Putting Plants to Work

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.

Ceils in the green leaves of plants work like tiny factories to convert sunlight, carbon dioxide, and water into¹ 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, Mafia Ghirardi of the National Renewable Energy Laboratory in Golden, Colo.², is working with green algae³. She’s trying to trick them into producing hydrogen⁴ 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 air free environment. It’s the oxygen in the air that prevents algae from making hydrogen most of the time.

Working in an air free 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.”

词汇:

panel /5pAnl/ n.嵌板，发热板，仪器板  

starch /stB:tF/ n. 淀粉

miniature /5minjEtFE/ adj.口巧．微型的

sulfate /5sQlfeit/ n. 硫酸盐，硫酸酯

carbon dioxide 二氧化碳  

photosynthesis /7fEutEu5sinWEsis/ n. 光合作用

algae /5AldVi:/ n. 水藻，海藻  

注释:    

1. convert … into…：将……转换为 ……     

2. Colo.：Colorado，（美国科罗拉多州）的缩写形式  

3. Green algae: 绿藻       

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.

Putting Plants to Work

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.

Ceils in the green leaves of plants work like tiny factories to convert sunlight, carbon dioxide, and water into¹ 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, Mafia Ghirardi of the National Renewable Energy Laboratory in Golden, Colo.², is working with green algae³. She’s trying to trick them into producing hydrogen⁴ 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 air free environment. It’s the oxygen in the air that prevents algae from making hydrogen most of the time.

Working in an air free 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.”

词汇:

panel /5pAnl/ n.嵌板，发热板，仪器板  

starch /stB:tF/ n. 淀粉

miniature /5minjEtFE/ adj.口巧．微型的

sulfate /5sQlfeit/ n. 硫酸盐，硫酸酯

carbon dioxide 二氧化碳  

photosynthesis /7fEutEu5sinWEsis/ n. 光合作用

algae /5AldVi:/ n. 水藻，海藻  

注释:    

1. convert … into…：将……转换为 ……     

2. Colo.：Colorado，（美国科罗拉多州）的缩写形式  

3. Green algae: 绿藻       

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.

Putting Plants to Work

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.

Ceils in the green leaves of plants work like tiny factories to convert sunlight, carbon dioxide, and water into¹ 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, Mafia Ghirardi of the National Renewable Energy Laboratory in Golden, Colo.², is working with green algae³. She’s trying to trick them into producing hydrogen⁴ 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 air free environment. It’s the oxygen in the air that prevents algae from making hydrogen most of the time.

Working in an air free 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.”

词汇:

panel /5pAnl/ n.嵌板，发热板，仪器板  

starch /stB:tF/ n. 淀粉

miniature /5minjEtFE/ adj.口巧．微型的

sulfate /5sQlfeit/ n. 硫酸盐，硫酸酯

carbon dioxide 二氧化碳  

photosynthesis /7fEutEu5sinWEsis/ n. 光合作用

algae /5AldVi:/ n. 水藻，海藻  

注释:    

1. convert … into…：将……转换为 ……     

2. Colo.：Colorado，（美国科罗拉多州）的缩写形式  

3. Green algae: 绿藻       

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.

Putting Plants to Work

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.

Ceils in the green leaves of plants work like tiny factories to convert sunlight, carbon dioxide, and water into¹ 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, Mafia Ghirardi of the National Renewable Energy Laboratory in Golden, Colo.², is working with green algae³. She’s trying to trick them into producing hydrogen⁴ 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 air free environment. It’s the oxygen in the air that prevents algae from making hydrogen most of the time.

Working in an air free 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.”

词汇:

panel /5pAnl/ n.嵌板，发热板，仪器板  

starch /stB:tF/ n. 淀粉

miniature /5minjEtFE/ adj.口巧．微型的

sulfate /5sQlfeit/ n. 硫酸盐，硫酸酯

carbon dioxide 二氧化碳  

photosynthesis /7fEutEu5sinWEsis/ n. 光合作用

algae /5AldVi:/ n. 水藻，海藻  

注释:    

1. convert … into…：将……转换为 ……     

2. Colo.：Colorado，（美国科罗拉多州）的缩写形式  

3. Green algae: 绿藻       

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.

Putting Plants to Work

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.

Ceils in the green leaves of plants work like tiny factories to convert sunlight, carbon dioxide, and water into¹ 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, Mafia Ghirardi of the National Renewable Energy Laboratory in Golden, Colo.², is working with green algae³. She’s trying to trick them into producing hydrogen⁴ 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 air free environment. It’s the oxygen in the air that prevents algae from making hydrogen most of the time.

Working in an air free 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.”

词汇:

panel /5pAnl/ n.嵌板，发热板，仪器板  

starch /stB:tF/ n. 淀粉

miniature /5minjEtFE/ adj.口巧．微型的

sulfate /5sQlfeit/ n. 硫酸盐，硫酸酯

carbon dioxide 二氧化碳  

photosynthesis /7fEutEu5sinWEsis/ n. 光合作用

algae /5AldVi:/ n. 水藻，海藻  

注释:    

1. convert … into…：将……转换为 ……     

2. Colo.：Colorado，（美国科罗拉多州）的缩写形式  

3. Green algae: 绿藻       

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.

The Sahara

    The nameSaharaderives from the Arabic word for "desert" or "steppe". At 3. 5 million square miles，an area roughly the size of the United States，the Sahara Desert in northern Africa is the largest desert in the world. lt spans the continent from theAtlantic Oceanto theRed Sea. Daytime temperatures can reach as high as 130°F. The humidity sometimes gets into the teens. But it can also be as low as 2. 5 percent，the lowest in the world. Most of the Sahara receives less than five inches of rain per year，while large areas sometimes have no rainfall at all for years.

    At the heart of the Sahara is the landlocked north African country ofNiger. Here the sand dunes can be 100 feet tall and several miles long. Here sand plains stretch over an area larger thanGermanywhere there is neither water nor towns. Yet sitting in the midst of the surrounding desert is the town ofBilma. Suddenly there are pools of cIear water. Surprisingly，there are groves of date palms. Underground water resources，or oases，sufficient to support irrigated agriculture are found in dry stream beds and depressions. ¹Irrigation ditches run off a creek to water fields. ²  Corn，cassava，tea，peanuts，hot peppers，and orange，lime，and grapefruit trees grow in these fields. Donkeys and goats graze on green grass. ³

    The Sahara of Niger is still a region where you can see a camel caravan of 500 camels tied together in loose lines as long as a mile，traveling toward such oasis towns. There a caravan will collect life-sustaining salt，which is mined from watery basins，and transport it up to 400 miles back to settlements on the edges of the desert. The round trip across the vast sands takes one month.

词汇:

Humidity / hju:ˈmɪdəti / n. 湿度

irrigate / " lrlgelt/ v. 灌溉

stretch / stretʃ / v. 伸展

camel / "kæml / n. 骆驼

date palms n. 椰枣树

注释:

1. Underground water resources，or oases，sufficient to support irrigated agriculture are found in dry stream beds and depressions. 在干河床和洼地处可找到充足的地下水资源或者绿洲来支持灌溉农业。

2. Irrigation ditches run off a creek to water fields. 灌溉沟渠通过一条小溪到达水田中。

In this passage caravan means _______.

A:traveling circus B:group traveling together through difficult country C:railroad train D:a small，fast sailing ship

The Sahara

    The nameSaharaderives from the Arabic word for "desert" or "steppe". At 3. 5 million square miles，an area roughly the size of the United States，the Sahara Desert in northern Africa is the largest desert in the world. lt spans the continent from theAtlantic Oceanto theRed Sea. Daytime temperatures can reach as high as 130°F. The humidity sometimes gets into the teens. But it can also be as low as 2. 5 percent，the lowest in the world. Most of the Sahara receives less than five inches of rain per year，while large areas sometimes have no rainfall at all for years.

    At the heart of the Sahara is the landlocked north African country ofNiger. Here the sand dunes can be 100 feet tall and several miles long. Here sand plains stretch over an area larger thanGermanywhere there is neither water nor towns. Yet sitting in the midst of the surrounding desert is the town ofBilma. Suddenly there are pools of cIear water. Surprisingly，there are groves of date palms. Underground water resources，or oases，sufficient to support irrigated agriculture are found in dry stream beds and depressions. ¹Irrigation ditches run off a creek to water fields. ²  Corn，cassava，tea，peanuts，hot peppers，and orange，lime，and grapefruit trees grow in these fields. Donkeys and goats graze on green grass. ³

    The Sahara of Niger is still a region where you can see a camel caravan of 500 camels tied together in loose lines as long as a mile，traveling toward such oasis towns. There a caravan will collect life-sustaining salt，which is mined from watery basins，and transport it up to 400 miles back to settlements on the edges of the desert. The round trip across the vast sands takes one month.

词汇:

Humidity / hju:ˈmɪdəti / n. 湿度

irrigate / " lrlgelt/ v. 灌溉

stretch / stretʃ / v. 伸展

camel / "kæml / n. 骆驼

date palms n. 椰枣树

注释:

1. Underground water resources，or oases，sufficient to support irrigated agriculture are found in dry stream beds and depressions. 在干河床和洼地处可找到充足的地下水资源或者绿洲来支持灌溉农业。

2. Irrigation ditches run off a creek to water fields. 灌溉沟渠通过一条小溪到达水田中。

In this passage caravan means _______.

A:traveling circus B:group traveling together through difficult country C:railroad train D:a small，fast sailing ship