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Lecture 19

BI111 Lecture Notes - Lecture 19: Ground Tissue, Pectin, Hemicellulose


Department
Biology
Course Code
BI111
Professor
Tristan Long
Lecture
19

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PLANT STRUCTURES AND ADAPTIVE IMPORTANCE FEB 22.2016
OVERVIEW OF THE PLANT BODY
ophoto auto – most plants
oshoot and root leaves and stems then roots
odendritic spread in branches
omorph that has shown due to selection
SHOOT SYS: FUNCS
ospecializations in di parts : stem, leaves, buds, owers
oparts help to make pollinator to move gametes for them
ovegetative: stem with leaves and buds
obuds grow more branches or shoots
oreprod: produce owers turn into fruits with seeds
ROOT SYS: FUNCS
oBelow ground
oAnchors and lets upright part grow tall for light
oAbsorb water and mins store carbs
VASC PLANT BODY:
oGround, vasc, dermal systems
oOrgan/tissue sys: body struc with 2+ types of tissue
oTissue: group pf 1+ cells and intercell subs
oGROUND : 3 cells parenchyma, collenchyma, sclerenchyma tissues
o1) primary wall, young tissue, thin, loosely attached air ow, huge vacuole for storage,
look like marshmallow balls
o2) exible, thicker prim cell wall, elongated in strands like cylinders, pectin mostly at
corners for elasticity
o3) rigid, protects, secondary cell wall of hemicellulose and lignin, in stems, leaf veins,
covers of seeds and nuts
Sclereids – protect , irregular cells fruit and seeds
Fibres – support, needle shaped cells, some elasticity
oVASCULAR SYS
oXylem: conduct water and mins, thick, lig secondary walls, dead when func
o2 types of xylem
Tracheids: elong, overlapping ends, hollow, water ow to leaves, lateral
connections through pits, reliable against air bubbles
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