学位英语

第三十五篇 Ptting Plants to Work【植物效能】

Using the power of the sun is nothing new. People have had solar-powered calculators and buildings with solar panels for decades. But plants are the real experts: They've been using sunlight as an energy source for billions of years.

Cells in the green leaves of plants work like tiny factories to convert sunlight, carbon dioxide, and water into sugars and starches, stored energy that the plants can use. This conversion process is called photosynthesis. Unfortunately, unless you're a plant, it's difficult and expensive to convert sunlight into storable energy. That's why scientists are taking a closer look at exactly how plants do it.

Some scientists are trying to get plants, or biological cells that act like plants, to work as miniature photosynthetic power stations. For example, Maria Ghirardi of the National Renewable Energy Laboratory in Golden, Colo. , is working with green algae. She's trying to trick them into producing hydrogen instead of sugars when they perform photosynthesis. Once the researchers can get the algae working efficiently, the hydrogen that they produce could be used to power fuel cells in cars or to generate electricity.

The algae are grown in narrow-necked glass bottles to produce hydrogen in the lab. During photosynthesis, plants normally make sugars or starches. "But under certain conditions, a lot of algae are able to use the sunlight energy not to store starch, but to make hydrogen." Ghirardi says. For example, algae will produce hydrogen in an airfree environment. It's the oxygen in the air that prevents algae from making hydrogen most of the time.

Working in an airfree environment, however, is difficult. It's not a practical way to produce cheap energy. But Ghirardi and her colleagues have discovered that by removing a chemical called sulfate from the environment that the algae grow in, they will make hydrogen instead of sugars, even when air is present.

Unfortunately, removing the sulfate also makes the algae's cells work very slowly, and not much hydrogen is produced. Still, the researchers see this as a first step in their goal to produce hydrogen efficiently from algae. With more work, they may be able to speed the cells' activity and produce larger quantities of hydrogen.

The researchers hope that algae will one day be an easy-to-use fuel source. The organisms are cheap to get and to feed, Ghirardi says, and they can grow almost anywhere: "You can grow them in a reactor, in a pond. You can grow them in the ocean. There's a lot of flexibility in how you can use these organisms."

1. What does the writer say about plants concerning solar energy?

A Plants are the real experts in producing solar energy.

B Plants have been used to produce solar energy.

C Plants have been using solar energy for billions of years.

D Plants have been a source of solar energy.

2. Why do some scientists study how plants convert sunlight carbon dioxide, and water into sugars

and starches ?

A Because they want algae to produce sugars and starches.

B Because they want green plants to become a new source of energy.

C Because they want to turn plant sugars to a new form of energy.

D Because they want to make photosynthesis more efficient.

3. According to the fifth paragraph, under what conditions are algae able to use solar energy to

make hydrogen?

A When there is a lot of oxygen in the air.

B When there is no oxygen in the air.

C When photosynthesis is taking place.

D When enough starch is stored.

4. Researchers have met with difficulties when trying to make algae produce hydrogen efficiently.

Which one of the following is one such difficulty？

A It is not possible to remove sulfate from the environment.

B It is not possible to work in an airfree environment to produce hydrogen.

C It is not easy to make sugars instead of hydrogen.

D It is too slow for algae to produce hydrogen when the sulfate is removed.

5. What is NOT true of algae?

A They are easy to grow. B They can be a very good fuel source.

C They are cheap to eat. D They can be used in many ways.

翻译：植物效能

太阳能的使用已经不足为奇。几十年前，人们就开始使用太阳能计算器，制造太阳能电热板镶嵌的建筑。但是植物当属应用太阳能的专家：十亿年来，植物一直把阳光作为能源资源。

绿叶植物细胞的工作就像微型加工厂一样，将阳光，二氧化碳和水转化为糖和淀粉，并且同时储存植物本身所需的能量。这种转换过程叫做光合作用。可惜你不是一株植物，必须困难的并且花上大价钱将阳光转换为稳定的能源。因此，科学家们正在对植株进行准确细致的研究。

一些科学家正试图像植物的作用过程一样，将植物，或生物的细胞活动看做微型光合发电站。例如，玛丽亚?奇若蒂在美国科罗拉多州的国家可再生能源实验室里对绿藻进行研究。她正想方设法的通过植物的产生氢来取代光合作用产生的糖。一旦研究人员了解藻类如何有效率的进行工作，由此产生的氢气可用于燃料电池动力汽车和发电。

在实验室里，藻类生长通过狭窄的颈玻璃瓶生产氢气的环境下。在光合作用下，植物通常产生糖类或淀粉。奇若蒂说：“但在一定条件下，有很多藻类能够利用日光能源产生氢气而不是储存淀粉。”例如，藻类会在空气存在环境下产生氢气。这是因为空气中的氧气，氧阻止绿藻制造氢。

藻类在空气中虽然可以工作，但是充满困难。这种方式不能切实可行的生产廉价的能源。但是奇若蒂和她的同事们已经发现，即使在目前的空气条件下，他们从藻类生长的环境中，除去所谓的硫酸化学品，能够产生氢来代替糖。

只可惜消除硫酸盐不仅使藻类细胞的工作速度减慢，而且大大减少了氢的数量。尽管如此，研究人员认为，对于实现有效率的利用藻类产生氢这一目标，他们已经迈出了第一步。随着工作量的加大，他们可以加速细胞的活动，从而产生大量的氢气。

研究人员们希望，总有一天藻类会成为很容易使用的燃料来源。藻类这种生物极易存活，他们可以在几乎任何地方成长。奇若蒂说，：“你可以将它放在一反应堆或是池塘里，也可以在海洋中找到它们，人们可以灵活的使用藻类的用途广泛。”

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