As the distance from Z line to Z line decreases, which bands shorten in a sarcomere?
1. | the I band and H band | 2. | the I band and A band |
3. | the A band and H band | 4. | all bands shorten |
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What protein is arranged along the length of actin filaments and is involved in regulation of skeletal muscle contraction?
1. | Troponin | 2. | Calmodulin |
3. | Tropomyosin | 4. | Light meromyosin |
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During relaxation of a skeletal muscle:
1. | Calcium ions that are bound to troponin C now bind to troponin A |
2. | Cross bridge formation between myosin head and actin takes place |
3. | The A band of the sarcomere lengthens |
4. | Calcium ions are pumped back to the sarcoplasmic cisternae |
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During muscle contraction, when the myosin head releases ADP and iP it:
1. forms cross bridge with actin
2. pulls actin towards M-line
3. goes back to its relaxed state
4. gets detached from the cross bridge
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Which of the following masks the active sites on actin when a skeletal muscle is relaxed?
1. | Tropomyosin | 2. | Troponin |
3. | Calmodulin | 4. | Ubiquitin |
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During muscle contraction, the event shown in the following diagram describes:
1. cross bridge detachment
2. the power stroke or working stroke
3. cross bridge formation
4. cocking of myosin head
Cross bridge formation during muscle contraction involves:
1. | troponin and actin | 2. | tropomyosin and myosin |
3. | myosin and troponin | 4. | myosin and actin |
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I. Sliding or rotation | A |
II. Breaking of cross bridge | B |
III. Formation of cross bridge | C |
I | II | III | |
1. | B | A | C |
2. | B | C | A |
3. | A | B | C |
4. | C | A | B |
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Arrange the following events in correct chronological order:
a: | acetylcholine hydrolyses into acetate and choline |
b: | acetylcholine diffuses across the synaptic cleft |
c: | Impulse reaches the terminal endings of the motor neuron |
d: | acetylcholine binds to its receptor on motor end plate |
e: | sarcolemma gets depolarized |
1. | b, c, d, a, e | 2. | c, b, d, e, a |
3. | c, d, b, a, e | 4. | d, e, b, a, c |