Edexcel A Level Biology A (Salters-Nuffield)
Edexcel A Level Biology A Topic 7: Run for Your Life Exam Questions
Free Edexcel A Level Biology A exam questions for Topic 7: Run for Your Life, with a mark scheme for every pack. Covers muscle structure and contraction, aerobic and anaerobic respiration, heart rate control, ventilation, homeostasis, thermoregulation and the effects of exercise.
Topic 7: Run for Your Life exam questions
1 question pack of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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About Edexcel A Level Biology A Topic 7: Run for Your Life
Topic 7 of Edexcel A Level Biology A (Salters-Nuffield) uses exercise and sport as its context. You study skeletal muscle structure, the sliding filament theory and slow and fast twitch fibres, then the detailed biochemistry of aerobic respiration (glycolysis, link reaction, Krebs cycle and oxidative phosphorylation) and anaerobic respiration. You learn how heart rate is controlled by the SAN, AVN and cardiovascular centre, how ECGs are interpreted, how ventilation is measured with a spirometer and controlled, and how homeostasis and thermoregulation use negative feedback. The topic ends with the effects of exercise, how hormones affect gene expression, and performance-enhancing drugs. It is assessed in Paper 2 and Paper 3.
What you need to know
- Muscles Muscles work in antagonistic pairs. In the sliding filament theory, calcium ions expose binding sites on actin, myosin heads form cross-bridges and ATP is used to detach and re-cock them. Slow twitch fibres are adapted for endurance, fast twitch for short bursts.
- Aerobic respiration Glycolysis in the cytoplasm produces pyruvate; the link reaction and Krebs cycle in the matrix produce reduced NAD and FAD; oxidative phosphorylation on the inner membrane makes most ATP by chemiosmosis.
- Anaerobic respiration Pyruvate is converted to lactate, regenerating NAD so glycolysis can continue. Lactate is later converted back to pyruvate or glucose in the liver.
- Heart rate control The SAN initiates a wave of excitation, the AVN delays it, and the bundle of His and Purkyne fibres carry it to the ventricles. The cardiovascular control centre in the medulla changes heart rate via sympathetic and parasympathetic nerves.
- Ventilation A spirometer measures tidal volume, vital capacity, breathing rate and oxygen consumption. The ventilation centre in the medulla responds to carbon dioxide levels detected by chemoreceptors.
- Homeostasis and exercise Thermoregulation by the hypothalamus uses negative feedback. Peptide hormones act via receptors on the cell surface, while steroid hormones enter cells and act as transcription factors. Know arguments about performance-enhancing drugs.
Common mistakes in Topic 7: Run for Your Life
- Saying muscle cells produce lactic acid because they run out of oxygen completely; anaerobic respiration supplements aerobic respiration when oxygen supply is insufficient.
- Placing the Krebs cycle on the cristae; it occurs in the matrix.
- Writing that the SAN contracts the ventricles directly; the impulse is delayed at the AVN and spreads through the Purkyne fibres.
- Confusing tidal volume with vital capacity; tidal volume is the volume of a normal breath.
- Stating that oxygen levels are the main stimulus for breathing rate; rising carbon dioxide concentration (lower pH) is the main stimulus.
Try three Topic 7: Run for Your Life exam-style questions
1. A person has a tidal volume of 0.5 dm3 and a breathing rate of 15 breaths per minute. Calculate the minute ventilation. (2 marks)
Show the mark scheme answer
0.5 x 15; = 7.5 dm3 min-1.
2. Explain how ATP is produced in oxidative phosphorylation. (4 marks)
Show the mark scheme answer
Reduced NAD and FAD deliver electrons to the electron transport chain; energy released pumps protons into the intermembrane space; protons flow back through ATP synthase; ADP phosphorylated to ATP; oxygen is the final electron acceptor forming water.
3. Describe how heart rate increases at the start of exercise. (3 marks)
Show the mark scheme answer
Chemoreceptors and receptors in muscles detect changes; cardiovascular control centre in the medulla sends impulses along sympathetic nerves; SAN fires more frequently.
Topic 7: Run for Your Life FAQs
What does Edexcel A Level Biology A Topic 7: Run for Your Life cover?
It covers muscles and movement, aerobic and anaerobic respiration, control of heart rate and ventilation, homeostasis and thermoregulation, and the health effects of exercise and drugs.
Which paper is Topic 7 examined in?
At A Level, Topic 7 is assessed in Paper 2 and can also appear in Paper 3, which covers all topics and practical skills.
Which core practicals are in Topic 7?
Expect investigations of respiration rate using a respirometer and of the effects of exercise on breathing using a spirometer, including calculating tidal volume, rate and oxygen consumption from traces.
