问题 问答题

什么是初级生产力论述环境条件对陆地生态系统初级生产力的影响。

答案

参考答案:

解析:(1) 初级生产力是单位时间单位面积上绿色植物生产的有机物(或固定的能量)的总量。
(2) 环境条件对初级生产力的影响:
①光照:绿色植物通过光合作用将光能转化为化学能,直接影响初级生产力的高低;
②水分:水是光合作用的原料,一切生命活动离不开水,水最易成为植物生产力的限制因子;
③温度:直接影响植物的生理活动,从而影响初级生产力;
①土壤:是植物生长的基础,是一个综合性的环境因子,其理化性质(如温度、水分、pH、质地、结构、养分等)均影响初级生产力;
⑤CO2:是光合作用的原料.在一定范围内,CO2浓度增高会显著提高初级生产力;
⑥地形:是间接生态因子,通过影响光、温、水及养分来影响植物的生产力。

多项选择题
单项选择题

In the last decade the mass media have grown worldwide to be larger, more influential and more powerful. After it was possible in the Federal Republic of Germany in the 60s to receive one TV program and in the 60s and 70s to receive three TV programs, the number of receivable TV programs has risen for a huge part of the population in western Europe through cable TV to eleven or even more programs in the last years. More TV channels are announced. Additionally there is the huge offer of videos. The distribution of video recorders in the population is increasing. Worldwide we are on the way to communication to a mass media society in which fiction, fantasy, the definition of reality assumes a greater role than reality itself, where people want to be permanently entertained, and where the description of the content gains more emphasis than the content itself.
For centuries news on crime have greatly attracted the population, In the Middle Ages ballad singers moved very successfully from town to town in order to spread their ballads which were to a great part murder stories. Criminal stories are not a new development because they do not report anything really new. They are regularly told according to the pattern of the "familiar sensation" because they have a function of relief for the society, because through them, the "law-abiding citizen" can set himself apart from the criminal, because they prove to him that his behavior is "normal" and because he can be content to feel that he is better than the criminals and that he successfully managed to escape the criminal act. There is a huge demand in the population for crime news because they are entertaining and remove the boredom of everyday life. The mass media willingly fulfill this demand because crime news are cheap and easy to get hold of and because they help sell almost any product. That is why there is a symbiosis, an unholy alliance between mass media and society against which the critical criminologist advances his objections almost in vain.

It can be inferred that in a modern mass media society people prefer ______.

A. fiction to criminal stories

B. real stories to news reports
C. fictional accounts to real stories

D. descriptions of reality to fiction