- 1(current)
Q. No.Calcium ions are released from the sarcoplasmic reticulum. What happens next?
| 1. | acetylcholine is released |
| 2. | active sites on the actin filaments are exposed |
| 3. | filaments slide past one another, and the muscle fiber shortens |
| 4. | myosin is activated |
Subtopic: Sliding Filament Theory |
82%
Level 1: 80%+
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The following events occur during a reflex response to a person placing a hand on a hot object.
1 Myosin binding sites on actin filaments uncovered.
2 ADP and phosphate ion released from myosin head.
3 Sodium voltagegated channels open.
4 Myosin head detaches from the binding sites on actin.
5 Calcium ions released by sarcoplasmic reticulum.
Which of the following options places four of these events in the correct order (from left to right)?
1. 3, 5, 4, 2
2. 5, 2, 1, 4
3. 1, 2, 4, 3
4. 5, 1, 2, 4
Subtopic: Sliding Filament Theory |
59%
Level 3: 35%-60%
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During muscle contraction in humans the:
| 1. | Sarcomere does not shorten | 2. | A band remains the same |
| 3. | A, H and I bands shorten | 4. | Actin filaments shorten |
Subtopic: Sliding Filament Theory |
85%
Level 1: 80%+
NEET - 2013
Hints
During muscular contraction, which of the following events occur?
| (a) | 'H' zone disappears |
| (b) | 'A' band widens |
| (c) | 'I' band reduces in width |
| (d) | Myosin hydrolyzes ATP, releasing the ADP and Pi |
| (e) | Z-lines attached to actins are pulled inwards |
Choose the correct answer from the options given below:
1. (b), (c), (d) and (e) only
2. (b), (d), (e) and (a) only
3. (a), (c), (d) and (e) only
4. (a), (b), (c) and (d) only
Subtopic: Sliding Filament Theory |
82%
Level 1: 80%+
NEET - 2021
Hints
Sliding filament theory can be best explained as:
| 1. | when myofilaments slide past each other, actin filaments shorten while myosin filament does not shorten |
| 2. | actin and myosin filaments shorten and slide past each other |
| 3. | actin and myosin filaments do not shorten but rather slide pass each other |
| 4. | when myofilaments slide past each other, myosin filaments shorten while actin filaments do not shorten |
Subtopic: Sliding Filament Theory |
52%
Level 3: 35%-60%
NEET - 2015
Hints
Calcium is important in skeletal muscle contraction because it:
| 1. | binds to troponin to remove the masking of active sites on actin for myosin. |
| 2. | activates the myosin ATPase by binding to it. |
| 3. | detaches the myosin head from the actin filament. |
| 4. | prevents the formation of bonds between the myosin cross bridges and the actin filament. |
Subtopic: Excitation Contraction Coupling I | Sliding Filament Theory | Muscle Contraction: Other Considerations |
87%
Level 1: 80%+
NEET - 2018
Hints
According to the sliding filament theory:
| 1. | Actin and myosin filaments slide over each other to increase the length of the sarcomere. |
| 2. | Length of A–band does not change. |
| 3. | I–band increases in length |
| 4. | The actin filaments slide away from A–band resulting in shortening of sarcomere |
Subtopic: Sliding Filament Theory |
74%
Level 2: 60%+
NEET - 2022
Hints
Calcium released into the sarcoplasm during muscle contraction:
| 1. | binds to the actin and myosin and makes them work together. |
| 2. | breaks apart ATP to ADP and P. |
| 3. | removes the tropomyosin block. |
| 4. | causes the release of acetylcholine. |
Subtopic: Sliding Filament Theory |
60%
Level 2: 60%+
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A skeletal muscle motor unit is best described as:
1. a section of myofibrils from Z lines to Z lines
2. one nerve fiber and all the muscle fibers innervated by that nerve fiber
3. all of the nerves that unite to make a whole muscle contract
4. all of the fascicles innervated by several neurons
1. a section of myofibrils from Z lines to Z lines
2. one nerve fiber and all the muscle fibers innervated by that nerve fiber
3. all of the nerves that unite to make a whole muscle contract
4. all of the fascicles innervated by several neurons
Subtopic: Sliding Filament Theory | Muscle Contraction: Other Considerations |
66%
Level 2: 60%+
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To form a cross bridge, during muscle contraction:
| 1. | the myosin head binds to the exposed active sites on actin utilising the energy from ATP hydrolysis |
| 2. | the myosin head binds to the exposed active sites on actin and then the ATP binds to its site on myosin head |
| 3. | the actin binds to the exposed active sites on myosin head utilising the energy from ATP hydrolysis |
| 4. | the actin binds to the exposed active sites on myosin head and then the ATP binds to its site on actin |
Subtopic: Sliding Filament Theory |
72%
Level 2: 60%+
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- 1(current)
Q. No.
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