Tag: muscle contraction

Questions Related to muscle contraction

Which one of the following option gives the correct categorisation of structure of contractile proteins ?

Actin  Myosin
1 Troponin Actinin
2 Troponin tropomyosin HMM and LMM
3 'G' - actin Tropomyosin
4 Tropomyosin troponin $Ca^{++}$ binding site
muscle contraction locomotion and movements biology

  1. 1

  2. 2

  3. 3

  4. 4

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Correct Option: A
Explanation:

Troponin is attached protein tropomyosin and lies within the groove between actin filaments in the muscle tissue. The calcium attaches the troponin which changes the shape exposing binding sites for myosin on the actin filament. So the correct answer is 1.

The energy of muscle contraction is most directly obtained from____________.

muscle contraction locomotion and movements biology

  1. Phosphocreatine

  2. ATP

  3. Anaerobic respiration

  4. Aerobic respiration

Show answer
Correct Option: B
Explanation:
Answer :
i) The contraction of skeletal muscles is an energy-requiring process. 
ii) To perform the mechanical work of contraction, actin and myosin utilize the chemical energy of the molecule Adenosine triphosphate (ATP).
iii) Adenosine triphosphate (ATP) is a complex organic chemical that provides energy to drive many processes in living cells, e.g. muscle contraction, nerve impulse propagation, and chemical synthesis. 
iv) Found in all forms of life, ATP is often referred to as the "molecular unit of currency" of intracellular energy transfer.

Therefore correct answer is option B- ATP.


In isometric contraction ;-

muscle contraction locomotion and movements biology

  1. Tone changed but length same

  2. Length changed but tone same

  3. Length and tone both same

  4. Length and tone both change

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Correct Option: A
Explanation:

Isometric is directly defined as ‘same length’ whereby ‘iso’ means the same and ‘metric’ means ‘length’ when referring to muscles. During isometric contractions, the muscle itself does not change in length while the tension never exceeds the load that must be carried. This means that while the muscle itself does not shorten, the tension will never exceed the opposing force.

Hence, the correct answer is 'Tone changed but length same'.

ATP provides energy for muscle contraction by allowing for

muscle contraction locomotion and movements biology

  1. An action potential formation in the muscle cell

  2. Cross bridge detachment of myosin from actin

  3. Cross bridge detachment of myosin to actin

  4. Release of $C{a^{ + 2}}$ from sarcoplasmic rectulum

Show answer
Correct Option: B
Explanation:
ATP enables the actin-myosin cross-bridge to detach, and release energy through its hydrolysis to enable the myosin head to return to its resting position.
So, the correct option is Cross bridge detachment of myosin from actin.

During muscular contraction, the myosin head binds to the exposed active sites on actin to form a?

muscle contraction locomotion and movements biology

  1. Motor unit

  2. Motor end plate

  3. Cross bridge

  4. None of the above

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Correct Option: A

Which of the following parts of the nephric tubule is incorrectly matched regarding osmotic concentration of filtrate in it?

muscle contraction locomotion and movements biology

  1. PCT - Isotonic

  2. Bowman's capsule - Hypotonic

  3. Ascending limp of loop of Henle - Hypotonic

  4. Descending limb of loop of Henle - Hypertonic

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Correct Option: A

During contraction of muscles,

muscle contraction locomotion and movements biology

  1. Actin filament slide over actin

  2. Myosin filament slide over actin

  3. Actin filament slide over myosin

  4. None of the above

Show answer
Correct Option: C
Explanation:

Mechanism of muscle contraction is best explained by the sliding filament theory, which states that contraction of a muscle fibre takes place by the sliding of the thin filaments over the thick filaments. The actin filament slide over myosin filament thus reduces the length of the sarcomere and contracts the muscle fibre.

So, the correct answer is option C.

Chemical ions responsible for muscle contraction are

muscle contraction locomotion and movements biology

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

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

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

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

Show answer
Correct Option: D
Explanation:
  • When a nerve impulse reaches the neuromuscular junction, the calcium ions are released from the sarcoplasmic reticulum. Then the calcium ions trigger muscle contraction cycle by binding to the protein complex troponin, exposing the active-binding sites on the action. and this enables the myosin molecule heads to “grab and swivel” their way along the thin filament. This is the driving force of muscle contraction.
  • Magnesium ions also play a role in regulating muscle contractions. The magnesium acts as a natural calcium blocker to help muscles relax. 
  • Hence Chemical ions responsible for muscle contraction are Ca++ and Mg++ ions.
  • So, the correct answer is 'Ca++ and Mg++ ions'.

The muscular contraction in which the tension remains the same and the mechanical work is also done is called

muscle contraction locomotion and movements biology

  1. Isotonic contraction

  2. Tetanus

  3. Isomeric contraction

  4. Single muscle twitch

Show answer
Correct Option: A
Explanation:

Answer is- A

Isotonic contractions maintain constant tension in the muscle as the muscle changes length. This can occur only when a muscle's maximal force of contraction exceeds the total load on the muscle. Isotonic muscle contractions can be either concentric (muscle shortens) or eccentric (muscle lengthens).

Cardiac muscles are characteristic in that they contract

muscle contraction locomotion and movements biology

  1. Slowly and get fatigued

  2. Quickly and get fatigued

  3. Slowly and do not get fatigued

  4. Rhythmically and do not get fatigued

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Correct Option: D
Explanation:

Cardiac muscles have mixture of properties of both  striated and unstriated muscles. .These muscle continue  rhythmic contraction throughout life under the control  of A.N.S.