问题 填空题

性状是指生物所具有的______,______,______的总称.

答案

孟德尔在研究豌豆等植物的性状遗传时,把植株所表现的性状总体区分为各个单位作为研究对象,这样区分开来的性状称为单位性状,如豌豆的花色、种子形状、子叶颜色、豆荚形状、豆荚(未成熟的)颜色、花序着生部位和株高等性状,就是7个不同的单位性状;不同个体在单位性状上常有着各种不同的表现,例如,豌豆花色有红色和白色,种子形状有圆和皱、小麦的抗锈病与易染锈病、大麦的耐旱性与非耐旱性、人的眼睛不同颜色和不同肤色等.遗传学中把同一性状的不同表现形式,称为相对性状;总之,遗传学中把生物体所表现的形态结构、生理特征和行为方式等统称为性状.

故答案为:形态结构特征;生理特性;行为方式.

阅读理解

How can we get rid of garbage? Do we have enough energy sources to meet our future energy needs?

These are two important questions that many people are asking today. Some people think that men might be able to solve both problems at the same time. They suggest using garbage as an energy source.

For a long time people buried garbage or dumped it on empty land. Now, empty land is scarce. But more and more garbage is produced each year. But garbage can be a good fuel to use. The things in garbage do not look like coal, petroleum, or natural gas; but they are chemically similar to these fossil fuels. As we use up our fossil-fuel supplies, we might be able to use garbage as an energy source.

Burning garbage is not a new idea. Some cities in Europe and the United States have been burning garbage for years. The heat that is produced by burning garbage is used to boil water. The steam that is produced is used to make electricity or to heat nearby buildings. In Paris, France, some power plants burn almost 2 million metric tons of the city's garbage each year. The amount of energy produced is about the same as the world produced by burning almost a half million barrels of oil!

But there are problems in using garbage as a fuel. Garbage that burns easily, such as food scraps and paper, must be separated from metals, glass, and other materials that do not burn easily. This separation process is normally costly. Another problem is that burning garbage can pollute the air.

Our fossil fuel supplies are limited. Burning garbage might be one kind of energy source that we can use to help meet our energy needs. This method could also reduce the amount of garbage piling up on the earth.

53. What two problems can be solved by burning garbage?

A. The shortage of energy; Air pollution.

B. The shortage of energy; the shortage of empty land for holding garbage.

C. Air pollution; the shortage of empty land for holding garbage.

D. Air pollution; the shortage of fossil fuel.

54.Which of the following is NOT a result of burning garbage?

A. The heat produced is used to boil water.

B. The steam produced is used to make electricity.

C. The garbage burned is turned into fossil fuels.

D. The steam produced is used to heat buildings.

55.According to the passage. Which of the following four groups of garbage is ready for burning?

A. food scraps and metals                    B. paper and glass

C. metals and glass                             D. food scraps and paper

56.What is the general tone of the passage?

A. optimistic                       B. indifferent                     C. advocating               D. anxious

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