BIO U.1

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  • The Eight Characteristics of Life
    • Sensitivity
      • Ability to sense and respond to the external environment.
      • Special receptors detect stimuli {light, sound, temperature and gravity} allowing the organism to alter its behaviour or growth.
    • Respiration
      • Process of releasing energy from food, and is a series of chemical reactions inside all living cells.
      • The energy produced drives processes such as growth and movement, so is essential.
    • Growth
      • Organisms increase in size.
      • Plants grow  throughout their lifetime.
      • Animals grow from young into adults, increasing in size and developing
    • Movement
      • All organisms move in a controlled way.
      • Animals quickly and plants slowly. Not Venus fly trap.
    • Excretion
      • Removal of waste materials produced within cells (often during respiration) that would build up to toxic levels if not eliminated. (Urea, and carbon dioxide).
      • Simple single-celled organisms eliminate these materials via diffusion, more complex organisms have organ systems e.g. kidneys and bladder
    • Reproduction
      • Allows organisms to continue the species after death, and to colonise new habitats to extend their range.
      • Asexually when the offspring product of 1 parent so is genetically identical.
      • Sexually when the  offspring  product of two parents. Gametes produced by both come together resulting in fertilisation –often by very elaborate means.
    • Environment
      • Control of the internal environment.
      • Maintaining a constant internal temperature, maintaining a suitable oxygen concentration, water levels, even pH, all allow cellular processes to proceed at their optimum rates.
    • Nutrition
      • Organisms need a source of food which can be respired to produce energy.
      • Plants combine carbon dioxide with water to produce simple sugars and oxygen as a by-product Photosynthesis. Autotrophs.
      • Other organisms eat other plants and animals (heterotrophs), some by feeding on dead plants and animals (saprobionts) and some bacteria can oxidise inorganic compounds.

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