Post on 11-Jan-2016
Chapter 21
Plant Nutrition and Transport
21.1 Nutrients from Soil and Air
ExperimentsAristotle - soil provides substanceVan Helmont - water provides
substance (mass)Willow tree
Hales - air provides substance
Air = CO2 --> photosynthesis --> sugars
Water = H2O --> H - photosynthesisSolvent for other molecules80-85% of mass
Soil = inorganic minerals
Minerals
17 chemical elements needed3 are not minerals; C, O, H
Macronutrients; large quantitiesNitrogen - protein and NA synthesis
Sulfur - protein synthesis
Phosphorus - NA and ATP synthesis
Potassium -protein syn. & osmosis regulation
Calcium - cell wall formation & enzyme activity
Magnesium - chlorophyll synthesis & enzyme activity
Other Minerals
• Micronutrients (small quantities)• Boron; Essential for seed and fruit development• Copper: carbohydrate and nitrogen metabolism• Iron; Essential for formation of chlorophyll• Chloride: salt effects (stomatal opening• Manganese: formation of chlorophyll; catalyst• Molybdenum: nitrogen and sulfur metabolism,
protein synthesis• Zinc: catalyst and regulator; energy production,
protein synthesis, growth regulator
Nitrogen
Produce proteins, nucleic acids, and hormonesUsually deficient
80% of atmosphere (N2)
Plants can only absorb NH4 or NO3
break down organic material into ammonia (NH4)
NH4 to NO3
N2 to NH4
Nitrogen-fixing Bacteria
Legumes: peas, beans, peanutsroot nodules: NF bacteria on roots
MutualisticBacteria fix (convert) nitrogen
Plant provides carbohydrates
Crop rotationSoybeans have NF bacteria
Convert tons of nitrogen
Corn depletes nitrogen
Fertilizers
SyntheticNitrogen
Phosphorus
Potassium
Plant doesn’t store nutrients
Leftovers are in soil and can contaminate runoff water
Polluted water goes into rivers and lakes
Do Now Questions
How does transpiration allow water to flow in a plant?
What is a sugar sink?
Why does a carnivorous plant need to eat insects?
21.2 Vascular TissueRoots absorb water and minerals root hairs: tiny outgrowths of root’s epidermal cells
Increase surface area
root pressure: helps push water through xylem; usually at night
Minerals move through the cells to xylem; cytoplasmic channels endodermis: waxy layer of cells surrounding the vascular tissue
Prevents water and mineral leakage
Water enters by osmosis
Water Movement
transpiration: loss of water through leaves due to evaporation, generates the pull of sap upward
Cohesion -
water sticking to
itself
Adhesion -
water sticking to
unlike molecules;
cellulose in xylem
Regulating Water Loss
TranspirationUpward transport
Evaporative cooling
Water loss from plantMaple Tree = 220L per hour in the summer
Stomata regulate transpiration guard cells: cells around each stoma that open and close by changing shape
Stomata
Day = open to allow CO2 in
Low CO2 = K accumulation; water flows in and swell the guard cells
Night = closed
2 Types of Xylem
tracheids: long cells with tapered ends
vessel elements: wider and shorter
Form tubes; inner cells died and left lignified cell walls
PhloemTransports sucrose and other organic compounds with water sieve-tube members: chain of cells in which phloem sap flows
Remain alive, but lose nuclei and other organelles
companion cells: cells alongside sieve tubes that provides proteins
Sugar Sink
Phloem moves sugar from where it is made (leaves) to where it is needed
Sugar sink: sugar stored or usedFruits
Roots
Shoot tips
Summer - beat, potatoes
Pressure-flow
Sugar is actively transported into a sieve-tube member
pressure-flow mechanism: water flows from high pressure to low
MonocotsStem
Root
Leaf
DicotsRoot
Stem
Leaf
21.3 Unique Adaptations
Carnivorous PlantsObtain nitrogen from insectsModified leaves form trapsLive in areas with poor nutrients
Bogs
Venus flytraps, sundews, pitcher plantsConsumer and producer(photosynthesis)
Epiphytes
Grows on the surface of another plant without harming itNutrition
PhotosynthesisAbsorb minerals from rainwater
Reason for adaptationLiving on high branches brings the plant closer to sunlight
Orchids, Spanish “moss”, ferns
Parasitic Plants
Obtain nutrients from other plants
Taps into vascular tissue
Damages plant
Take away sunlight
Can kill the host by robbing nutrients
Mistletoe, fig