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One day, “supercharged plants” may help feed people around the world. Supercharged plants are ones that grow faster than normal plant life. Scientists can speed up the growth by modifying, or changing, the structure of plants' genes. The modifications make them react quickly to changes in light. This all has to do with photosynthesis(光合作用), the process in which plants turn sunlight, carbon dioxide and water into food.

Plants grow fastest in the sun. That is when they make the most food for themselves. But their rate of growth can slow when things like clouds or trees block sunlight. But when the sun returns, it can take many minutes for growth to speed up again.

This can be a problem because it means some of our most important crop plants are not as productive as they could be. Researchers say demand for food is expected to increase up to 70 percent by the middle of the century. They also note rising temperatures on Earth's surface. That is why they are looking for ways to improve photosynthesis and make plants more productive.

Steve Long is a plant biologist at the University of Illinois. He wanted to find a way to help plants get back up to speed quickly after a period of darkness. So he and his team added genes that shortened the recovery time. It also increased the speed at which the plants grew. His modified plants grew up to 20 percent more than untreated ones.

In Long's study, his group used a form of genetic engineering called transgenics (转基因). It means taking genes from one plant, then putting them into another. Now they are experimenting soybeans, rice, cowpeas and cassavas.

【小题1】What is the advantage of supercharged plants?
A.They can grow more quickly.
B.They can grow in severe conditions.
C.They can offer high-quality grains.
D.They can replace normal plants.
【小题2】What can make plant growth slow down?
A.Too hot weather.B.Old farming methods.
C.Lack of sunlight.D.Too much sunlight.
【小题3】What was Steve Long's goal in his study?
A.To find out what makes plants grow slowly.
B.To create a new plant that can grow with weak sunlight.
C.To find another way to help plants benefit each other.
D.To make plants recover quickly when the sun returns.
【小题4】How can researchers shorten the recovery time of plants?
A.By changing their nature.B.By adding new genes to them.
C.By developing new plants.D.By supplying more sunlight.
18-19高二下·吉林长春·期中
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British scientists have discovered the willow trees planted at an angle could increase sugars for biofuel production.

Willow is a fast-growing species. It is already used to produce fuels for the renewable heating and power market. In future it could also help to produce biofuel to power vehicles. It has been known that when willows growing in the wild are blown sideways, they tend to produce more sugars. But for a while it has not been known why this happens.

Researchers at Imperial College London, led by Dr Nicholas Brereton and Dr Michael Ray of the Department of Life Sciences, have now solved the mystery. When the tree is blown sideways, its genes (基因) produce large numbers of sugar molecules (分子) to straighten the tree upwards.

“This is an important breakthrough. Our study now shows that natural genetic changes are related to these differences. And this could well be the key to unlocking the future for green energy from willow,” said Dr Brereton.

The research was carried out under lab conditions. The willows were grown at an angle of 45 degrees. They were compared to willows which grow naturally straight upwards. The team then looked for the same effect among the willows growing on the Isle of Orkney where strong winds cause the trees to bend at extreme angles. They discovered that the Orkney trees produce five times the amount of sugars found in willows grown in sheltered conditions.

Willow is widely planted across the UK. The results show that biofuel crops such as willows could be grown in climatically changeable conditions where chances of growing food crops are limited.

The study is published in Biotechnology for Biofuels.

【小题1】What may happen when willows are planted in strong winds?
A.They stop growing.B.Few sugars are produced.
C.They try to grow sideways.D.Changes in genes take place.
【小题2】The Orkney willows ________.
A.are unusually rich in sugarsB.grow naturally straight upward
C.look taller than ordinary willowsD.are stronger than those growing in labs
【小题3】Farmers living in changeable climate _______.
A.use biofuel for heating and powerB.are encouraged to grow biofuel crops
C.can plant different kinds of food cropsD.should make their willows grow straight
【小题4】Where does this passage most probably come from?
A.A personal diary.B.A travel magazine.
C.A scientific journal.D.A newspaper advertisement.

Dyeing eggs has long been an Easter tradition, but it’s the dyeing of baby chicks that is upsetting in some states.

The dye, which is often ordinary food coloring, is either injected into eggs being hatched or sprayed onto newly hatched chicks. Although hatchery owners say the practice is harmless, critics argue that spraying the birds with color is stressful and that dyeing the animals transforms them into something attractive that can be thrown away when their colorful feathers disappear.

“These are living creature and dyeing them sends out a message saying that they are more of a new and unusual object than a living animal,” said Dr. Marc Copper, senior scientific manager for the Royal Society for the Prevention of Cruelty to Animals.

Dyed chicks --- and sometimes rabbits --- have been a traditional part of the Easter holiday in some parts of the world, but the practice has gone largely underground in the U.S. because many people view it as cruel.

Today, about half of U.S. states ban the dyeing of animals, but last month the Florida Legislature passed a bill to remove the state’s 45-year-old ban. The drive to end the law wasn’t related to Easter chicks; it was done at the request of a dog groomer(美容师) who wanted to enter pet beauty contests.

Florida governor Rick Scott must agree to remove the ban, which would be lifted July 1, but the Animal Rights Foundation of Florida(ARFF) has asked him not to remove the ban. In addition to allowing animals dyeing, the law would also lift a ban on selling baby animals as pets, and the organization fears that next year the state could see hundreds of dyed baby chicks on the market.

As long as the dye is not poisonous, experts say the birds’ health isn’t affected, and there are scientific reasons to dye animals. Wildlife researchers often inject eggs with dye to track birds in the wild, and teachers have dyed chicks for educational purposes. However, animal advocates are quick to point out that dyeing baby chicks for Easter isn’t educational --- it’s done simply to earn profits.

【小题1】What can we infer from Cooper’s words?
A.He finds it dangerous to dye eggs.
B.He likes dyed birds’ colorful feathers.
C.He is in support of the hatchery owners.
D.He is among the critics of dyeing animals.
【小题2】What do we learn about dyed baby chicks in the U.S.?
A.They are mainly sold in secret.
B.They are as common as dyed eggs.
C.They are welcomed by most Americans.
D.They are getting more popular in the world.
【小题3】What was the purpose of the bill?
A.To protect Easter chicks.
B.To ban pet beauty contests.
C.To make animals dyeing legal.
D.To prevent the sale of baby animals.
【小题4】What is the ARFF’s attitude toward the bill?
A.Tolerance.
B.Opposition.
C.Doubt.
D.Caution.

Oxygen, I'm sure you'd agree, is pretty important for life on Earth. We breathe it in, our cells survive on it and without it, we hardly live. Basically all multicellular life on Earth evolved over millions of years to make use of oxygen.

But take a deep breath, because we need to talk about Henneguya salminicola, a tiny parasite(寄生虫) containing fewer than100 cells that lives within the muscle tissue of salmon, a large fish with silver skin and pink flesh. The strange-looking parasite does not busy itself with such small matters as breathing oxygen. Nope, it seems that H. salminicola is the first multicellular animal we've found that survives without the stuff.

“Aerobic respiration(有氧呼吸) was thought to be commonly found in animals, but now we confirmed that this is not the case, "said Dorothee Huchon, a zoologist at Tel Aviv University in Israel, in a press release.

Huchon and a team of international researchers examined and sequenced(排序) all of. salminicola's' genes in their study, published in the journal Proceedings of the National Academy of Sciences. They found that the parasite, which is closely related to jellyfish, lacks the DNA machinery necessary to“breathe”---it doesn't' have mitochondria(线粒体), often called the "powerhouse" of the cell, because they use oxygen to make energy. It's like a little factory inside almost all cells, and DNA detectives can find mitochondrial genes during sequencing.

The discovery came as something of an accident for the team, who were examining the genome (the complete set of genes) of the species. When they went searching for the mitochondrial genes,   they came up empty-handed. "Our discovery shows that evolution can go in strange directions, ”Huchon said. "Aerobic respiration is a major source of energy, and yet we found an animal that gave up this important pathway.”

Some single-celled life forms have evolved the ability to survive without oxygen and do not have mitochondria, either. Plenty of bacteria can exist without oxygen at all. Instead of oxygen, they get their energy from fermentation(发酵) or use other molecules like iron.

But how H. salminicola produces energy is still unclear. Huchon suggests it could draw oxygen from the cells in salmon or it could have evolved similar methods to those of single-celled organisms which scientists have documented in the past.

【小题1】What can we learn about Henneguya salminicola?
A.It is an animal consisting of a cell.
B.It can still survive without oxygen.
C.It takes on a normal appearance.
D.It has a longer lifespan than salmon.
【小题2】What is the main function of mitochondria?
A.To make cells breathe fast.
B.To help to produce oxygen.
C.To provide energy for cells.
D.To help cells absorb oxygen.
【小题3】How did Huchon probably feel about the discovery?
A.Interested.B.Satisfied.C.Astonished.D.Frightened.
【小题4】What could be the most suitable title for the text?
A.The natural evolution of animal cells
B.Different kinds of life forms on earth
C.A research on single-celled organisms
D.A creature that doesn't breathe oxygen

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