Anaerobic respiration
Cambridge IGCSE Biology (0610) · Unit 12: Respiration · 10 flashcards
Anaerobic respiration is topic 12.3 in the Cambridge IGCSE Biology (0610) syllabus , positioned in Unit 12 — Respiration , alongside Respiration and Aerobic respiration. In one line: Anaerobic respiration is the chemical reactions in cells that break down nutrient molecules (like glucose) to release energy *without* using oxygen. This process occurs in the cytoplasm. An example is fermentation in yeast cells.
This topic is examined in Paper 1 (multiple-choice) and Papers 3/4 (theory), plus Paper 5 or Paper 6 (practical / alternative to practical).
The deck below contains 10 flashcards — 5 definitions, 4 key concepts and 1 application card — covering the precise wording mark schemes reward. Use the 5 definition cards to lock down command-word answers (define, state), then move on to the concept and application cards to handle explain, describe and compare questions.
Anaerobic respiration
Anaerobic respiration is the chemical reactions in cells that break down nutrient molecules (like glucose) to release energy *without* using oxygen. This process occurs in the cytoplasm. An example is fermentation in yeast cells.
What the Cambridge 0610 syllabus says
Official 2026-2028 specThese are the exact learning objectives Cambridge sets for this topic. Match the command word (Describe, Explain, State, etc.) in your answer to score full marks.
- Describe Describe anaerobic respiration as the chemical reactions in cells that break down nutrient molecules to release energy without using oxygen
- State State that anaerobic respiration releases much less energy per glucose molecule than aerobic respiration
- State State the word equation for anaerobic respiration in yeast as: glucose → alcohol + carbon dioxide
- State State the word equation for anaerobic respiration in muscles during vigorous exercise as: glucose → lactic acid
- State State the balanced chemical equation for anaerobic respiration in yeast as: C6H12O6 → 2C2H5OH + 2CO2 Supplement
- State State that lactic acid builds up in muscles and blood during vigorous exercise causing an oxygen debt Supplement
- Outline Outline how the oxygen debt is removed after exercise, limited to: (a) continuation of fast heart rate to transport lactic acid in the blood from the muscles to the liver (b) continuation of deeper and faster breathing to supply oxygen for aerobic respiration of lactic acid (c) aerobic respiration of lactic acid in the liver Supplement
What is anaerobic respiration?
Anaerobic respiration is the chemical reactions in cells that break down nutrient molecules (like glucose) to release energy *without* using oxygen. This process occurs in the cytoplasm. An example is fermentation in yeast cells.
Does anaerobic respiration release more or less energy per glucose molecule compared to aerobic respiration?
Anaerobic respiration releases *much less* energy per glucose molecule compared to aerobic respiration. This is because glucose is not fully broken down in the absence of oxygen. Think of a quick burst of energy versus sustained activity.
What is the word equation for anaerobic respiration in yeast?
The word equation for anaerobic respiration in yeast is: glucose → alcohol + carbon dioxide. This process is used in brewing (alcohol production) and baking (carbon dioxide for rising dough).
What is the word equation for anaerobic respiration in muscles during vigorous exercise?
The word equation for anaerobic respiration in muscles during vigorous exercise is: glucose → lactic acid. This build-up of lactic acid causes muscle fatigue and soreness after intense activity, like sprinting.
What is the balanced chemical equation for anaerobic respiration in yeast?
The balanced chemical equation for anaerobic respiration in yeast is: C6H12O6 → 2C2H5OH + 2CO2. This shows how one molecule of glucose yields two molecules of ethanol (alcohol) and two molecules of carbon dioxide.
What is meant by the term 'oxygen debt' in the context of anaerobic respiration?
Oxygen debt refers to the extra oxygen required after vigorous exercise to remove the lactic acid that built up during anaerobic respiration in muscles and blood. It represents the 'cost' of anaerobic respiration.
What are two ways the body removes the oxygen debt *after* exercise?
Two ways include: (a) continued fast heart rate to transport lactic acid in the blood from muscles to the liver and (b) continued deeper and faster breathing to supply oxygen for aerobic respiration of lactic acid. This allows the body to recover.
Where does aerobic respiration of lactic acid occur in the body after exercise?
Aerobic respiration of lactic acid primarily occurs in the liver. The liver converts lactic acid back into glucose or other usable substances, requiring oxygen to complete the process.
Why does lactic acid build up in muscles during vigorous exercise?
Lactic acid builds up because the oxygen supply cannot keep up with the energy demands of the muscle cells. The cells switch to anaerobic respiration to produce energy, leading to lactic acid as a byproduct.
Describe one industrial application of anaerobic respiration.
Anaerobic respiration in yeast is crucial for the production of alcoholic beverages like beer and wine. Yeast ferments sugars, producing ethanol (alcohol) and carbon dioxide as byproducts in the absence of oxygen.
Key Questions: Anaerobic respiration
What is anaerobic respiration?
Anaerobic respiration is the chemical reactions in cells that break down nutrient molecules (like glucose) to release energy *without* using oxygen. This process occurs in the cytoplasm. An example is fermentation in yeast cells.
What is the word equation for anaerobic respiration in yeast?
The word equation for anaerobic respiration in yeast is: glucose → alcohol + carbon dioxide. This process is used in brewing (alcohol production) and baking (carbon dioxide for rising dough).
What is the word equation for anaerobic respiration in muscles during vigorous exercise?
The word equation for anaerobic respiration in muscles during vigorous exercise is: glucose → lactic acid. This build-up of lactic acid causes muscle fatigue and soreness after intense activity, like sprinting.
What is the balanced chemical equation for anaerobic respiration in yeast?
The balanced chemical equation for anaerobic respiration in yeast is: C6H12O6 → 2C2H5OH + 2CO2. This shows how one molecule of glucose yields two molecules of ethanol (alcohol) and two molecules of carbon dioxide.
What is meant by the term 'oxygen debt' in the context of anaerobic respiration?
Oxygen debt refers to the extra oxygen required after vigorous exercise to remove the lactic acid that built up during anaerobic respiration in muscles and blood. It represents the 'cost' of anaerobic respiration.
More topics in Unit 12 — Respiration
Anaerobic respiration sits alongside these Biology decks in the same syllabus unit. Each uses the same spaced-repetition system, so progress in one informs the next.
Key terms covered in this Anaerobic respiration deck
Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.
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