Support and transport in plants Flashcards
Seed plants are divided into two main groups
- gymnosperms
- angiosperms
gymnosperms
- Non-flowering seed plants
- e.g. pine trees, yellowwood trees and cycads
angiosperms
- flowering plants
- e.g. sunflowers, corn and orange trees
Angiosperms are divided into two main groups
- dicotyledons (dicots)
- monocotyledons (monocots)
Main support tissues in plants
- collenchyma
- sclerenchyma
- xylem
Main transport tissues in plants
- xylem
- phloem
Xylem tissue is made up of…
- xylem vessels
- xylem tracheids
- xylem sclerenchyma fibres
- xylem parenchyma
Xylem vessel features…
- primary cell wall made of cellulose
- dead cells, no cytoplasm
- long, cylindrical tubes
- ends of tubes (cross walls) have perforated plates
- thick secondary walls of lignin
- lignin either annular, spiral, scalariform or pitted
Xylem tracheid features…
- similar to tracheids
- cell ends tapered (pointed)
- narrow diameter
Xylem suited for support because…
- thick secondary walls of lignin
- round shape in cross section
- strong to resist shearing forces (forces acting at different angles to the cell)
Xylem suited for transport because…
- cross walls perforated
- cells are dead and hollow
- pits and gaps in thickening allow water to move sideways between cells
Xylem transports…
- water
- dissolved mineral salts
Phloem transports…
- manufactured organic foods
- e.g. glucose and sucrose
Phloem tissue is made up of…
- sieve tubes
- companion cells
- phloem schlerenchyma fibres
- phloem parenchyma
Sieve tube features…
- Primary cell wall of cellulose
- no secondary thickening
- living cells with no nucleus or cytoplasm
- long, tube like
- sieve plates at ends with holes
- Large vacuoles (cell body) with cytoplasmic threads
Companion cell features…
- Living cells
- dense cytoplasm with a nucleus
- found next to sieve tubes to manage their metabolism
Functions of the root system in plants…
- anchorage
- support
- storage
- nutrient uptake
- transport
- reproduction
First root in angiosperms?
- Primary embryonic root
- called the radicle
First shoot in angiosperms?
- Embryonic shoot
- called the plumule
Describe dicot roots
- tap root system
- radicle develops into a tap root
- lateral roots branch outwards from this
Describe monocot roots
- Fibrous or adventitious
- radicle dies
- replaced with secondary roots from stem
- form a shallower fibrous root system
Region of root where xylem and phloem are found…
- the stele
Support tissues in a root…
- collenchyma
- schlerenchyma
- xylem
Transport tissues in a root…
- Xylem
- Phloem
Describe the outermost layer of a root…
- Epidermis tissue
- No cuticle to be able to absorb water
- Root hairs may be present to increase surface area
The two main root regions of a dicot (cross section)
- Cortex (outer)
- Stele (inner)
Describe the cortex in a dicot…
From outside inwards:
- (Epidermis)
- Exodermis
- central cortex
- endodermis (innermost layer)
Describe the endodermis…
- Single layer of parenchyma cells
- Wall thickening called Casparian band (helps control water movement)
Describe the stele…
- Pericycle tissue - produces secondary roots
- Conducting tissue - xylem and phloem
