These seven original questions follow the four lessons in the chapter. Answer in full sentences first, then open the model answer.
Questions
Question 1. Write the word equation for aerobic respiration.
Answer
Glucose + oxygen → carbon dioxide + water + energy.
Oxygen and glucose go in, and carbon dioxide and water come out.
Question 2. State one product of anaerobic respiration in muscle cells and one product in yeast.
Answer
Muscle cells produce lactic acid. Yeast produces ethanol (and carbon dioxide).
Question 3. A student says, “Anaerobic respiration releases no energy.” Correct this statement.
Answer
Anaerobic respiration does release energy, but less than aerobic respiration, because glucose is only partly broken down.
Question 4. Explain why your muscles feel tired after a sprint.
Answer
During a sprint, oxygen cannot reach the muscle cells fast enough, so the cells respire anaerobically.
This produces lactic acid, which builds up in the muscles and causes the tired feeling.
Question 5. A respirometer with germinating seeds moves a coloured liquid 8 mm in 10 minutes at 20 °C and 13 mm at 35 °C. Describe the result and give a reason.
Answer
The distance moved increases from 8 mm to 13 mm as the temperature rises from 20 °C to 35 °C.
The enzymes in respiration work faster at the higher temperature, so the seeds use oxygen faster.
Question 6. Boiled seeds are placed in the same respirometer and the liquid does not move. What is the purpose of this set-up?
Answer
It is a control. The boiled seeds are dead, so they do not respire. It shows that the liquid moved in the other flask because the living seeds were respiring.
Question 7. State two differences between breathing and cellular respiration.
Answer
- Breathing is a physical process that moves air in and out of the lungs, but cellular respiration is a chemical process that releases energy from glucose.
- Breathing happens in the lungs and with the diaphragm and rib muscles, but cellular respiration happens in the cells.
If you got these wrong
Wrong equations or products in questions 1 to 3 point to comparing aerobic and anaerobic respiration. Question 4 uses relating substrates, products and energy.
Questions 5 and 6 need interpreting respiration investigation data. Question 7 comes from distinguishing breathing from cellular respiration.
Log each slip in the mistake log and paper-error review, then build a timed set with the timed original practice session builder.
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