Week 8 - Plant Structure Flashcards
What are the three basic plant organs?
Roots
Stems
Leaves
What are the functions of roots?
Anchoring the plant
Storing carbs
Absorbing water and nutrients
Describe the taproot system
One main root (taproot), with lateral roots branching out of it
What root system do eudicots have?
Taproot
What root system do monocots have?
Fibrous root system
Describe the fibrous root system
Adventitious root emerge from the base of the stem. No main root. Lateral roots come out of the many adventitious roots
What are root hairs?
Hair-like extensions that cove the outside surface of young roots. Increases absorptive surface area
Name and explain the modified roots
Prop roots: extra roots for structure. Type of adventitious root
Storage roots: Stockpile carbs
Green roots: can photosynthesize
Pneumatophores: Get atmospheric oxygen. MANGROVE TREES- the other roots can’t get much from the water (waterlogged)
What are the functions of stems
Support
Distribute water and minerals, and sugar
Name and explain the modified stems
Rhizomes: stem that grows horizontally underground to store carbs and take up more room
Stolons: Above ground. Grow horizontally to propagate (ex: strawberry plants)
Tubers: Store carbs
Explain apical dominance
As long as apical buds stay intact, axillary buds stay dormant
Explain the function of leaves
Photosynthesis
What is the difference between simple and compound leaves?
Simple: flattened blade
Compound leaf: many leaflets
Name and explain the different modified leaves
Tendrils: spiral to climb
Spines: deter herbivory
Storage: store water
Plantlets: asexual reproduction
Explain dermal tissue
Dermal tissue
Covers outside surface.
Defense against physical damage. EPIDERMIS, guard cells and stomates (guard cells open and close stomata)
Includes periderm in woody plants
Explain the vascular tissue (general)
Vascular tissue
Continuous vascular conduits.
Xylem- water from roots to shoots
Phloem- hormones, sugars, amino acids from where they are made to where they are needed
Explain the ground tissue
Ground tissue.
The rest. Whatever is not occupied by vascular or dermal
Structural support and storage.
EUDICOTS
Ground tissue closest to the edge = cortex
Ground tissue closest to the center= pith
MONOCOTS
No difference in ground tissue
What type of cell makes up the ground tissue?
Mesophyll
Upper layer if palisade mesophyll and loser layer of spongy mesophyll (less dense)
Name the major plant cell types
Parenchyma
Collenchyma
Sclerenchyma
Describe parenchyma cells
Thin, flexible primary cell walls. NO SECONDARY CELL WALLS
Metabolic functions of the plant (ex: photosynthesis and storage of photosynthates)
Can still divide and differentiate
Describe collenchyma cells
Thickened, uneven cell walls
Lack secondary cell walls
Structural support
Found on the underside of the epidermal layer
VERY THICK FIRST CELL WALL
Describe scherenchyma cells
Protection, support, long distance transport
LIGNIN IN SECODNARY CELL WALL
primary source of dietary fibre
- SCLEREID CELLS
found in nut shells. Short, regularly shaped - FIBRE CELLS
long and slender.
Describe the specialized xylem cells
- Tracheids. Long, tapered end.
- Vessel elements (angiosperms only) Wider.
Describe the specialized phloem system cells
Move the products of photo where it iss needed or stored
- Sieve tube elements. Like a straw. It’s emptied.
- Companion cells. Serves the sieve tube elements
What is the junction where two sieve tube elements meet called? What does it do?
Sieve plates
Enables the flow of phloem sap
What is the root collar?
Where the stem transition into the root
What is the difference between determinate and indeterminate growth?
Determinate: ex: leaves. Stop growing at maturity
Indeterminate (2 KINDS): primary and secondary
What are the three zones if primary growth
Dufferentiation
Elongation
Division (nearest to root cap)
What does secondary growth do?
Increases diameter of stems and roots
What is the rule about differenciation and the vascular cambium?
If cells differenciate on the inside, it’s a xylem cell
outside = pholem
Which cells accumulates?
XYLEM ACCUMULATES
PHLOEM DOES NOT
What is the star pattern on a cut tree?
Vascular rays
provide substances from secondary xylem to secondary phloem
Explain growth rings on trees
Xylem cells with different diameters
In spring xylem is thicker bc of water need to make new leaves
In summer structure is more important so it’s more densely packed.
Rings are alternating between esrly and late wood
Is heartwood vascular? What is it?
Old xylem. not vascular anymore just for support
What do cork cells have?
Pseuborin
