The ATPase activity of the myosin head is dependent on:

1. Magnesium ions

2. Manganese ions

3. Calcium ions

4. Ferric ions

The neurotransmitter released at the neuromuscular junction is:

1. Adrenaline

2. Nor-adrenaline

3. Dopamine

4. Acetylcholine

Consider the following statements:

I. A motor neuron along with the muscle fibres connected to it constitute a motor unit

II. The neurotransmitter released at the neuro-muscular junction is Acetylcholine.

III. Myosin head has ATPase activity.

Which of the above statements are true?

1. I and II only

2. I and III only

3. II and III only

4. I, II, and III

Ca⁺² bind ________ in the skeletal muscles and leads to exposure of the binding site for ________ on the filament _______:

(1) Troponin, myosin, actin                

(2) Troponin, actin, relaxin

(3) Actin, myosin, troponin                

(4) Tropomysin, myosin, actin

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