B.1.1

State the roles of bones, ligaments, muscles, tendons and nerves in human movement.

1

B.1.2

Label a diagram of the human elbow joint, including cartilage, synovial fluid, joint capsule, named bones and antagonistic muscles (biceps and triceps).

1

B.1.3

Outline the functions of the structures in the human elbow joint named in B.1.2.

2

B.1.4

Compare the movements of the hip joint and the knee joint.

3

Aim 7: Video analysis of motion is possible here.

B.1.5

Describe the structure of striated muscle fibres, including the myofibrils with light and dark bands, mitochondria, the sarcoplasmic reticulum, nuclei and the sarcolemma.

2

B.1.6

Draw and label a diagram to show the structure of a sarcomere, including Z lines, actin filaments, myosin filaments with heads, and the resultant light and dark bands.

1

No other terms for parts of the sarcomere are expected.

B.1.7

Explain how skeletal muscle contracts, including the release of calcium ions from the sarcoplasmic reticulum, the formation of cross-bridges, the sliding of actin and myosin filaments, and the use of ATP to break cross-bridges and re-set myosin heads.

3

Details of the roles of troponin and tropomyosin are not expected.

Aim 7: Data logging could be carried out using a grip sensor to study muscle fatigue and muscle strength.

B.1.8

Analyse electron micrographs to find the state of contraction of muscle fibres.

3

Muscle fibres can be fully relaxed, slightly contracted, moderately contracted and fully contracted.

B.2.1

Define total lung capacity, vital capacity, tidal volume and ventilation rate.

1

Total lung capacity: volume of air in the lungs after a maximum inhalation.

Vital capacity: maximum volume of air that can be exhaled after a maximum inhalation.

Tidal volume: volume of air taken in or out with each inhalation or exhalation.

Ventilation rate: number of inhalations or exhalations per minute (this term is used, not breathing rate).

Aim 7: Data logging using a spirometer could be used.

B.2.2

Explain the need for increases in tidal volume and ventilation rate during exercise.

3

B.2.3

Outline the effects of training on the pulmonary system, including changes in ventilation rate at rest, maximum ventilation rate and vital capacity.

2

Ventilation rate at rest can be reduced from about 14 to 12 bpm. Maximum ventilation rate can be increased from about 40 to 45 bpm or more. Vital capacity may increase slightly.

Aim 7: Data logging using a gas pressure sensor and a ventilation rate monitor belt can be performed.

B.3.1

Define heart rate, stroke volume, cardiac output and venous return.

1

Heart rate: number of contractions of the heart per minute.

Stroke volume: volume of blood pumped out with each contraction of the heart.

Cardiac output: volume of blood pumped out by the heart per minute.

Venous return: volume of blood returning to the heart via the veins per minute.

B.3.2

Explain the changes in cardiac output and venous return during exercise.

3

Detection of lowered blood pH causes impulses to be sent by the brain to the pacemaker, increasing cardiac output. Contraction of muscles used during exercise squeezes blood in adjacent veins, increasing venous return.

B.3.3

Compare the distribution of blood flow at rest and during exercise.

3

Blood flow to the brain is unchanged during exercise. Blood flow to the heart wall, skeletal muscles and skin is increased, but blood flow to the kidneys, stomach, intestines and other abdominal organs is reduced.

B.3.4

Explain the effects of training on heart rate and stroke volume, both at rest and during exercise.

3

B.3.5

Evaluate the risks and benefits of using EPO (erythropoietin) and blood transfusions to improve performance in sports.

3

Aim 8: There are clear ethical issues involved in the use of performance-enhancing drugs.

TOK: Decisions about what constitutes an acceptable level of risk could be discussed, together with differences between different groups and their views—scientists, sportsmen, doctors and spectators.

B.4.1

Define VO2 and VO2 max.

1

B.4.2

Outline the roles of glycogen and myoglobin in muscle fibres.

2

Limit the role of glycogen to glucose storage, and the role of myoglobin to oxygen storage, for use during exercise.

B.4.3

Outline the method of ATP production used by muscle fibres during exercise of varying intensity and duration.

2

Creatine phosphate can be used to regenerate ATP for 8–10 seconds of intense exercise. Beyond 10 seconds, ATP is produced entirely by cell respiration. As the intensity of exercise decreases and the duration increases, the percentage of anaerobic cell respiration decreases and aerobic cell respiration increases.

B.4.4

Evaluate the effectiveness of dietary supplements containing creatine phosphate in enhancing performance.

3

B.4.5

Outline the relationship between the intensity of exercise, VO2 and the proportions of carbohydrate and fat used in respiration.

2

As the intensity of exercise increases, VO2 rises until it reaches VO2 max. Use of fat in respiration falls and use of carbohydrate rises until it reaches 100%.

B.4.6

State that lactate produced by anaerobic cell respiration is passed to the liver and creates an oxygen debt.

1

B.4.7

Outline how oxygen debt is repaid.

2

Lactate is turned into pyruvate, which is converted to glucose or used in aerobic respiration in the mitochondrion, using oxygen taken in during deep ventilations after exercise.

B.5.1

Define fitness.

1

B.5.2

Discuss speed and stamina as measures of fitness.

3

B.5.3

Distinguish between fast and slow muscle fibres.

2

Fast muscle fibres (typical of sprinters) have greater oxygen needs, low myoglobin levels and provide a maximum work rate over shorter periods (strength).

Slow muscle fibres (typical of marathon athletes) have a very good blood supply, plenty of myoglobin and are capable of sustained activity (stamina) and high rates of aerobic respiration.

B.5.4

Distinguish between the effects of moderate-intensity and high-intensity exercise on fast and slow muscle fibres.

2

Moderate-intensity exercise stimulates the development of slow muscle fibres. High-intensity exercise stimulates the development of fast muscle fibres.

B.5.5

Discuss the ethics of using performance-enhancing substances, including anabolic steroids.

3

B.6.1

Discuss the need for warm-up routines.

3

TOK: There is almost universal belief in the need for warm-up and sometimes also warm-down routines, but much of the evidence for these theories is at best anecdotal and at worst non-existent. The difficulty of conducting controlled trials without a placebo effect could be discussed. The willingness of athletes to believe what they are told, without questioning it, could also be considered.

B.6.2

Describe injuries to muscles and joints, including sprains, torn muscles, torn ligaments, dislocation of joints and intervertebral disc damage.

2