Aerobic & Anaerobic Respiration
Cellular respiration is an exothermic chemical reaction that occurs continuously in all living cells to transfer energy from glucose for metabolic processes. Respiration takes place aerobically (using oxygen in the mitochondria to release a large amount of energy) or anaerobically when oxygen is in short supply.
- Aerobic respiration
- Respiration with oxygen; occurs in mitochondria.
- Anaerobic respiration
- Respiration without oxygen; occurs in the cytoplasm.
- Lactic acid
- The product of anaerobic respiration in animal cells, causing muscle fatigue.
Interactive Human Body & Cell Structure Explorer
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Heart (Double Circulatory Pump)
Structure & Function:
Pumps blood in a double circulatory system: the right ventricle pumps deoxygenated blood to the lungs, and the thick muscular left ventricle pumps oxygenated blood at high pressure around the whole body.
Key Exam Mark-Scheme Point:
Exam tip: The left ventricle has a much thicker muscular wall than the right ventricle because it must pump blood at high pressure all the way around the entire body, not just to the lungs.
What happens if this organ fails or is removed?
Without pressure from the heart, blood flow stops immediately. Oxygen and glucose cannot reach tissues, and waste carbon dioxide cannot be removed.
Tip: Use the “Simulate Organ Failure” button above to see how each organ system depends on the others to maintain homeostasis and cellular respiration.
Key Concepts & Exam Definitions (5)
- Aerobic respiration
- Respiration with oxygen; occurs in mitochondria.
- Anaerobic respiration
- Respiration without oxygen; occurs in the cytoplasm.
- Lactic acid
- The product of anaerobic respiration in animal cells, causing muscle fatigue.
- Oxygen debt
- The amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid.
- Fermentation
- Anaerobic respiration in plant and yeast cells, producing ethanol and carbon dioxide.
Quick-Fire Flashcards (5)
Click any card to check the answer, then mark it as Known to track your progress.
Where does aerobic respiration take place?
What are the products of anaerobic respiration in yeast?
Which type of respiration releases more energy?
What is the chemical symbol for glucose?
What causes muscle fatigue during vigorous exercise?
Exam-Style Questions & Mark Schemes (3)
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- Q1
Compare aerobic and anaerobic respiration in mammalian muscle cells.
Click “Check Mark Scheme” to compare your answer, Aerobic uses oxygen, anaerobic does not. Aerobic produces CO2 and water, anaerobic produces lactic acid. Aerobic releases much more energy per glucose molecule than anaerobic.
- Q2
Explain why heart rate and breathing rate increase during exercise.
Click “Check Mark Scheme” to compare your answer, To supply muscles with more oxygen and glucose for increased aerobic respiration, and to remove carbon dioxide more quickly.
- Q3
What is fermentation and why is it economically important?
Click “Check Mark Scheme” to compare your answer, Fermentation is anaerobic respiration in yeast. It is used to make bread rise (carbon dioxide) and to produce alcoholic drinks (ethanol).
Common Exam Questions (4)
What is aerobic respiration?
Aerobic respiration is the exothermic chemical breakdown of glucose using oxygen inside mitochondria, releasing a large quantity of energy for cell activities alongside carbon dioxide and water.
What is anaerobic respiration in muscles?
During vigorous exercise when oxygen delivery cannot meet demand, muscle cells respire anaerobically by converting glucose into lactic acid (glucose → lactic acid), transferring much less energy and building up an oxygen debt.
What is the word equation for aerobic respiration?
The word equation for aerobic respiration is: glucose + oxygen → carbon dioxide + water (+ energy transferred). In balanced symbols: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O.
Why do we respire?
Organisms respire continuously to transfer energy for chemical reactions that build larger molecules (such as proteins from amino acids), for muscle contraction and movement, and for maintaining a constant body temperature in mammals and birds.
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Homeostasis & Body Temperature
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