Characteristics of Organisms

Key notes :

Living vs. Non-living Things:

  • Living organisms grow, reproduce, respond to stimuli, and carry out basic life processes.
  • Non-living things do not exhibit these characteristics.

Basic Characteristics of Living Organisms:

  • Movement: All living organisms move in some way, either voluntarily (like animals) or involuntarily (like plant leaves).
  • Respiration: Organisms need oxygen or other gases to break down food for energy.
  • Growth: Living organisms grow in size and develop throughout their life stages.
  • Reproduction: Living organisms reproduce to ensure the survival of their species.
  • Excretion: Waste products of metabolism are expelled from the body.
  • Nutrition: Organisms need food to obtain energy. Plants make their own food (photosynthesis), while animals eat other organisms.
  • Sensitivity: Organisms respond to environmental changes (stimuli), such as light, temperature, or sound.
  • Adaptation: Organisms adapt to their environments over time for survival.

Classification of Organisms:

  • Plants: Multicellular organisms that make their own food through photosynthesis.
  • Animals: Multicellular organisms that must consume food for energy.
  • Fungi: Organisms that absorb nutrients from other organisms, often decomposing organic material.
  • Bacteria: Single-celled organisms that can live in a wide variety of environments.
  • Protists: Mostly single-celled organisms that live in water or damp environments.

Cell Structure:

  • Organisms are made up of cells. They can be:
    • Unicellular: Made of one cell (e.g., bacteria).
    • Multicellular: Made of many cells working together (e.g., humans, plants).

Organisms and Environment:

  • Organisms interact with their environment to meet basic needs like food, water, and shelter.
  • They play specific roles in ecosystems (producers, consumers, decomposers).

Life Cycle:

  • Organisms go through stages of life: birth, growth, reproduction, and death. Each stage is essential for the continuation of the species.

Variation in Species:

  • Within a species, there is variation among individual organisms. This helps populations adapt to changing environments and ensures survival over time.

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