diffusion, osmosis and active transport

• A higher temperature means rate of diffusion will be...


  faster
• What is diffusion?

  The spreading out of particles from an area of high concentration to low concentration
• Diffusion goes from high concentration to..

  low concentration
• Where does diffusion happen? (what states)

  in a solution or gas
• Why does diffusion only happen in solutions and gases?

  because the particles move freely
• The bigger the concentration gradient, the faster the what?

  diffusion rate
• In cell membranes only what size particles can diffuse?

  small
• Give examples of particles that are small enough to diffuse across a cell membrane.

  oxygen

  glucose

  amino acids

  water
• Dissolved substances move in and out of cell membrane by diffusion.
• A larger surface area means a..

  faster diffusion rate
• A larger surface area means a faster diffusion rate
• Diffusion across cell membranes goes both ways as it is random.
• Active transport requires energy.
• Active transport requires what?

  energy
• Active transport acts against a concentration gradient.
• Active transport goes from lower concentration to a higher concentration.
• Why does active transport require energy?

  Because it acts against a concentration gradient
• Give two examples of the use of active transport.

  root hair cells

  our gut
• Active transport allows plants to absorb minerals from very dilute solutions against a concentration gradient.
• Active transport is essential for what in plants?

  growth
• Active transport requires energy from respiration to work.
• Active transport happens in humans - for example taking glucose from the gut and from kidney tubules.
• Osmosis is a special case of diffusion
• Osmosis happens with water.
• Osmosis is movement of water particles from high to low concentration across a partially permeable membrane.
• In osmosis, particles move about randomly.
• Active transport is used when there is a lower concentration of nutrients in the gut but a higher concentration in the blood.
• When there is a higher concentration of glucose and amino acids in the gut they diffuse naturally into the blood.
• Active transport allows nutrients to be taken into the blood despite the fact that the concentration gradient is the wrong way round.
• Glucose is transported to cells where it is used for respiration.
• Root hair cells take in minerals using active transport.
• Water is taken into root hair cells by osmosis
• Root hair cells have a large surface area because of the millions of hairs covering each branch of a root.
• A partially permeable membrane is a membrane with very small holes.
• Cell membranes control what comes in and out of a cell whilst holding the cell together.
• Root hair cells take in minerals using active transport.
• Active transport stops us from starving.