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 muscle contraction locomotion and movements biology

Active sites on the actin filaments are exposed when the

  1. $Mg^{+}$ ions bind with troponin
  2. $Ca^{++}$ ions bind with tropomyosin
  3. $Ca^{++}$ ions bind with troponin
  4. $Mg^{++}$ ions bind with troponin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • When an electrical signal passes down the motor nerve to the muscle it causes the depolarisation of the muscle membrane.
  • This triggers the release of calcium ions into the muscle interior where they bind to troponin.
  • This causes the tropomyosin to shift from the face of the actin filament to which myosin heads needs to bind to produce contraction.
  • Thus, the active sites on actin filaments are exposed.
Multiple choice muscle contraction locomotion and movements biology

The protein whose removal enables myosin to bind actin in smooth muscle is 

  1. Tropomyosin

  2. Caldesmon

  3. Myosin light chain kinase

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

In smooth muscle, contraction is regulated by the binding of calcium to calmodulin, which then activates myosin light chain kinase.

Multiple choice muscle contraction locomotion and movements biology

If a second stimulus is applied to a muscle that is still in contraction phase; a second contraction is added to the first and results in greater muscle shortening than caused by a single stimulation; it is called

  1. Absolute refraction

  2. Double muscle twitch

  3. Summation

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

When a weak signal is sent by the CNS to contract a muscle, the smaller motor units, being more excitable than the larger ones, are stimulated first. As the strength of the signal increases, more motor units are excited in addition to larger ones, with the largest motor units having as much as 50 times the contractile strength as the smaller ones. As more and larger motor units are activated, the force of muscle contraction becomes progressively stronger. This is known as multiple fibre summations.

Multiple choice muscle contraction locomotion and movements biology

During resting stage the binding site of action of myosin remains masked by

  1. Troponin

  2. Gactin

  3. Tropomyosin

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

  • The resting stage is also called interphase. The interval in the cell cycle between two cell divisions when the individuals cannot be distinguished, the interphase goes through the resting stage. 
  • A subunit of troponin called tropomyosin is masked during the resting stage binds myosin on the actin filaments.

So, the correct option is 'Tropomyosin'.

Multiple choice muscle contraction locomotion and movements biology

The contraction of muscles of shortest duration is seen in

  1. Heart

  2. Jaws

  3. Intestine

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

Fastest-reacting muscle in the body is the Orbicularis oculi: the muscle that encircles the eye and closes the eyelid. It contracts in less than 0.01 second.

Multiple choice muscle contraction locomotion and movements biology

Which of the following type of muscle fibers are supplied with both central and autonomic nervous system and are not under the control of the will of the organism, have a rich blood supply and have the property of contraction even when they are isolated from the body temporarily?

  1. Single unit smooth muscle

  2. Multi unit smooth muscle

  3. Involuntary striated muscle

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

Cardiac muscles are the special types of muscles that show striations but they are not under the will of the organism. These are also called involuntary striated muscles because of this reason. They have rich blood supply as they have to perform the contraction regularly for the heart. They show the property of contraction even when they are isolated from the body temporarily. They are supplied with both the central and autonomic nervous system that regulate the heartbeat.

Hence, the correct answer is 'Involuntary Striated Muscles'.

Multiple choice muscle contraction locomotion and movements biology

If some skeletal muscle fibres are soaked in glycerol or a dilute salt solution, a number of proteins leak out of the fibres without any change in the appearance of the sarcomeres. Such a preparation will contract, if the fibres are supplied with magnesium ions, ATP and calcium ions. The proteins that have leaked out are of the type known as_____________.

  1. Myosin and enzymes of glycolysis

  2. Myoglobin (oxygen-binding protein)

  3. Enzymes including those of glycolysis and myoglobin

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

When skeletal muscle fibers are treated with glycerol, soluble proteins like myoglobin and various glycolytic enzymes leak out, while the structural proteins (actin and myosin) remain in the sarcomeres.

Multiple choice muscle contraction locomotion and movements biology

Read the statements about the mechanism of muscle contraction and select the correct answer.
I. Acetylcholine is released when the neural signal reaches the motor end plate.
II. Muscle contraction is initiated by a signal sent by CNS via a sensory neuron.
III. During muscle contraction, isotropic band gets elongated.
IV. Repeated activation of the muscles can lead to lactic acid accumulation.

  1. I and IV alone are correct.

  2. I and III alone are correct.

  3. II and III alone are correct.

  4. I, II and III alone are correct.

  5. I and II alone are correct.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Acetylcholine (ACh) is a neurotransmitter released by motor neurons that binds to receptors in the motor endplate when the neural signal reaches the motor endplate. Neurotransmitter release occurs when an action potential travels down the motor neuron's axon, resulting in altered permeability of the synaptic terminal membrane and an influx of calcium. Hence statement I is correct.
  • Repeated activation of the muscles can cause the anaerobic breakdown of glucose which leads to the formation of lactic acid and its accumulation. Accumulation of lactic acid can irritate muscles and cause discomfort and soreness. Hence Statement IV is correct.
  • So, the correct answer is 'I and IV alone are correct'.
Multiple choice muscle contraction locomotion and movements biology

Which of the following option shows correct order of some stages of muscle contraction from the beginning to the end of the process?

  1. Stimuli $\rightarrow$ Neurotransmitter secretion $\rightarrow$ Release of Ca$^{2+}$ $\rightarrow$ Cross bridges formation $\rightarrow$ Excitation of T-system $\rightarrow$ Sliding of actin filaments
  2. Stimuli $\rightarrow$ Neurotransmitter secretion $\rightarrow$ Excitation of T-system $\rightarrow$ Release of Ca$^{2+}$ $\rightarrow$ Cross bridges formation $\rightarrow$ Sliding of actin filaments $\rightarrow$ H band diminishes
  3. Stimuli $\rightarrow$ Excitation of T-system$\rightarrow $ Neurotransmitter secretion $\rightarrow$ Cross bridges formation $\rightarrow$ Sliding of actin filaments $\rightarrow$ H band diminishes
  4. Stimuli $\rightarrow$ Neurotransmitter secretion $\rightarrow$ Cross bridges formation $\rightarrow$ Excitation of T-system$\rightarrow$ Sliding of actin filaments
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The contraction of skeletal muscle includes ultrastructural and biochemical events. Ultrastructural events lead with stimuli excitation of T-system followed by cross-bridge formation (myosin and actin filaments involved) and the cross-bridge breakage. The biochemical events explain that stimuli lead to neurotransmitter secretion, excitation of T-system and release of Ca$^{2+}$.

Multiple choice muscle contraction locomotion and movements biology

Which of the following is not involved in muscle contraction?

  1. Creatine phosphokinase

  2. Troponin

  3. Calcium ions

  4. All of these are involved in muscle contraction
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

  • Myofibril activity is required for muscle contraction on the molecular level. 
  • When ATP binds to myosin, it separates from the actin of the myofibril, which causes a contraction.
  • Creatine phosphokinase helps in the regeneration of ATP.
  • H zone disappears and Z zone moves towards each other.
  • The muscle contraction cycle is triggered by calcium ions binding to the protein complex troponin, exposing the active-binding sites on the actin.
  • ATP then binds to myosin, moving the myosin to its high-energy state, releasing the myosin head from the actin active site.
So, the correct option is 'All of these' are involved in muscle contraction'.

Multiple choice muscle contraction locomotion and movements biology

Consider the following statements each with one or two blanks.
(i) Repeated activation of the muscles can lead to the accumulation of  (A)  due to anaerobic breakdown of glycogen in them, causing fatigue.
(ii) The globular head of meromyosin is an active ATPase enzyme and has binding sites for (B) and active sites for (C).
(iii) This central part of thick filament, not overlapped by thin filaments is called the  (D) .
Which one of the following options correctly fills the concerned blanks?

  1. (A) - glucose, (D) - A-band

  2. (A) - pyruvic acid, (B) - troponin, (C) - myosin

  3. (B) - ATP, (C) - actin, (D) - H-zone

  4. (A) - lactic acid, (D) - I-band
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Repeated activation leads to lactic acid accumulation (A). The myosin head binds ATP (B) and actin (C). The H-zone (D) is the central part of the thick filament.

Multiple choice muscle contraction locomotion and movements biology

Relaxation of muscle is due to -

  1. Pumping of $Ca^{+2}$ into sarcoplasmic cisternae

  2. Presence of ATP

  3. Confirmational change in troponin and masking of actin filaments

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

When calcium is pumped back into the sarcoplasmic reticulum breaking the link between actin and myosin. Actin and myosin return to their unbound state causing the muscle to relax.

So, the correct option is 'Pumping of 
Ca+2Ca+2 into sarcoplasmic cisternae'.

Multiple choice muscle contraction locomotion and movements biology

ATPase of the muscle is located in:

  1. actinin

  2. troponin

  3. myosin

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

The myosin filament has meromyicin and it has two important parts, a globular head and a tail. The globular head has the site for ATPase enzyme and has binding sites for ATP and active sites for actin.

This helps in the attachment of actin filament during the sliding motion.
So, the correct option is 'myosin'

Multiple choice physics the essence of change forms of energy and energy conservation energy for everything forms of energy

The muscular energy required by our body is given to us by :

  1. Air

  2. Water

  3. Oxygen

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

chemical energy is the potential of a chemical substance to undergo a transformation through a chemical reaction to transform other chemical substances.

In food different different reaction occurs which provide energy to run the body, so energy possessed in food is chemical energy and which is converted to muscular energy required to run our body.
so option D.