Match Column-I with Column-II:

Column-I	Column-II
A.   Structural and functional unit of a myofibril B.   Protein of thin filament C.   Protein of thick filament D.   The central part of thick filament not overlapped by thin filament	I. H-zone II. Myosin III. Sarcomere IV. Actin

1. A - I, B - II, C - III, D - IV

2. A - I, B - III, C - II, D - IV

3. A - I, B - IV, C - III, D - II

4. A - III, B - IV, C - II, D - I

Sarcomere is the area between:

(1) 2 H-zones       

(2) 2 Z-lines                  

(3) 2 M-lines                  

(4) 2 A-bands

Light bands (thin filaments) contain actin and are called:

1. A-bands or Isotropic band            

2. A-bands or Anisotropic bands

3.  I-bands or Isotropic bands           

4.  I-bands or Anisotropic bands

Dark bands (thick filaments) contain myosin and are called:

1. A-bands or Isotropic band            

2. A-bands or Anisotropic bands

3. I-bands or Isotropic bands           

4. I-bands or Anisotropic bands

Choose the letter from the figure that most appropriately corresponds to the structure:

I.A-band       II. I-band           III.    Sarcomere         IV.     H-zone

V.Myosin       VI.Actin, Troponin, Tropomyosin             VII.   Z –line

1. I - E, II - D, III - F, IV - G, V - B, VI- C, VII - A

2. I - E, II - D, III - C, IV - G, V - B, VI - A, VII - F

3. I - E, II - D, III - F, IV - G, V - C, VI - A, VII - B

4. I - E, II - D, III - F, IV - A, V - B, VI - C, VII - G

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

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

Following is the figure of actin (thin) filaments. Identify A, B and C:

1. A - Tropomyosin, B - Troponin, C - F-actin

2. A - Troponin, B - Myosin, C - Tropomyosin

3. A - Troponin, B - Tropomyosin, C - Myosin

4. A - Troponin, B - Tropomyosin, C - F-actin

The above figure is related with myosin monomer (meromyosin). Identify A to C:

1. A - head, B - cross arm, C - GTP binding sites

2.  A - head, B - cross arm, C - Ca⁺² binding sites

3.  A - head, B - cross arm, C - ATP binding sites

4.  A - cross arm, B - head, C - ATP binding sites

The action potential that triggers a muscle contraction travels deep within the muscle cell by means of:

(1) Sarcoplasmic reticulum                

(2) Transverse tubules

(3) Synapse                                      

(4) Motor end plates