Chapter 9 Transport in Plants Flashcards
What is the need for plant transport systems?
Metabolic demands - many parts of the cell don’t photosynthesise. There is a need for transporting of minerals to areas where they are needed.
Size - some plants are really large so there is a need for the nutrients to be passed through out the whole plant.
SA:V - the roots and stems of plants have a bad SA:V so they cant rely on diffusion.
What is a dicotyledonous plant
they make seeds that contain two cotyledons, and contain the food stores for the developing embryo and form the first two leaves when a seed germinates.
What are the two types of dicotyledonous plants?
herbaceous - soft tissues and short life cycles.
arborscent dicots - have hard lignified tissues and long life cycles.
Where are the vascular bundles in the leaf, stem and root
Leaf - the midrib has the vascular bundle
Stem - vascular bundles are around the edge to give strength and support.
Root - They are in the middle to help with stand tugging strains that result of the wind blowing the stem and leaves.
What is the structure and function of the xylem?
mostly non-living tissue
transports water and mineral ions
flow of materials is from the roots to the shoots and leaves.
xylem vessels are the main part which are long hollow structures made of several columns of cells which fuse together end to end.
they also have xylem parenchyma packs around the vessels which have tannin deposits and store food.
Tannin is a bitter chemical that protects from attacks from herbivores.
xylem fibres are long cells with lignified secondary walls that provide mechanical strength but are insolluble.
Lignin can be in rings, spiral or solid tubes with lots of small unlignified areas called bordered pits.
What is the structure and function of the phloem?
is a living tissue that transports food in the form or organic solutes around the plant.
They have sieve tubes which let phloem content flow through. No lignin.
phloem cells have no nucleus.
close to them are companion cells which are linked to sieve tubes by plasmodesmata.
contains supporting tissues including fibres and sclereids,
