Download Atoms, Elements, Compounds and Mixtures

Transport in Plants
Spot the Difference!
Transport in Plants
• Xylem
water and soluble minerals
travel upwards
• Phloem
sugars travel up and down
Section of a Plant Root
xylem
phloem
• Xylem cells arranged
in a cross shape
• Phloem cells within
the corners of the
xylem
Section of a Leaf
• Vascular bundles form
the midrib and veins of
the leaf
• Xylem above phloem
Section of a Stem
Vascular bundle
xylem
phloem
cambium
(in between the
xylem and phloem)
• Separate vascular bundles
• Bundles towards outer edge
of stem
• Ring of vascular tissue
around the edge of stem
• Xylem towards inside and
phloem towards outside of
stem
• Cambium - layer of meristem
cells. Undifferentiated.
Produce new xylem and
phloem
phloem
phloem
xylem
cambium
Function of Xylem
• Transports water and minerals from
roots to the rest of plant
• Transported upwards
Structure of Xylem
• Tubes to carry water and dissolved minerals,
fibres for support
• Xylem vessel elements (living parenchyma
cells) impregnated by lignin
• Lignin waterproofs the cell walls and
prevents them from collapsing. This leaves a
long column of dead cells
• Water can pass through the cell walls
through pits
• No cell contents, nucleus or cytoplasm
Function of Phloem
• Transports sugars from one part of
plant to another
• Transported up or down
2 types of cell
– sieve tube elements
– companion cells
Linked by
plasmodesmata
Structure of Phloem
Sieve tube element
• Very little cytoplasm, no nucleus
• Lined end to end forming a tube
• Contains perforated cross-walls (sieve plates)
– allows sap through the pores
Companion cell
• Large nucleus, dense cytoplasm, many
mitochondria
• Responsible for metabolic processes (requires
ATP)