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 biology locomotion and movement locomotion in animals bones and movements muscle contraction types of muscles muscles

Upon stimulation of skeletal muscles, calcium is immediately made available for binding to troponin from :

  1. Blood

  2. Lymph

  3. Sacroplasmic reticulum

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

Answer is option C i.e. "Sacroplasmic reticulum"
Neurotransmitter acetylcholine generates an action potential in the sarcolemma causing the release of calcium ions into the sarcoplasm from the sarcoplasmic reticulum.
When Ca++ level increases it leads to the binding of calcium with a sub-unit of troponin on actin(thin) filaments and thereby activating the movement.

Multiple choice biology locomotion and movement locomotion in animals bones and movements muscle contraction types of muscles muscles

An iron-containing protein myoglobin is present in the

  1. Spleen

  2. Lungs

  3. Muscles

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Myoglobin is the iron and oxygen-binding protein that is found in the muscle tissue of the vertebrates and in almost all mammals. This contains heme, the pigment responsible for the red color of meat.

Therefore, the correct answer is option C.

Multiple choice biology locomotion and movement locomotion in animals bones and movements muscle contraction types of muscles muscles

What would be the result of an allele that codes for all actin molecules to be synthesized in linear chains?

  1. Immovable muscles

  2. Smooth muscle tissue

  3. Normal sarcomere structure

  4. Degeneration of muscle tissue

  5. Muscle tendons that cannot attach
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Sarcomere is the structural and functional unit of a myofibril and consists of thick myosin filaments and thin actin filaments. If the allele for actin filament continues to synthesize linear chains of the protein, sarcomere structure would be same as normal. Thus, the correct answer is option C.

Multiple choice biology locomotion and movement locomotion in animals bones and movements muscle contraction types of muscles muscles

Which of the following is the result of synthesis of actin molecule(coded by allele) in a linear chain?

  1. Immovable muscles

  2. Smooth muscle tissue

  3. Normal sarcomere structure

  4. Degeneration of muscle tissue

  5. Muscle tendons that cannot attach
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • A sarcomere is the functional unit (contractile unit) of a muscle fibre. 
  • Each sarcomere contains two types of myofilaments: thick filaments, composed primarily of the contractile protein myosin, and thin filaments, composed primarily of the contractile protein actin. Hence, Normal sarcomere structure is the result of the synthesis of actin molecule(coded by allele) in a linear chain.
So, the correct answer is 'Normal sarcomere structure'.
 
Multiple choice biology locomotion and movement locomotion in animals bones and movements muscle contraction types of muscles muscles

The binding of troponin to calcium in muscle cells exposes the binding site of

  1. Tropomyosin

  2. Myosin

  3. ATP

  4. ADP
  5. ${P} _{i}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

  • Muscle contraction thus results from an interaction between the actin and myosin filaments that generates their movement relative to one another. 
  • The molecular basis for this interaction is the binding of myosin to actin filaments, allowing myosin to function as a motor that drives filament sliding. Hence, The binding of troponin to calcium in muscle cells exposes the binding site of Myosin.
So, the correct answer is 'Myosin'.

Multiple choice biology locomotion and movement locomotion in animals bones and movements muscle contraction types of muscles muscles

ATP-ase needed for muscle contraction is present over

  1. Aetinin

  2. Troponin

  3. Myosin

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

ATPase needed for muscle contraction is present over the myosin. Myosin binds to actin at a binding site. Myosin has another binding site for ATP at which enzymatic activity of myosin ATPase hydrolyzes ATP to ADP which releases an inorganic phosphate molecule and energy. The energy released during ATP hydrolysis changes the angle of the myosin head into a cocked position. The myosin head is then in a position for further movement possessing potential energy. The enzyme myosin ATPase catalyses the reaction in the presence of Ca$^{2+}$ and Mg$^{2+}$. So, the correct answer is 'Myosin'.

Multiple choice biology locomotion and movement locomotion in animals bones and movements muscle contraction types of muscles muscles

Which among the following is not involved in the muscular contraction?

  1. Ca ion

  2. Troponin

  3. Actin

  4. Mg ion
Reveal answer Fill a bubble to check yourself
D 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. 
  • 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.
  • magnesium acts as a natural calcium blocker to help muscles relax. Hence Mg ion is not involved in the muscular contraction but it is involved in muscle relaxation by blocking calcium ions.
  • So, the correct answer is 'Mg'
Multiple choice biology locomotion and movement locomotion in animals bones and movements muscle contraction types of muscles muscles

Name the ion responsible for unmasking of active sites for myosin for cross-bridge activity during muscle contraction.

  1. Calcium

  2. Magneisum

  3. Sodium

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

Calcium is the ion released into the sarcoplasma from sarcoplasmic reticulum during the polarisation.  Ca++ attaches to the Troponin-C. This brings a confirmational change in the tropomyosin. As a result unmasking of active sites on actin for myosin takes place. Cross bridges are formed between actin and myosin. This results in muscle contraction.

Magnesium is used in phosphorylation reactions involving ATP.
Sodium and potassium help in maintaining the membrane potential.
So the correct option is A.

Multiple choice biology locomotion and movement locomotion in animals bones and movements muscle contraction types of muscles muscles

Calcium ions bring about muscle contraction through

  1. Activation of myosin ATP-ase

  2. Exposing active sites of actin filaments

  3. Mobilisation of food reserve

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

  • The muscle contraction cycle is triggered by calcium ions binding to the protein complex troponin, exposing the active-binding sites on the actin. 
  • ATP can then attach to myosin, which allows the cross-bridge cycle to start again; further muscle contraction can occur. 
  • Cardiac myosin activators stimulate myosin ATPase, thereby increasing force generation. Hence, Calcium ions bring about muscle contraction
  • through Activation of myosin ATP-ase.
 So, the correct answer is 'Activation of myosin ATP-ase'.

Multiple choice biology skeleton and movements locomotion in animals bones and movements muscle contraction

EDTA injected into muscles combines with $Ca^{2+}$ and

  1. Stops contraction

  2. Causes contraction

  3. Slows down contraction

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • Active sites for myosin 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. 
  • 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.
  • When EDTA  injected into muscles combines with Ca ++ and prevents the binding of calcium with troponin and slows down contraction.
  • So, the correct answer is 'Slows down contraction'. 
Multiple choice biology control and co-ordination in plants and animals voluntary and involuntary movements impulse and its transmission coordination in human beings- nervous control

Muscle A and muscle B are the same size, but muscle A is capable of much finer control than muscle B. Which B. Which one of the following is likely to be true of muscle A?

  1. It contains fewer motor units than muscle B.

  2. It has larger sarcomeres than muscle B.

  3. IT is controlled by more neurons than muscle B.

  4. It is controlled by ewer neurons than muscle B.
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice biology control and co-ordination in plants and animals voluntary and involuntary movements impulse and its transmission coordination in human beings- nervous control

Muscles cell are branched. 

  1. True

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

Cardiac muscle cells are branched, but skeletal muscle cells are cylindrical and unbranched. Since the question refers to muscle cells generally, the statement is false as it does not apply to all muscle types.