Transport in Plants

• what is the function of the xylem vessel?

  transport water and mineral ions to leaves, and support the stems
• what is the function of the phloem vessel?

  transport sucrose and amino acids to roots
• what does a cross section of a stem look like?

  cell wall, cell membrane, and vascular bundle arranged in a circle pattern, phloem on outside and xylem on inside

  
• what does a cross section of a root look like?

  root hairs, root cortex cells, phloem tissue in 4s around an axis of xylem tissue

  
• describe the adaptations of the xylem vessel

  thick walls made of lignin, no cell contents, cells joined end to end with no cross walls to form a long continuous tube, lignin strengthens plant for strong pressure
• state the adaptations of root hair cells

  larger surface area to increase rate ofabsorptionbyosmosisandmineral ions by active transport
• describe the pathway of water through a root to a leaf

  osmosis into root hair cell, through root cortex, into xylem, carried up to leaves, enter mesophyll cells
• what is transpiration

  thelossofwater vapourfrom plant leaves byevaporationat the surface ofmesophyll cellsand thendiffusionofwater vapourthrough thestomata
• what is the movement in a xylem vessel?

  from roots to leaves
• what are the functions of transpiration?

  transportation of mineral ions, providing water to keep cells turgid, provide water for photosynthesis, prevent leaves from overheating
• how does transpiration occur?

  evaporation takes place at the surface of spongy mesophyll cells. many air spaces between cells creates large surface area, more evaporation can occur when stomata is open
• what is the transpiration stream

  the way that water moves upwards in a xylem vessel
• how is the transpiration stream created?

  transpiration producestensionin the xylem, water is held together byforces of attractionbetween the molecules
• what is wilting

  when more water evaporates from the leaves of a plant than is available for uptake via osmosis
• what are the consequences of wilting

  the strength of cell walls weakens and the plant begins to collapse
• what is the effect on the rate of transpiration with temperature

  an increase of temperature means an increase in the rate of transpiration
• what is the effect on the rate of transpiration with humidity

  an increase in humidity decreases the rate of transpiration
• describe the features of a xylem vessel

  transports water and mineral ions, transpires, flows from roots to leaves, cells are dead
• describe the features of a phloem vessel


  transports amino acids and sucrose, translocate, flows in all direction, cells are living
• describe the cell wall in a phloem vessel

  the cells are alive and have sieve plates which allow easy flow of substsances
• what is translocation

  the transport of sucrose and amino acids in phloem from source to sink
• what is the path of translocation during winter

  from the sink/storage organs to the sources or leaves
• what is the path of translocation during a growth period

  the roots are sources and the leaves are sinks
• what is the path of translocation after a plant has fully grown


  leaves become sources and roots become sinks
• what is a source


  a part of a plant that releases sucrose or amino acids
• what is a sink

  a part of a plant that use or store sucrose or amino acids