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.

Out of ‘X’ pairs of ribs in humans only 'Y' pairs are true ribs. Select the option that correctly represents values of X and Y and provides their explanation:

Which of the following joints would allow no movement?

1. Fibrous joint

2. Cartilaginous joint

3. Synovial joint

4. Ball and socket joint

Which of the following is not a function of the skeletal system?

1. Production of erythrocytes

2. Storage of minerals

3. Production of body heat

4. Locomotion

Sliding filament theory can be best explained as:

Glenoid cavity articulates:

The characteristics and an example of a synovial joint in humans are:

Select the correct matching of the types of the joint with the example in the human skeletal system:

1. 1
2. 2
3. 3
4. 4

Stimulation of a muscle fiber by a motor neuron occurs at:

1. the neuromuscular junction

2. the transverse tubules

3. the myofibril

4. the sarcoplasmic reticulum