When a skeletal muscle shortens during contraction which of these statements is false?
1. The l-band shortens
2. The A-band shortens
3. The H-zone becomes narrow
4. The sarcomeres shorten

Which of the following is not a feature of red muscle fibres?
1. They have plenty of mitochondria.
2. They have a high content of Myoglobin.
3. They have a high amount of Sarcoplasmic reticulum.
4. They are called aerobic muscles.

During resting stage the binding site of actin for myosin remains masked by
1. Troponin                2. Gactin
3. Tropomyosin          4. Meromyosin

Calcium is important in skeletal muscle contraction because it:
1. Detaches the myosin head from the actin filament.
2. Activates the myosin ATPase by binding to it.
3. Binds to troponin to remove the masking of active sites on actin for myosin.
4. Prevents the formation of bonds between the myosin cross bridges and the actin filament.

A motor unit consists of:
1. A motor neuron and all the muscle fibers innervated by it
2. All the motor neurons innervating one muscle fiber
3. All the muscle fibers in a fasciculus
4. All the muscle fibers in a skeletal muscle

Myasthenia gravis is an autoimmune disease in which antibodies are formed against:
1. Myelin sheath
2. Articular cartilage
3. Neuro-muscular junctions
4. Thyroid follicle

The first carpo-metacarpal joint is a/an:
1. Saddle joint             2. Ellipsoidal joint
3. Pivot joint               4. Fibrous joint

The central part of the thick myofilaments, not overlapped by thin filaments, is called the:
1. Z line         
2. M line
3. I band       
4. H zone

Vertebrochondral ribs attach to the seventh rib with the help of:

1. Elastic cartilage

2. Hyaline cartilage

3. Fibrous cartilage

4. White fibrous tissue

Myosin head cleaves ATP for:

1. Formation of cross bridges

2. Breaking of cross bridges

3. Both 1 and 2

4. Neither 1 nor 2