topic 5 - transport in plants - mr jackson Flashcards
why do plants need transport systems?
size - cells inside the plant are too far from the supply oxygen and nutrients to rely on diffusion alone
surface area : volume ratio - for plants that are larger than a single cell the rate of diffusion is inefficient and too slow for their supply needs
what is a vascular bundle?
they are made up of phloem and xylem and cambium (undifferentiated cell which grows and changes to become a new xylem or phloem)
where are vascular bundles found and explain the structure of which they are found in?
ROOT - xylem in centre surrounded by phloem for support as it pushes through soil (vascular bundle)
stems or leaves of a plant
STEAMS - vascular bundles on the outside of the stem to provide ‘scaffolding’ which reduces bending
LEAVES - xylem and phloem make a network of veins, these support thin leaves
xylem function?
used to transport water and dissolved minerals from roots up to shoots (leaves)
phloem function?
used to transport sugar (sucrose) from one part of plant to another, up or down - multidirectional
structure of the xylem?
DEAD - cell is dead, (no organelles) end walls have decayed
THICK - thick walls containing lignin
HOLLOW - hollow centre (no cytoplasm)
structure of phloem?
sieve tube - a lot of mitochondria, dense cytoplasm
companion cells - thin walls, lined up end to end to form tube
adaptations of phloem?
many mitochondria in companion cells - provide ATP for active processes: loading of sucrose
into the sieve tubes
Plasmodesmata between cells - allow communication and flow of minerals between cells
adaptations of xylem?
tubes are narrow - capillary action is effective
force of attraction - between water and lignin
lignin is strong - keeps vessels open
what are tracheid’s?
elongated cells with narrow ends that carry water
what do monocots and dicot represent?
monocotyledons - one cotyle (leaf)
dicotyledon - two cotyle (leaves)
