Tag: muscle contraction

Questions Related to muscle contraction

Which of the following ions help in muscle contraction ?

muscle contraction locomotion and movements biology

  1. $K^+$ and $Mg^{++}$

  2. $Na^+$ and $K^+$

  3. $Ca^{++} $ and $Na^{++}$

  4. $Ca^{++}$ and $Mg^{++}$

Show answer
Correct Option: C
Explanation:

' Ca${++}$ and Na${++}$ ' help in muscle contraction. So, the correct answer is (c).

Which of the following is incorrect regarding muscle contraction ?

muscle contraction locomotion and movements biology

  1. Actin and myosin make actomyosin

  2. Phosphate reserve comes from phosphoaeatine

  3. Chemical energy is converted into mechanical energy

  4. Mechanical energy is converted into chemical energy

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Correct Option: D
Explanation:

During muscle contraction, actin and myosin form actomyosin, phosphate reserve comes from phosphocreatine and chemical energy is changed into mechanical energy. So, the correct answer is (d).

Active sites on the actin filaments are exposed when the

muscle contraction locomotion and movements biology

  1. $Mg^{+}$ ions bind with troponin

  2. $Ca^{++}$ ions bind with tropomyosin

  3. $Ca^{++}$ ions bind with troponin

  4. $Mg^{++}$ ions bind with troponin

Show answer
Correct Option: C
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.

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

muscle contraction locomotion and movements biology

  1. Tropomyosin

  2. Caldesmon

  3. Myosin light chain kinase

  4. Calmodulin

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Correct Option: D

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

muscle contraction locomotion and movements biology

  1. Absolute refraction

  2. Double muscle twitch

  3. Summation

  4. Fatigue

Show answer
Correct Option: C
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.

If a solution of actin is mixed with a solution of myosin, the resulting mixture becomes very viscous. If ATP is added to this viscous mixture, the viscosity is eliminated and ATP is hydrolysed to ADP and inorganic phosphate. The mixture regains viscosity if all the ATP is hydrolysed. These observations suggest that

muscle contraction locomotion and movements biology

  1. Actin and myosin bind together

  2. The complex of actin and myosin (actomyosin)

  3. ATP seems to alter the binding between actin and myosin

  4. All of the above

Show answer
Correct Option: D
Explanation:

Actomyosin is a contractile complex of actin and myosin, that together with ATP, is active during muscular contraction.
Disruption of the myosin-actin interaction requires ATP, while the myosin molecule can hydrolyze ATP into ADP and Pi.
ATP disconnects actin from myosin, after which it is hydrolyzed by the myosin molecule to produce the energy required for muscle contraction.

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

muscle contraction locomotion and movements biology

  1. Troponin

  2. Gactin

  3. Tropomyosin

  4. Meromyosin

Show answer
Correct Option: C
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'.

The contraction of muscles of shortest duration is seen in

muscle contraction locomotion and movements biology

  1. Heart

  2. Jaws

  3. Intestine

  4. Eyelids

Show answer
Correct Option: D
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.

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?

muscle contraction locomotion and movements biology

  1. Single unit smooth muscle

  2. Multi unit smooth muscle

  3. Involuntary striated muscle

  4. All of these

Show answer
Correct Option: C
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'.

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_____________.

muscle contraction locomotion and movements biology

  1. Myosin and enzymes of glycolysis

  2. Myoglobin (oxygen-binding protein)

  3. Enzymes including those of glycolysis and myoglobin

  4. Actin

Show answer
Correct Option: C