characteristics of life

• life is describes an organism which shows metabolism and continuity of life
• metabolism is the sum of all the chemical reactions that take place in the body
• continuity of life describes how cells arise from cells of the same type and organisms arise from other organisms of the same type
• anabolic reactions are the build up of smaller molecules into larger ones eg. photosynthesis
• catabolic reactions are the breakdown of large molecules to form small ones eg. respiration
• cell - tissue - organ - system - organism
• organisation - the way living things are arranged into cells
• nutrition - the way organisms obtain and use their food
• autotrophic nutrition - organisms make their own food
• heterotrophic nutrition - organisms cannot make their own food
• excretion - removal of waste products of metabolism from the body eg. urea
• reproduction - production of new individuals
• sexual reproduction occurs in most animals and plants by the fusing of gametes - produces variation
• asexual reproduction occurs in single celled organisms(eg bacteria) and some plants - no variation occurs
• response - the way in which living organisms react to their environment