问题 选择题

下图6中甲为某区域地形图、乙为该区域人口密度和人口合理承载力情况图,读图完成小题。

小题1:该区域最主要环境问题是(   )

A.凌汛

B.水土流失

C.森林面积减少

D.泥石流频发小题2:造成这种环境问题的人为原因是(   )

A.人口密度超过该地区合理承载力

B.A地区的人口密度高于B地区

C.人口密度在北部最为合理

D.本区人口合理承载力较大

答案

小题1:B

小题2:A

题目分析:

小题1:根据图示的河流轮廓和经纬度位置判断该地区位于我国黄土高原,水土流失严重。

小题2:根据乙图,本区的人口合理承载力为每平方千米30人,而目前A、B地区的人口密度已分别高达64人/平方千米、47人/平方千米,说明该地的人口密度已超过该地区的承载力,从而导致人口与资源、环境不相适应,出现严重的环境和资源问题。

点评:本题难度不大,学生只要通过图示的经纬度位置和区域轮廓判断我国的区域位置,并结合乙图的人口合理承载力和实际人口密度的差异分析即可。

填空题

Long before Man lived on the Earth, there were fishes, reptiles, birds, insects, and some mammals. Although some of these animals were ancestors of kinds living today, others are now extinct, that is, they have no descendants alive now. (41) . Very occasionally the rocks show impression of skin, so that, apart from color, we can build up a reasonably accurate picture of an animal that died millions of years ago. That kind of rock in which the remains are found tells us much about the nature of the original land, often of the plants that grew on it, and even of its climate. (42) Nearly all of the fossils that we know were preserved in rocks formed by water action, and most of these are of animals that lived in or near water. Thus it follows that there must be many kinds of mammals, birds, and insects of which we know nothing. (43) . There were also crablike creatures, whose bodies were covered, with a horny substance. The body segments each had two pairs of legs, one pair for walking on the sandy bottom, the other for swimming. The head was a kind of shield with a pair of compound eyes, often with thousands of lenses. They were usually an inch or two long but some were 2 feet. (44) . Of these, the ammonites are very interesting and important. They have a shell composed of many chambers, each representing a temporary home of the animal. As the young grew larger it grew a new chamber and sealed off the previous one. Thousands of these can be seen in the rocks on the Dorset Coast. (45) . About 75 million years ago the Age of Reptiles was over and most of the groups died out. The mammals quickly developed, and we can trace the evolution of many familiar animals such as the elephant and horse. Many of the later mammals though now extinct, were known to primitive man and were featured by him in cave paintings and on bone carvings.
[A] The shellfish have a long history in the rock and many different kinds are known
[B] Nevertheless, we know a great deal about many of them because their bones and shells have been preserved in the rocks as fossils. From them we can tell their size and shape, how they walked, the kind of food they ate.
[C] The first animals with true backbones were the fishes, first known in the rocks of 375 million years ago. About 300 million years ago the amphibians, the animals able to live both on land and in water, appeared. They were giant, sometimes 8 feet long, and many of them lived in the swampy pools in which our coal seam, or layer, or formed. The amphibians gave rise to the reptiles and for nearly 150 million years these were the principal forms of life on land, in the sea, and in the air.
[D] The best index fossils tend to be marine creature. There animals evolved rapidly and spread over large over large areas of the world.
[E] The earliest animals whose remains have been found were all very simple kinds and lived in the sea. Later forma are more complex, and among these are the sea-lilies, relations of the star-fishes, which had long arms and were attached by a long stalk to the sea bed, or to rocks.
[F] When an animal dies, the body, its bones, or shell, may often be carried away by streams into lakes or the sea and there get covered up by mud. If the animal lived in the sea its body would probably sink and be covered with mud. More and more mud would fall upon it until the bones or shell become embedded and preserved.
[G] Many factors can influence how fossils are preserved in rocks. Remains of an organism may be replaced by minerals, dissolved by an acidic solution to leave only their impression, or simply reduced to a more stable form.

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