问题 填空题 案例分析题

已知卵巢分泌的雌性激素能促进子宫发育。研究人员为探究垂体能分泌促性腺激素影响卵巢和子宫的发育,用一批幼鼠做了如下实验:

第3组实验结果产生的原因是()

答案

参考答案:切除垂体后,促性腺激素减少,导致卵巢不能正常发育,而定期注射的雌性激素促进了子宫发育

解析:

无关变量是除自变量外,可能还会存在一些可变因素,对实验结果造成影响。本实验的无关变量是食物,温度,实验材料(幼鼠的生理状况)等。实验是探究垂体能否分泌促性腺激素影响卵巢和子宫的发育,选择的幼鼠的性别是雌性。根据自变量,A处的处理方法是:切除垂体,同时注射等量溶剂(生理盐水)。第3组由于切除垂体后,促性腺激素减少,导致卵巢不能正常发育,而定期注射的雌激素则可以促进子宫的发育,所以卵巢和子宫的平均重量与对照组接近。

选择题
阅读理解

     Ask someone what they have done to help the environment recently and they will almost certainly

mention recycling. Recycling in the home is very important of course. However, being forced to recycle

often means we already have more material than we need. We are dealing with the results of that_

overconsumption in the greenest way possible, but it would be far better if we did not need to bring so

much material home in the first place.

     The total amount of packaging increased by 12% between 1999 and 2005. It now makes up a third

of a typical household's waste in the UK. In many supermarkets nowadays food items are packaged

twice with plastic and cardboard.

     Too much packaging is doing serious damage to the environment. The UK, for example, is running

out of it for carrying this unnecessary waste. If such packaging is burnt, it gives off greenhouse gases

which go on to cause the greenhouse effect. Recycling helps, but the process itself uses energy. The

solution is not to produce such items in the first place. Food waste is a serious problem, too. Too many

supermarkets encourage customers to buy more than they need. However, a few of them are coming

round to the idea that this cannot continue, encouraging customers to reuse their plastic bags, for

example.

     But this is not just about supermarkets. It is about all of us. We have learned to associate packaging

with quality. We have learned to think that something unpackaged is of poor quality. This is especially

true of food. But it also applies to a wide range of consumer products, which often have far more

packaging than necessary.

     There are signs of hope. As more of us recycle, we are beginning to realise just how much

unnecessary material we are collecting. We need to face the wastefulness of our consumer culture, but

we have a mountain to climb. 

1. What does the underlined phrase "that overconsumption" refer to?

A. Using too much packaging.

B. Recycling too many wastes.

C. Making more products than necessary.

D. Having more material than is needed. 

2. The author uses figures in Paragraph 2 to show________. 

A. the tendency of cutting household waste

B. the increase of packaging recycling

C. the rapid growth of supermarkets

D. the fact of packaging overuse

3. According to the text, recycling________. 

A. helps control the greenhouse effect

B. means burning packaging for energy

C. is the solution to gas shortage

D. leads to a waste of land

4. What can be inferred from Paragraph 4?

A. Unpackaged products are of bad quality.

B. Supermarkets care more about packaging.  

C. It is improper to judge quality by packaging.  

D. Other products are better packaged than food. 

5. What can we learn from the last paragraph?

A. Fighting wastefulness is difficult.  

B. Needless material is mostly recycled.  

C. People like collecting recyclable wastes.

D. The author is proud of their consumer culture.