| Most growing plants contain much more
water than all other materials combined. C. R. Barnes has suggested that it is
as proper to term the plant a water structure as to call a house composed mainly
of brick a brick building. Certain it is that all essential processes of plant
growth and development occur in water. The mineral elements from the soil that
are usable by the plant must be dissolved in the soil solution before they can
be taken into the root. They are carried to all parts of the growing plant and
are built into essential plant materials while in a dissolved state. The carbon
dioxide from the air may enter the leaf as a gas but is dissolved in water in
the leaf before it is combined with a part of the water to form simple
sugars—the base material from which the plant body is mainly built. Actively
growing plant parts are generally 75 to 90 perce A. (A) forming sugars B. (B) sustaining woody stems C. (C) keeping green D. (D) producing carbon dioxide [单项选择]Most growing plants contain much more water than all other materials combined. C.R. Dames has suggested that it is as proper to term the plant a water structure as to call a house composed mainly of bricks as a brick building. It is certain that all the essential processes of plant growth and development occur in water. The mineral elements from the soil that are usable by the plant must be dissolved in the soil solution before they can be taken into the root. They are carded to all parts of the growing plant and are built into essential plant materials while in a dissolved state. The carbon dioxide (CO2) from the air may enter the leaf as a gas but is dissolved in the leaf before it is combined with a part of the water to form simple sugars — the base material from which the plant body is mainly built. Actively growing plant parts are generally 75 to 90 percent water. Structural parts of plants, such as woody stems no longer actively growing, may have much less water than g
A. forming sugars B. sustaining actively growing parts as well as woody stems C. absorbing mineral elements D. taking in carbon dioxide from the air [单项选择]Rainforests may store much less carbon than we thought. It could be time to dramatically revise our estimates following the discovery that apparently similar forests hold vastly different amounts of the stuff. The finding is important because there are plans for governments worldwide to compensate tropical countries for protecting their forests as "carbon sinks" to curb global warming. If carbon cannot be counted, then dollars cannot be disbursed (支付).
Greg Asner of the Carnegie Institution for Science in Stanford, California, and colleagues say they used satellite mapping, laser probing of forest undergrowth from aircraft and local ground surveys across a large area of Peruvian rainforest to crack the problem of estimating how much carbon is locked up in forests. But the new technique has revealed a large, previously unknown variability in the density of carbon stored in apparently similar forests. The Intergovernmental Panel on Climate Change says that there should be about A. be provided with valid data on forest carbon B. reduce carbon emission from stopping deforestation C. carry out the compensation scheme D. conduct studies on carbon emission 我来回答: 提交
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