Biology · General Awareness

Muscle Biology

798 Questions

Muscle biology covers the structures, functions, and contraction mechanisms of skeletal, cardiac, and smooth muscles. Test questions target filaments, stimuli, and specific muscle roles. A clear understanding helps secure marks in biology sections.

Skeletal muscle controlCardiac muscle propertiesMuscle contraction mechanismActin and myosin filamentsMuscle functions

Muscle Biology Questions

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

Which of the following are the regulatory protein in the  muscle contraction?

  1. Troponin and tropomyosin

  2. Troponin and actin

  3. Myosin and tropomyosin

  4. Actin and tropomyosin
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Actin and myosin are the contractile proteins, and they interact with each other, causing contraction, while troponin and tropomyosin are regulatory proteins that regulate the interaction between actin and myosin. 
  • Myofilaments(actin and myosin) are packed in functional units of striated muscle referred to as sarcomeres. 
  • Hence, Troponin and tropomyosin are the regulatory protein in muscle contraction.
  • So, the correct answer is 'Troponin and tropomyosin'.
Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

In the sarcoplasmic reticulum of resting muscle, Ca$^{2+} $ are held together by which protein?

  1. Nebulin

  2. Desmin

  3. Calsequestrin

  4. Calmodulin
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In the sarcoplasmic reticulum of resting muscle, Ca2+ are held together by calmodulin. Calmodulin is also called as calcium-modulated protein, is a calcium-binding protein present in the cytoplasm. It is present in all eukaryotic cells.it's the function is to bind calcium ions in resting muscle. when the motor impulse is generated and reached to neuromuscular junctions calcium is released from calmodulin which facilitates muscle contraction.

So, the correct answer is 'Calmodulin'.

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

Cross bridges between actin and myosin is broken up by

  1. Hydrolysis of AP

  2. Binding of ATP to the myosin head

  3. Binding of calcium to the subunit of troponin

  4. Exposure of tropomyosin
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • Each myosin (thick) filament is also a polymerized protein. Many monomeric proteins called Meromyosins constitute one thick filament.
  • Each meromyosin has two important parts, a globular head with a short arm and a tail. The globular head is an active ATPase enzyme and has binding sites for ATP and active sites for actin.
  • The globular head of a myosin molecule that projects from a myosin filament in muscle and is held to attach temporarily to an adjacent actin filament and draw it into the A band of a sarcomere between the myosin filaments to form a cross bridge.
  • Cross bridges between actin and myosin are broken up by Binding of ATP to the myosin head and The myosin, releasing the ADP and P1 and muscle goes back to its relaxed state.
  • So, the correct answer is 'Binding of ATP to the myosin head'.
Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

Muscle cells contain _________ protein.

  1. Casein

  2. Actin

  3. Myosin

  4. Both B and C
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Muscle is a soft tissue found in most animals. Muscle cells contain protein filaments of actin and myosin that slide past one another, producing a contraction that changes both the length and the shape of the cell. Therefore, (d) is the correct answer. 

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

Major protein in the thick filaments of skeletal muscle fiber is

  1. Myosin

  2. Actin

  3. Tropomyosin

  4. Troponin
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Skeletal muscle fiber is made up of two types of filaments. They are thick filament and thin filament.
  • Thick filament is made up of a protein called Myosin.
  • Each myosin (thick filament) is made up of Many monomeric proteins called Meromyosins.
  • Hence Major protein in the thick filaments of skeletal muscle fiber is Myosin.
  • So, the correct answer is 'Myosin'.
Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

Myosin filaments are localized in

  1. Z-Band

  2. H-Band

  3. A-Band

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • Each myofibril (muscle filament)has alternate dark and light bands on it. 
  • The light bands contain actin and are called I-band or Isotropic band, whereas the dark band called ‘A’ or Anisotropic band contains Myosin.
  • Myosin filaments are also called as Thick filaments.
  • Hence Myosin filaments are localized in A-Band.
  • So, the correct answer is 'A-Band'.
Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

Which one of the following is wrongly matched.

  1. Myosin - Contractile protein

  2. Tendon - Connective tissue

  3. Smooth muscle - Involuntary muscle

  4. Red muscle - Myoglobin

  5. Troponin - Fibrous protein
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Troponin is a regulatory protein, not a fibrous protein. Fibrous proteins are typically structural, like collagen or keratin.

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

Component of actin filament of a sarcomere is

  1. Myosin and troponin

  2. Troponin and actin

  3. Actin and myosin

  4. Actin, troponin and tropomyosin
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • Skeletal muscle fiber is made up of two types of filaments. They are thick filament(myosin) and thin filament(actin). 
  • Each actin (thin) filament is made of two ‘F’ (filamentous) actins helically wound to each other. 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 Component of actin filament of a sarcomere is Actin, troponin, and tropomyosin.
  • So, the correct answer is 'Actin, troponin, and tropomyosin'.
Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

Which is wrongly matched?

  1. Red muscle-myoglobin

  2. Tendon-connective tissue

  3. Troponin-fibrous protein

  4. Smooth muscle-involuntary muscle

  5. Myosin-contractile protein
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • The myofibril is composed of two types of filaments. They are thick filament(Myosin) and Thin filament(Actin).
  • 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. In the resting state tropomyosin partially covers myosin binding site on actin. Tropomyosin is a fibrous protein and Troponin is a globular protein.
  • So, the correct answer is 'Troponin-fibrous protein'
Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

Read the statements regarding muscle proteins and identify the correct statements
i. Actin is a thin filament and is made up of two F-actins
ii. Complex protein, tropomyosin is distributed at regular intervals on the troponin
iii. Myosin is a thick filament which is also a polymerized protein
iv. Globular head of meromyosin consists of light meromyosin (LMN)

  1. i, iii and iv are correct

  2. i and iii are correct

  3. i, ii and iii are correct

  4. i, ii and iv are correct

  5. ii and iv are correct
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • Myofibril is made up of two types of filaments.They are thin filament(actin) and thick filament(myosin).
  • 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.
  • Each myosin (thick) filament is also a polymerized protein. Many monomeric proteins called Meromyosins, constitute one thick filament. Globular head of meromyosin consists of Heavy meromyosin (HMM).
  • So, the correct answer is 'i, ii and iii are correct'
Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

In a resting muscle fibre, tropomyosin partially covers

  1. Ca-binding sites on actin

  2. Ca-binding sites on troponin

  3. Actin binding sites on myosin

  4. Myosin binding sites on actin
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • The myofibril is composed of two types of filaments. They are thick filament (Myosin) and Thin filament (Actin).
  • 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. In the resting state tropomyosin partially covers myosin binding site on 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.
  • Hence In a resting muscle fibre, tropomyosin partially covers myosin binding sites on actin.
  • So, the correct answer is 'Myosin binding sites on actin'.
Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

Which one of the following is the thick filament of muscle?

  1. Actin

  2. Troponin

  3. Tropomyosin

  4. Myosin
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • Myofibril is made up of two types of filaments. They are thick filament (myosin) and thin filament (actin). 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.
  • Hence myosin is the thick filament of muscle.
  • So, the correct answer is 'Myosin'.
Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

Which one of the following is wrongly matched?

  1. Myosin - contractile protein

  2. Tendon - connective tissue

  3. Smooth muscle - involuntary muscle

  4. Troponin - fibrous protein
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
A. Myosin are made up of polymerised protein which make thick myofilament. They are found in A- band of sarcomere and are contractile protein.
B. Tendon is dense regular connective tissue which join muscle to bone and made up of white collagen fibres.
C. Smooth muscle is non striated muscle with tapering ends and spindle shaped. They are involuntary muscles which are not under control and do not get fatigue.
D. Thin myofilament is made up of three proteins - actin, tropomyosin and troponin. Actin is a globular protein. Tropomyosin is a fibrous protein. At regular intervals of tropomyosin, a complex protein called troponin. It is a trimeric protein having three units - troponin I, troponin T and troponin C.
So, the correct answer is 'Troponin-fibrous protein'.
Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

The microfilaments of a muscle

  1. Are arranged in compartments known as sarcomeres

  2. Are composed of proteins known as actin and myosin

  3. Are the actual contractile elements of the fibre

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

  • Myofilament is the filaments of myofibrils, constructed from proteins, principally myosin or actin.
  • They are made up of thick and thin myofilament, which helps to give it a striped appearance.
So, the correct option is 'all of the above'.