, Transport systems in plants
Plants need transport systems as:
Plants are multicellular so have a small SA:V meaning that plants cannot
rely on diffusion alone to supply their cells with everything they need.
Oxygen & glucose need to be transported for respiration & waste
products need to be transported to be removed.
Water & mineral ions need to travel from the roots to all the cells
Hormones made in one part of a plant need to be transported to the
areas where they have an effect
Differences between multicellular plant & multicellular animal transport
systems
Plants do not have a heart to act as a central pump, whereas many
multicellular animals have a heart
In plants 1 type of vessel is made up of dead cells whereas all animal
vessels are made of living tissue
In plants there are 2 different transport systems carrying different
materials whereas animals have different types of vessels but the same
transport medium in both
, Dicotyledonous plants
Dicotyledonous plants (dicots) make seeds that contain 2 cotyledons which are
organs that act as food stores for the developing embryo plant & form the first
leaves when the seed germinates.
Herbaceous dicots have soft tissues & a relatively short life cycle whereas woody
(arborescent) dicots have hard, lignified tissues & a long life cycle.
Dicotyledonous plants have a vascular system consisting of specialised vascular
tissue (tissue consisting of cells specialised for transporting fluids by mass flow):
Water & soluble mineral ions travel upwards in xylem tissue from the roots to
the leaves
Assimilates (substances made by the plant e.g. sugars) travel both up or down in
phloem tissue.
Other plant tissues:
Parenchyma- a packing tissue in plants which fills spaces between other tissues.
In roots parenchyma cells may store starch.
In leaves parenchyma tissue (called chlorenchyma) have chloroplasts & can
photosynthesise.
In aquatic plants aerenchyma tissue is parenchyma with air spaces to keep the
cell buoyant.
, Xylem and phloem in the young root
In a root, the xylem is in the centre surrounded by the
phloem. This arrangement provides strength to withstand
the pulling forces to which the roots are exposed e.g. when
the stem & leaves blow in the wind.
The endodermis, found
around the vascular
bundle, has a key role in
getting water into the
xylem vessels.
Just inside the
endodermis is a layer of
meristem cells (cells
which remain able to
divide) called the
pericycle.
Plants need transport systems as:
Plants are multicellular so have a small SA:V meaning that plants cannot
rely on diffusion alone to supply their cells with everything they need.
Oxygen & glucose need to be transported for respiration & waste
products need to be transported to be removed.
Water & mineral ions need to travel from the roots to all the cells
Hormones made in one part of a plant need to be transported to the
areas where they have an effect
Differences between multicellular plant & multicellular animal transport
systems
Plants do not have a heart to act as a central pump, whereas many
multicellular animals have a heart
In plants 1 type of vessel is made up of dead cells whereas all animal
vessels are made of living tissue
In plants there are 2 different transport systems carrying different
materials whereas animals have different types of vessels but the same
transport medium in both
, Dicotyledonous plants
Dicotyledonous plants (dicots) make seeds that contain 2 cotyledons which are
organs that act as food stores for the developing embryo plant & form the first
leaves when the seed germinates.
Herbaceous dicots have soft tissues & a relatively short life cycle whereas woody
(arborescent) dicots have hard, lignified tissues & a long life cycle.
Dicotyledonous plants have a vascular system consisting of specialised vascular
tissue (tissue consisting of cells specialised for transporting fluids by mass flow):
Water & soluble mineral ions travel upwards in xylem tissue from the roots to
the leaves
Assimilates (substances made by the plant e.g. sugars) travel both up or down in
phloem tissue.
Other plant tissues:
Parenchyma- a packing tissue in plants which fills spaces between other tissues.
In roots parenchyma cells may store starch.
In leaves parenchyma tissue (called chlorenchyma) have chloroplasts & can
photosynthesise.
In aquatic plants aerenchyma tissue is parenchyma with air spaces to keep the
cell buoyant.
, Xylem and phloem in the young root
In a root, the xylem is in the centre surrounded by the
phloem. This arrangement provides strength to withstand
the pulling forces to which the roots are exposed e.g. when
the stem & leaves blow in the wind.
The endodermis, found
around the vascular
bundle, has a key role in
getting water into the
xylem vessels.
Just inside the
endodermis is a layer of
meristem cells (cells
which remain able to
divide) called the
pericycle.
