plant organs term 3 Flashcards
what are the plant organs
roots - anchor plants and absorb water minerals
stems - support leaves for photosynthesis
leaves - for photosynthesis, transpiration and gaseous exchange
flowers - for reproductiom through pollination
fruit - for reproduction through seed dispersal
what are the two types of leaves
isobilateral leaves - both surfaces look the same
dorsiventral leaves - both surfaces are different
Seed plants are divided into two main groups
gymnosperms
angiosperms
gymnosperms
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
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
regulation of gas movement by the stomata
stomata opens durinfg the day
photosynthesis occurs in the guard cell and water moves in by endosmosis
guard cells become turgid and pores open.
two types of root systems
tap root
fibrous root
function of stem in plants
transport
support and position
what is the secondary meristematic tissue found in roots and stems of plants
cambium
define transpiration
loss of water vapour from the aerial parts of the plant
what are the two types of transpiration
stomatal transpiration- loss of water vapour through stomata
cutiular transpiration- loss of water through the cuticles
what is wilting
plant cells become soft and tear away from the cell wall
what is guttation
happens when more water is absorbed into the plant from the roots than the transpiration rate and water evaporation from the leaves
what is root pressure
water continuously pushed up the xylem
what are the benefits of transpiration
cooling the plant: loss of water vapour cools down the plant
transpirational pull: water and mineral salts continuously brought up from the stem
plant structure: helps maintain turgidity
factors that affect the rate of transpiration
temperature
light intensity
wind
humidity
what is the device that measures the rate of transpiration
the potometer
what is translocation
transport of food from the source to other parts of the plant
