(b)The length of anisotropic band shortens.
(c)The distance between two successive Z-lines decreases.
(d)The length of Henson's zone shortens.

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Important Questions on Locomotion and Movement
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(i) Actin is a thin filament and is made up of two F-actins
(ii) The complex protein, tropomyosin is distributed at regular intervals on the troponin
(iii) Myosin is a thick filament which is also a polymerised protein
(iv) The globular head of meromyosin consists of light meromyosin (LMM)

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The thin filaments of myofibril contain __(i)__ actin and two filaments of __(ii)__ protein along with __(iii)__ protein for masking binding site for myosin.
(i) | (ii) | (iii) | |
---|---|---|---|
(a) | 1F | troponin | tropomyosin |
(b) | 1F | tropomyosin | troponin |
(c) | 2F | troponin | tropomyosin |
(d) | 2F | tropomyosin | troponin |

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Read the following statements and choose the correct option:
Statement I: During contraction of skeletal muscles, calcium binds with troponin so that myosin head binding sites on actin are exposed.
Statement II: The process of muscle contraction continues till sodium ions are pumped back to sarcoplasmic reticulum, resulting in masking of actin filaments which results in the return of Z-lines back to their original position.

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Column I | Column II | ||
---|---|---|---|
Structrual and functional unit of a myofibril | H-zone | ||
Protein of thin filament | Myosin | ||
Protein of think filament | Sarcomere | ||
The central part of thick filament not overlapped by thin filament | Actin |

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(i) H-zone disappears
(ii) A-band widens
(iii) I-band reduces in width
(iv) Width of A-band is unaffected
(v) M-line and Z-line come closer

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