The combination of a neuron and the muscle fiber it associates with is called a/an.

1. fascicle

2. motor end plate

3. motor unit

4. myoneural junction

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

(1)  Calcium              

(2)  Magnesium

(3)  Sodium              

(4)  Potassium.

Sliding filament theory can be best explained as
1. when myofilaments slide pass each other actin filaments shorten while myosin filament do not shorten
2. actin and myosin filaments shorten and slide pass each other
3. actin and myosin filaments do not shorten but rather slide pass each other
4. when myofilament slide pass each other myosin filament shorten while actin filaments do not shorten

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

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

Sliding Filament Theory states that

1. Contraction of muscle fibre takes place by the sliding of thin filaments over the thick filaments

2. Contraction of muscle fibre takes place by the sliding of thick filament over thin Filaments

3. Relaxation of muscle fibre takes place by the sliding of thick filament over thin filaments

4. Relaxation of muscle fibre takes place by the sliding of thin filament over thick filament

The cross-bridge formation actually involves

1. ATP hydrolysis

2. Binding of Myosin head to the exposed active sites for myosin

3. Both A and B

4. None of these

During contraction of muscle fibers which of the following does not happen?

1. The length of the A band gets reduced

2. The attached actin Filaments are pulled towards the centre of A band

3. The Z line attached to actin Filaments is pulled inward

4. Shortening of sarcomere

Which of the following step during sliding Filament Theory is the last step before a relaxing state?

1. ATP utilization

2. Release of ADP and inorganic phosphate

3. Cross bridge formation

4. Binding of calcium with troponin

What masks the active sites for myosin head present on the actin myofilaments?
1. Light meromyosin
2. Heavy meromyosin
3. G – actin
4. Troponin