Lecture 1-Plant Parts Flashcards
what is plant cell box made of
cellulose and hemicellulose
How are plant cells glued together?
Pectin
Plasmodesmata
connects plant cells, allows materials to move between living cells
Symplast
interconnected network of living cells
Apoplast
interconnected network of dead cells
Acetabularia
algae made of just one cell
Advantage of multicellularity
Great complexity in form
3 Types of Simple Tissue
parenchyma, collenchyma, sclerenchyma
Parenchyma Tissue
very common in plants, isodiametric shape
Functions: storage, photo, secretion, reserve for wounds
Aerenchyma
specialized parenchyma, aeration of roots in water
Collenchyma Tissue
not generally common
Sclerenchyma Tissue
common, various shapes. Fibres and Sclereids
Fibres
cell length 1-10cm (ramie, Boehmeria 1/2m)
in all organs.
linen, rope, clothing, bioplastics
Sclereids
defense. stone cells. asterosclereids (water lily stem)
abrasives, walnut shell grit
2 Types of Complex tissues
xylem, phloem
Xylem
dead cells: water roots to leaves
Living: hormones top to bottom
parenchyma, sclerenchyma and tracheary elements (dead)
2 Tracheary Elements
tracheids and vessel elements
Tracheids
water-conducting, secondary cell walls, more common than v.e, bordered pits for strength, cells interdigitate
Vessel elements
only in angiosperms, water conduction, convergent evo. open-ended cells connected by performation plate
Parenchyma cells in xylem
transports hormone indole-3-acetic acid (auxin), which controls development (inhibits branching) resin ducts (defence)
Sclerenchyma in xylem
structural. fibres, sclereids
Phloem
mostly alive
dead cells: support/defense
living: transport of organic cmpds, hormone transport bottom to top (cytokinins that regulate cell division)
sieve elements, parenchyma, sclerenchyma
Sieve elements
sieve tube members-missing a nucleus but alive
paired w/ protein-rich cell (companion cell) that transfers materials in/out of phloem
Parenchyma cells in phloem
loads/unloads organic compounds and minerals
specialize parenchyma-transfer cells
resin ducts (defense)
Sclerenchyma cells in phloem
fibres, sclereids
Functions of Phloem tissue
transport of organic cmpds (passive)
offloading cmpnds to storage cells (active)
transport of plant hormone (cytokinin)
defense (phloem parenchyma prevents microbes)
Three tissue systems
dermal tissue, ground tissue, vascular tissue
Dermal tissue
epidermis, always on outside
Ground tissue
parenchyma, sclerenchyma, collenchyma (simple tissues)
stem: cortex and pith
root: cortex and pith (not always pith)
Leaf: mesophyll and palisade tissue
Vascular tissue
xylem and phloem (complex tissues)
root: in middle, no need for mech. support
shoot: towards edges-better mech. support
leaf: netowrk of veins in middle of leaf
Shoot apical meristem
gives rise to tissue systems
Root zones
zone of division, zone of elongation, zone of differentiation
X-section order of tissues from outside in
epidermis-cortex (mostly parenchyma tissue, innermost layer is endodermis)-vascular tissue (xylem in middle, phloem between arms of xylem, endodermis in circle around bundle)
endodermis
living cylinder of cells that acts as barrier to apoplastic fluids