1 . Global warming does more than just kill plant species — it also changes the way plants grow. Researchers at Martin Luther University Halle — Wittenberg(MLU) joined forces with the Leibniz Institute for Plant Biochemistry(IPB) to discover the molecular (分子) process of plant growth. In Current Biology, a scientific journal, they presented their findings on high-temperature plant growth. This could lead to developing plants that can survive global warming.

Plants react to even small temperature changes, but they are unable to move to new locations. “When temperatures rise, plants grow taller ... to cool themselves off. Their stems become taller, and their leaves become narrower and grow farther apart. Yet, this makes the plant more unstable overall,” explains Professor Marcel Quint, an agricultural scientist at MLU. Unstable plants bend faster in the rain and produce less food that’s also less nutritious.

There’s still lots to learn about plant reactions to temperatures. “We are just starting to understand how plants feel the changes in temperature ...,” Quint says. Earlier studies have shown that the protein (蛋白质) PIF4 directly controls plant growth and is also dependent on temperature. When it’s cold, PIF4 is less active, meaning the plant doesn’t grow. At higher temperatures, PIF4 activates growth-promoting genes, and the plant grows taller. This is new information, says Quint.

To understand it, they studied the growth of thale cress (拟南芥) seedlings. Normally, its seedlings form short stems at 20℃. These stems become much longer at 28℃. They discovered a hormone (荷尔蒙) that activates the PIF4 at high temperatures, thus producing the protein.

The findings may help to develop plants that remain stable even at high temperatures and produce many crops.

1. Why did the researchers at MLU and IPB conduct their research?

A．To study the negative effects of global warming.

B．To find out how plants help reduce global warming.

C．To observe how global warming affects plant growth.

D．To understand the ways that plants cause global warming.

2. What can we learn from Paragraph 2?

A．Low temperatures have little impact on plants.

B．Plants prefer dry weather to rainy weather.

C．Plants are very sensitive to change in soil.

D．High temperatures reduce crop production.

3. What do we know about PIF4?

A．It mainly exists in thale cress seedlings.

B．It works differently at different temperatures.

C．It is a kind of gene that controls plant growth.

D．It is a plant hormone that works at high temperatures.

4. Who will probably benefit most from the findings?

A．Farmers.	B．Teachers.
C．Researchers.	D．Environmentalists.

2 . It is quite apparent that competition surrounds every aspect of human life whether in the United States or the Amazon rainforest. Without it we would not have grown into primates (灵长类动物) . Or we would probably still be struggling to sharpen a bronze tool while crawling around on four legs in search of meat. Without competition, Columbus wouldn’t have discovered America and Edison would never have invented the light bulb.

Friendship, like all relationships between two people, involves competition. It isn’t competition in a traditional sense because there are no goals to be scored and no prize. Perhaps the ecological definition --- the simultaneous (同时) demand by two or more organisms for limited environmental resources, such as nutrients, living space, or light --- better explains it.

As in nature, high school life is governed by a set of laws, similar to a shortened version of Darwin’s theory of evolution, overpopulation, and competition. There is an abundance of high school students and to distinguish them, ranking and categorizing (分类) take place. In high school, friendships learn to coexist with competition even though at times the relationship is rough. In fact, in some circumstance, competition is too much of a burden for a friendship to bear, causing it to fall apart. College admission is the final high school objective. Four years of hard work is to achieve good grades, and a student’s fate is determined not only by these achievements, but by the records of thousands of other seniors trying to achieve a similar recognition.

Nevertheless, by necessity, competition between students exists in all aspects of high school life. It sets and improves the standards in everything from sports to schoolwork. A healthy, friendly competition can have only benefits, but when it becomes too fierce, jealousy (妒忌) can tear friendships apart. Yet, despite all this, without competition, we would be lost.

1. What does the ecological definition mainly explain?

A．How to win the competition.	B．What competition exactly is.
C．What the result of competition is.	D．How friends compete with each other.

2. According to the writer, what causes the high school students to compete?

A．They know the laws of nature well.	B．Friendship is a burden for them.
C．The number of them is too large.	D．They are divided into different groups.

3. Which best describes the relationship of friendship and competition?

A．Friendship is always based on competition.

B．Competition is a result of lost friendship.

C．Competition is terribly harmful to friendships.

D．The degree of competition is vital to friendship.

3 . Researchers continue to show the power behind our sense of smell. Recent studies have found, among other things, that the smell of foods like pizza can cause uncontrollable anger in drivers on roads.

The study explains that smell is unique in its effects on the brain. According to Conrad King, the researcher who carried out the study, “more than any other senses, the sense of smell goes through the logical part of the brain and acts on the systems concerned with feelings. This is why the smell of baking bread can destroy the best intentions of a dieter.”

Smell, which determines the unbelievable complexity of food tastes, has always been the least understood of our senses. Our noses are able to detect up to 10,000 distinct smells. Our ability to smell and taste this extremely large range of smells is controlled by something like 1,000 genes (基因), which make up an amazing 3% of the human genome.

According to Conrad King’s study, smelling fresh pizza or even the packaging of fast foods can be enough to make drivers feel impatient with other road users. They are then more likely to speed and experience uncontrollable anger on roads. The most reasonable explanation is that these can all make drivers feel hungry, and therefore desperate to satisfy their appetites. In contrast, the smells of peppermint （薄荷）and cinnamon（桂皮香料） were shown to improve concentration levels as well as reduce drivers’ impatience. Similarly, the smells of lemon and coffee appeared to promote clear thinking and mental focus.

However, the way genes control smell differs from person to person. A study by researchers in Israel has identified at least 50 olfactory(嗅觉) genes which are switched on in some people and not in others. They believe this may explain why some of us love some smells and tastes while others hate them. The Israel researchers say their study shows that nearly every human being shows a different pattern of active and inactive smell-detecting receptors.

1. What does the author think of human sense of smell?

A．It is complex.	B．It is uncontrollable.
C．It is changeable.	D．It is powerful.

2. Why did Conrad King conduct the research about smell?

A．To find out how smell influences people.

B．To teach people how to choose proper food.

C．To study why some food like pizza harm people.

D．To explain why different people love different foods.

3. What can we conclude from the last paragraph?

A．Only a few genes decide our sense of smell.

B．Different genes have different effect on people.

C．Different people are sensitive to different smells.

D．Every person owns at least 50 different olfactory genes.

4. What is the passage mainly about?

A．Logic and behavior.	B．Smell and its influence.
C．Sense ability and food tastes.	D．Olfactory genes and our olfactory system.