transport in cells

• Definition for diffusion

  The movement of molecules/particles from an area of high concentration to an area of low concentration
• Definition for osmosis

  The movement of water molecules from a dilute solution to a more concentrated solution through a partially permeable membrane.
• Definition for active transport.

  The movement of molecules/particles from a low concentration to high concentration using energy from respiration.
• Examples of where diffusion takes place in an animal

  Oxygen diffuses from the alveoli into the blood.

  Carbon dioxide diffuses from the blood into the alveoli.

  Food molecules diffuse from the small intestines to the blood.
• Examples of diffusion in a plant.

  Carbon dioxide diffuses into the leaf, through the stomata.

  Oxygen diffuses from the leaf, through the stomata.
• Example of osmosis in plants

  Water moves via osmosis into the root hairs of a plant from the soil.
• Examples of active transport in animals.

  Glucose is actively transported from the intestines into the blood.
• Examples of active transport in plants

  Mineral ions are actively transported into the roots of plants from the soil
• Why does a higher temperature increase the rate of diffusion?

  Higher temperature means particles have more (kinetic) energy so they move around faster and can diffuse more quickly
• in which states does diffusion happen?

  Liquid and gas - the particles in theses substances are free to move about randomly
• What does partially permeable mean?

  lets some molecules through but not others
• Which molecules are able to diffuse into and out of cells?

  water

  glucose

  amino acids
• three factors that affect the rate of diffusion.

  concentration gradient

  temperature

  surface area
• example of osmosis in animals

  the alveoli give the lungs a really big surface area.

  this helps gas exchange happen easily and efficiently

  they have moist, thin walls (just one cell thick) for a shorter diffusion pathway

  they have a lot of tiny blood vessels called capillaries giving them a good blood supply to maintain the concentration gradient
• what organelle prevents a plant bursting?

  cell wall