Decomposers: Converting Organic Matter to Humus

The process of decomposition is vital for nutrient cycling in ecosystems. Specific micro-organisms are responsible for breaking down dead organic material.

• Decomposition: This is the process where complex organic matter from dead plants and animals is broken down into simpler inorganic substances.
• Humus Formation: A key outcome of decomposition is the formation of humus, which is the stable, dark, nutrient-rich organic material found in soil.
• Role of Micro-organisms: Certain micro-organisms, primarily bacteria and fungi, act as decomposers. They consume the dead organic matter and facilitate its breakdown.
• Conclusion: Therefore, the micro-organisms that convert dead plants and animals into humus are called decomposers.

The correct option is 4, Decomposers.