variety of living organisms

• 8 characteristics of life


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


  Changing position, not moving from place to place
• Respiration


  Release of energy as ATP from food, usually glucose, through chemical/metabolic reactions in cells. The main organelle is the mitochondrion.
• Sensitivity


  Responding to changes in the surroundings, responding to a stimulus
• Homeostasis


  Control of a constant internal environment, e.g. maintaining body temperature at 37°C or blood glucose at a steady level
• Reproduction


  Production of new organisms, producing offspring (e.g. bacterium dividing, horse giving birth)
• Excretion


  Removal of metabolic waste from the body (e.g. breathing out CO2, urinating)
• Nutrition


  Providing food for the organism. Heterotrophs absorb their food, autotrophs make their own glucose by photosynthesis.
• Growth


  Permanent increase in number or size of cells
• All living organisms contain nucleic acids (DNA) and can die
• 5 kingdoms of living organisms


  • Eukaryotes
  • Bacteria
  • Animals
  • Plants
  • Fungi
  • Protoctista
• Eukaryotes


  Organisms with cells containing a nucleus with a distinct membrane
• Prokaryotes


  Organisms without a true nucleus
• Animals


  • Multicellular, cells do not contain chloroplasts, cannot carry out photosynthesis, have nervous coordination, able to move, store carbohydrate as glycogen
• Plants


  • Multicellular, cells contain chloroplasts so can carry out photosynthesis, cell walls made of cellulose, store carbohydrates as starch and sucrose
• Fungi


  • Saprophytic (feed by excreting digestive enzymes and absorbing products), cells do not contain chloroplasts so cannot carry out photosynthesis, cells joined in hyphae threads forming a mycelium, cell walls made of chitin, store carbohydrates as glycogen
• Protoctista


  • Aquatic, microscopic single-celled organisms, can have animal-like or plant-like characteristics
• Bacteria


  • Microscopic single-celled organisms, cell walls made of peptidoglycan, have cell membrane, cytoplasm, plasmids, may have flagella, do not have a true nucleus but have a bacterial chromosome, some can carry out photosynthesis, others are saprophytes
• Viruses


  Small particles not made of cells, totally parasitic, reproduce inside host cells but cannot replicate on their own, infect all types of living organisms, have protein coat (capsid) and contain DNA or RNA
• Virus structure

  • Envelope around outside used to gain entry into host cells, capsid protein coat to protect genetic information and give structure, DNA or RNA genetic material
• Types of pathogens


  • Fungi (e.g. athlete's foot, ringworm)
  • Bacteria (e.g. salmonella)
  • Protoctista (e.g. amoebic dysentery, malaria)
  • Viruses (e.g. HIV, SARS-CoV-2)
• Pathogens are organisms that cause disease
• Characteristics of living organisms


  • Movement
  • Reproduction
  • Sensitivity
  • Growth and development
  • Respiration
  • Excretion
  • Nutrition
  • Control of internal conditions
• Movement


  The ability of an organism to change its position. Easy to see in animals, but plants also show movement by growing in the direction of a stimulus such as sunlight or gravity.
• Reproduction


  The ability of an organism to produce offspring
• Sensitivity


  The ability of an organism to detect and respond to stimuli. Stimuli include light, temperature, etc. and are detected by specialized cells called receptors.
• Growth and development


  The ability to increase in size or dry mass by increasing the number of cells or size of cells
• Respiration


  A crucial metabolic reaction that releases energy in the form of ATP
• Excretion


  The ability of an organism to remove waste products from metabolism. In animals, this includes the skin, lungs, and kidneys.
• Nutrition


  The ability of taking in material for energy, growth, and development
• Control of internal conditions


  The ability of an organism to control its internal conditions within narrow limits, known as homeostasis
• Together, these characteristics can be used to classify something as living or not
• Eukaryotic organisms


  • Protists
  • Plants
  • Animals
  • Fungi
• Eukaryotic organisms


  Organisms whose cells contain membrane-bound organelles
• Plants


  • Multicellular
  • Able to carry out photosynthesis using chloroplasts and chlorophyll
  • Cell walls made of cellulose
  • Excess glucose stored as starch or sucrose
• Animals


  • Multicellular
  • Cannot carry out photosynthesis
  • No cell walls
  • Have nervous coordination to move from place to place
  • Excess glucose stored as glycogen
• Fungi


  • Can be single-celled or multicellular (mycelium)
  • Cannot carry out photosynthesis
  • Cell walls made of chitin
  • Feed through saprotrophic nutrition (extracellular digestion)
• Fungi


  • Mucor (hyphal structure)
  • Yeast (single-celled)
• Protists


  • Most are unicellular, some are multicellular
  • Have a nucleus
  • Some have cell walls and chloroplasts (photosynthesize), some feed on organic substances
• Prokaryotic organisms (bacteria)


  • Single-celled
  • Smaller than plant and animal cells
  • Have a cell wall, cell membrane, and cytoplasm, but no membrane-bound organelles
  • Some can photosynthesize, most feed by saprotrophic nutrition