Transport in Plants

Page 92 Application1a) phloemb) xylem2a) sieve plateb) pit - allows water and mineral ions to move in/out of xylem vessels

Page 92 Fact recall1) Diffusion would be too slow for the demand of the plant2) x in middle3) a - phloem, b - xylem, c - vein4) Water and minreal ions5) Lignin6) via pits in xylem vessel walls7) Sugars8a) Livingb) No nucleus, few organelles and thin layer of cytoplasm

Page 95 Application1) Root hair cell2) C3) Casparian strip4) Increased water potential in root cortex, some plant cells won't receive enough water and plant can wilt

Page 95 Fact recall1) Root hair cell - cortex, endodermis - xylem2) symplast = root hair cell - through cytoplasm of cells in cortex - xylemapoplast = root hair cell - along cell walls - casparian strip - symplast pathway - xylem3) Evaporation of water from plants surface4) Movement of water from roots to leaves5) Adhesion is where water molecules are attracted to the walls of the xylem vessels, this helps water to rise up through vessels

Page 98 Application1) B, leaves are spine, curled leaves, layer of hairs on epidermis, stomata sunken in pits2a) 10 degrees = 13.7mm20 degrees = 18.0mm30 degrees = 23.3mmc) As temp increased, distance moved by bubble in 10mins increased too. Rate of transpiration increased with increasing temperatures. Water molecules had more energy so they evaporate from cells inside leaf faster, increasing water potential between the inside and outside of leaf. Water diffuses out of leaf faster

Page 98 Fact recall1) Gas exchange for photosynthesis2) Moves water molecules away from around the stomata, decreasing water potential in surrounding air, meaning water diffuses out of leaf into air down water potential gradient3) temperature, humidity, light4) That uptake of water is directly related to evaporation of water at leaf

Page 101 Application1) meristems2a) At roots, active transport is used to load assimilates into sieve tubes. This lowers water potential inside sieve tubes, so water enters by osmosis b) At sink, assimilates are removed from phloem to be used up. This increases water potential inside sieve tubes, so water leaves by osmosis

Page 101 Fact recall1) The movement of assimilates from source to sink2) Source is where the assimilates are produced, sink is where the assimilates are used up3) If you remove a ring of bark, including phloem but not xylem, a bulge forms above ring. The fluid in the bulge has a higher concentration of sugars than fluid below bulge = sugars can't move past the area where bark has been removed. Supporting evidence for downward flow of sugars.4) Sugar travels to many different sinks, not just to the one with the highest water potential as the model would suggest

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