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.

 

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

(1) fatigue   

(2) tetanus   

(3) tonus   

(4) spasm

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

The characteristics and an example of a synovial joint in humans is 

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

Given diagram shows bone of the left human hindlimb as seen from front. It has certain mistakes in labeling. Two of the wrongly labelled bones are

(1) tibia and tarsals 

(2) femur and fibula

(3) fibula and phalanges

(4) tarsals and femur 

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).

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