triple content

• transpiration?

  the evaporation of water off the surface of plants
• transpiration in plants: evaporation o fwater out spongey mesophyll layer air and diffuse out of stomata
• effects of transpiration practical: potometer = cut shoot underwater to stop air entering xylem - put in apparatus and make air tight, add air bubble and measure start, leave 30 minutes and measure end distance - distance travelled is the amount of water lost
• transpiration on xylem: less water = draws water up stem to replace (like sucking a straw)
• root hair cells: increases surface area of roots - take water by osmosis and minerals by active transport
• sunlight effect = more sun - stomata opens - more transpiration (more water lost)
• warmer effect = more evaporation - more water loss or higher kinetic energy = quicker diffusion
• windy effect = increase in concentration gradient - quicker diffusion
• low humidity = less water in air - higher concentration gradient - more transpiration
• biodiversity = the variety of organisms in an area
• nitrogen cycle = decomposing bacteria turn dead/waste matter to ammonium ions (called ammonification) - nitrifying bacteria turn ammonium ions to nitrite ions (called nitrification part 1) - another nitrifying bacteria turns nitrite ions to nitrate ions (called nitrification part 2) - denitrifying bacteria can turn some nitrate ions to nitrogen gas when there is a lack of oxygen (eg. waterlogged soil) - legumes contain nitrogen fixing bacteria that can turn nitrogen gas into any nitrogen containing compound: ammonium, nitrite, nitrate etc (eg. beans, peanuts, peas)
• deforestation is caused by trees being cut down for wood and farming land
• disturbs evapotranspiration = less trees = less transpiration = drier limate
• leeching = soils dry in sun = rainwater runs of soils and take minerals from soils = can't use again - unfertile
• soil erosion = rain washes soils away = no tree roots to hold soils together
• unbalance of atmospheric gases (more CO2 and less O2) = trees burned and release CO2, less trees = nothing to take in CO2 and give out O2
• vaccines = injects a piece of deactive pathogen into body - stimulates lymphocytes to create antibodies and memory cells
• memory cells = stay in blood for long time after - recognise pathogen quicker and produce more antibodies faster
• secondary immune response = faster and better response to pathogen than first time
• platelets = clot the blood - respond to damaged blood vessels and produce fibres to create a net that catches RBCs
• platelets - prevent blood loss and pathogens entering blood
• day: respiration and photosynthesis happens - O2 and CO2 go in and out
• night: only respiration - CO2 out and O2 in
• single cell gas exchange = short diffusion path so quick diffusion
• multi-cellular organisms = use exchange surfaces and organs to increase exchange of materials
• organs increase exchange efficiency: larger surface area:volume ratio =increases rate of diffusion, short diffusion path (thin) = quicker diffusion, well ventilated = steep concentration gradient
• practical: (light effect on gas exchange) 20cm3 of hydrocarbonate indicator in 4 tubes and add cotton wool at top - A=no plant (control) B=plant and light C=plant and no light D=plant and half light (aluminium foil) - results: A+D = orange (stays same), B=purple (less CO2) C=yellow (more CO2)
• stomata in gas exchange = opens and closes to control gas exchange and water loss: open = water into guard cells = turgid = gases move in and out, closed = water out of guard cells = flaccid = no diffusion of gases in or out
• gases in gas exchange = water vapour, carbon dioxide and oxygen
• CO2 moves into leaf: higher CO2 concentration in atmosphere than in leaf = steep gradient = diffusion through stomata into air in spongey mesophyll layer - CO2 diffuses through cell wall and membrane in palisade mesophyll layer and into chloroplasts for photsynthesis