Which of the following is correct about the given figure?

(1) The length of the thick and thin myofilaments has changed.

(2) Length of both anisotropic and isotropic band has changed.

(3) The myosin cross-bridges move on the surface of actin and the thin and thick myofilaments slide past each other.

(4) Length of the sacromere remains same.

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

During muscular contraction, which of the following events occur?

(i)   H-zone disappears

(ii)  A band widens

(iii)  I band shortens

(iv)  Width of A band is unaffected

(v)  M line and Z line come closer

(1)  (i),(iii),(iv) and (v)

(2)  (i),(ii) and (v)

(3)  (ii),(iv) and (v)

(4)  (i),(ii) and (iii).

Which of the following is true for the labelled parts in the figure below?

(1) A - Z-line              - located at centre of I - band

(2) B - Thin filament   - occurs in A-band only

(3) C - Thick filament  - confined to I-band

(4) D - H-zone           - located at centre of M-line

What is the oxidation state of iron in haemoglobin?

(1)  Fe^-

(2)  Fe²⁺

(3)  Fe³⁺

(4)  Fe⁴⁺

The H-Zone in the skeletal muscle fibre is due to 

(1) the central gap between actin filaments extending through myosin filaments in the A-band

(2) extension of myosin filaments in the central portion of the A-band

(3) the absence of myofibrils in the central portion of A-band

(4) the central gap between myosin filaments in the A-band

An example of stretch reflex triggered by passive muscle movement is the

(1) tendon reflex               

(2) ipsilateral reflex

(3) flexor reflex         

(4) patellar reflex

Gerdy fibres are 

(1) ligament of neck       

(2) ligament of ankles

(3) ligament of palm       

(4) ligament of face.

Consider the diagram given below.

Parts labelled as A, B, C, D, E and F respectively indicate.

(1) Sacrum, ilium, pubis, femur, tibia and fibula

(2) Ilium, pubis, sacrum, femur, fibula and tibia

(3) Sacrum, pubis, ilium, femur, tibia and fibula

(4) Ilium, sacrum, pubis, femur, tibia and fibula

In old age, stiffness of joints is due to the 

(1) hardening of bones

(2) inefficiency of muscles

(3) decrease in synovial fluid

(4) enlargement of bones