Plant structures and their functions

• whats biomass ?

  the total mass in living organisms, usually shown as the mass after drying
• whats a limiting factor ?

  a single factor, that when in short supply can limit the rate of a process such as photosynthesis
• whats photosynthesis ?

  a chemical reaction that is carried out in the green chloroplasts of a plant. Carbon dioxide and water combine to form glucose and oxygen in the presence of light energy
• whats diffusion ?

  the random movement of particles from an area of high concentration to an area of low concentration
• whats osmosis ?

  the movement of water through a semi permeable membrane from an area of high concentration of water molecules to an area of lower concentration of water molecules
• whats active transport ?

  the movement of particles across a cell membrane from a region of lower concentration to a region of a higher concentration, this is against the concentration gradient, this requires energy
• whats phloem tissue ?

  living tissue formed of sieve tubes and companion cells that transports sugars and other soluble compounds
• whats a potometer ?

  a device used for measuring the rate of water uptake by a plant
• whats translocation ?

  the transport of sugars (mainly sucrose) and other soluble compounds in the phloem tissue of a plant
• whats transpiration ?

  the flow of water into a root, up the stem and out of any leaves
• what are xylem vessels/ cells ?

  a long thick walled tube found in plants, formed from many dead xylem cells. The vessels carry water and dissolved mineral salts through the plant
• what does isotonic mean ?

  two solutions at the same concentration are isotonic
• why are photosynthetic organisms the main producers of food ?

  because they produce biomass for life on earth
• how do photosynthetic organisms produce biomass for life on earth ?

  by converting light energy from the sun into chemical energy for use by organisms
• what is photosynthesis ?

  an endothermic reaction that uses light energy to react carbon dioxide and water to produce glucose and oxygen
• what an endothermic reaction ?

  it means the reaction takes an external energy source and internalises it
• whats the opposite of an endothermic reaction ?

  Exothermic reaction
• what 3 things is photosynthesis affected by ?

  • temperature
  • light intensity
  • carbon dioxide
• how is photosynthesis affected by temperature ?

  temperature is affected by the number of collisions between the enzyme and the substrate
• how is the rate of photosynthesis affected at low temperatures ?

  the rate of photosynthesis is affected by the number of collisions between the enzyme and the substrate being low
• how is the rate of photosynthesis affected by increasing temperature ?

  as the temperature increases the number of collisions goes up
• what happens to the rate of photosynthesis at really high temperature ?

  the enzyme denatures and the rate will decrease
• what happens to the rate of photosynthesis if the light intensity is too low ?

  without enough light a plant cannot photosynthesise very quickly, even if there's enough water and carbon dioxide, this will slow down the rate
• what happens to the rate of photosynthesis if you increase the light intensity ?

  this increases the rate of phtosynthesis
• what is carbon dioxides involvement with photosynthesis ?

  carbon dioxide is one of the reactants and the substrate in photosynthesis
• what happens to the rate of photosynthesis if you increase carbon dioxide levels ?

  increased photosynthesis
• explain direct proportion for the effect of light intensity and distance from a light source on the rate of photosynthesis ?

  as light intensity increases, the rate of photosynthesis increases
• explain inverse proportion for the effect of light intensity and distance from a light source on the rate of photosynthesis ?

  as distance increases, light intensity decreases
• Explain the interactions of temperature, light intensity and carbon dioxide concentration in limiting the rate of photosynthesis ?

  if the level of one of these is not correct, it will become a limiting factor in the rate of photosynthesis
• what does the law of limiting factors state ?

  the rate of a physiological process will be limited by the factor in the shortest supply
• explain why as distance increases light intensity falls and why this results in the rate of photosynthesis decreasing ?

  because energy transferred by light is needed for photosynthesis to take place
• how is the structure of a root hair cell adapted to absorb water and mineral ions ?

  • root hair cells have long extensions that stretch out into the soil this gives them a larger surface area where osmosis can take place, which means that more water molecules can cross at the cell membrane into the cell at the same time
  • this also gives a larger surface area for mineral ions to enter the root hair cell by diffusion and active transport
• how do you calculate percentage gain and loss of mass in osmosis ?

  • take the mass at the end, the subtract it from the original mass
  • divide this value by the original mass
  • to get the percentage, you must then multiply by 100

  
• what are the xylem and phloem ?

  plant tissues that form the transport system of the pant
• Describe xylem vessels ?

  narrow, hollow, dead tubes containing lignin
• what do xylem vessels do ?

  transport water and minerals from the root to the stem and onwards
• what do phloem do ?

  it transports substances like sugar and amino acids from the leaves to the rest of the plants (translocation)
• how is xylem tissue adapted to its function ?

  xylem transports water and minerals from the plant roots, up the stem, into the leaves. The water moves in by osmosis and minerals move by active transport
• what are xylem made of and how is this adapted to its function ?

  its made of dead cells that lose their end walls to make a hollow tube, their vessel walls become strengthened by a carbohydrate substance called lignin that strengthen and support plants
• what do we call lignified cells ?

  wood