Unit 5 Section Ⅰ Starting out & Understanding ideas-【精讲精练】2023-2024学年高中英语选择性必修第一册外研版（课时作业）

Ⅰ.阅读理解

A

Hundreds of native North American plants，often dismissed as weeds，deserve a lot more respect，according to a new study.These plants，distant cousins of foods like sunflowers and lettuce(莴苣)，actually represent a botanical treasure now facing increased threats from climate change and habitat loss.The crops that the human race now depends on，including grains like wheat and tree fruit like peaches，originally were selected or bred(培育) from plants that grew wild hundreds or thousands of years ago.In the U．S.，there are wild ancestors of blueberries，sweet potatoes，onions，potatoes，and many other food crops.“Some of them are quite common，” says Colin Khoury，a research scientist at the International Center for Tropical Agriculture.“Wild lettuce plants grow along sidewalks，or in backyards，but go unrecognized.”

Other crop relatives are rare and threatened.One of Khoury's favorites is the paradoxical sun flower.“It grows just in wetlands of the deserts of New Mexico and Texas.Little salty areas where there's a little bit of water beneath the soil，” he says.So plant growers crossbred it with commercial sunflowers and created new varieties that can grow in places where the soil contains more salt.Other wild relatives may be hiding similarly remarkable gifts，Khoury says，such as genes that could help their domesticated relatives survive diseases，or deal with pests.

Khoury and some of his colleagues just finished a survey of about 600 wild crop relatives that grow in North America，and they found that most of these plants are threatened by things like fires，farming and development.The scientists argue that they deserve more protection.For one thing，“gene banks” should collect and preserve them.In addition，these plants need more protection in their natural habitat.

According to Khoury，that doesn't necessarily mean setting aside land for them.In many cases，the plants already are growing on public land that's managed by the U．S.Forest Service (USFS) or the Bureau of Land Management(BLM)．“It's more about just being aware that these plants actually exist，” he says.

[语篇解读]　本文是一篇说明文。我们现在所食用的多种植物都是从远古时期就存在的野生植物嫁接或育种而来。然而，这些植物的“野生远亲”现在却被人们弃之如草芥，没有得到应有的保护和尊重。研究人员认为，这些野生植物在帮助我们现存的植物应对气候变化、病虫害及栖息地丧失方面可以发挥巨大的作用，我们应该对其加大保护力度。

1．What did the new study mainly focus on?

A．Endangered plant species.

B．Wild relatives of food crops.

C．The impacts of climate change.

D．The threats from plant habitat loss.

解析：选B　推理判断题。根据第一段的“Hundreds of native North American plants，often dismissed as weeds，deserve a lot more respect，according to a new study.These plants，distant cousins of foods like sunflowers and lettuce，actually represent a botanical treasure now facing increased threats from climate change and habitat loss.”可知，这项新研究主要关注的是粮食作物的野生亲缘。

2．What do we know about the paradoxical sunflower?

A．It needs much water to grow well.

B．It grows along sidewalks or in backyards.

C．It seems capable of surviving various diseases.

D．It helps commercial sunflowers adapt to salty soil.

解析：选D　细节理解题。根据第二段中的“So plant growers crossbred it with commercial sunflowers and created new varieties that can grow in places where the soil contains more salt.”可知，“the paradoxical sunflower”与商用向日葵杂交产生的向日葵可适应含盐高的土壤。

3．How might the scientists feel about their survey results?

A．Relieved.　　　　　 B．Concerned.

C．Annoyed.  D．Critical.

解析：选B　推理判断题。根据第三段中的“Khoury and some of his colleagues just finished a survey of about 600 wild crop relatives that grow in North America，and they found that most of these plants are threatened by things like fires，farming and development.”可知，科学家们对约600种野生植物进行了调研后发现，其中绝大多数的生存状况不容乐观，受到了诸如火灾、农耕及社会发展的威胁。由此可推知，科学家们对其发现会感到担忧。

4．What might Khoury suggest the BLM do?

A．Join hands with the USFS.

B．Set aside land for wild plants.

C．Collect genes of threatened crop species.

D．Learn about plants on its managed land.

解析：选D　推理判断题。根据最后一段的“In many cases，the plants already are growing on public land that's managed by the U．S.Forest Service(USFS) or the Bureau of Land

Management(BLM)．”和“It's more about just being aware that these plants actually exist”可推知，Khoury可能会建议美国内政部土地管理局去了解其管辖范围内的植物，从而保护这些野生植物。

B

In general，the riches of the natural world aren't spread evenly across the globe.Places like the tropical(热带的) Andes in South America are simply packed with unique species，many of which can't be found in any other places.Until recently，the main explanation for the biological riches concentrated in places like the Amazon Basin was that such places must be engines of biodiversity (生物多样性)，with new species evolving at a faster rate than other parts of the world.But now，new research on bird evolution may turn that assumption on its head，instead supporting the idea that areas with fewer species actually tend to produce new species faster.

The researchers say these biodiversity “coldspots” are generally found in environments featuring freezing，dry and unstable conditions.Though the researchers found these locations with few bird species tend to produce new ones at high rates，they fail to accumulate many species because the unstable conditions frequently make the new life forms die out.

The more well­known“hotspots”，by contrast，have accumulated their large numbers of species by being warm，hospitable and relatively stable.Indeed，the researchers found that the countless bird species that call the Amazon home tend to be older in evolutionary terms.“New species do form in places like the Amazon，just not as frequently as in the dry grasslands in the Andes，” says Elizabeth，an evolutionary biologist at the University of Tennessee.

The researchers managed to collect 1,940 samples representing 1,287 of the 1,306 bird species from South America.Their analysis showed that the best predictor of whether an area would produce new species at a high rate was how many species lived there，rather than climate or geographic features like mountains.Species­rich areas tended to produce new species more slowly.

“Maybe had environments generate new species more frequently because there's less competition and more available opportunities for new species，” says Gustavo Bravo，a lead researcher.

The study's findings add new urgency to protect ecosystems that may look barren, but may actually be nature's hothouses for the evolution of new species.

[语篇解读]　本文是一篇说明文。一项新的研究发现，物种较少的地方比物种丰富的地方会更快地产生新物种。

5．Why is South America mentioned in the first paragraph?

A．To make comparison.

B．To introduce the topic.