Characteristics of Living Organisms (Cambridge International IGCSE Science)

Characteristics of Living Organisms

• Living organisms share a series of characteristics:

  • Movement

    • Movements are actions that cause a change in the position or location of an organism

  • Respiration

    • The chemical reactions of respiration occur inside living cells
    • Nutrient molecules are broken down to release energy
    • The energy can be used to fuel other reactions of metabolism

  • Sensitivity

    • Organisms have the ability to sense stimuli in the internal or external environment and to make appropriate responses

  • Growth

    • Growth results in a permanent increase in the size and dry mass of an organism
    • This can be the result of an increase in cell number, cell size or both

  • Reproduction

    • Reproduction leads to an increase in number of the same kind of organism

  • Excretion

    • Toxic substances, the waste products of metabolism and substances present in excess are removed from organisms

  • Nutrition

    • Organisms take in materials that can be used for release of energy, growth and development, e.g.

      • Plants require light, carbon dioxide, water and mineral ions
      • Animals need organic compounds, ions and water

Exam Hint The well-known MRS GREN mnemonic can be used to help remember the characteristics of living organisms:

• Movement
• Respiration
• Sensitivity
• Growth
• Reproduction
• Excretion
• Nutrition