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(Bio) (Chem) Leaves and Autumn: A Change in Leaf Color

 
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adedios
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PostPosted: Sat Sep 23, 2006 8:03 am    Post subject: (Bio) (Chem) Leaves and Autumn: A Change in Leaf Color Reply with quote






A Change in Leaf Color
27 September 2006
Emily Sohn

Every autumn, traffic creeps along New England's roads as visitors look everywhere but at the road. These tourists flock to the region as soon as leaves begin to change color from a summery green to spectacular shades of red, orange, yellow, and purple.

For the full article:

http://www.sciencenewsforkids......ature1.asp

*************************************************************

Questions to explore further this topic:

What are leaves?

http://koning.ecsu.ctstateu.ed.....eaves.html
http://en.wikipedia.org/wiki/Leaf

What is photosynthesis?

http://www.emc.maricopa.edu/fa.....ookPS.html

Anatomy of a Leaf

http://www.ftexploring.com/pho.....plast.html

Why do leaves change color in autumn?

http://scifun.chem.wisc.edu/ch.....lcolr.html
http://www.na.fs.fed.us/spfo/p.....leaves.htm
http://www.esf.edu/pubprog/bro.....leaves.htm
http://www.dnr.state.wi.us/org.....ecolor.htm
http://harvardforest.fas.harva.....eaves.html
http://www.sciencenews.org/art.....6/bob8.asp

Images of autumn (Fall)

http://www.fs.fed.us/news/fallcolors/

Color in plants and antioxidants

http://www.sciencenewsforkids......ature1.asp
http://www.5aday.org/html/colo.....y_home.php
http://www.ext.nodak.edu/extpu.....fn595w.htm

How are leaves alike and different?(classroom activity)

http://www.teachers.net/lessons/posts/186.html

Identifying trees

http://arborday.org/trees/wtit/
http://arborday.org/kids/TreemazeFINAL.pdf
http://arborday.org/kids/TreeDiversityActv.pdf

Leaves and autumn (classroom activity)

http://www.sciencemadesimple.com/leaves.html

Surface area of a leaf (classroom activity)

http://www.pbs.org/teachersour.....vity3.shtm
http://www.mathcats.com/grownu.....lmath.html

Leaf collection (classroom activity)

http://www.bbc.co.uk/gardening.....leaf.shtml

Leaf experiments (classroom activity)

http://www.hometrainingtools.c.....ments.html

Chlorophyll (classroom activity)

http://arborday.org/kids/beataleaf.pdf


GAMES


http://pbskids.org/caillou/games/matching.html
http://arborday.org/kids/carly/leafminer/
http://arborday.org/kids/carly.....ursuit.cfm
http://arborday.org/kids/carly...../index.cfm
http://arborday.org/kids/treetrivia/
http://arborday.org/kids/carly...../index.cfm
http://arborday.org/kids/carly/puzzles/index.cfm
http://www.sesameworkshop.org/nl?ID=15006
http://www.sesameworkshop.org/nl?ID=17996


Last edited by adedios on Sat Jan 27, 2007 3:41 pm; edited 2 times in total
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adedios
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PostPosted: Mon Oct 16, 2006 8:37 pm    Post subject: Fall Foliage: Why Leaves Change Color Reply with quote

Fall Foliage: Why Leaves Change Color

By Corey Binns
Special to LiveScience
posted: 16 October 2006
12:20 pm ET



For years, scientists have studied how leaves prepare for the annual show of fall color. The molecules behind bright yellows and oranges are well understood, but brilliant reds remain a bit of a mystery.

In response to chilly temperatures and fewer daylight hours, leaves stop producing their green-tinted chlorophyll, which allows them to capture sunlight and make energy. Because chlorophyll is sensitive to the cold, certain weather conditions like early frosts will turn off production more quickly.

Meanwhile, orange and yellow pigments called carotenoids—also found in orange carrots—shine through the leaves' washed out green.

"The yellow color has been there all summer, but you don't see it until the green fades away," said Paul Schaberg, U.S. Forest Service plant physiologist. "In trees likes aspens and beech, that's the dominant color change."

Scientists know less about the radiant red hues that pepper northern maple and ash forests in the fall.

For the full article:

http://www.livescience.com/env.....eaves.html
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adedios
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PostPosted: Fri Jan 19, 2007 1:09 pm    Post subject: 'Speechless' and 'Mute' help break the silence of the leaves Reply with quote

University of Washington
18 January 2007

'Speechless' and 'Mute' help break the silence of the leaves


Researchers have discovered two genes that guide land plants to develop microscopic pores that they can open and close as if each pore was a tiny mouth.

Plants wouldn't have been able to move from water to land 400 million years ago if they hadn't evolved this ability, which protects them from losing too much moisture.

The leaves and stems of land plants are dotted with the "tiny mouths," called stomata. When open, stomata allow the plant to take in carbon dioxide gas needed for photosynthesis and allow moisture to evaporate, pulling water from the roots into the plant. But when too much moisture is being lost, the two cells around the stomatal pore close it completely.

Without the genes guiding stomatal development, plants won't develop any mouthlike pores, hence the names Speechless and Mute for the newly discovered genes, according to Keiko Torii, a University of Washington associate professor of biology.

Two separate papers on the genes, one by Torii's UW group and the other by Stanford University researchers, have been published online by Nature, and are scheduled to appear in the print publication Feb. 1. Each group describes independently finding the gene that came to be called Speechless and its role in initiating the process that leads to stomata.

In addition, Torii's UW group published findings in its Nature article about another gene, one they named Mute, that triggers the key middle step that decides when a cell will fully become a stomata. Earlier this year the Stanford group published findings about the gene that controls the final step in stomata development, called Fama.

"In the last few months, we've gone from knowing surprisingly little about the genes involved to knowing all three major factors – Speechless, Mute and Fama," says Lynn Pillitteri, a research associate in biology and lead author of the Nature paper.

That the three are so closely related will be of interest to biologists studying both plants and animals, she says. Each is a basic protein with a helix-loop-helix domain, a sequence that is quite ancient and controls a vast range of physiological and developmental processes. Speechless, Mute and Fama also have very similar DNA sequences and could have arisen from a single gene that replicated and evolved, giving plants additional genes with slightly different characteristics.

Having two or three genes with similar characteristics would give plants what Torii terms "the freedom to play, to make functions that are the more elaborate stomata in modern plants."

Other biologists have seen something similar in animals. The ability to differentiate cells that become muscles also is controlled by consecutive action of basic helix-loop-helix proteins with DNA closely related to each other.

Molecular conservation of such key regulatory genes between plants and animals – genes that switch on and off cell-type differentiation programs from precursor stem cells – is intriguing and exciting, Torii says.


###
In addition to Pillitteri and Torii, who is the corresponding author, the other co-authors are Daniel Sloan, a former UW technician now pursuing a doctorate at University of Virginia, and Naomi Bogenschutz, a research technician.

The group works with Arabidopsis, a weedlike member of the crucifer family that also includes broccoli and cabbage. The work is funded by the U.S. Department of Agriculture, U.S. Department of Energy, National Science Foundation and the Japanese Science and Technology Agency, which are interested in understanding basic plant growth to provide insights to improving plant growth, or biomass, suitable for producing fuel.


The article "Termination of asymmetric cell division and differentiation of stomata" and the letter "Transcription factor control of asymmetric cell divisions that establish the stomatal lineage" were published Dec. 20 in Nature's advance online publication.

Torii group Web site: http://faculty.washington.edu/ktorii/stomata.html
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PostPosted: Mon Oct 22, 2007 12:21 pm    Post subject: Climate Change Blamed for Fading Foliage Reply with quote

Climate Change Blamed for Fading Foliage
By Dave Gram, Associated Press

posted: 22 October 2007 10:55 am ET

EAST MONTPELIER, Vt. (AP)—Every fall, Marilyn Krom tries to make a trip to Vermont to see its famously beautiful fall foliage. This year, she noticed something different about the autumn leaves.

"They're duller, not as sparkly, if you know what I mean," Krom, 62, a registered nurse from Eastford, Conn., said during a recent visit. "They're less vivid."

Other "leaf peepers" are noticing, too, and some believe climate change could be the reason.

For the full article:

http://www.livescience.com/env.....eaves.html
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adedios
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PostPosted: Thu Oct 25, 2007 2:29 pm    Post subject: Why Do Autumn Leaves Bother to Turn Red? Reply with quote

Why Do Autumn Leaves Bother to Turn Red?
25 October 2007
The Geological Society of America

Boulder, CO, USA - Soils may dictate the array of fall colors as much as the trees rooted in them, according to a forest survey out of North Carolina.

By taking careful stock and laboratory analyses of the autumn foliage of sweetgum and red maple trees along transects from floodplains to ridge-tops in a nature preserve in Charlotte, N.C., former University of North Carolina at Charlotte graduate student Emily M. Habinck found that in places where the soil was relatively low in nitrogen and other essential elements, trees produced more red pigments known as anthocyanins.

Habinck's discovery supports a 2003 hypothesis put forward to explain why trees bother to make red pigments, by plant physiologist William Hoch of Montana State University, Bozeman. Hoch found that if he genetically blocked anthocyanin production in red-leafed plants, their leaves were unusually vulnerable to fall sunlight, and so sent less nutrients to the plant roots for winter storage.

For trees living in nutrient-poor soils, then, it makes sense to produce more anthocyanins, which protect the leaves longer, so as much nutrient as possible can be recovered from leaves before winter sets in. It is, after all, the process of recovering of nutrients from leaves which turns leaves from green to yellow, orange and sometimes anthocyanin-red.

The trees Habinck studied appear to be acting in accordance with Hoch's hypothesis. "It makes sense that anthocyanin production would have a function, because it requires energy expenditure," said Habinck. Put in economic terms, anthocyanins are an investment made by stressed trees in situations where they stand to gain from the extra recovery of nutrients from leaves. It's not about the showy color, but about survival.

"The rainbow of color we see in the fall is not just for our personal human enjoyment -- rather, it is the trees going on about their lives and trying to survive," said Habinck's advisor, Martha C. Eppes, a soil scientist and assistant professor of Earth sciences at the University of North Carolina at Charlotte. Eppes will present the research at the Geological Society of America Annual Meeting, Monday, 29 October, in Denver, CO.

The reason the soil-leaf color connection wasn't made long ago is partly because Hoch's hypothesis was needed to put it into perspective. It also might be that many plant researchers were missing the forest for the trees.

"I think that most of the work has been done by biologists looking at production of anthocyanins in trees themselves," said Eppes. They hadn't stepped back and looked at patterns of tree color.

Eppes wants to follow up Habinck's study with a wider analysis of satellite data showing tree color which can be compared to geological maps of the types of soils over large portions of land.
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PostPosted: Mon Oct 29, 2007 12:23 pm    Post subject: Study: Fall Colors Are Sunscreen for Trees Reply with quote

Study: Fall Colors Are Sunscreen for Trees
By Andrea Thompson, LiveScience Staff Writer

posted: 29 October 2007 09:15 am ET

The fiery red hues that seem to set forest leaves ablaze in autumn are produced in part as a result of the soil that trees grow in and help protect the trees in the winter, a new study finds.

The reasons why leaves change from their summer greens to brilliant yellows, oranges and reds has been something of a mystery to scientists because the process required energy, but didn't seem to benefit the trees.


For the full article:

http://www.livescience.com/env.....eaves.html
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PostPosted: Sat Nov 17, 2007 7:05 am    Post subject: Why Autumn Colors Are So Late Reply with quote

Why Autumn Colors Are So Late
By Andrea Thompson, LiveScience Staff Writer

posted: 16 November 2007 02:46 pm ET

A gray, grim landscape used to greet residents of the Northeastern United States each November, but autumn's riot of red, orange and yellow came late this year. Delayed fall foliage also occurred in Chicago and parts of Europe.

Some say droughts and a warm summer played a role, while others wonder more broadly about global warming. In fact, it's rising levels of carbon dioxide, not the warmer temperatures fueled by the greenhouse gas, that have been delaying the transformation of green leaves, at least in Europe for a few decades, a new study suggests.

For the full article:

http://www.livescience.com/env.....delay.html
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PostPosted: Wed Jan 23, 2008 1:24 pm    Post subject: Forests Could Benefit When Fall Color Comes Late Reply with quote

Forests Could Benefit When Fall Color Comes Late
22 January 2008
Michigan Technological University

Do those fall colors seem to show up later and later—if at all? Scientists say we can blame increasing amounts of carbon dioxide in the atmosphere for prolonging the growing season of the trees. And that may actually be good news for forestry industries.

Writing in the current issue of the journal Global Change Biology, Michigan Technological University Professor David F. Karnosky and colleagues from two continents present evidence that rising carbon dioxide levels in the atmosphere act directly to delay the usual autumn spectacle of changing colors and falling leaves in northern hardwood forests.

“Basically, this is a good-news story for our region’s forests,” said Karnosky. “It suggests that they will become a bit more productive due to the extra carbon being taken up in the autumn, along with the increased photosynthesis throughout the growing season.”

The Michigan Tech professor of forest resources and environmental science and colleagues from Illinois, Wisconsin, Belgium, England, Estonia and Italy collected and analyzed data over two years on what they call “autumnal senescence” or the changing of colors and falling of leaves as photosynthesis decreases. They studied forests near Rhinelander, Wisconsin, and Tuscania, Italy.

They found that the forests on both continents stayed greener longer as CO2 levels rose, independent of temperature changes. However, the experiments were too brief to indicate how mature forests may be impacted over time. Also, Karnosky’s research in Wisconsin suggests that other factors, such as increasing ozone levels in the part of the atmosphere closest to the ground, can negate the beneficial effects of elevated carbon dioxide.

The study’s results are another example of an expanding body of scientific evidence that global climate change is affecting the world’s forests. There has been plenty of evidence gathered previously to show that increased carbon dioxide in the atmosphere is causing tree growth to begin earlier in the spring, but until now, most scientists believed that other factors, such as temperature and length of day, were the primary elements influencing autumnal senescence.

Michigan Technological University is a leading public research university, conducting research, developing new technologies and preparing students to create the future for a prosperous and sustainable world. Michigan Tech offers more than 120 undergraduate and graduate degree programs in engineering, forestry and environmental sciences, computer sciences, technology, business and economics, natural and physical sciences, arts, humanities and social sciences.
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PostPosted: Sat Jul 05, 2008 7:30 am    Post subject: Optimizing leafy networks Reply with quote

Optimizing leafy networks
By Davide Castelvecchi
June 30th, 2008

Plant leaf plumbing designed to move water fast

Using an artificial model of a leaf, scientists have unveiled a mathematical principle underlying how leaf veins are arranged to enable water to perspire as fast as possible.


Because water perspiration is closely linked to how plants absorb CO2, the findings could help researchers learn about past climates by studying the patterns of veins found on fossilized leaves.

For the full article:

http://sciencenews.org/view/ge.....y_networks
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