BI111 Lecture Notes - Lecture 5: Endodermis, Indeterminate Growth, Main Stem
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Plants Lecture Notes (#5)
What is a plant?
Multicellular eukaryotes
Almost all* are photoautotrophs
Photosynthetic (chlorophylls a and b and carotenoids in thylakoid membranes.)
Cell walls
Food storage molecule: amylose starch
Structural polysaccharide: cellulose
Sessile or stationary
Alternation of generations life cycle
Embryo retained inside gametophyte tissues
Overview of the “Plant Body”
Almost all plants are photosynthetic autotrophs
Shoot system above ground
oPhotosynthetic leaves, stems
Root system below ground
oNonphotosynthetic roots
Plant bodies are dendritic
oSpreading and branched in form
Shoot System: Functions
Stems, leaves, buds, flowers
Highly adaptive for photosynthesis & positions flowers for pollination
Vegetative (nonreproductive) shoot
oStem with attached leaves and buds
oBud gives rise to extension of shoot or new, branching shoot
Reproductive shoot
oProduces flowers which later develop fruits containing seeds
Root System: Functions
Usually grows below ground
Anchors plant and supports upright parts
Absorbs water and dissolved minerals from soil
Stores carbohydrates
Vascular Plant Body
3 Tissue Systems: Ground, Vascular & Dermal
Organ/Tissue system: Body structure that contains two (or more!) types of tissues and
have a definite form and function
Tissue: Group of one (or more!) types of cells and intercellular substances that function
together in one (or more!) specialized tasks
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Plant Cell: General Properties
Primary cell wall (surrounding plasma membrane and cell contents)
oCellulose fibers in matrix of hemicellulose
oRigid but flexible
Large vacuole (30-80% of internal volume) Tonoplast membrane
oUsed for storage and to maintain turgor pressure against the cell wall
Plasmodesmata
oCytoplasmic connections between adjacent cells
Plant Cell Wall Structure
Lignin
Some plant cells have “lignified” secondary cell wall
oCellulose fibers anchored with lignin: stronger and more rigid
oCreates waterproof barrier (hydrophobic)
oResistant to decay and attack by microbes
Plant Tissue System: Form & Function
3 Tissue Systems: Ground, Vascular & Dermal
Ground tissues are all structurally simple but exhibit important differences
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Vascular tissues are specialized for conducting fluids
The dermal tissue system protects plant surfaces
3 Plant Tissue Systems
Ground, Vascular & Dermal Tissues
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