Biology · General Awareness

Muscle Biology

798 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 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

Lactic acid is generally formed in very fast acting muscle but exceptional muscle is

  1. Muscles of Iris and pupil

  2. No exception is found

  3. Muscles of heart

  4. Muscles of jaw
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cardiac muscle is exceptional because it continuously contracts rhythmically and relies entirely on aerobic metabolism, preventing the accumulation of lactic acid that causes fatigue in skeletal muscles. It contains abundant myoglobin and mitochondria to sustain continuous aerobic respiration.

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.

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

The dark bands (Black bands) (A-bands) of a skeletal
muscle are known as

  1. Isotropic bands

  2. Anisotropic bands

  3. Intercalated disc

  4. Cross bridges
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Each myofibril shows dark and light bands' The dark bands of the myofibril are termed as A-bands or anisotropic bands.

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

The muscle fatigue occurs due to accumulation of

  1. Pyruvic acid

  2. ATP

  3. Lactic acid
  4. Eroman $CO _{2}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

During muscle fatigue due to deposition of lactic acid, cytoplasm becomes acidic thereby enzyme activity stops and food is not oxidised and as the energy is not available, muscular contraction stops.

Multiple choice zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects

Glycogen is degraded to lactic acid by enzymes in muscles and liver when the animal is

  1. Exhausted

  2. Starved

  3. Killed

  4. Defaecated

  5. Copulated
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Glucose is the major source of energy in the body. excess glucose is stored in the form of glycogen in muscles and liver.
  • Most of the glycogen is stored in liver i.e 10 % of the mass of liver and the muscles contain a low amount of glycogen i.e 1% of the muscle mass.
  • When the glucose is completely utilized the animal feels exhausted, to overcome this the glycogen is degraded to lactic acid by enzymes in muscles and liver. 
  • So, the correct answer is 'Exhausted'.
Multiple choice zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects

Lactic acid deposition leads to

  1. Tetany

  2. Muscle fatigue

  3. Muscle strain

  4. Convulsions
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • Generally, the glucose undergoes metabolism in the presence of oxygen to form ATP(adenosine triphosphate) which is essential for the muscle contraction but during vigorous exercise, the body cannot meet the oxygen demand and the glucose undergoes metabolism in the absence of oxygen which results in the formation and accumulation of lactic acid.
  • Feeling of fatigue after vigorous exercise for some time is due to the accumulation of lactic acid in muscles.
  • Hence lactic acid deposition leads to muscle fatigue.
  • So, the correct answer is 'Muscle fatigue'.
Multiple choice zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects

Muscles, which are immune to fatigue, are

  1. Striped muscles

  2. Cardiac muscles

  3. Jaw muscles

  4. Skeleton muscles
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The internal movements are performed by the involuntary muscles. The involuntary muscles function on their own and cannot be controlled willingly. The cardiac muscles are the involuntary muscles which are responsible for the pumping of the heart. The heart pumps and supplies the oxygenated blood to the different tissues in the body. The smooth muscles are responsible for carrying out peristalsis in the tube like structures of the alimentary canal.

Thus, the correct answer is option B. 

Multiple choice zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects

Which of the following type of muscles are not fatigued soon?

  1. Cardiac muscle

  2. Smooth muscle

  3. Voluntary muscle

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

The correct option is D.

Cardiac and smooth muscle are not fatigued soon. Muscle fatigue is a symptom that decreases our muscles ability to perform overtime. 
Cardiac muscles, In smooth muscle myosin, the rate of ATPase activity is 10 to 100 slower than in skeletal muscle myosin. 

It must also be noted that nerve stimulation can cause a excitation or inhibition of the muscle cell.

Multiple choice zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects

Substance that accumulates in a fatigued muscle is

  1. Pyruvic acid

  2. Lactic acid
  3. CO$ _2$

  4. ADP
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Generally, the glucose undergoes metabolism in the presence of oxygen to form ATP(adenosine triphosphate) which is essential for the muscle contraction but during vigorous exercise, the body cannot meet the oxygen demand and the glucose undergoes metabolism in the absence of oxygen which results in the formation and accumulation of lactic acid. Hence Substance that accumulates in a fatigued muscle is lactic acid.
So, the correct answer is 'Lactic acid'.
Multiple choice zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects

Prolonged activation of striated muscle causes it to fatigue. What is the reason?

  1. Breakdown of glycogen into lactic acid in muscle during aerobic respiration

  2. Breakdown of lactic acid in muscle during anaerobic respiration

  3. Breakdown of lactic acid into glycogen during anaerobic respiration

  4. Produce ethanol in muscle
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • Generally, the glucose undergoes metabolism in the presence of oxygen to form ATP (adenosine triphosphate) which is essential for the muscle contraction but during vigorous exercise, the body cannot meet the oxygen demand and the glucose undergoes metabolism in the absence of oxygen (anaerobic respiration)which results in the formation and accumulation of lactic acid. The breakdown of lactic acid in muscle causes the muscle to fatigue.
  • Hence prolonged activation of striated muscle causes it to fatigue because of breakdown of lactic acid in muscle during anaerobic respiration.
  • So, the correct answer is 'Breakdown of lactic acid in muscle during anaerobic respiration'.
Multiple choice zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects

Lactic acid causes fatigue in muscles due to

  1. Sensitivity of neuromuscular junction

  2. Acidity

  3. Binding of muscle calcium

  4. Causing expulsion of cations
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

  • Lactic acid is formed and accumulated in the muscle under conditions of high energy demand, rapid fluctuations of the energy requirement and insufficient supply of O2.
  •  During exercise, there is a progressive reduction in the ability to produce muscle forces processes within the nervous system, as well as within the muscles contribute to this fatigue. 
  •  Finally, the small-diameter muscle afferents that increase firing with exercise and fatigue. Hence, Lactic acid causes fatigue in muscles due to the Sensitivity of neuromuscular junction.
 So, the correct answer is 'Sensitivity of neuromuscular junction'.

Multiple choice zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects

When a threshold stimulus is applied to a muscle, the muscle fibres will contract fully or will not contract at all. This is known as:

  1. Sliding filament theory

  2. All or none principle

  3. Maximal oxygen uptake

  4. Contraction period
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The all or none law states that the strength by which a nerve or muscle fiber responds to a stimulus that is independent of the strength of the stimulus. If that stimulus exceeds the threshold potential, the nerve or muscle fiber will give a complete response, otherwise, there is no response.
So, the correct option is 'All or none principle'.
Multiple choice zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects
Though vertebrates are aerobes, their .....(i)..... show anaerobic respiration during ......(ii)..... During this, ......(iii)...... of skeletal muscle fibers is broken down to release lactic acid and energy. Lactic acid, if accumulates causes muscle fatigue.
Fill up the blanks in the above paragraph and select the correct option.

  1. i- Skeletal muscles ; ii-heavy exercise ; iii-glucose

  2. i- Skeletal muscles ; ii-mild exercise ; iii-glycogen

  3. i- Skeletal muscles; ii-heavy exercise ; iii-glycogen

  4. i- Cardiac muscles; ii-heavy exercise ; iii-glycogen
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Muscle fatigue is the reduction in force of contraction of a muscle after prolonged stimulation. In the absence of oxygen, skeletal muscle of human beings can contract for a short time, but it gets fatigued soon. This is due to the fact that in the absence of oxygen, products of glycolysis mainly lactic acid is not disposed of and accumulates in the muscles. This leads to muscle fatigue and pain in the muscles. A muscle gets fatigued sooner after a strenuous exercise than after a mild exercise. Faster breathing for sometime after a strenuous exercise supplies extra oxygen disposes off excess lactic acid and muscle fatigue disappears.

So the correct option is 'i-Skeletal muscles ; ii-heavy exercise ; iii-glucose'.