Muscular Movement (Edexcel International A Level Biology)

Many athletes train to improve muscle strength.

In an experiment, the effect on a muscle of 12 weeks of low or moderate training was investigated.

The graphs show the effect of 12 weeks of training on muscle strength and muscle cross-sectional area. 

The muscle strength of the athlete before moderate training was 12.5 a.u.

Calculate the muscle strength of the athlete after 12 weeks of moderate training.

Give your answer to 3 significant figures.

The types of muscle fibre present in samples taken before the training and after 12 weeks of low and moderate training were determined.

Intermediate fibres have structural properties between those of slow and fast twitch fibres.

(3)

Comment on the effect of exercise on this muscle.

Use the information in the graphs and the table to support your answer.

(3)

Skeletal muscles function to move the limbs of an organism.

The diagram represents a sarcomere from skeletal muscle.

• Calcium ions bind to troponin
• Calcium ions are released from the sarcoplasmic reticulum
• Myosin changes shape

(1)

Exercise affects the cardiac output of a person.

The graph shows the change in heart rate following exercise for an unfit person and for a fit person.

The heart rate of the unfit person decreased by 16%, 120 seconds after exercise.

Calculate the difference in percentage decrease in heart rate of these two people, 120 seconds after exercise.

Give your answer to an appropriate number of decimal places.

Calculate the heart rate of the unfit person at 5 minutes.

The change in heart rate of the unfit person is a linear relationship.

Use the equation for a straight line y = mx + c.

Explain the difference in the time it would take for these two individuals to recover from the exercise.

Describe how heart rate is controlled in response to changes in the blood, following exercise.

Many people swim as part of their regular exercise.

The table gives some information about the effect of the intensity of exercise on heart rat

Describe the relationship between the intensity of exercise and heart rate.

Regular swimming affects resting heart rate and cardiac output.

cardiac output = stroke volume × heart rate

The table shows the mean resting cardiac output and mean resting stroke volume for a group of regular swimmers and a control group.

Using the data in the table, calculate the difference in resting heart rate between these two groups.

Give your answer to 2 decimal places with appropriate units.

Explain the role of the heart in responding to regular exercise.

Use the information in both tables and your own knowledge to support your answer.

Researchers investigated how groups of rats, treated with drugs, responded to stress.

Groups of rats were stressed by moving them into a new environment. The rats were then treated with a salt solution, drug A or drug B.

The graph shows the change in mean heart rate measured over a 15‐minute period.

Calculate the percentage difference in the change in heart rate when using drug B between 5 and 12.5 minutes.

Answer ...................................................%

Compare and contrast the effects of drug A and drug B on the heart rate during the investigation.

Explain the effect of these drugs on the control of the heart rate.

Skeletal muscle is made of bundles of fibres.

Describe the role of calcium ions in producing contraction of a muscle fibre.

The table shows some features of slow and fast twitch muscle fibres.

Olympic marathon runners have a high proportion of slow twitch fibres in their muscles.

Explain how the features of slow twitch fibres, shown in the table, are of benefit to an Olympic marathon runner.

The graph shows the rate of heat loss at rest and during exercise.

Comment on the rate of heat loss during exercise.

In humans the sinoatrial node, atrioventricular node and bundle of His are involved in regulation and coordination of the cardiac cycle.

The diagram shows a human heart.

Which one of the following statements is correct?

(1)

The electrical impulse that initiates the cardiac cycle begins without the need for a nerve impulses.

What is the term for this process?

(1)

A football player undertook regular exercise as part of a training programme.

During exercise there is a change in the duration of the cardiac cycle.

(i)

Explain why there is a change in the cardiac cycle during this exercise.

(3)

(ii)

The table shows the effect of the training programme on the cardiac output and resting heart rate of this football player.

Calculate the stroke volume of this football player, after training.

(1)

After training, the footballer had an ECG.

This ECG trace is shown in the diagram.

Calculate the heart rate of the footballer using the ECG in this diagram.

(1)

Two hours later a second ECG was recorded.

Comment on the changes that have occurred in the activity of the heart as shown in these two ECG traces.

(3)

The scientific document you have studied is adapted from an article in Journal of Cachexia, Sarcopenia and Muscle entitled Skeletal muscle performance and ageing. (Tieland, 2018).

Use the information from the scientific document and your own knowledge to answer the following questions.

Describe the structure of a skeletal muscle fibre (paragraph 2).

Explain how myokines may exert endocrine effects on organs such as the liver (paragraph 3).

Explain why the changes that occur to muscle structure and composition in the elderly can affect their ability to rise from a chair (paragraph 4).

Explain why Ca²⁺ binding to troponin C allows muscle fibres to contract (paragraph 5).

Explain how the ‘high-energy phosphates’ provide the energy necessary for muscle activity (paragraph 11).

Suggest explanations for the effects that a ‘reduction in tendon stiffness’ resulting from ageing could have on the movement at a joint (paragraph 12).

Suggest how myostatin might act as a negative regulator of muscle growth (paragraph 13).

Muscles, bones and joints enable movement of the skeleton.

(i)

Which structure attaches one bone to another bone at a flexible joint?

(1)

(1)

• Antagonistic pairs of muscles move the bones at a joint
• Muscles acting on a joint are myogenic
• Tendons are more elastic than ligaments 
  
  

The athlete Usain Bolt’s world record of 9.58 seconds for the 100m men’s sprint is unbeaten.

Erik van Leeuwen (GFDL <http://www.gnu.org/copyleft/fdl.html> or GFDL <http://www.gnu.org/copyleft/fdl.html>), via Wikimedia Commons

(i)

What is the role of myoglobin in muscle fibres?

(1)

(3)

In an investigation, an athlete ran for 10 minutes on a running machine moving at constant speed.

The investigation was repeated at seven running speeds.

At each speed, the heart rate and lactate concentration in the blood of the athlete were measured.

The results are shown in the graph.

Comment on the results of this investigation.

Alpha‐1 antitrypsin (AAT) deficiency is an inherited disease that can affect different organ systems.

Alpha‐1 antitrypsin (AAT) is a protein produced in the liver.

Investigation of the breathing of a patient with AAT deficiency found that the:

• Resting tidal volume (VT) was 500 cm³
• Dead space (DS) was 150 cm³
• Resting respiratory rate (RR) was 12 breaths per minute.

Calculate the volume of air that enters the alveoli (AV) each hour.

A_V = (V_T – DS)×RR

Give your answer to 2 significant figures with appropriate units.

Activity of the heart was investigated in the same patient.

The trace shows a normal electrocardiogram (ECG).

(i)

Name the stage of the cardiac cycle at T on this ECG.

(1)

(ii)

The ECG of the patient with AAT is shown in the trace.

Calculate the mean heart rate shown in this ECG trace.

(1)

Compare and contrast the ECG trace of this patient with the normal ECG trace.

(3)

One potential treatment for AAT deficiency uses adenoviruses to genetically modify cells in an affected person.

Adenoviruses contain double‐stranded DNA.

Explain how adenoviruses can be used to treat AAT deficiency in a person.