Tag: muscles and their structure

Questions Related to muscles and their structure

Cross bridges of sarcomere in skeletal muscle are made up of 

zoology movement and locomotion in man structure of skeletal muscle muscles and their structure skeletal muscles

  1. Actin

  2. Myosin

  3. Troponin

  4. Tropomyosin

Show answer
Correct Option: B
Explanation:
  • Active sites for myosin (Thick filament) are present on actin which are masked by troponin in resting state. when  Ca++ level increases it leads to the binding of calcium with a subunit of troponin on actin(thin) filaments and thereby remove the masking of active sites for myosin.
  • Utilizing the energy from ATP hydrolysis, the myosin head now binds to the exposed active sites on actin to form a cross bridge. thus myosin forms cross bridges.
  • This pulls the attached actin filaments towards the centre of ‘A’ band.
  •  The ‘Z’ line attached to these actins are also pulled inwards thereby causing a shortening of the sarcomere, i.e., contraction.
  • Hence cross bridges of sarcomere in skeletal muscle are made up of myosin.
  • So, the correct answer is 'Myosin'.

Biceps muscle is found on

zoology movement and locomotion in man structure of skeletal muscle muscles and their structure skeletal muscles

  1. Radius

  2. Femur

  3. Ulna

  4. Scapula

Show answer
Correct Option: A
Explanation:

Bicep muscles are present at front of our upper arm. It contains two tendons that help it to attach it from the bones of the shoulder and other one is attached to the radius bone of the elbow.

So the correct option is "Radius".
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State whether the following statements are true or false.
Intercalated discs make up striations in the skeletal muscle.

zoology movement and locomotion in man structure of skeletal muscle muscles and their structure skeletal muscles

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

Intercalated discs support synchronized contraction of cardiac tissues. They occur at the Z line of the sarcomere and can be visualized easily when observing a longitudinal section of the tissue. Three types of cell junction make up an intercalated disc.

So, the option is 'False'.

Which muscles having functionally multinucleated conditions?

zoology movement and locomotion in man structure of skeletal muscle muscles and their structure skeletal muscles

  1. Cardiac muscle

  2. Smooth muscle

  3. Voluntary muscle

  4. All of these

Show answer
Correct Option: C
Explanation:

There are cardiac, skeletal and smooth muscle cells of which only skeletal or voluntary muscle cells are multinucleated. Such cells are syncytial. Skeletal muscle cells arise in the embryo as uninucleated entities. Later the cells fuse to give rise to the multinucleated muscle fibre.

So the correct answer should be option C "voluntary muscles".

Consider the following statements each with one or two blanks.
(i) Each half of pectoral girdle consists of a (A) and a (B) 
(ii) (C) is a condition of rapid spasms (wild contractions) in muscle due to low $Ca^{++}$ in body fluid.
(iii) Each organised skeletal muscle In our body is made of a number of (D) held together by a common collagenous connective tissue layer called (E) Which one of the following options correctly fills the blanks in any two of the statements ?

zoology movement and locomotion in man structure of skeletal muscle muscles and their structure skeletal muscles

  1. (C) - Muscular dystrophy, (D) - fascia, (E) - fascicle

  2. (A) - clavicle, (B) - scapula, (C) - Tetany

  3. (A) - ilium, (B) - ischium, (D) - fascicles, (E) - fascia

  4. (C) - Myasthenia gravis, (D) - fascicles. (E) - fasda

Show answer
Correct Option: B
Explanation:

Each half of pectoral and pelvic girdle consist of clavicle & scapula, tetany is a condition of rapid spasms in muscle due to low calcium ion in body fluid.

So, the correct option is '(A) - clavicle, (B) - scapula, (C) - Tetany'.

The important muscle proteins that helps in the movement are 

zoology locomotion and movement contractile protein structure of muscle muscles and their structure

  1. Actin and myosin

  2. Troponin

  3. Tropomyosin

  4. All of the above

Show answer
Correct Option: D
Explanation:
  • Skeletal muscle fiber is made up of two types of filaments. They are thick filament (myosin) and thin filament (actin). Contraction of a muscle fiber takes place by the sliding of the thin filaments over the thick filaments.
  • Myosin (thick) filament is also a polymerized protein. Many monomeric proteins called meromyosins constitute one thick filament. 
  • Each actin (thin) filament is made of two ‘F’ (filamentous) actins helically wound to each other. Each ‘F’ actin is a polymer of monomeric ‘G’ (Globular) actins. Two filaments of another protein, tropomyosin also run close to the ‘F’ actins throughout its length. A complex protein troponin is distributed at regular intervals on the tropomyosin.
  • Hence, the important muscles proteins that help in the movement are actin and myosin, troponin and tropomyosin.
  • So, the correct answer is 'All of the above'.

In resting stage, binding sites for myosin on actin filaments are masked by

zoology locomotion and movement contractile protein structure of muscle muscles and their structure

  1. Troponin

  2. Light meromyosin

  3. Heavy meromyosin

  4. Calcium ions

Show answer
Correct Option: A
Explanation:
  • Skeletal muscle fiber is made up of two types of filaments. They are thick filament (myosin) and thin filament (actin). Contraction of a muscle fiber takes place by the sliding of the thin filaments over the thick filaments.
  • Myosin (thick) filament is also a polymerized protein. Many monomeric proteins called meromyosins constitute one thick filament. 
  • Each actin (thin) filament is made of two ‘F’ (filamentous) actins helically wound to each other. Each ‘F’ actin is a polymer of monomeric ‘G’ (Globular) actins. Two filaments of another protein, tropomyosin also run close to the ‘F’ actins throughout its length
  •  In the resting state a subunit of troponin masks the active binding sites for myosin on the actin filaments.
  • So, the correct answer is 'Troponin'.

Thick filaments in muscles are polymerised proteins of

zoology locomotion and movement contractile protein structure of muscle muscles and their structure

  1. Meromyosin

  2. Actin

  3. Troponin

  4. Tropomyosin

  5. Keratin

Show answer
Correct Option: A
Explanation:
  • Myofibrils are composed of two types of filaments i.e thin filament (actin) and thick filament (myosin).
  • Actin filaments are thinner as compared to the myosin filaments, hence are commonly called thin and thick filaments respectively
  • Each myosin (thick) filament is a polymerized protein. Many monomeric proteins called meromyosins constitute one thick filament (Myosin).
  • Hence thick filaments in muscles are polymerized proteins of meromyosin.
  • So, the correct answer is 'Meromyosin'.

 The thin filaments of myofibril contain  __(A)_ actin and two filaments of (B) protein along with  (C)_  protein for masking binding site for myosin. 

zoology locomotion and movement contractile protein structure of muscle muscles and their structure

  1. A - 1F B - troponin C - Tropomyosin

  2. A - 1F B - tropomyosin C - troponin

  3. A - 2F B - troponin C - tropomyosin

  4. A - 2F B - tropomyosin C - troponin

Show answer
Correct Option: A
Explanation:

Thin filaments of myofibril contain one filament of actin and two filaments of troponin, along with tropomyosin protein.

So, the correct option is 'A - 1F B - troponin C - Tropomyosin'.

ATPase activity in muscle fibre lies with

zoology locomotion and movement contractile protein structure of muscle muscles and their structure

  1. Light meromyosin

  2. Head of heavy meromyosin

  3. Troponin

  4. Short arm of heavy meromyosin

Show answer
Correct Option: B
Explanation:
  • The myofibril is composed of two types of filaments. They are thick filament(Myosin) and Thin filament(Actin).
  • Increase in Ca++ level leads to the binding of calcium with a subunit of troponin i.e troponin-C on actin filaments and thereby remove the masking of active sites for myosin. Utilizing the energy from ATP hydrolysis, the myosin head now binds to the exposed active sites on actin to form a cross bridge.
  • Each myosin (thick) filament is also a polymerized protein. Many monomeric proteins called Meromyosins constitute one thick filament. Each meromyosin has the globular head which is an active ATPase enzyme and has binding sites for ATP and active sites for actin. Hence ATPase activity in muscle fibre lies with Head of heavy meromyosin.
  • So, the correct answer is 'Head of heavy meromyosin'.