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Decomposition and microbial decay practical

Ecology • Organisation of an ecosystem

Key concepts

What you'll likely be quizzed about

  • Decomposition involves the chemical and physical breakdown of dead organisms and organic waste into smaller molecules and inorganic ions.
  • This process returns essential elements like carbon and nitrogen to the abiotic environment, making them accessible for reuse by producers and other organisms.
  • Microorganisms primarily conduct decomposition.
  • Bacteria digest dissolved substances while fungi release extracellular enzymes that decompose complex compounds, such as lignin or cellulose, outside their structures.
  • These processes are crucial for nutrient cycling in ecosystems.

Flashcards

Test your knowledge with interactive flashcards

Describe the effect of oxygen availability on decay rate.

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More oxygen enhances aerobic respiration among decomposers, typically accelerating decay, while low oxygen promotes anaerobic pathways that often proceed more slowly.

Key notes

Important points to keep in mind

Decomposition returns carbon and nitrogen to usable forms for producers.

Bacteria digest soluble compounds; fungi secrete enzymes for absorption.

Rate calculations involve change and time, expressed with units (g month−1, pH units day−1).

Higher temperature, moisture, and oxygen generally increase decay rates until optimal limits are reached.

pH changes in milk indicate bacterial fermentation to lactic acid and breakdown of fat to fatty acids.

Autoclaving or sterilizing biological samples is required before disposal to mitigate pathogenic risks.

Anaerobic decay generates methane; aerobic decay produces carbon dioxide and water.

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