biology year 9

• Characteristics of living things

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


  Organisms that produce their own food (organic substances) by photosynthesis
• Heterotrophic nutrition


  Organisms that have to feed on ready-made organic compounds (food)
• Autotrophs


  • Plants
  • Algae
  • Photosynthetic bacteria
• Respiration


  The breakdown of glucose (food) into simpler products to release energy in the form of ATP
• Excretion


  The removal of waste products, resulting from metabolism, from the body
• Excretion in living things

  • Gaseous exchange: Removal of Carbon Dioxide
  • Sweating: Removal of Urea
  • Gaseous exchange: Removal of Oxygen in autotrophs
  • Leaf Shedding
• Growth


  The increase in size, mass or volume of an organism through cell division and enlargement
• Movement


  The change in position of any part of an organism's body
• Sensitivity


  The ability of a living organism to respond to stimuli or a change in the environment
• Reproduction


  The production of offspring to ensure the survival of the species
• Sexual reproduction


  Involves the union of two individuals, male and female
• Asexual reproduction


  An organism reproducing on its own, the offspring are identical to the parent
• Cells


  The basic unit of life, showing the 7 vital functions
• Unicellular organism


  An organism made up of one cell
• Multicellular organism


  An organism with more than one cell
• Prokaryotic cells


  Cells without a nucleus, their DNA is clumped and floats around the cell
• Eukaryotic cells


  Cells with a cell membrane, nucleus and other membrane bound structures called organelles
• Animal cell


  • Contains cytoplasm, cell membrane, nucleus, mitochondria
• Plant cell


  • Contains cytoplasm, cell membrane, nucleus, mitochondria, cell wall, vacuole, chloroplast
• Animal vs Plant cells

  Animal cells lack cell wall, chloroplasts, and have small temporary vacuoles. Plant cells have cell wall, chloroplasts, and a permanent large central vacuole.
• Cell division


  1. Parent cell grows large

  2. Nucleus starts dividing into two

  3. Pinching of cell and the cytoplasm divides into two

  4. Cells detach and divide becoming two exactly identical daughter cells
• Plant cells


  • Has chloroplasts
  • Has small temporary vacuoles
  • Has a permanent large central vacuole
  • Does not photosynthesise
  • Photosynthesises
  • Has a spherical shape
  • Has a cuboidal shape
  • Nucleus at the centre
  • Nucleus and chloroplasts at the edge

  
• Animal Photomicrograph as seen under the Electron Microscope
• Plant Photomicrograph as seen under the Electron Microscope
• Cell specialisation


  Cells vary a lot in shape and each has a particular function to carry out
• Cell organisation


  1. A group of specialised cells of similar structure and function form Tissues

  2. A number of tissues working together to do a particular function form organs

  3. Multiple organs working together form an Organ system

  4. Different organ systems working together form the organism
• Specialised Animal Cells


  • Red blood cells
  • White blood cells
  • Nerve cells
  • Muscle cells
  • Sperm cells
  • Egg cells
• Specialised Plant Cells


  • Root hair cells
  • Palisade cells (Leaf Cells)
• Diffusion


  The passive movement of particles from a high concentration to a low concentration
• Oxygen concentration inside the cell


  Lower than outside as it is being used up in respiration
• Carbon dioxide concentration inside the cell

  Higher than outside as it is being produced in respiration
• Factors that speed up the rate of diffusion

  • Higher temperature
  • Smaller size of molecules
  • Shorter diffusion distance (thinner membrane)
  • Larger concentration gradient
  • Larger diffusion surface area
• Surface area to volume ratio

  Affects how much an organism can rely on diffusion across the body surface. The larger the surface area to volume ratio the more the organism can depend on diffusion from the body surface.
• Osmosis


  The passive diffusion of water molecules from a dilute solution to a more concentrated solution, through a selectively permeable membrane
• Types of solutions


  • Hypotonic solution
  • Isotonic solution
  • Hypertonic solution
• Hypotonic solution


  When the solution on the outside of the cell is a very weak solution
• Isotonic solution


  When the solution on the outside of the cell is very similar (equal) to that of within
• Hypertonic solution


  When the solution on the outside of the cell is a very concentrated solution
• Animal cells in hypotonic solution

  Water enters the cell by osmosis, cell bursts