This definitions covers Key Definitions within Decomposition for GCSE Biology. Topic 4: Decomposition It is section 7 of 12 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.
Topic position
Section 7 of 12
Practice
22 questions
Recall
12 flashcards
📖 Key Definitions
Decomposition: The breakdown of dead organic material into simpler inorganic substances (CO₂, water, mineral ions) by the action of decomposers.
Decomposer: An organism (bacterium or fungus) that breaks down dead organic material by secreting enzymes externally (saprotrophic nutrition), absorbing the soluble products, and returning mineral ions to the soil.
Detritivore (detritus feeder): An animal (e.g., earthworm, woodlouse) that feeds on dead organic material (detritus), breaking it into smaller pieces and increasing the surface area available for decomposers.
Saprotrophic nutrition: A feeding method used by fungi and some bacteria in which enzymes are secreted externally onto dead organic material, digested outside the organism, and the soluble products are then absorbed.
Compost: Decomposed organic material (food waste, plant matter) broken down by decomposers under warm, moist, aerobic conditions — used as a nutrient-rich soil improver.
Biogas: A mixture of gases (mainly methane and CO₂) produced by anaerobic decomposition of organic material by bacteria in the absence of oxygen; used as a fuel.
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Practice Questions for Decomposition
Which organisms are the main decomposers?
Explain how temperature affects the rate of decomposition.
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