题目内容
Rice plants normally grow well in still water. But most will die if they are completely underwater for more than four days. Now, researchers have identified a gene (基因) that helps rice survive longer underwater. They say the discovery will lead to new kinds of rice plants that can survive flooding, and therefore reach their final aim, ensuring more dependable food supplies.
Tests are now being done in
On a genetic (遗传的) map of rice, the scientists became interested in a group of three genes. They experimented with one of them, a gene known as Sub-One-A. They found that when this gene becomes very active, it improves the ability of rice to survive longer when rice is covered by water. They believe it succeeds because it affects the reaction to hormones (荷尔蒙). They control the ability of a flooded plant to survive. Placing the gene into rice plants that are especially good for conditions in
The researchers are now trying to identify all the genes governed by the Sub-One-A gene. Being able to leave water on rice plants for an additional week might also help farmers prevent the growth of weeds. Less weed growth around their crops would mean less need for herbicide (除草剂) chemicals.
41. Crop loss depends on all the following conditions EXCEPT _______.
A. soil conditions and plant age
B. the amount of water the plant stands in
C. the amount of fertilizer used on the crop
D. the amount of time the plant is underwater
42. What is the final aim of this research?
A. To identify the gene that helps rice survive underwater.
B. To increase the ability of rice to fight against floods.
C. To help farmers spend less time removing weeds.
D. To make sure of enough food supplies.
43. What does the underlined word “They” in Paragraph 3 refer to?
A. Genes. B. The experiments.
C. Genetically engineered plants. D. Hormones.
44. What would be the best title for the passage?
A. Rice research is going on in
B. How to reduce the influence of floods on rice
C. Gene researchers work on flood-resistant rice
D. A great discovery in the agricultural field
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53天天练系列答案阅读下面短文，根据所读内容在表格中的空白处填入恰当的词。
注意：每个空格只填一个单词。
Fruit also makes up a flowering plant. It carries the seeds . The purpose of fruit is to protect a plant’s seeds and help them get spread about. Wind and water spread seeds .So do animals when they eat fruit and drop the seeds .
There are two main types of fruit: fleshy and dry. Fleshy fruits are soft and juicy , the way we usually think of fruits . Peaches ,plums ,and apples are all fleshy fruits . Dry fruits are thin and hard . Grains like wheat and rice , or nuts are dry fruits.
You’ve eaten seedless oranges and grapes . How can they be fruits? It’s because people have changed the way they grow fruit. They can now grow seedless fruit . Seedless fruit comes from special plants called hybrids(杂交生物体) . A hybrid is made by combining two varieties of a fruit to form a new variety . This hybrid grows and produces seeds . But the plants grown from these seeds are seedless . These plants cannot reproduce themselves.
A tomato is a vegetable , right? No , it’s actually a fruit . Other food we think of as vegetables—such as squash , peppers ,and eggplant—also are fruit . They’re fruit because they carry seeds and develop from flowers . Here’s another surprise . Scientists classify the tomato as a berry(浆果) . In addition , they don’t consider some fruits we call berries to be true berries because a berry is normally a type of fruit with a lot of seeds inside it . Technically , a strawberry , isn’t a berry , because it has its seeds on the outside . The red part is just the tip of the strawberry stem that’s enlarged.
Fruits are a source of nourishing(滋养) substances that keep us alive and healthy . For example , they contain many vitamins , especially vitamins A and C, and many minerals . They also provide fibre for a healthy digestive system and carbohydrates that the body needs to make energy.
| Title： | |
| Basic knowledge | Being of a flowering plant and carrying seeds. Protecting a plant’s seeds and helping spread them about. Mainly on wind , water and animals to spread. |
| Fleshy fruit :Juicy and , like peaches , plums ,apples ,etc . Dry fruit : Thin and hard , like wheat ,rice , nuts ,etc . | |
| Fruit seeds | Coming from a ,which is made by combining two kinds of fruit to form a new kind. |
| Some surprises | Tomato , squash ,peppers and eggplant are fruits because they carry seeds and develop from . Some fruits like strawberry aren’t technically berries because they have seeds on the . |
| Being to humans | Keeping people alive and . Providing vitamins , fiber and carbohydrates. |
Some plants get so hungry they eat flies, and even small frogs. What's more amazing is that these plants occur naturally (in special environments) in every state. In fact, they're found on every continent except Antarctica.
You've probably seen a Venus' flytrap -- a small plant, which grows 6 to 8 inches tall in a container. At the end of its stalks (茎) are leaves that act like traps (陷阱). Inside each trap is a lining of tiny hairs. When an insect lands on them, the traps suddenly shut. Over the course of a week or so, the plant feeds on its catch.
The Venus' flytrap is just one of more than 500 species of meat-eating plants, says Barry Meyers-Rice, the editor of the International Carnivorous Plant Society's Newsletter. He states although you might have read some science-fiction stories, no meat-eating plant does any danger to humans.
Barry says a plant is meat-eating, only if it does all four of the following: "attract, kill, digest, and absorb" some form of insects. Meat-eating plants look and act like other green plants -- well, most of the time.
All green plants make sugar to produce food. What makes meat-eating plants different is their special leaves, which need insects for one reason: nitrogen (氮). Nitrogen is a nutrient that they can't obtain any other way. Why?
Almost all green plants on our planet get nitrogen from the soil. Meat-eating plants can't. They live in places where nutrients are hard to get from the soil because of its acidity. So they've come to rely on getting nitrogen from insects and small animals. In fact, nutrient-rich soft is poisonous to meat-eating plants. Never fertilize (施肥) them! But don't worry, either, if they never seem to catch any insects. They can survive, but they'll grow very slowly.
【小题1】According to the passage, a Venus' flytrap ______.
| A．is a small plant which grows in a container |
| B．is a kind of plant which gets hungry easily |
| C．can trap and feed on some form of insects |
| D．can only grow 6-8 inches tall |
| A．meat-eating plants are found nowhere else except Antarctica |
| B．all green plants get nitrogen from the soil |
| C．meat-eating plants endanger humans in science-fiction stories |
| D．the nutrient-poor soil is beneficial to meat-eating plants |
| A．so you'd better fertilize them |
| B．probably because the supply of nitrogen is cut off |
| C．simply because they can't absorb nitrogen from the soil |
| D．and then they will die slowly |
| A．Meat-eating plants look and act like other green plants. |
| B．It's hard to get nutrients in the soil when acidity is high. |
| C．The Venus' flytrap eats flies to get nutrient from them. |
| D．Green plants make sugar at night. |
阅读下面短文，根据所读内容在表格中的空白处填入恰当的词。
注意：每个空格只填一个单词。
Fruit also makes up a flowering plant. It carries the seeds . The purpose of fruit is to protect a plant’s seeds and help them get spread about. Wind and water spread seeds .So do animals when they eat fruit and drop the seeds .
There are two main types of fruit: fleshy and dry. Fleshy fruits are soft and juicy , the way we usually think of fruits . Peaches ,plums ,and apples are all fleshy fruits . Dry fruits are thin and hard . Grains like wheat and rice , or nuts are dry fruits.
You’ve eaten seedless oranges and grapes . How can they be fruits? It’s because people have changed the way they grow fruit. They can now grow seedless fruit . Seedless fruit comes from special plants called hybrids(杂交生物体) . A hybrid is made by combining two varieties of a fruit to form a new variety . This hybrid grows and produces seed
s . But the plants grown from these seeds are seedless . These plants cannot reproduce themselves.
A tomato is a vegetable , right? No , it’s actually a fruit . Other food we think of as vegetables—such as squash , peppers ,and eggplant—also are fruit . They’re fruit because they carry seeds and develop from flowers . Here’s another surprise . Scientists classify the tomato as a berry(浆果) . In addition , th
ey don’t consider some fruits we call berries to be true berries because a berry is normally a type of fruit with a lot of seeds inside it . Technically ,
a strawberry , isn’t a berry , because it has its seeds on the outside . The red part is just the tip of the strawberry stem that’s enlarged.
Fruits are a source of nourishing(滋养) substances that keep us alive and healthy . For example , they contain many vitamins , especially vitamins A and C, and many minerals . They also provide fibre for a healthy digestive system and carbohydrates that the body needs to make energy.
| Title：【小题1】 | |
| Basic knowledge | Being【小题2】 of a flowering plant and carrying seeds. Protecting a plant’s seeds and helping spread them about. Mainly【小题3】 on wind , water and animals to spread. |
| Fleshy fruit :Juicy and【小题4】 , like peaches , plums ,apples ,etc . Dry fruit : Thin and hard , like wheat ,rice , nuts ,etc . | |
| Fruit【小题5】 seeds | Coming from a 【小题6】 ,which is made by combining two kinds of fruit to form a new kind. |
| Some surprises | Tomato , squash ,peppers and eggplant are fruits because they carry seeds and develop from 【小题7】 . Some fruits like strawberry aren’t technically berries because they have seeds on the 【小题8】 . |
| Being 【小题9】 to humans | Keeping people alive and【小题10】 . Providing vitamins , fiber and carbohydrates. |