问题 单项选择题

人体内细胞外液构成的液体环境称为内环境,内环境的稳态是细胞生活所必需的。下列说法错误的是()

A.抗体、激素、神经递质等都是内环境的成分

B.pH和温度的稳定,都给酶正常发挥催化作用创造了条件

C.免疫系统识别并清除异物和外来病原微生物,也是维持内环境稳态的机制

D.内环境稳态是在神经和体液调节的共同作用下维持的,体液调节占主导地位

答案

参考答案:D

解析:

内环境是细胞生活的液体环境,包括血浆、组织液和淋巴,存在的物质有营养物质、代谢废物和调节物质,如抗体、激素、神经递质、淋巴因子等;A正确。稳态的意义是机体进行正常生命活动的必要条件,如pH和温度的相对稳定,酶活性正常,细胞代谢正常;B正确。免疫系统识别并清除抗原性异物,维持内环境稳态;C正确。内环境稳态是在神经-体液-免疫调节作用下维持的,神经调节占主导地位,体液调节可以看做神经调节的一个环节;D错误。

考点:内环境的物质,稳态的意义和调节机制。

阅读理解

阅读理解。

     Most new people were born in developing countries. These countries are found in much of Africa, South

America and some parts of Asia. In the developed countries of Europe and North America, the population is

growing very slowly. This is because women in these countries have, on average (平均), only one or two

children. In the developing countries, many women have five or more children. In 1950, around one quarter

of the world's population lived in the developed countries. By 2050, these countries will be home to only

around one tenth of the world's people.

     In the developing countries, more than one billion people are still living below the poverty (贫困) line.

These people do not have enough food to eat and they live in poor housing. Children get little time at school

and people suffer (遭受痛苦) from many kinds of diseases.

     At the beginning of the 21st century, the world's population was around six billion people. The U.N. has

said that the world's population will level off (平稳下降) at 12.5 billion by the year 2100. Other groups think

the world's population will continue to grow, reaching 14 billion before it becomes stable (稳定的), or even

falls.

根据短文内容,回答下列问题。

1. In what areas of the world can developing countries be found?

                                                                                                                                    

2. In 1950, what percent (百分比) of the world's population lived in developing countries? 

                                                                                                                                    

3. How can we describe the people who are living below the poverty line?

                                                                                                                                    

4. There will be twelve and a half billion people on the earth in 2100, won't there?

                                                                                                                                    

5. 将文中画线部分翻译成汉语。 

                                                                                                                                    

多项选择题