Biology · General Awareness

Muscle Biology

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

Find out the correct sequence of muscle structures/components present one within the other 

  1. Muscle fibre $\longrightarrow $ Myofilament $\longrightarrow $ Muscle bundle $\longrightarrow $ Myofibril
  2. Muscle bundle $\longrightarrow $ Muscle fibre$\longrightarrow $ Myofibril $\longrightarrow $ Myofilament
  3. Muscle bundle $\longrightarrow $ Muscle fibre $\longrightarrow $ Myofilament $\longrightarrow $ Myofibril
  4. Muscle fibre $\longrightarrow $ Muscle bundle $\longrightarrow $ Myofilament $\longrightarrow $ Myofibril
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice zoology movement and locomotion in man structure of skeletal muscle muscles and their structure skeletal muscles

The protoplasmic segment of a striated muscle fibre is termed as

  1. Sarcoplasm

  2. Sarcomere

  3. Neuromere

  4. Metamere
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sarcomere is the smallest contractile unit of striated muscle fibre. Sarcomere occurs as repeating units along the length of a myofibril, occupying the region between Z lines of the myofibril. 

Sarcoplasm is the cytoplasm of a muscle fibre. It is a water solution containing ATP and phosphogens, as well as the enzymes of intermediate and product molecules involved in many metabolic reactions. 
Neuromere is a metameric segment of CNS. 
Metamere is a linear series of primitively similar segments into which the body of higher invertebrate and vertebrate is divisible.

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

Contractile fibrils of muscles are called

  1. Neurofibrils

  2. Callogen fibres

  3. Myofibrils

  4. Yellow fibres
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

  • Each muscle fibre(muscle cell) is lined by the plasma membrane called sarcolemma enclosing the sarcoplasm(cytoplasm of muscle fibre). 
  • The characteristic feature of the muscle fibre(muscle cell) is the presence of a large number of parallelly arranged filaments in the sarcoplasm called myofilaments or myofibrils.
  • Each myofibril is made up of two kinds of proteins. They are actin and myosin.
  • The function of the myofibril is to perform muscle contraction via the sliding-filament model. Hence Contractile fibrils of muscles are called myofibrils.
  • So, the correct answer is 'Myofibrils'.

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

Sarcomere is the functional unit of contraction in a muscle fibre. Identify the portion of myofibril that constitutes a sarcomere

  1. Portion of myofibril between two successive Z-lines

  2. Portion of myofibril between two successive I-bands

  3. Portion of myofibril between two successive A-bands

  4. Portion of myofibril between two successive M-lines
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • The ‘A’ and ‘I’ bands are arranged alternately throughout the length of the myofibrils. The light bands contain actin(thin filament) and are called I-band or Isotropic band, whereas the dark band called ‘A’ or Anisotropic band contains myosin(thick filament).
  •  In the centre of each ‘I’ band is an elastic fibre called ‘Z’ line which bisects it. The thin filaments are firmly attached to the ‘Z’ line. The portion of the myofibril between two successive ‘Z’ lines is considered as the functional unit of contraction and is called a sarcomere Sarcomere is considered as the functional unit of contraction in a muscle fibre.
  • So, the correct answer is 'Portion of a myofibril between two successive Z-lines'.
Multiple choice zoology movement and locomotion in man structure of skeletal muscle muscles and their structure skeletal muscles

Anisotropic band is made of

  1. Myosin filaments

  2. Actin filaments

  3. Elastin filaments

  4. Both A and B
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). The ‘A’ and ‘I’ bands are arranged alternately throughout the length of the myofibrils.
  • The A band in skeletal muscle is also called as anisotropic band.
  • The anisotropic band is made of both actin filaments and myosin filaments.
  • So, the correct answer is 'Both A and B'.
Multiple choice zoology movement and locomotion in man structure of skeletal muscle muscles and their structure skeletal muscles

Skeletal muscles are controlled by

  1. Somatic nerves

  2. Autonomic nerves

  3. Parasympathetic nerves

  4. Sympathetic nerves
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Somatic nerves are part of the peripheral nervous system and are responsible for the voluntary control of skeletal muscles. Autonomic, sympathetic, and parasympathetic nerves control involuntary functions like heart rate and digestion.

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

H-zone in skeletal muscle fibre is due to

  1. Extension of myosin filaments in central portion of A-band.

  2. Absence of myofibrils in the central portion of A-band.

  3. Central gap between filaments in A-band.

  4. Central gap between actin filaments extending through myosin filaments in A-band.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • Myofibril is made up of two types of filaments. They are thin filament(actin) and thick filament(myosin).
  • The light bands contain actin and are called I-band or Isotropic band, whereas the dark band called ‘A’ or Anisotropic band contains myosin. The ‘A’ and ‘I’ bands are arranged alternately throughout the length of the myofibrils.
  •  In a resting state, the edges of thin filaments on either side of the thick filaments partially overlap the free ends of the thick filaments leaving the central part of the thick filaments. This central part of thick filament, not overlapped by thin filaments is called the ‘H’ zone.
  • Hence H-zone in skeletal muscle fibre is due to Central gap between actin filaments extending through myosin filaments in A-band.
  • So, the correct answer is 'Central gap between actin filaments extending through myosin filaments in A-band'.
Multiple choice zoology movement and locomotion in man structure of skeletal muscle muscles and their structure skeletal muscles

Identify the correct statements.

1. A-bands are dark and contain myosin.
2. I-bands are light and contain actin.
3. During the action, A band contracts.
4. The part between two Z-lines is sarcomere.
5. The central part of thin filament, not overlapped by thick filament is the H-zone.

  1. 1, 2 and 3 are correct

  2. 1, 3 and 5 are correct

  3. 1, 2 and 4 are correct

  4. 1 and 2 are correct

  5. 1, 2, 3 and 5 are correct
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • The ‘A’ and ‘I’ bands are arranged alternately throughout the length of the myofibrils. The light bands contain actin(thin filament) and are called I-band or Isotropic band, whereas the dark band called ‘A’ or Anisotropic band contains myosin(thick filament). In the centre of each ‘I’ band is an elastic fibre called ‘Z’ line which bisects it. The thin filaments are firmly attached to the ‘Z’ line. The portion of the myofibril between two successive ‘Z’ lines is considered as the functional unit of contraction and is called a sarcomere 
  • Utilizing the energy from ATP hydrolysis, the myosin head now binds to the exposed active sites on actin to form a cross bridge. 
  • 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 the ‘I’ bands get reduced, whereas the ‘A’ bands retain the length.
  •  The central part of thick filament, not overlapped by thick filament is the H-zone.
  • So, the correct answer is '1,2 and 4
Multiple choice zoology movement and locomotion in man structure of skeletal muscle muscles and their structure skeletal muscles

Myofibrils show dark and light bands in

  1. Cardiac muscles

  2. Unstriped muscles

  3. Striped muscles

  4. Both A and C
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • The striated appearance of skeletal and cardiac muscle tissue is a result of repeating bands of the proteins actin and myosin that are present along the length of the myofibril.
  • The light bands contain actin and are called I-band or Isotropic band, whereas the dark band called ‘A’ or Anisotropic band contains myosin. Hence called striped muscles due to the presence of striations.
  • Hence Myofibrils show dark and light bands in Cardiac muscles and striped muscles.
  • So, the correct answer is 'Both A and C'.
Multiple choice zoology movement and locomotion in man structure of skeletal muscle muscles and their structure skeletal muscles

Cross bridges of sarcomere in skeletal muscle are made up of 

  1. Actin

  2. Myosin

  3. Troponin

  4. Tropomyosin
Reveal answer Fill a bubble to check yourself
B Correct answer
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'.
Multiple choice zoology movement and locomotion in man structure of skeletal muscle muscles and their structure skeletal muscles

State whether the following statements are true or false.
Intercalated discs make up striations in the skeletal muscle.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
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'.

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

Which muscles having functionally multinucleated conditions?

  1. Cardiac muscle

  2. Smooth muscle

  3. Voluntary muscle

  4. All of these
Reveal answer Fill a bubble to check yourself
C Correct answer
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".

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

  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
Reveal answer Fill a bubble to check yourself
B Correct answer
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'.

Multiple choice biology animal tissue muscular tissues muscle tissue muscle tissues

The muscle fatigue occurs due to accumulation of

  1. ${ CO } _{ 2 }$

  2. Lactic acid

  3. Creatine phosphate

  4. Myosin ATPase
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Aerobic respiration gives more energy but is a slow process. Anaerobic respiration like lactic acid fermentation is a fast process but releases less energy. In the case of rapid muscular contraction, the muscles perform lactic acid fermentation to provide for rapid energy intake. This process releases lactic acid which causes pain and muscle fatigue. So, the correct answer is option B.