3.1.3 a and b transport systems Flashcards
why do multicellular plants need transport systems?
metabolic demands- substances need transporting all around the plant eg glucose, oxygen , carbon dioxide, hormones
size- some plants live a long time so they grow to be very big and substances need to be transported from the tips of the roots to eh leaves of the plants and diffusion would take too long and isn’t efficient enough
surface area to volume ratio- small so can’t rely on diffusion alone
what are dicotyledonous plants?
have 2 place where seeds are arranged- 2 cotyledons
where is the vascular bundle in a stem and why is it there?
around the edge to give it strength and support
where is the vascular bundle in the root and why is it there?
in the middle to help the plant withstand the tugging strains that result when the stem and leaves are blown in the wind
where is the vascular bundle in the dicot leaf and why?
in the midrib of the leaf to help support the structure of the leaf
where is the xylem and phloem in the vascular bundle in the stem?
phloem on the outside and xylem on the inside
where is the xylem and phloem in the vascular bundle in the root?
xylem in the x shape in the middle and phloem in four dots around it
where is the xylem and phloem in the vascular bundle in the leaf?
xylem on top and phloem below
what is the function of the xylem?
to transport water and mineral ions up from the roots and for support
what is xylem made from?
dead cells and lignin
what is the function of the lignin?
lignin breaks down the organelles in the cells that make the xylem and make them waterproof
how is lignin laid down in the walls of the xylem vessels?
it forms rings, spirals or solid tubes which have lots of small unlignified areas called bordered pits
what are bordered pits?
where water leaves the xylem and moves into other cells of the plant
what are phloem made from?
living tissue
what is the function of the phloem?
to transport sugars and amino acids needed for respiration around the plant
what is the main transporting vessel of the phloem?
sieve tube elements
what is in the area between sieve cells?
sieve plates which let the phloem contents flow through
what is linked to the sieve tube cell?
companion cells
what are companion cells linked to the sieve tube cells by?
plasmodesmata
what are the cell contents of the companion cells?
have nuclei and all other common organelles
what is the function of the companion cells?
very vatic cells which function as a life support system for the sieve tube elements
carry out metabolic processes needed by the sieve tube elements
what else makes up the phloem?
phloem fibres- cell wall is lignin, empty, provides mechanical strength and support and is imbedded within the phloem
parenchyma- cellulose cell wall, plays a role in storage and transport within the phloem, unspecialised and gives turgidity
what is the difference between xylem tracheids and vessels?
tracheids are unicellular, narrower lumen, ends are tapering or oblique and closed
vessels are multicellular and larger, broader lumen due to less lignified walls, ends are rounded and open
equation for surface area of a sphere
4 pi r squared
equation for volume of a sphere
4/3 pi r cubed
