Following is the figure of actin (thin) filaments. Identify A, B and C:

1. A - Tropomyosin, B - Troponin, C - F-actin

2. A - Troponin, B - Myosin, C - Tropomyosin

3. A - Troponin, B - Tropomyosin, C - Myosin

4. A - Troponin, B - Tropomyosin, C - F-actin

Subtopic:  Skeletal Muscle: Myofilaments |
 76%
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The above figure is related with myosin monomer (meromyosin). Identify A to C:

(1) A - head, B - cross arm, C - GTP binding sites

(2) A - head, B - cross arm, C - Ca+2 binding sites

(3) A - head, B - cross arm, C - ATP binding sites

(4) A - cross arm, B - head, C - ATP binding sites

Subtopic:  Skeletal Muscle: Myofilaments |
 89%
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The action potential that triggers a muscle contraction travels deep within the muscle cell by means of:

(1) Sarcoplasmic reticulum                

(2) Transverse tubules

(3) Synapse                                      

(4) Motor end plates

Subtopic:  Excitation Contraction Coupling I |
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ATP provides energy for muscle contraction by allowing for:

1. An action potential formation in the muscle cell

2. Cross-bridge attachment of myosin to actin

3. Cross-bridge detachment of myosin from actin

4. Release of Ca+2 from sarcoplasmic reticulum

Subtopic:  Energy for Muscle Contraction |
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A motor unit is best described as:

(1) All the nerve fibres and muscle fibres in a single muscle bundle

(2) One muscle fibre and its single nerve fibre

(3) A single motor neuron and all the muscle fibres that it innervates

(4) It is the neuron which carries the message from muscle to CNS

Subtopic:  Excitation Contraction Coupling I | Excitation Contraction Coupling II | Sliding Filament Theory |
 62%
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Electrical excitation in a muscle fibre most directly causes:

(1) Movement of tropomyosin

(2) Attachment of the cross bridges to actin

(3) Release of Ca+2 from sarcoplasmic reticulum

(4) Splitting of ATP

Subtopic:  Excitation Contraction Coupling I |
 80%
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The energy for muscle contraction is most directly obtained from:

(1) Phosphocreatine                          

(2) ATP

(3) Anaerobic respiration                   

(4) Aerobic respiration

Subtopic:  Energy for Muscle Contraction |
 81%
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Put the following phrases in proper order to describe what occurs at the neuromuscular junction to trigger muscle contraction:

I. Receptor sites on sarcolemma.
II. Nerve impulse.
III. Release of Ca+2 from sarcoplasmic reticulum
IV. The neurotransmitter acetylcholine is released
V. Sarcomere shorten
VI. Synaptic cleft
VII. Spread of impulses over sarcolemma on T-tubules


1. II, IV, I, VI, VII, III, V           

2. II, IV, VI, I, VII, III, V

3. I, II, III, IV, V, VI, VII             

4. VII, VI, V, IV, III, II, I

Subtopic:  Excitation Contraction Coupling I |
 63%
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Go through the following diagram describing muscle contraction:

Now identify A to E:
(1) A - Cross bridge, B - Cross bridge formation, C - Breaking of cross bridge, D - Sliding (rotation), E - ATP

(2) A - Cross bridge, B - Cross bridge formation, C - Sliding / rotation, D - Breaking of cross bridge, E - ATP

(3) A - Cross bridge, B - Breaking of Cross bridge, C - sliding / rotation, D - Cross bridge formation, E - AMP

(4) A - Cross bridge, B - Cross bridge formation, C - Sliding / rotation, D - ADP, E - Breaking of cross bridge

Subtopic:  Sliding Filament Theory |
 72%
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The muscle band that remains unchanged during muscle contraction and relaxation of the skeletal muscle is:

(1) I                     

(2) A                    

(3) H                    

(4) Z-line

Subtopic:  Skeletal Muscle: Sarcomere |
 89%
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