Living organisms are characterised by

Options

A. Catabolism
B. Irritability
C. Anabolism
D. All of these

Answer

**Step-by-Step Solution:**

1. **Understanding Living Organisms**: Living organisms are entities that exhibit certain characteristics distinguishing them from non-living things. These characteristics help define what it means to be "alive."

2. **Key Characteristics of Living Organisms**:
- **Growth**: Living organisms have the ability to grow and develop. This growth can be in size, complexity, or both.
- **Reproduction**: Living organisms can reproduce, either sexually or asexually, to produce offspring and ensure the continuation of their species.
- **Metabolism**: This encompasses all the biochemical processes that occur within an organism. Metabolism can be divided into two categories:
- **Catabolism**: The breakdown of complex molecules to release energy.
- **Anabolism**: The synthesis of complex molecules from simpler ones, requiring energy.
- **Self-Consciousness (Irritability)**: Living organisms can respond to stimuli from their environment. This includes the ability to sense changes and react accordingly.

3. **Conclusion**: The main characteristics that define living organisms include growth, reproduction, metabolism, and self-consciousness (or irritability). These traits are essential for the survival and functioning of living beings.

**Final Answer**: Living organisms are characterized by growth, reproduction, metabolism, and self-consciousness.

---