biology revision ap2

• Diffusion


  Movement of particles from a high concentration to a low concentration
• Isotonic solution

  Solution where the concentration of solutes is the same inside and outside the cell
• Hypotonic solution

  Solution where the concentration of solutes is lower than the inside of the cell
• Vascular bundle xylem

  • Vessels with thick walls
  • Transports in one direction
  • Made from dead cells
• Companion cell

  Provides energy and transfers substances
• Carbon dioxide + water -> glucose + oxygen
• Large surface area

  Increases surface area for carbon dioxide and absorption of light for photosynthesis
• Chlorophyll

  Absorbs light energy so that photosynthesis can take place
• Stomata


  Allows carbon dioxide to diffuse into the leaf and oxygen to diffuse out
• Thin epidermis

  Allows more light to reach the palisade cells
• Thin cuticle made of wax

  A waterproof layer to protect the leaf without blocking sunlight
• Palisade cell layer

  Maximises the absorption of light as it will hit chloroplasts in the cells directly
• Spongy mesophyll layer

  Air spaces allow carbon dioxide to diffuse through the leaf, increasing the surface area
• Vascular bundles

  Thick cell walls of the tissue help to support the stem and leaf
• Factors affecting transpiration

  • Temperature
  • Humidity
  • Wind speed
  • Light intensity
• Temperature increase

  Increases transpiration rate
• Humidity increase

  Decreases transpiration rate
• Wind speed increase

  Increases transpiration rate
• Light intensity increase

  Increases transpiration rate
• Glucose molecules are used for plant growth
• Starch is made of long chains of glucose molecules
• Glucose that isn't used is stored as starch
• Respiration transfers energy through movement and growth
• Respiration uses glucose and oxygen to produce carbon dioxide and water
• phloem

  transport dissolved sugars and amino acids

  transports up and down the vessel

  companion cells provide energy

  no nuclei
• describe how function of phloem vessels and how its adapted

  transports sugar and amino acids in a 2 way flow with the use of companion cells which provide energy for the flow
• what is omosis

  the net movement of water molecules from a high water concentration to a low water concentration across a partially permeable membrane
• where do plants get the substances needed for photosynthesis?

  • water via roots from the soil
  • co2 diffuses from air
• whats the name of the pigment in the chloroplast

  chlorophyll
• what do the guard cells do?

  open and close the stomata to allow co2 to diffuse to palaside cells
• two adaptations of a leaf and how its carried out its function ?

  chlorophyl allows photosynthesis to take place by absorbing the light energy

  stomata allows co2 to diffuse in and o2 out the cell
• the solution is highly concentrated, explain the effect on potato cell 


  the net movement of water from a high concentration to a low concentration across a partially permeable membrane will move from inside of the plant cell to outside of the solution, the vacuole and cytoplasm will shrink and the cell membrane will split from the cell wall.
• potato cylinder placed into hypertonic solution it will…

  potato’s water mass will leave the potato via osmosis because the concentration is higher in the outside than the inside the cell
• hypertonic solution

  concentration of solutes is higher outside the cell than the inside
• large surface area

  increase area for diffusion of co2 and absorption of light for photosynthesis
• chlorophyll

  absorb light energy so photosynthesis can take place
• how to work out mean

  add all results together, except anomaly / by how many results
• what happens to red blood cells when put in hyptonic solution

  it will burst because waters moves into the cell by omsosis and will burst due to not having a cell wall, there is a higher concentration of solutes inside the cell compared to the solution
• temprature decreasing, what reaction is it

  endothermic because energy is being transferred from the surroundings decreasing the temperature and also transferring it to the themometer, temp in endothermic reaction decreases
• what solution is this

  hypertonic