Which of the following has ATPase activity?

1. Actin                            2. Tropomyosin

3. Head of myosin             4. Troponin

The globular head of the myosin filament has active site/s for binding to:

 I. ATP

II. the binding site for actin filament 

III. Calcium

1. Only I

2. Only I and II

3. Only II and III

4. I, II, and III

The contractile protein of skeletal muscle involving ATPase activity is :

1. tropomyosin                 

2. myosin       

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

4. troponin

Skeletal muscles appear striated due to the presence of two characteristic proteins in alternating dark and light bands. Which of the following is a correct match of the protein with its light refractive property and color?

       Protein                  Colour                 Property

(1)  Myosin                   Light                 Anisotropic

(2)  Actin                      Dark                 Anisotropic

(3)  Myosin                   Dark                  Isotropic

(4)  Actin                      Light                  Isotropic

The functions of tropomyosin in skeletal muscle include:
(1) Sliding on actin to produce shortening

(2) Release Ca+2 after initiation of contraction

(3) Acting as "relaxing protein" at rest by covering up the sites where myosin binds to actin

(4) Generates ATP