Identify which of the following joints allows abduction and adduction movement.
Shoulder
Knuckle
Knee
Elbow
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Syllabus Edition
First teaching 2014
Last exams 2024
Identify which of the following joints allows abduction and adduction movement.
Shoulder
Knuckle
Knee
Elbow
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The diagram shows the structures in a human elbow.
Which numbers represent a pair of antagonistic muscles?
I and II
V and IV
VI and II
II and III
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Which row correctly identifies the features of the myofibril shown in the diagram.
I. | II. | III. | IV. | |
A | Z-line | Sarcomere | A-band | H-zone |
B | H-zone | A-band | Z-line | I-band |
C | Sarcomere | H-zone | I-band | Z-line |
D | Sarcomere | I-band | A-band | Z-line |
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Which of the given options accurately identifies molecule X and describes its function?
X is troponin which provides binding sites for calcium ions
X actin which provides binding sites for myosin allowing cross-bridges to form
X is tropomyosin which changes shape to expose binding sites on actin filaments
X is ATP hydrolase enzyme used to release energy through hydrolysis of ATP to ADP and inorganic phosphate
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Which of the following explains the use of fluorescence to study muscle contraction?
I and III
I and II
I, II and III
II only
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Identify which answer gives the correct labels when describing how the skeleton can act as a lever.
X | Y | Z | |
A | Fulcrum | Effort | Load |
B | Effort | Load | Fulcrum |
C | Fulcrum | Load | Effort |
D | Load | Fulcrum | Effort |
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Select the correct answer to describe what is happening to the muscles in the insect leg to move from position 1 to position 2.
A | Flexor contracts | Extensor relaxes |
B | Flexor relaxes | Extensor Relaxes |
C | Flexor Contracts | Extensor contracts |
D | Flexor relaxes | Extensor contracts |
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Which of the following is not a range of movement demonstrated by a synovial joint such as an elbow or knee joint?
Abduction
Flexion
Extension
Inversion
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The diagram below shows the sarcomere of a muscle fibre.
Which of the following statements correctly describes the events observed during a muscle contraction?
The length of the sarcomere stays the same, the dark band gets longer and the light bands stay the same
The length of the sarcomere gets shorter, the dark band gets shorter and the distance between the two Z lines gets shorter
The length of the sarcomere stays the same, the dark band gets longer and the distance between the two Z lines gets shorter
The length of the sarcomere gets shorter, the dark band stays the same and the light bands get shorter
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One myosin powerstroke requires hydrolysis of one molecule of ATP and moves one actin filament 20 nm.
How many ATP molecules would be required to move a single actin filament 0.3 µm when the sarcomere contracts?
150 ATP
15 ATP
20 ATP
1.5 ATP
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What is the role of calcium in muscle contraction?
It initiates hydrolysis of ATP to ADP and phosphate
It binds to tropomyosin causing a conformational change in the tropomyosin protein
It binds to troponin resulting in myosin binding sites being exposed
It binds to receptors on the myosin causing cocking of the myosin head
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Which of the following describes a function of ATP in muscle contraction?
To actively transport calcium ions into myofibrils from the sarcoplasmic reticulum
To move tropomyosin and expose myosin binding sites
To allow crossbridge formation
To cause cocking of the myosin head
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Phosphocreatine is a chemical found in the muscles of vertebrates. It provides a store of phosphate ions used during muscle contraction. The graph shows the effect of phosphocreatine production on the force of muscle contraction in mice.
Which of the following best explains the results shown in the graph?
Mice that can produce phosphocreatine can run faster.
Phosphate ions can be combined with ADP to make ATP for contraction.
Phosphate ions initiate the formation of crossbridges.
Phosphate ions inhibit muscle contraction by creating an electrochemical gradient.
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Fluorescent proteins can be used to study muscle fibres during contraction.
What is the reason for the fluorescence shown as the muscle contracts?
Fluorescent protein reacts with calcium ions released during contractions
Fluorescent protein binds to the myosin filaments when cross-bridges form
Fluorescent proteins bind to the ADP released during muscle contraction
Energy from ATP activates fluorescent proteins during muscle contraction
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Identify the correct label from the electron micrograph which correctly represents the transverse section of muscle fibre shown.
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Which row of the table best describes the roles of calcium and ATP in muscle contraction?
Calcium | ATP | |
A | Binds to the tropomyosin during muscle contraction to trigger movement of the troponin | Hydrolysed to ADP and Pi to release energy to allow crossbridge formation |
B | Released from the sarcomere in response to an action potential reaching the neuromuscular junction | Binds to myosin heads resulting in 'cocking' of the myosin head |
C | Binds to myosin heads to allow crossbridge formation | Attaches to binding sites on the troponin to trigger the movement of tropomyosin |
D | Binds to the troponin to cause a change in structure and open up binding sites on actin molecules | Binds to the myosin heads producing a change in shape resulting in the release of the actin filament |
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The masseter is the strongest muscle in the human body and is responsible for lifting the lower jaw to close the mouth. The location of the masseter can be seen in the diagram.
Which of the following is not an event which would occur in the masseter as the jaw is moved towards its closed position?
Myosin heads perform a power stroke which is driven by energy released in the hydrolysis of ATP
The sarcomeres shorten as the Z lines are pulled together but the A band remains the same length.
Calcium ions are actively pumped back into the sarcoplasmic reticulum and tropomyosin covers binding sites
Troponin complexes change shape leading to the exposure of binding sites on actin molecules
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Polymyositis (PM) is an autoimmune disease of the muscles in which T-cells and B-cells are activated by antigens located on striated muscles of the body.
Which of the following statements is unlikely to result from polymyositis?
Muscle biopsies of patients shows increased levels of antibodies
Blood pressure may decrease as vascular muscle deteriorates
Patients exhibit weakening of biceps and triceps muscles
Progression of the disease may result in poor posture
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Isolated muscle fibres from frogs were injected with fluorescent indicator to allow the study of muscle contraction.
Fluorescent proteins extracted from the jellyfish species Aequorea victoria showed the processes occurring in the sarcomere during muscle contraction.
Which of the following is/are true about the indicator?
I, II and III
I and III only
I only
I and II only
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Rigor mortis describes the stiffening of body muscles due to chemical change in myofibrils after death. Knowledge of the stages of rigor mortis allows pathologists to estimate the time of death accurately.
Algor mortis refers to the gradual decrease in the body's temperature after death.
The graph shows the onset of Rigor mortis and Algor mortis after death.
Which of the following options shows a valid explanation for the trends shown in the graph?
Trend | Explanation | |
A | Body temperature decreases from 0 to 36 hours after death | Calcium is not replenished due to lack of ATP |
B | Rigor mortis peaks at 12 hours after death | ATP is no longer available to break actin-myosin cross bridges |
C | Body temperature increases slightly 36 hours after death | Energy is released from hydrolysis of the remaining ATP |
D | Rigor mortis increases gradually after death | ATP becomes depleted so muscles cannot remain relaxed. |
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