Sarcomere

Q.

Draw the diagram of a sarcomere of skeletal muscle showing different regions.

Q. Sliding filament theory can be best explained as:

1. Actin and myosin filaments do not shorten but rather slide each other
2. When myofilaments slide each other, myosin filaments shorten while actin filaments do not shorten
3. When myofilaments slide each other actin filaments shorten while myosin filament do not shorten
4. Actin and myosin filaments shorten and slide each other

Q. How to identify pseudo chiral center?

Q. Calcium is important in skeletal muscle contraction because it -

1. Detaches the myosin head from the actin filament
2. Activates the myosin ATPase by binding to it
3. Binds to troponin to remove the masking of active sites on actin for myosin
4. Prevents the formation of bonds between the myosin cross bridges and the actin filament

Q. In the resting state of muscle, the H zone is the

1. Central part of thin filament overlapped with thick filament
2. Central part of thick filament not overlapped with thin filament
3. Central part of thin filament not overlapped with thick filament
4. Central part of thick filament overlapped with thin filament

Q. Choose the option having all the correct statements:
I. Thin and thick filaments consist of myosin and actin, respectively.
II. The H-zone and I-band consists of only myosin and actin, respectively.
III. A-band contains both actin and myosin.
IV. M-line and Z-line are in the middle of thin and thick filaments, respectively.

1. Only II and III
2. Only I and IV
3. Only I and II
4. Only III and IV

Q. Which of the following statements is/are correct/incorrect?
I. A-bands of the muscle is dark and contain myosin.
II. I-bands are the light bands and contain actin.
III. During muscle contraction, the A-band contracts
IV. The part between the two Z-lines is called a sarcomere.
V. The central part of thin filament, not overlapped by thick filament is called H-zone.
Select the correct answer using the codes given below:

1. I, II and III are correct, While IV and V are incorrect
2. I, III and V are correct, while II, IV are incorrect
3. I and II are correct, while III, IV and V are incorrect
4. I, II, III, and V are correct, while IV is incorrect
5. I, II, and IV are correct, while III and V are incorrect

Q. When muscles are at rest, thin filaments overlap with thick filaments

1. inside I-band
2. inside M-line
3. outside H-zone
4. inside Z-line

Q. The smallest functional unit of striated muscle is

1. I band
2. Z band
3. Myofibril
4. Sarcomere

Q. O.S . of Mn in MnO3F is ?

Q.

Identify different regions in the structure of myofibril

​

1. 1.Z disc 2.H Zone 3.M Line 4.I band 5.A band

2. 1.Z disc 2.A Band 3.M line 4.H zone 5.I band

3. 1.Z disc 2.H Zone 3.M Line 4.A band 5.I Band

4. 1.Z disc 2. M line 3. H zone 4.A band 5.I band

Q.

Fill in the blanks.

$a.$The light band contains actin and is called …$1$… band.
$b$.The thick filaments in the …$2$… band are held together in the middle of this band by a thin fibrous membrane called …$3$… line.
c.In the centre of each ‘I’ band is an elastic fibre called …$4$… line which bisects it.
$d$.The central portion of the thick filament which is not overlapped by thin filaments is called the …‘$5$’...

Q. Which statement is correct for muscle contraction?

1. Length of H-zone is increased
2. Length of A-band remains constant
3. Length of I-band gets increased
4. Length between two Z-lines gets increased

Q. Assertion: Myofibrils have thick and thin myofilaments.
Reason: Thick myofilament consists of myosin. Thin myofilament constitutes of actin.

1. Both the assertion and reason are true and the reason is the correct explanation for the assertion
2. Assertion is true but the reason is false
3. Reason is true but the assertion is false
4. Both the assertion and reason are true but the reason is not the explanation for the assertion

Q. The term intercalated disc is used to describe special cell junctions in which tissue?

1. nervous
2. cardiac muscle
3. smooth muscle
4. connective

Q. The region between two successive Z-lines in a myofibril is

1. Sarcomere
2. Sarcosome
3. Isotropic band
4. Fascia

Q. Which of the following statements is/are correct/incorrect?
I. A-bands of the muscle is dark and contain myosin.
II. I-bands are the light bands and contain actin.
III. During muscle contraction, the A-band contracts
IV. The part between the two Z-lines is called a sarcomere.
V. The central part of thin filament, not overlapped by thick filament is called H-zone.
Select the correct answer using the codes given below:

1. I, II and III are correct, While IV and V are incorrect
2. I, III and V are correct, while II, IV are incorrect
3. I, II, III, and V are correct, while IV is incorrect
4. I, II, and IV are correct, while III and V are incorrect
5. I and II are correct, while III, IV and V are incorrect

Q. Hensen’s disc are found in

1. Myofibril of unstriated muscle
2. Myofibril of cardiac muscle
3. Myofibril of striated muscle
4. None of the above

Q. What is the name of the fundamental repeating unit of skeletal muscle fibre?

1. Sarcoplasmic reticulum
2. Motor unit
3. Myosin cross bridge
4. Sarcomere

Q.

Define myofibrils.

Q.

Draw the diagram of a sarcomere of skeletal muscle showing different regions.

Q. During muscular contraction, the myosin head binds to the exposed active sites on actin to form a

1. Motor unit
2. Cross arm
3. Cross bridge
4. Motor-end plate

Q.

The contracting units of a myofibril are called

1. flexors

2. extensors

3. sarcoplasms

4. sarcomeres

Q. Which statement is the correct for muscle contraction

1. Length of I-band increases
2. Length of the H-zone decreases
3. Length of A-band remains constant
   
4. Length of two Z-lines increases

Q. Select the correct set in options given below that represents contractile proteins of skeletal muscles.

1. Tropomyosin and myosin
2. Myosin and actin
3. Troponin and meromyosin
4. Tropomyosin and troponin

Q. The protein present in milk is

1. Casein
2. Glutelin
3. Myosin
4. Globulin

Q.

Thick and thin filaments form the (i)__________. The thick and thin filaments overlap and form a definite pattern that form repeating units called (ii)______.

1. Sarcomere and Myofibrils

2. Myofibrils and sarcomere

3. Fascia and fascicle

4. Fascicle and Fascia

Q. What is sarcomere?

1. Part between two H-lines
2. Part between two A- lines
3. Part between two I - bands
4. Part between two z - lines

Q. Sliding filament theory can be best explained as:

1. Actin and myosin filaments do not shorten but rather slide each other
2. When myofilaments slide each other, myosin filaments shorten while actin filaments do not shorten
3. When myofilaments slide each other actin filaments shorten while myosin filament do not shorten
4. Actin and myosin filaments shorten and slide each other

Q. Why pulling is preferred over pushing?