Tag: zoology

Questions Related to zoology

Substance that accumulates in a fatigued muscle is

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

  1. Pyruvic acid

  2. Lactic acid

  3. CO$ _2$

  4. ADP

Show answer
Correct Option: B
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'.

When  muscles begin converting glucose into lactic acid?

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

  1. Muscles run out of oxygen

  2. Accumulation of creatine in the muscles

  3. Muscle collapse

  4. All the above

Show answer
Correct Option: A
Explanation:

  • When you exercise, your muscles move more vigorously than when you are at rest. Their metabolic rate increases. 
  • They need more energy, so they produce more of the chemical energy molecule ATP. 
  • Your muscles begin converting glucose into lactic acid instead of energy when anaerobic exercise takes over, power output drops and fatigue sets in. Hence, when Muscles run out of oxygen muscles begin converting glucose into lactic acid.
So, the correct answer is 'Muscles run out of oxygen'.

During strenuous exercise, glucose is converted into

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

  1. Glycogen

  2. Pyruvic acid

  3. Starch

  4. Lactic acid

Show answer
Correct Option: D
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 strenuous 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 during strenuous exercise,glucose is converted into lactic acid.

So,the correct answer is 'Lactic acid'.

Panting after vigorous exercise is due to

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

  1. Oxygen debt

  2. Continuity of deep breathing even after exercise

  3. Continuity of mouth breathing started during exercise

  4. Requirement of rapid dissipation of energy

Show answer
Correct Option: A
Explanation:
  • During a vigorous physical exercise, lactic acid and carbon dioxide are formed in the muscles of the body.
  • The production of lactic acid can be prevented by the flow of required oxygen to the muscles thus, our body uses more oxygen than replenished.
  • Therefore, after a vigorous exercise people pant due to to decrease in the oxygen level in the body.
  • So, the correct answer is 'Oxygen debt'.

All or none law is not applicable for

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

  1. Whole skeletal muscle

  2. Single skeletal muscle

  3. Whole cardiac muscle

  4. Single smooth muscle fibre

Show answer
Correct Option: A
Explanation:

All or none law is the principle that states that the strength by which a muscle fiber responds to a stimulus is independent of the strength of the stimulus. If that stimulus exceeds the threshold potential, the muscle fiber will give a complete response, otherwise, there is no response. 

Each muscle fiber is innervated by each nerve terminal or a nerve terminal innervates 2 or 3 muscle fibers. So their response is not related to others. The all or none law is seen is single fibers of skeletal muscles and smooth muscles but not the whole fiber. Whereas the cardiac muscle innervation is continuous and the whole muscle act as a single unit. So the whole cardiac muscle is applicable to all or none law. 
So the correct option is A.

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

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

  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

Show answer
Correct Option: B
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'.

Lactic acid causes fatigue in muscles due to

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

  1. Sensitivity of neuromuscular junction

  2. Acidity

  3. Binding of muscle calcium

  4. Causing expulsion of cations

Show answer
Correct Option: A
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'.

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:

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

  1. Sliding filament theory

  2. All or none principle

  3. Maximal oxygen uptake

  4. Contraction period

Show answer
Correct Option: B
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'.

State whether the following statements are true or false.
A drop in the force of contraction after prolonged stimulation is known as muscle fatigue.

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

  1. True

  2. False

Show answer
Correct Option: A
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.
  • 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.
  • When ATP is exhausted resulting in fatigue, lactic acid is produced 
So, the correct option is 'True'.

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.
zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects

  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

Show answer
Correct Option: A
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'.