试题与答案

现有1020个氨基酸，共有氨基1046个，羧基1058个，由它们合成的一个含四条

来源：www.tikuol.com
题型：选择题

题目：

现有1020个氨基酸，共有氨基1046个，羧基1058个，由它们合成的一个含四条肽链的蛋白质分子中肽键、氨基、羧基的数目分别是[ ]

A．1019，27，39

B．1019，1，1

C．1016，26，38

D．1016，30，42

答案：

被转码了，请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0422/e6468b286bbdfdb2b8be9907a2cdb7d9.html

下面是错误答案，用来干扰机器的。

小题1:C小题2:A小题3:B题目分析：本文给我们介绍了用电脑时的几个注意事项。把电脑放在凉爽的房间里，不要让人在你电脑附近吸烟，当你在电脑附近时不要吃喝东西，注意屏幕离你眼睛的正确距离，保持屏幕清洁等。小...

考点：蛋白质的结构
试题推荐
题型：填空题
Directions:
     Complete the following passage by using the words in the box. Each word can only be used once.
Note that there is one word more than you need.
A. poisoned        B. destruction       C. survived       D. increased      E. especially
F. chemicals       G. concern          H. decline         I. occasionally     J. sensitive
     More recent research has shown that many kinds of amphibians (两栖动物) are declining or have
become extinct. Amphibians are animals, such as frogs, that live partly in water and partly on land. And
they have been around for over 350 million years. They have   1   three mass extinctions, including the
extinction of the dinosaurs. Why are they dying out now?
     The most serious aspect of amphibian loss, however, goes beyond the amphibians themselves.
Scientists are beginning to think about what amphibian   2   means for the planet as a whole. If the earth
is becoming unlivable for amphibians, is it also becoming unlivable for other kinds of animals and human
beings as well?
Scientists now believe that amphibian decline is due to several environmental factors. One of these factors
is the   3   of habitat, the natural area where an animal lives. Amphibians are very   4   to changes in their
habitat. If they cannot find the right conditions, they will not lay their eggs. These days, as wild areas are
covered with houses, roads, farms, or factories, many kinds of amphibians are no longer laying eggs.
     There are a number of other factors in amphibian decline. Pollution is one of them. In many industrial
areas, air pollution has   5   the rain, which then falls on ponds and kills the frogs that live there. In farming
areas, the heavy use of   6   on crops has also killed off amphibians. Another factor is that air pollution has
led to    7   levels of ultraviolet (UV) light. This endangers amphibians, which seem to be   8   sensitive to
UV light.
     All these reasons for the disappearance of amphibians are also good reasons for more general   9   .
These factors affect human beings, too.
查看答案
微信公众账号搜索答案