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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 carried to all parts of the growing plant and are built into essential plant materials while in a dissolved state. The carbon dioxide (CO(下标)2) 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 growing tissues.

The actual amount of water in the plant at any one time, is only a very small part of what passes through it during its development. The processes of photosynthesis (光合作用), by which carbon dioxide and water are combined in the presence of chlorophyll (叶绿素) and with energy derived from light--to form. sugars, require that carbon dioxide from the air enter the plant. This occurs mainly in the leaf. The leaf surface is not solid but contains great numbers of minute openings, through which the carbon dioxide enters. The same structure that permits the one gas to enter the leaf, however, permits another gas--water vapor to be lost from it. Since carbon dioxide is present in the air only in trace quantities (3 to 4 parts in 10,000 parts of air) and water vapor is near saturation in the air spaces within the leaf (at 80F, saturated air would contain about 186 parts of water vapor in 10,000 parts of air), the total amount of water vapor lost is many times the carbon dioxide intake. Actually because of wind and other factors, the loss of water in proportion to carbon dioxide intake may be even greater. Also, not all of the carbon dioxide that enters the leaf is synthesized into carbohydrates.

A growing plant needs water for all of the following except ______.

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

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更多“Most growing plants contain mu…”相关的问题
第1题
GardeningThe technology of beautyNow, gardening was driven by three main trends: technolog

Gardening

The technology of beauty

Now, gardening was driven by three main trends: technological change, plant prospecting and fashion. Of these, the most important was technology, whose advances made it possible for the middle classes to enjoy what had once been affordable only to the very rich.

The most dramatic example of popularizing technology was surely the invention of the lawnmower. Nothing was more labour-intensive, in the 18th century, than maintaining a large lawn. It would take three men with scythes (大镰刀) a whole day to cut an acre (two-fifths of a hectare) of grass; they would be followed by lawn women whose task was to gather up the cuttings.

Just one man went to mow

Then, in 1830, Edwin Beard Budding realised that the rotary blade used in the cloth industry to produce an even pile on textiles could be used on grass. The rotary lawnmower meant that suburban homes could afford the neat greensward (草皮) previously available only to the rich.

The other technology that transformed Victorian gardening was the development of the art of growing plants under glass. Importing plants from countries as distant as Australia became a commercial possibility once they were sealed in wooden boxes with glass tops. From the 1830s on, Victorian gardens, private and public, used masses of bedding plants. In 1877, 2 million plants were bedded out in London's parks, often in elaborate geometric designs. Growing them under glass protected them both from frost and from pollution.

In the past century, technology has once again transformed and simplified gardening. Among the most significant advances is the growing of plants in containers. Instead of ordering plants grown in open fields and dug up bare-rooted for planting in autumn, gardeners now typically buy plants which, because they have been grown in containers, can be transplanted at almost any time of year. Container growing has in turn become possible largely because of the development of lighter composts.

Other men's flowers

The past two centuries have seen an immense increase in the range of garden plants. Native species have been refined and developed; and explorers have brought back plants from all parts of the world. The passion for plant collecting sprang partly from the expansion of Catholic religious orders (神职) abroad in the 16th century, looking for medicinal plants as well as souls to convert. Many early plant-hunters are commemorated in plant names, such as the Tradescants, father and son; Sir Joseph Banks, who sailed with Captain Cook and brought home 3500 species from Australia.

Fashion is every bit as important in determining what people grow as in what they wear. The geometry, gravel and bedding plants of the mid-19th-cenmry town-house garden had given way, by the century's end, to a passion for informality and English cottage gardens, fostered by two of the great designers of the age. Their influence has proved enduring. "All over the world, people want to rival English gardens, often in a climate that makes it very difficult," says Sarah Bond, an enthusiastic amateur gardener in Manhattan.

A growing business

Both gardening and looking at gardens are developing rapidly. Give people a piece of ground and they will buy something to put in it. Mark Bhatti and Andrew Church of Brighton University in England point to the fact that people now seem to spend far more on machinery and chemicals, and more again on benches, barbecues, pots and sun-loungers, than they spend on plants themselves.

Moreover, the range of places where people can buy gardening supplies has expanded. Supermarkets and general stores frequently carry plants and other gardening necessities. On the contrary, Britain's Garden Centre Association says that around 12% of the typical turnover of a garden centre now comes from the cafe. A trip to a ga

A.Y

B.N

C.NG

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第2题
Most growing plants contain much more water than all other materials combined. C. R. Darne
s has suggested that it is as proper to term the plant a water structure as to call a house composed mainly of bricks 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 percent water. Structural parts of plants, such as woody stems no longer actively growing, may have much less water than growing tissues.

The actual amount of water in the plant at any one time, however, is only a very small part of what passes through it during its development. The processes of photosynthesis, by which carbon dioxide and water are combined—in the presence of chlorophyll (叶绿素) and with energy derived from light to form. sugars, require that carbon dioxide from the air enter the plant. This occurs mainly in the leaves. The leaf surface is not solid but contains great numbers of minute (细小的) openings, through which the carbon dioxide enters. The same structure that permits the one gas to enter the leaf, however, permits another gas—water vapor to be lost from it. Since carbon dioxide is present in the air only in trace quantities (3 to 4 parts in 10, 000 parts of air) and water vapor is near saturation in the air spaces within the leaf (at 80 F , saturated air would contain about 186 parts of water vapor in 10,000 parts of air), the total amount of water vapor lost is many times the carbon dioxide intake. Actually, because of wind and other factors, the loss of water in proportion to carbon dioxide intake may be even greater than the relative concentrations of the two gases. Also, not all of the carbon dioxide that enters the leaf is synthesized into carbohydrates(碳水化合物).

A growing plant needs water for all of the following except ______.

A.forming simple sugars

B.keeping woody stems

C.keeping green

D.producing carbon dioxide

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第3题
听力原文:M: Hello and welcome to today's show, Shirley's Garden. Today, we'll be interview
ing Shirley on her amazing techniques at growing a garden. Thank you for being here, Shirley.

W: You're welcome.

M: Shirley, you truly have an amazing garden. Can you tell tm how you learned about gardening?

W: Well, this spring I took a gardening class. Then I decided to try some of the things I had learned. So I have tried various attempts at gardening and with different degrees of success.

M: From the pictures of your garden, I've seen 'all kinds of different vegetables, including cucumbers, tomatoes, straw berries, carrots and so on. Could you let us know how you put these plants together in your garden?

W: Well, one of the most important things in gardening is that you choose a good location. You need at least 6 to 8 hours of direct sunshine. Um, you also need to choose a location that has good drainage, and it should be a convenient location. After choosing a good location, I just decided what I wanted to plant, and based on what the final plant would took like, I divided the whole garden into different parts.

M: Shirley, I've noticed some vertical beams in your garden. I'm truly amazed by them. Could you explain that to us a little bit?

W: Well, take cucumbers for instance. Cucumbers take a lot of space when you grow them out on the ground, but I don't have that much space. So I just grow them up. Just grow them vertically. I just used a metal frame. and some strings to allow them to grow up, and they will support themselves.

M: Well, Shirley, this is truly amazing. Thank you very much for being with us today.

W: My pleasure.

(23)

A.The pleasure derived from gardening.

B.How to grow an amazing garden.

C.How to choose a good location for a garden.

D.How to succeed in growing many plants in a small garden.

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第4题
A.By eating various kinds of fish.B.By eating large amounts of plants and small animal

A.By eating various kinds of fish.

B.By eating large amounts of plants and small animals growing in very salty water.

C.By providing enough food for fish.

D.By increasing the salt in the water.

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第5题
听力原文: Burning fallen leaves used to be standard practice across North America, but (29

听力原文: Burning fallen leaves used to be standard practice across North America, but (29)most districts now ban or discourage this practice due to the air pollution it causes.

(30) What's more, because of the moisture that is usually trapped within leaves, they tend to bum slowly and thus generate large amounts of particles in the air, such as bits of dust, smoke and other solid materials. These particles can reach deep into lung tissue and cause coughing, chest pain, shortness of breath and other breathing problems.

Individual leaf fires from time to time usually don't cause any major pollution, but multiple fires in one geographic area can cause concentrations of air pollutants that exceed federal air quality standards. According to the U. S. Environmental Protection Agency (EPA), several leaf and yard waste fires burning simultaneously in a particular place can cause air pollution which equals that from factories, motor vehicles and lawn equipment.

(31) On the contrary, leaves can be made fertilizer, which is the most eco-friendly alternative to burning. Dry leaves alone will take a long time to break down, but mixing in green plant materials, such as grass, will speed up the process. Sources of nitrogen, such as livestock wastes or commercial fertilizer, will also help.

Another option is to chop leaves for use as cover for your lawn or to help protect garden and landscape plants. But before you add no more than a two-to-three-inch layer of leaves around actively growing plants, chop the leaves first so they don't prevent air from reaching roots.

(30)

A.Because burning them may cause fire accidents.

B.Because burning them may cause air pollution.

C.Because burning them may cause people out of breath.

D.Because burning them may cause water pollution.

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第6题
It is the business of the scientist to accumulate knowledge about the universe and all
that is in it, and to find, if he is able, common factors which explain the facts that he knows. He chooses, when he can, the method of the "controlled experiment". If he wants to find out the effect of light on growing plants, he takes many plants, as alike as possible. Some he stands in the sun, some in the shade, some in the dark; all the time keeping all other conditions (temperature, moisture, nourishment) the same. In this way, by keeping other conditions constant, and by varying the light only, the effect of light on the plants can be clearly seen. This method can be applied to a variety of situations.In the course of his inquiries the scientist may find what he thinks is one common explanation for an increasing number of facts. The explanation, if it seems consistently to fit various facts, is called a hypothesis. If a hypothesis continues to stand the test of numerous experiments and remains unshaken, it becomes a law.

1.In order to investigate the effect of light on growing plants the scientist____.

A、has to stand in the sun

B、can keep the same plants under different conditions of light

C、takes as many plants as possible

D、both b and c

2.The word "constant" in the first paragraph means____.

A、continual

B、faithful

C、various

D、unchanging

3.What should be kept the same in a "controlled experiment"? ____

A、All the factors.

B、The common factors.

C、The factor under investigation.

D、All factors except the one being investigated.

4.According to the passage, a hypothesis is____.

A、an explanation for a large number of facts likely to be accepted as a truth

B、a factor which explains the facts already known to the scientist

C、an explanation that stands the test of numerous experiments

D、a common explanation that will definitely become a law

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第7题
Researches in the wild field evaluating the two most common Bt corn plants showed that the
toxin absorbed was too ______.

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第8题
A.Insects are the most adaptable creatures.B.Insects would be out of control if nothin

A.Insects are the most adaptable creatures.

B.Insects would be out of control if nothing were done.

C.Insects will some day devour all plants on the Earth.

D.Insects have developed resistance to both botanical and artificial poison rapidly.

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第9题
What is the most alarming consequence of the fast growing population?A.Species are dying o

What is the most alarming consequence of the fast growing population?

A.Species are dying out at an unnatural high speed.

B.Living areas for wildlife are disappearing rapidly.

C.The global weather is becoming warmer.

D.All kinds of natural resources are draining.

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第10题
Why do we call Madagascar a Darwinian playground?A.Because of its geographic isolation.B.B

Why do we call Madagascar a Darwinian playground?

A.Because of its geographic isolation.

B.Because its nature is still in original form.

C.Because most of its plants are endemic.

D.Because most of its animals are endemic.

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