Transport processes

• Diffusion


  -particles go from high concentration to low concentration

  -can be any substance

  -is a passive process
• Passive process


  doesnt require energy
• active process


  does require energy
• osmosis


  -only uses water

  -moves from high to low concentration through a partially permeable membrane that only allows certain types of particles to move through

  -passive process
• active transport


  -moves from low concentration to high

  -needs energy to do this

  -needs a transporter protein

  -any substances
• Concentration gradient


  the difference in concentration
• concentration


  amount of particles or molecules in a substance thats in a given volume
• dilute


  low concentration of particles,
• Surface area


  the larger the surface area the quicker the rate of diffusion
• temperature


  the higher the temperature the more kinetic energy is given to particles making them move more increasing the rate of diffusion
• concentration gradient


  the higher the concentration gradient the higher the rate of diffusion
• Osmosis core practical


  The dilute solution containing the most water had gained the highest amount of weight- this is due to osmosis where water molecules go from high to low concentration througha permeable membrane
• for simple organisms


  the smaller the organism, the larger surface area to volume ratio is

  -as the size increases the surface area to volume ratio isnt increased by the same rate
• for bacterium


  -substances diffuse in and out across surfaces

  -once inside it needs to diffuse 1 micrometre or less to the place its needed due to the bacteriums size
• for simple multicellular organisms


  -substances diffuses in and out across surface

  -when inside they dont need to move far

  -diffusion and osmosis
• examples of diffusion


  in leafs

  in lungs

  in liver
• in pure water (plant cells)


  cells gain a lot of water and push against the cell wall

  they become turgid

  fully turgid cells support non wood stems

  -hyptonic
• turgid


  swollen with water
• in concentrated solution


  • cell membrane pull away from the cell wall

  -lose water and begin to shrink

  cell becomes flaccid(soft or floppy)

  -hypertonic
• in high concentrated

  -cell membrane pulls away cell wall completely

  -this is plasmolysis

  -hypertonic
• Animal cell concentrated solution


  -lose water and shrink
• animal cell gains water


  -in a dilute solution or distilled water

  -becomes swollen and bursts
• animal cells osmosis


  -blood plasmas and tissue fluid must be kept strictly limited

  -otherwise it wont function properly
• Root hair cell


  nitrates in the soil move by active transport to the root hair cell from low concentration to high concentration
• Glucose


  -if it has a higher concentration in the instestine than in the blood it diffused into the blood

  -if it has a lower concentration it is moved by active transport and uses energy from respiration
• What is diffusion?

  The movement of particles from high to low concentration
• What is osmosis?

  The diffusion of water across a membrane
• What does active transport do?

  Moves particles from low to higher concentration
• What are the key concepts in biology related to transport in cells?

  • Diffusion
  • Osmosis
  • Active transport
• What is the definition of osmosis?

  Movement of water across a selectively permeable membrane
• What happens to water molecules during osmosis?

  They move from higher to lower water concentration
• What is a partially permeable membrane?

  A membrane allowing small molecules to pass through
• What is a dilute solution?

  A solution with a high concentration of water molecules
• What is a concentrated solution?

  A solution with a low concentration of water molecules
• What does the term 'net movement' refer to?

  The overall effect when all additions and deductions are calculated
• What happens when the concentration of water is the same on both sides of a membrane?

  There is no net movement of water molecules
• What is the role of root hair cells in plants?

  They increase surface area for water uptake
• What happens to leaf cells in dry conditions?

  They tend to lose water
• What is the function of the cellulose cell wall in plant cells?

  Provides support and prevents bursting
• What is turgidity in plant cells?

  Cells become enlarged and swollen with water