Literacy Design Collaborative (LDC)
Photosynthesis-Related Writing Task
Question: How do increased levels of atmospheric carbon dioxide affect the production of food grains, such
as wheat and sorghum?
After reading the four attached articles, write 3 paragraphs in which you discuss the effect of increased
atmospheric carbon dioxide and evaluate the advantages and disadvantages to the production of food crops.
Support your position with evidence from the texts.
Guidelines:
• Your paper must be typed, double-spaced, and no longer than 2 pages.
• Include your name and hour at the top right corner of the first page.
• You must cite at least two of the four articles in your discussion.
• Use parenthetical citations to cite the sources within the text of your writing.
• Because the references are provided, you do not need to include a reference page.
Tips:
• Before forming an opinion, carefully consider all sides of the issue, including ecological, economic,
political, and social impacts.
• Be sure you deeply understand the effects of increased atmospheric carbon dioxide on a global scale
and how such an increase might impact local environments.
Due Date: Friday, November 7th
Argumentation Teaching Task Rubric for Template Task Collection Version 2.0
Scoring
Elements
Focus
Controlling
Idea
Reading/
Research
Development
Not Yet
1
Attempts to address prompt,
but lacks focus or is off-task.
Attempts to establish a claim,
but lacks a clear purpose. (L2)
Makes no mention of counter
claims.
Attempts to reference reading
materials to develop response,
but lacks connections or
relevance to the purpose of the
prompt.
Attempts to provide details in
response to the prompt, but
lacks sufficient development or
relevance to the purpose of the
prompt. (L3) Makes no
connections or a connection
that is irrelevant to argument or
claim.
1.5
Approaches Expectations
2
Addresses prompt appropriately
and establishes a position, but
focus is uneven.
Establishes a claim. (L2) Makes
note of counter claims.
Presents information from
reading materials relevant to the
purpose of the prompt with
minor lapses in accuracy or
completeness.
Presents appropriate details to
support and develop the focus,
controlling idea, or claim, with
minor lapses in the reasoning,
examples, or explanations. (L3)
Makes a connection with a weak
or unclear relationship to
argument or claim.
2.5
Meets Expectations
3
Addresses prompt appropriately and
maintains a clear, steady focus.
Provides a generally convincing
position.
Advanced
4
Addresses all aspects of prompt
appropriately with a consistently strong
focus and convincing position.
Establishes a credible claim. (L2)
Develops claim and counter claims
fairly.
Establishes and maintains a substantive
and credible claim or proposal. (L2)
Develops claims and counter claims fairly
and thoroughly.
Accurately presents details from
reading materials relevant to the
purpose of the prompt to develop
argument or claim.
Accurately and effectively presents
important details from reading materials
to develop argument or claim.
Presents appropriate and sufficient
details to support and develop the
focus, controlling idea, or claim. (L3)
Makes a relevant connection to clarify
argument or claim.
Presents thorough and detailed
information to effectively support and
develop the focus, controlling idea, or
claim. (L3) Makes a clarifying
connection(s) that illuminates argument
and adds depth to reasoning.
Organization
Attempts to organize ideas, but
lacks control of structure.
Uses an appropriate
organizational structure for
development of reasoning and
logic, with minor lapses in
structure and/or coherence.
Conventions
Attempts to demonstrate
standard English conventions,
but lacks cohesion and control
of grammar, usage, and
mechanics. Sources are used
without citation.
Demonstrates an uneven
command of standard English
conventions and cohesion.
Uses language and tone with
some inaccurate, inappropriate,
or uneven features.
Inconsistently cites sources.
Demonstrates a command of standard
English conventions and cohesion, with
few errors. Response includes language
and tone appropriate to the audience,
purpose, and specific requirements of
the prompt. Cites sources using
appropriate format with only minor
errors.
Content
Understanding
Attempts to include disciplinary
content in argument, but
understanding of content is
weak; content is irrelevant,
inappropriate, or inaccurate.
Briefly notes disciplinary content
relevant to the prompt; shows
basic or uneven understanding
of content; minor errors in
explanation.
Accurately presents disciplinary
content relevant to the prompt with
sufficient explanations that
demonstrate understanding.
LDC Template Task Collection Version 2.0 • © Literacy Design Collaborative, 2013
3.5
Maintains an appropriate
organizational structure to address
specific requirements of the prompt.
Structure reveals the reasoning and
logic of the argument.
Maintains an organizational structure that
intentionally and effectively enhances the
presentation of information as required
by the specific prompt. Structure
enhances development of the reasoning
and logic of the argument.
Demonstrates and maintains a welldeveloped command of standard English
conventions and cohesion, with few
errors. Response includes language and
tone consistently appropriate to the
audience, purpose, and specific
requirements of the prompt.
Consistently cites sources using
appropriate format.
Integrates relevant and accurate
disciplinary content with thorough
explanations that demonstrate in-depth
understanding.
Page 8
Elevated Carbon Dioxide in Atmosphere Trims Wheat, Sorghum Moisture
Needs
Mar. 25, 2013 — Plenty has been written about concerns over elevated levels of carbon
dioxide in Earth's atmosphere, but a Kansas State University researcher has found an
upside to the higher CO2 levels. And it's been particularly relevant in light of drought
that overspread the area in recent months.
"Our experiments have shown that the elevated carbon dioxide that we now have is mitigating the effect
that drought has on winter wheat and sorghum and allowing more efficient use of water," said K-State
agronomy professor Mary Beth Kirkham.
Kirkham, who has written a book on the subject, "Elevated Carbon Dioxide: Impacts on Soil and Plant Water
Relations," used data going back to 1958. That's when the first accurate measurements of atmospheric
carbon dioxide were made, she said.
"Between 1958 and 2011 (the last year for which scientists have complete data), the carbon dioxide
concentration has increased from 316 parts per million to 390 ppm," she said. "Our experiments showed that
higher carbon dioxide compensated for reductions in growth of winter wheat due to drought. Wheat that
grew under elevated carbon dioxide (2.4 times ambient) and drought yielded as well as wheat that grew
under the ambient level carbon dioxide and well-watered conditions."
The research showed that sorghum and winter wheat used water more efficiently as a result of the
increased levels of carbon dioxide in the atmosphere, Kirkham said. Because elevated carbon dioxide closes
stomata (pores on the leaves through which water escapes), less water is used when carbon dioxide levels
are elevated. Evapotranspiration is decreased.
Studies done subsequent to the early work confirmed the findings.
Over the past few months, the researcher said she's heard people comparing the dry summer of 2012 with
the Dust Bowl years of the 1930s and the drought of the mid-1950s in Kansas.
The first accurate measurements of CO2 levels were made in 1958, so while scientists do not know what the
concentration of CO2 was in the 1930s, Kirkham said, she used the data that she and her students collected
to calculate how much the water use efficiency of sorghum has increased since 1958, which was about the
time of the middle of 1950s drought.
"Due to the increased carbon dioxide concentration in the atmosphere, it now takes 55 milliliters (mL) less
water to produce a gram of sorghum grain than it did in 1958," she said. "Fifty-five mL is equal to about onefourth of a cup of water. This may not seem like a lot of water savings, but spread over the large acreage of
sorghum grown in Kansas, the more efficient use of water now compared to 1958 should have a large
impact.
"The elevated carbon dioxide in the atmosphere in 2012 ameliorated the drought compared to the drought
that occurred in the mid-1950s."
At the basis of Kirkham's book are experiments that she and other researchers conducted in the
Evapotranspiration Laboratory at K-State from 1984-1991.
"They were the first experiments done in the field in a semi-arid region with elevated carbon dioxide,"
Kirkham said. The lab no longer exists, but the work continues.
Story Source:
The above story is based on materials provided by Kansas State University Research and Extension.
Note: Materials may be edited for content and length. For further information, please contact the source
cited above.
Need to cite this story in your essay, paper, or report? Use the following citation (APA format):
Kansas State University Research and Extension (2013, March 25). Elevated carbon dioxide in atmosphere
trims wheat, sorghum moisture needs. ScienceDaily. Retrieved November 22, 2013,
from http://www.sciencedaily.com/releases/2013/03/130325124402.htm
Note: If no author is given, the source is cited instead.
Gathering greenhouse-effect clues; Carbon dioxide makes leaves
less healthful for bugs
By David Poulson
Newhouse News Service
PELLSTON, Mich. - In a northern Michigan forest clearing, carbon dioxide flows through a tangle of tubes into
42 chambers made of PVC pipe and plastic wrap.
Sensors sniff the chambers every five minutes, sending air samples to separate tanks that are analyzed every
half-hour. A computer ensures that the carbon dioxide inside the chambers is twice that found outside.
But the bugs in this sophisticated experiment that mimics global industrial pollution are, well, the bugs.
"We go on grasshopper patrol and if they're around, we remove them from the gene pool," said David
Karowe, a researcher at the University of Michigan's Biological Station. "We've hated them the last three
years because they get in the chamber and eat our plants."
But they don't get much of a meal.
What Karowe and other researchers are finding is that while plants grow faster in the carbon-dioxide-rich air
that cars, power plants and factories may produce in coming decades, the nutritional value of their leaves
drops dramatically.
It is an important observation as politicians, scientists, environmentalists and industries wrestle with global
climate change from so-called greenhouse gases.
To what degree such industrial emissions cause the Earth to warm and disrupt its weather is under intense
debate. But there is little question that concentrations of one of those emissions - carbon dioxide - have
increased since the dawn of the industrial revolution in 1750. A monitor in Hawaii has measured a more than
19 percent increase since 1959, and some scientists project a doubling from pre-industrial levels in 75 years.
There is no question that carbon dioxide spurs plant growth.
"In a sense, it's a fertilizer," said Chip Knappenberger, a climatologist with New Hope Environmental
Services, which advises industry groups on climate change issues. "These guys who grow stuff for a living in
greenhouses like to boost their carbon dioxide."
But Karowe has found that caterpillars eating plants grown in his chambers munch about 50 percent more
food and grow 15 percent more slowly than those fed a regular diet.
"It's like we'd have to eat two lunches and another half a dinner, but we wouldn't grow as much," said
Karowe, a biology professor at Western Michigan University.
What sounds like a dieter's dream could be a nutritionist's nightmare.
This year Karowe is looking at how grasses that provide basic foods - like wheat, corn, sorghum and oats could be affected by increased carbon dioxide.
"Agriculture is largely the science of making grasses work for us," he said. "We eat their seeds."
But the direct effect on the food we eat is unclear.
Sylvan Wittwer, retired director of Michigan State University's Agricultural Research Station, credits
increasing carbon dioxide with boosting crop and forest production between 10 percent and 12 percent. It
also increases nutritional value, he said.
Wittwer, who has written a book on the subject, bristles when the gas is called a pollutant.
"The benefits are unmistakable," he said.
And Karowe said that while leaves may be less nutritious, plants may devote their energy to keeping their
seeds - the stuff people eat - healthy for reproduction.
There are also uncertain implications for chain reactions throughout complex ecosystems. Caterpillars
chewing food grown in air high in carbon dioxide damage more leaves and excrete more waste. Both prompt
chemical signals that parasitic wasps home in on.
That means more dead caterpillars. It also means that new wasps that hatch from eggs laid in the
caterpillars do poorly on their nutrient-starved hosts.
And the caterpillars that do survive develop more slowly, perhaps producing butterflies long after plants
that need them for pollination have blossomed.
What else might happen is difficult to say as the impact pulses through upper levels of food webs and even
into aquatic ecosystems.
Nancy Tuchman, another researcher at the Pellston station and a biology professor at Loyola University in
Chicago, grinds up aspen leaves grown in chambers similar to Karowe's.
She feeds them to micro-organisms that typically eat dead leaves in streams. Those in turn are fed to the
larvae of mosquitoes and black flies gathered from nearby streams.
Both the micro-organisms and the larvae grow much more slowly than those eating more typical fare, she
said.
Some may view mosquitoes that grow 60 percent more slowly as a huge benefit. But how that affects other
organisms - say the trout that eat mosquitoes - is difficult to predict.
Tuchman notes that her experiments are but a tiny piece of the vast, unknown consequences of a worldwide
increase in carbon dioxide.
"If all the plants are altered on a global level, then it's certainly going to affect all the organisms on Earth,"
she said. "No one is going to escape."
Need to cite this story in your essay, paper, or report? Use the following citation (APA format):
Poulson, David (2000, July 18). Gathering Greenhouse-Effect Clues; Carbon Dioxide Makes Leaves Less
Healthful For Bugs. Seattle Times Company. Retrieved November 12, 2013,
from http://community.seattletimes.nwsource.com/archive/?date=20040428&slug=uw28
High On Carbon Dioxide, Crops of Tomorrow May Yield More Grain
July 15, 1998 — MARICOPA, ARIZ. -- Researchers at The University of Arizona in Tucson
are planning to cultivate a crop of the future this summer in Maricopa.
The sorghum they will plant will not differ from the everyday variety. It's the atmosphere around the crops
that will give the project its air of distinction.
Equipment to be installed soon after planting will encircle some of the sorghum plots to pipe in additional
carbon dioxide. By adjusting the amount released based on wind direction and existing carbon dioxide
levels, the elaborate set-up will keep the carbon dioxide level in these experimental plots consistently 200
parts per million above normal levels.
In other words, the circular design will help ring in a new year -- a year when carbon dioxide levels reach hit
about 560 parts per million. The researchers will then compare the crops grown within the experimental
plots to "control" plots growing under current normal carbon dioxide levels of about 360 parts per million.
The experiment with sorghum is part of the Free Air -- CO 2 Enrichment (FACE) project, a years-long effort
under way at the UA's Maricopa Agricultural Center (MAC), a 2,100 acre farm located 20 miles south of
Phoenix and east of the town of Maricopa.
"About 50 to 100 years in the future, carbon dioxide concentration in the atmosphere is going to be about
200 parts per million greater than it is now," explained Steve Leavitt, a professor of dendrochonology at the
UA Tree-Ring Laboratory who is affiliated with the project. "The experiment we're doing is trying to find out
the future response of crops to higher CO 2 levels."
Scientists have documented an ongoing rise in atmospheric carbon dioxide (CO 2 ), mainly from deforestation
and the burning of fossil fuels such as oil, coal and gas. "Greenhouse gases" like carbon dioxide are projected
to increase the temperature at the Earth's surface from between 2 to 7 degrees Fahrenheit over the next
century.
While many researchers have focused on the global warming potential of carbon dioxide, a smaller but
growing group of international researchers has been studying the direct effect of elevated carbon dioxide
levels on plant growth. Interestingly, the same gas that humans fear for its heat-trapping effect seems to
inspire plants to reach new heights.
For instance, earlier research in Maricopa found that both cotton and wheat thrived when carbon dioxide
levels in the field were "enriched" by about 200 parts per million above the usual level.
"That degree of enrichment was increasing cotton growth by about 40 percent, and cotton yield by about 40
percent as well," noted Bruce Kimball, a scientist with the USDA Water Conservation Lab in Phoenix who has
been involved with the carbon dioxide enrichment project since its inception in 1989. Similarly, the wheat
plants grown under enriched carbon dioxide levels tended to weigh about 20 percent more than those grown
under normal conditions, he said.
The advantage of carbon dioxide enrichment stems from the way plants grow. Plants use energy from the
sun to transform carbon dioxide and water molecules into carbohydrates, releasing oxygen as waste in the
process. However, sometimes plants err by trying to fuel the carbohydrate production factory with oxygen
instead of carbon dioxide, a mistake that can waste a lot of energy.
The presence of more carbon dioxide molecules mingling with the 210,000 parts per million of oxygen
molecules, then, can improve the odds that a plant will be able to make the carbohydrates that form the
bulk of its mass.
A greater abundance of carbon dioxide also has another advantage from a plant's point of view: It can lead
to improved water-use efficiency. Carbon dioxide enters the plant through the same openings, known as
stomata, from which water can escape. Under higher CO2 levels, the stomata can remain partially closed.
So comparisons between experimental plants and controls can be more dramatic when water is scarce.
In the Maricopa wheat experiment, for instance, CO 2 -enriched plants that were watered adequately yielded
about 15 percent more grain and seeds than controls, while CO 2 -enriched plants grown in drought-like
conditions yielded about 25 percent more than controls.
Now for the bad news. It seems the increase in quantity can decrease the quality of grains for some plants
enriched by carbon dioxide. Thomas Thompson and Allan Matthias, both of the UA department of soil, water
and environmental sciences, found that an increase in the number of wheat grains under enriched-CO 2
conditions translated into a decrease in protein content per grain.
"This may take on importance in areas where grains are a main source of protein," Thompson speculated.
Americans tend to use grain to feed livestock, while people in developing countries generally depend upon it
for their own meals.
The pattern holds true for sorghum, used for cattle here but for cereal in Africa. So the results of this
summer's work in Maricopa could have repercussions around the globe.
"Sorghum is number six as a crop in this country, but it's number two in Africa. So it's a very important crop
globally," Kimball noted.
Story Source:
The above story is based on materials provided by University Of Arizona.
Note: Materials may be edited for content and length. For further information, please contact the source
cited above.
Need to cite this story in your essay, paper, or report? Use the following citation (APA format):
University Of Arizona (1998, July 15). High On Carbon Dioxide, Crops Of Tomorrow May Yield More
Grain. ScienceDaily. Retrieved November 12, 2013, from http://www.sciencedaily.com/releases/1998/07/980715084612.htm
Note: If no author is given, the source is cited instead.
Higher Carbon Dioxide Levels Mean Poorer Wheat Quality
Dec. 10, 2012 — Rising levels of atmospheric carbon dioxide have a negative impact on
the protein content of wheat grain and thus its nutritional quality. This is the finding of
researchers at the University of Gothenburg, Sweden, in a recently published study in
the journal Global Change Biology.
Elevated levels of atmospheric carbon dioxide stimulate the photosynthesis and growth of most plants.
However, unless plants increase their uptake of nutrients to a corresponding degree, their yields will have a
lower nutritional value. A lower level of the nutrient nitrogen results in a lower protein content, and thus
poorer nutritional quality.
"Protein content is the most important quality aspect for crops, with implications for both nutritional value
and the baking properties of the grain," explains Håkan Pleijel, Professor of Environmental Science at the
University of Gothenburg's Department of Biological and Environmental Sciences.
Researchers Håkan Pleijel and Johan Uddling have summarized the way in which experimentally elevated
carbon dioxide levels affect the harvest index and protein content of wheat. The study includes 43 field
experiments with 17 different varieties of wheat, carried out in ten countries across four continents. The
results of the study are unequivocal:
"Elevated carbon dioxide levels often increase the size of the grain yield, but also lead to a reduction in
quality in the form of lower protein content," says Professor Pleijel.
Wheat -- together with rice -- is the world's most important crop in quantitative terms. Wheat grain is also
unusually rich in protein, and wheat is the crop that provides the human race with the most protein.
Reduced protein content as a result of elevated carbon dioxide levels is therefore a serious negative
consequence of ongoing atmospheric change.
One reason why the protein content of wheat grain drops as carbon dioxide levels rise is that nitrogen
uptake does not keep pace with the increased growth of the wheat grain -- a kind of dilution effect.
However, elevated carbon dioxide levels reduce the protein content of wheat even when the size of the
wheat yield is unaffected.
"This indicates that carbon dioxide has a negative impact on plants' ability to absorb nitrogen," continues
Professor Pleijel. "This is a novel and unexpected finding, and is something we need to study in greater
depth in order to understand the causes."
Laboratory studies have shown that elevated carbon dioxide levels can disrupt the process whereby plants
convert the inorganic nitrogen molecule nitrate into the forms of nitrogen found in proteins.
Johan Uddling and Professor Pleijel are currently investigating whether the effects they have demonstrated
in wheat are also seen in other crops.
"Our results indicate that reduced nitrogen and protein content as a result of elevated carbon dioxide levels
is a general response in crops, and cannot be countered simply through increased fertilization," adds
Uddling.
The overall positive effect of elevated carbon dioxide levels on grain yield therefore has a downside in the
form of a reduction in the nutritional quality of our most important foodstuff.
"This is a serious consequence of rapidly rising global carbon dioxide levels on global food security,"
concludes Professor Pleijel.
Story Source:
The above story is based on materials provided by University of Gothenburg, via AlphaGalileo.
Note: Materials may be edited for content and length. For further information, please contact the source
cited above.
Need to cite this story in your essay, paper, or report? Use the following citation (APA format):
University of Gothenburg (2012, December 10). Higher carbon dioxide levels mean poorer wheat
quality. ScienceDaily. Retrieved November 22, 2013, from http://www.sciencedaily.com/releases/2012/12/121210080631.htm
Note: If no author is given, the source is cited instead.