Exam #2 F 4/1 (bring cheat sheet)•Q&A Th 3/31 TBAToday: Material Transport

CB 36.2

Plants transport water, sugar, minerals, hormones, etc through the vascular system comprised of xylem and phloem

Water travels from ground out through leaves via xylem

CB 36.2

Sunlight powers photosynthesis and these sugars are transported via phloem

CB 36.2

Phloem transport is from source to sink.

Sugar is loaded at sources and unloaded at sinks...

consuming ATP(energy)

source:leaf

sink:root, flower, emerging leaf etc…

CB 36.20

Source and sink locations vary...

The direction of Phloem transport is versatile.

Water travels from ground out through leaves via xylem

CB 36.2

CB 36.15

Water moves from the ground through roots into the shoot and out stomata in the leaves.

Stomata control entry of CO2 and exit of H2O from plant leaves

Stomata

CB 36.14

Stomata on the underside of a leaf

CB 36.16

Guard cells regulate the opening of stomata

CB 36.15

Water is pulled up through the xylem:Transpiration, Adhesion, Cohesion, andTension

water transport limits plant growth

xylem

phloem

More xylem is needed for more water transport: secondary growth

CB 35.11 Primary vs. secondary growth

CB 35.19

Primary growth in a stem

Secondary growth:a vascular meristem (cambium) forms between the xylem and phloem

CB 35.19

Secondary growth:new xylem to the inside, new phloem to the outside

CB 35.19

Secondary xylem (wood) and phloem

The major component of

plant cell walls is cellulose

xylem

phloem

Xylem is made mostly of cellulose,but also lignin

Lignin: a complex branched, aromatic polymer

http://www.ccrc.uga.edu/~mao/intro/ouline.htm

Lignin cross-links

cellulose fibers and

makes xylem

waterproof

Cellulose, sugars as structural support

Fermentation: break down sugar to ethanol

http://www.iogen.ca/images/m1_fuel_cycle2.jpg

Nature Biotechnology 20, 557 - 558 (2002)

Lignin removal is necessary for cellulose processing, and it is energy intensive

xylem

Research is ongoing to produce woody and non-woody plants with decreased lignin to improve the efficiency of biofuel production

Loosening lignin's grip on biofuel production Clint Chapple, Michael Ladisch & Rick Meilan Nature Biotechnology 25, 746 - 748 (2007)

Treatment efficiencies of untreated transgenic biomass are comparable to that of unmodified biomass subjected

to pretreatment

~28% of U.S. energy is used in transportation

http://www.eia.doe.gov/kids/energyfacts/uses/transportation.html U.S. Department of Energy, Transportation Energy Data Book: Edition 26-2007.

In 2005, there were almost 239 million vehicles (cars, buses, and trucks) in the United States.

http://www.eia.doe.gov/kids/energyfacts/uses/transportation.html U.S. Department of Energy, Transportation Energy Data Book: Edition 26-2007.

http://www.eia.doe.gov/kids/energyfacts/uses/transportation.html U.S. Department of Energy, Transportation Energy Data Book: Edition 26-2007.

Vehicle Energy Use

Automobiles, motorcycles, trucks, and buses drove nearly 3.0 trillion miles in 2005. That’s almost 1/12th the distance to the nearest (non-sun) star. It’s like driving to the sun and back 13,440 times.

Transportation fuel use

http://www.eia.doe.gov/kids/energyfacts/uses/transportation.html U.S. Department of Energy, Transportation Energy Data Book: Edition 26-2007.

http://www.sciencemag.org/cgi/content/full/sci;319/5862/424

World Primary Energy Supply 2004

http://www.sciencemag.org/sciext/sustainability/

http://www.iogen.ca/images/m1_fuel_cycle2.jpg

Biofuel production

http://www.sciencemag.org/sciext/sustainability/

Much of our Alternative Energy Research is in Biofuels

CB53.22

Human resource production and use

Worldwide Grain Production per Person

http://www.earth-policy.org/Updates/2008/Update69.htm

7

World Grain Stocks as Days of Consumption

http://www.earth-policy.org/Updates/2008/Update69.htm

~60 percent of the world grain harvest is consumed as food, ~36 percent as feed, and ~3 percent as fuel. While the use of grain for food and feed grows by roughly 1 percent per year, that used for fuel is growing by over 20 percent per year.

http://www.earth-policy.org/Updates/2008/Update69.htm

Corn prices late 1999 – Nov 2008

http://futures.tradingcharts.com/

Corn prices Oct 2007-Nov 2008

http://futures.tradingcharts.com/

Increasing oil prices drive up potential profit, and cost of food crops

Cost of oil----Profitable cost of corn for ethanol

$50 ---- $4/bushel

$100 ---- $7/bushel

$140 ---- $10/bushel

Summer 2008 corn price: ~$8/bushelAugust '10 corn price: ~$4.00/bushelCurrent March '11 price: ~$6.90/bushelhttp://www.farmdoc.uiuc.edu/manage/newsletters/fefo07_11/fefo07_11.html,http://www.earth-policy.org/Updates/2008/Update69.htm, http://www.agriculture.com

Whereas previous dramatic rises in world grain prices were weather-induced, this one is policy-induced and can be dealt with by policy adjustments. If the entire U.S. grain harvest were converted into ethanol, it would satisfy scarcely 18 percent of our automotive fuel needs.

http://www.earth-policy.org/Updates/2008/Update69.htm

Exam #2 F 4/1 (bring cheat sheet)•Q&A Th 3/31 TBAToday: Material Transport