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Muscular System — Free MYP4 Biology Practice Questions
1QuestionTypes of musclesConcept Practice
2 marks~3 minCriterion D
During a 400 m sprint, fast-twitch muscle fibres rely heavily on anaerobic respiration, producing lactate and hydrogen ions that lower intracellular pH and contribute to muscle fatigue. Some athletes use buffering supplements such as sodium bicarbonate to delay this pH drop and sustain performance.
a
Outline one real-world application of understanding anaerobic respiration in fast-twitch muscle fibres for athletic training or performance. [1]
b
Discuss one ethical issue raised by the use of supplements that delay muscle fatigue in competitive sport. [1]
Solutions
2QuestionHow muscles workAssessment Practice
3 marks~5 minCriterion A
The graph below shows how sarcomere length affects the force of contraction in a skeletal muscle fibre.
a
Describe the trend shown in the graph. [1]
b
Using the sliding filament theory, explain why force is greatest at a sarcomere length of 2.0–2.2 μm. [1]
c
A muscle that has been overstretched to a sarcomere length of 3.5 μm generates almost no force. Analyse why this occurs and predict what would happen to force if the sarcomere were then compressed to 1.0 μm. [1]
Solutions
3QuestionInteraction with other systemsConcept Practice
4 marks~6 minCriterion A
The diagram below shows a bicep curl: the arm moves from a fully extended position to a fully flexed position. The humerus, radius, ulna, biceps brachii, and triceps brachii are labelled.
a
Identify the bones that move during a bicep curl and state the type of joint present at the elbow. [2]
b
Explain how the biceps brachii and triceps brachii function as an antagonistic pair to produce both the flexion and extension phases of a bicep curl. [2]
Solutions
4QuestionHow muscles workAssessment Practice
5 marks~8 minCriterion D
An experiment measured sarcomere length and tension during a single muscle contraction.
Sarcomere length (m): 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6
Tension (relative units): 10, 45, 80, 95, 100, 90, 60, 25, 5
Sarcomere length (m): 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6
Tension (relative units): 10, 45, 80, 95, 100, 90, 60, 25, 5
a
State the sarcomere length at which maximum tension is produced and describe the trend in tension as sarcomere length increases beyond this point. [1]
b
Explain how the degree of overlap between actin and myosin filaments determines the tension a sarcomere can generate, using the sliding filament theory. [2]
c
Justify the conclusion that reduced actin–myosin filament overlap is responsible for the decline in tension at sarcomere lengths greater than 2.8 m, using specific data from the table in your reasoning. [2]
Solutions
5QuestionCommon problemsAssessment Practice
5 marks~8 minCriterion C
During intense exercise, muscles produce lactate as a by-product of anaerobic respiration. A study investigated whether lactic acid buildup directly causes muscle fatigue.
Three groups of ten athletes each were assessed:
Sprint group: 30-second sprint intervals
Jog group: steady-state jogging at 60% maximum heart rate
Control group: rested
Blood lactate (mmol/L) measured immediately after:
All athletes reported muscle fatigue after sprinting; none reported fatigue after jogging.
Three groups of ten athletes each were assessed:
Sprint group: 30-second sprint intervals
Jog group: steady-state jogging at 60% maximum heart rate
Control group: rested
Blood lactate (mmol/L) measured immediately after:
| Sprint | 12.1 | 14.5 | 11.8 | 13.2 | 15.0 | 10.9 | 16.2 | 12.7 | 13.9 | 14.1 |
|---|---|---|---|---|---|---|---|---|---|---|
| Jog | 2.3 | 2.1 | 2.5 | 2.0 | 2.4 | 2.2 | 2.6 | 2.3 | 2.1 | 2.4 |
| Control | 1.0 | 0.9 | 1.1 | 1.0 | 1.2 | 0.8 | 1.0 | 1.1 | 0.9 | 1.0 |
All athletes reported muscle fatigue after sprinting; none reported fatigue after jogging.
a
Calculate the mean blood lactate concentration for each group. [1]
b
Describe the trend in lactate concentration across the three groups and identify one anomaly in the sprint data, justifying your choice. [2]
c
Evaluate the hypothesis that lactic acid buildup directly causes muscle fatigue, using the data and identifying two limitations of the experimental design that affect this conclusion. [2]
Solutions
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