Plants

Cards (17)

  • Diffusion
    The spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration
  • Substances transported in and out of cells by diffusion
    • Oxygen
    • Carbon dioxide
    • Urea
  • Diffusion
    Substances move into and out of cells across the cell membranes
  • Factors affecting the rate of diffusion

    • Difference in concentrations (concentration gradient)
    • Temperature
    • Surface area of the membrane
  • Surface area to volume ratio
    Allows sufficient transport of molecules into and out of the cell to meet the needs of the organism
  • Single-celled organisms have a relatively large surface area to volume ratio
  • In multicellular organisms, surfaces and organ systems are specialised for exchanging materials to allow sufficient molecules to be transported into and out of cells for the organism's needs
  • Factors that increase the effectiveness of an exchange surface
    • Having a large surface area
    • Having a membrane that is thin, to provide a short diffusion path
    • (In animals) Having an efficient blood supply
    • (In animals, for gaseous exchange) Being ventilated
  • The glucose produced in photosynthesis may be:
    • used for respiration
    conver printo in solut estor for storage
    used to produce ani a hior song sent the el all
    To produce proteins, plants also use nitrate ions that are absorbed from the soil
  • Root hair cells
    • Adapted for the efficient uptake of water by osmosis
    • Adapted for the efficient uptake of mineral ions by active transport
  • Xylem tissue
    • Transports water and mineral ions from the roots to the stems and leaves
    • Composed of hollow tubes strengthened by lignin
    • Adapted for the transport of water in the transpiration stream
  • Stomata and guard cells
    Control gas exchange and water loss
  • Phloem tissue
    • Transports dissolved sugars from the leaves to the rest of the plant for immediate use or storage
    • Movement of food molecules through phloem tissue is called translocation
  • Phloem
    • Composed of tubes of elongated cells
    • Cell sap can move from one phloem cell to the next through pores in the end walls
  • Substances may move into and out of cells across the cell membranes via diffusion.
    Diffusion is the spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration.
    Some of the substances transported in and out of cells by diffusion are oxygen and carbon dioxide in gas exchange, and of the waste product urea from cells into the blood plasma for excretion in the kidney.
  • In multicellular organisms, surfaces and organ systems are specialised for exchanging materials. This is to allow sufficient molecules to be transported into and out of cells for the organism's needs. The effectiveness of an exchange surface is increased by:
    • having a large surface area
    • a membrane that is thin, to provide a short diffusion path
    • (in animals) having an efficient blood supply
    • (in animals, for gaseous exchange) being ventilated.
  • Factors which affect the rate of diffusion are:
    • the difference in concentrations (concentration gradient)
    • the temperature
    • the surface area of the membrane.
    A single-celled organism has a relatively large surface area to volume ratio. This allows sufficient transport of molecules into and out of the cell to meet the needs of the organism.