Plant Nutrition and Transport Chapter 21 Plant Nutrition and Transport

21.1 Nutrients from Soil and Air Experiments Aristotle - soil provides substance Van Helmont - water provides substance (mass) Willow tree Hales - air provides substance Air = CO2 --> photosynthesis --> sugars Water = H2O --> H - photosynthesis Solvent for other molecules 80-85% of mass Soil = inorganic minerals

Minerals 17 chemical elements needed Macronutrients; large quantities 3 are not minerals; C, O, H Macronutrients; large quantities Nitrogen - 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 hormones Usually deficient 80% of atmosphere (N2) Plants can only absorb NH4 or NO3 N2 to NH4 NH4 to NO3 break down organic material into ammonia (NH4)

Nitrogen-fixing Bacteria Legumes: peas, beans, peanuts root nodules: NF bacteria on roots Mutualistic Bacteria fix (convert) nitrogen Plant provides carbohydrates Crop rotation Soybeans have NF bacteria Convert tons of nitrogen Corn depletes nitrogen

Fertilizers Synthetic Plant doesn’t store nutrients Nitrogen 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 Tissue Roots 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 - unlike molecules; cellulose in xylem

Regulating Water Loss Transpiration Stomata regulate transpiration Upward transport Evaporative cooling Water loss from plant Maple 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 Night = closed 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

Phloem Transports 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 used Fruits 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

Monocots Root Stem Leaf

Dicots Stem Root Leaf

21.3 Unique Adaptations Carnivorous Plants Obtain nitrogen from insects Modified leaves form traps Live in areas with poor nutrients Bogs Venus flytraps, sundews, pitcher plants Consumer and producer(photosynthesis)

Epiphytes Grows on the surface of another plant without harming it Nutrition Photosynthesis Absorb minerals from rainwater Reason for adaptation Living 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