Transcript Nutrition and Transport - Woodstown

Nutrition and Transport
Nutrients


95% of plant’s dry weight is carbon,
hydrogen, and oxygen (carbohydrates, CO2
and water)
Minerals – provide proteins and nucleic acids

Essential nutrients – had role, no substitute, and a
deficiency results in death.


Macro and micronutrients according to concentration
Beneficial – required or enhances growth
soil



Mixture of mineral particles, decaying organic
material, living organisms, air and water
Humus – decaying organic matter
Mineral particles –




Sand – largest sized particles, water drains
Silt - intermediate
Clay – fine particles, not good drainage, - charge,
can retain + charged minerals.
Loam – equal portions of silt, clay and sand, good
Soil profile


Vertical section of ground
Horizons, parallel layers




A – uppermost, litter and humus
B – inorganic nutrients leached form A
C – weathered and shattered rock
Soil erosion – water and/or wind carry soil
away to new location

Loss of topsoil
Water and mineral uptake



Casparian strip – suberin and lignin border
sides of root endodermal cells, force water to
enter cells
Root hairs – allow water in at epidermal cells
Minerals enter plants in ionic forms via
electrochemical gradient with ATP pump


Root nodules – fix atmospheric nitrogen to NH4.
Epiphytes – air plants, roots can absorb water or
in pockets at base of leaves.
Transport mechanisms

Xylem



Tracheids – contain pits at ends that allow fluid to
flow from cell to cell
Vessel elements – long, tubular, form hollow
pipeline
Phloem


Sieve tube members Companion cells – provide proteins to sieve-tube
members
Water transport

Root pressure – formed when water enters the root,
usually at night


Guttation – drops of water are forced out of vein endings
along edges of leaves
Cohesion-tension model of xylem transport




Tension is created from the loss of water out of the leaves
(transpiration), draws water up from roots in vessels
Cohesion – water molecules cling together
Adhesion – water molecules cling to walls of vessel
elements
Continuous water column
Stomata


Bordered by guard cells
Potassium ions accumulate within guard
cells, water follows, stomata open

Turgor pressure is increased in guard cells

Hydrogen ions accumulate outside guard
cells

Stoma close when turgor pressure decreases

K+ decreased and water leaves guard cells
Organic Nutrient Transport

Girdling – removing a strip of bark from
around a tree

Pressure Flow Model of Phloem Transport



Source (photosynthesis production – leaves) to
Sink (growth areas) – usually leaves to roots
Sucrose is actively transported from leaves to
area of need, water follows per osmosis
Sugar is used for respiration, water exits via
osmosis to xylem