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HMS, BM EQ-Bank 37

Describe TWO characteristics and functions of fast twitch muscle fibres.  (3 marks)

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Sample Answer

  • Fast twitch fibres have fewer mitochondria compared to slow twitch fibres
  • They rely primarily on anaerobic glycolysis for energy production
  • They are capable of producing greater force in a shorter time period
  • They fatigue more quickly than slow twitch fibres due to their energy system reliance
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Sample Answer

  • Fast twitch fibres have fewer mitochondria compared to slow twitch fibres
  • They rely primarily on anaerobic glycolysis for energy production
  • They are capable of producing greater force in a shorter time period
  • They fatigue more quickly than slow twitch fibres due to their energy system reliance

HMS, BM EQ-Bank 36

Explain the relationship between muscle fibre types and the production of movement.  (4 marks)

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Sample Answer

Structural Characteristics

  • Type I fibres have more mitochondria and are smaller in diameter, allowing them to contract steadily but with less force, making them suited for postural control and sustained movements.

  • Type II fibres are larger in diameter with fewer mitochondria, enabling them to contract quickly and produce greater force for powerful movements like jumping or lifting.

Production of movement

  • These fibre types work together but are recruited differently.

    • Type I fibres are recruited first for basic movements and maintaining posture.

    • When more force is required, Type II fibres are recruited to produce more powerful movements.

  • This relationship between fibre types allows for a range of movement capabilities, from maintaining balance to producing explosive actions.

Show Worked Solution

Sample Answer

Structural Characteristics

  • Type I fibres have more mitochondria and are smaller in diameter, allowing them to contract steadily but with less force, making them suited for postural control and sustained movements.

  • Type II fibres are larger in diameter with fewer mitochondria, enabling them to contract quickly and produce greater force for powerful movements like jumping or lifting.

Production of movement

  • These fibre types work together but are recruited differently.

    • Type I fibres are recruited first for basic movements and maintaining posture.

    • When more force is required, Type II fibres are recruited to produce more powerful movements.

  • This relationship between fibre types allows for a range of movement capabilities, from maintaining balance to producing explosive actions.

HMS, BM EQ-Bank 35

Compare the basic characteristics of fast and slow twitch muscle fibres.  (4 marks)

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Sample Answer

  • Contrasts in fibre size/diameter
  • Differences in mitochondrial density
  • Variations in capillary network
  • Differences in contraction speed capabilities
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Sample Answer

  • Contrasts in fiber size/diameter
  • Differences in mitochondrial density
  • Variations in capillary network
  • Differences in contraction speed capabilities

HMS, BM EQ-Bank 34

Outline TWO structural characteristics of slow twitch muscle fibres.  (3 marks)

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Sample Answer

  • High number of mitochondria
  • Extensive capillary network
  • High myoglobin content
  • Smaller in diameter than fast twitch fibres
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Sample Answer

  • High number of mitochondria
  • Extensive capillary network
  • High myoglobin content
  • Smaller in diameter than fast twitch fibres

HMS, BM EQ-Bank 33 MC

Which statement about Type I (slow twitch) muscle fibres' physiological adaptations is INCORRECT?

  1. They have high oxidative capacity
  2. They produce rapid, powerful contractions
  3. They have high fatigue resistance
  4. They support endurance activities
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\(B\)

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Type I (slow twitch) muscle fibres:

  • Are characterised by slower contraction speeds and lower power output compared to Type II fibres.
  • Have excellent fatigue resistance and oxidative capacity for endurance activities.
  • Do not produce rapid, powerful contractions – this is a characteristic of Type II (fast twitch) muscle fibres.

\(\Rightarrow B\)

HMS, BM EQ-Bank 32 MC

Which characteristic best describes Type IIb (fast twitch) muscle fibres?

  1. High mitochondrial density
  2. Slow contraction speed
  3. Rapid force production
  4. High fatigue resistance
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\(C\)

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Considering all Options:

A. High mitochondrial density – INCORRECT

  • This is actually a characteristic of Type I (slow twitch) fibres
  • Type IIb fibres have relatively low mitochondrial density
  • This feature wouldn’t support their primary function of rapid force production

B. Slow contraction speed – INCORRECT

  • This is the opposite of Type IIb fibre characteristics
  • Type IIb fibres have fast contraction speeds
  • This is a characteristic of Type I (slow twitch) fibres

C. Rapid force production – CORRECT

  • Type IIb (fast twitch) muscle fibres are characterised by their ability to produce rapid, powerful contractions.
  • This is their primary distinguishing characteristic and function within the muscular system.

D. High fatigue resistance – INCORRECT

  • Type IIb fibres fatigue quickly
  • High fatigue resistance is a characteristic of Type I (slow twitch) fibres
  • Type IIb fibres’ rapid force production capability means they tire quickly

\(\Rightarrow C\)