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.

(1) X = 12, Y = 7           True ribs are attached, dorsally to 

                                      vertebral column and ventrally to

                                      the sternum.

(2) X = 12, Y = 5           True ribs are attached dorsally to

                                      vertebral column and sternum on

                                      the two ends.

(3) X = 24, Y = 7           True ribs are dorsally attached to

                                      vertebral column, but are free on

                                      ventral side.

(4) X = 24, Y = 12         True ribs are dorsally attached to 

                                      vertebral column, but are free on 

                                      ventral side.

The pivot joint between atlas and axis is a type of

(1) fibrous joint                 

(2) cartilaginous joint

(3) synovial joint               

(4) saddle joint

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.

Lack of relaxation between successive stimuli in sustained muscle contraction is known as 

(1) fatigue   

(2) tetanus   

(3) tonus   

(4) spasm

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
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

Select the correct matching of the type of the joint with the example in human skeletal

system

Types of joint                                     Example

1.  Cartilaginous joint                   Between frontal and parietal

2.  Pivot joint                               Between third and fourth Cervical vertebrae

3. Hinge joint                               Between humerus and pectoral girdle

4. Gliding joint                             Between carpals 

Which one of the following items gives its correct total number?

1.  Floating ribs in humans           - 4 

2.  Amino acids found in proteins  -16

3.  Types of diabetes                   - 3

4.  Cervical vertebrae in humans  - 8

In human body, which one of the following is anatomically correct ?

1. Floating ribs-2 pairs

2. Collar bones-3 pairs

3. Salivary glands-1 pair

4. Cranial nerves-10 pairs

The contractile protein of skeletal muscle involving ATPase activity is :

1. tropomyosin                 

2. myosin       

3. $\mathrm{\alpha }$-actinin                     

4. troponin