问题 填空题

很多同学长得像自己的父母,这是因为父母直接把性状传给了后代.______.

答案

在形成精子和卵细胞的细胞分裂过程中,染色体都要减少一半.而且不是任意的一半,是每对染色体中各有一条进入精子和卵细胞.生殖细胞中的染色体数是体细胞中的一半,成条存在.当精子和卵细胞结合形成受精卵时,染色体又恢复到原来的水平,基因又随着染色体成对存在,成对的基因中一条基因来自父方,一条基因来自母方,因此,后代就具有了父母双方的许多性状.生物体的各种性状都是由基因控制的,性状的遗传实质上是亲代通过生殖细胞把基因传递给了子代,在有性生殖过程中,精子与卵细胞就是基因在亲子代间传递的桥梁.因此父母的性状是通过生殖细胞把控制性状的基因传递给子女的,而不是父母直接把性状传给了后代.

故答案为:×

问答题 简答题
阅读理解

(CNN)-China will sometimes say “no” and the world should get used to it.

That message came through when China joined Russia in blocking action on Syria.

“Do not mistakenly think that because China takes a careful and responsible position on the Syria issue, China will not use its veto power (否决权) or will always abstain(弃权),” said Cui Tiankai, China’s vice foreign minister, “When China must use its veto power to say no, it will surely use it.”

On Saturday, Susan Rice, the U.S. ambassador to the United Nations, called the vetoes “disgusting and shameful.”

He Wenping, director of African Studies at the Chinese Academy of Social Sciences, said the veto shows China’s confidence in foreign affairs. “A country expressing its true opinion – that’s progress. China opposes the use of threat or force to achieve regime( * * )change in other countries. This agrees with China’s long-standing diplomacy principle. It is also not acceptable for China to rush a U.N. vote without sufficient discussion.”

So why did China use its veto this time?

China’s critics say China’s veto of the U.N. draft proposal(草案) was in part due to Beijing’s fear that allowing a regime change in Syria could encourage the spread of the Arab revolution and eventually threaten China.

He Wenping disagrees, “China has a completely different political system and economic development path. If someone in the international community thinks that the Arab Spring will happen in China, then I think they misjudge the situation in China, exaggerate(夸大) some problems in the Chinese society and underestimate the ability of the Chinese government to control the situation in China.”

小题1:Which of the following is TRUE according to the passage?

A.China often uses its veto power on international issues.

B.China never uses its veto power on international issues.

C.China’s normal practice in the U.N. is to abstain rather than veto.

D.China should not have veto power in the U.N.小题2:What is the international reaction to China’s veto on the Syria issue?

A.Russia supports China

B.The U.S. feels very unhappy.

C.The international community is used to it.

D.The Arab countries show no concern.小题3:Why did China use its veto power this time?

A.Because Russia and China are friends.

B.Because China wants to hold an opposite stand against the U.S.

C.Because China is worried about a chain-action resulting from Syria’s revolution.

D.Because China opposes the use of threat or force to achieve regime change in other countries.小题4:What can we learn from the passage?

A.China has a firm stand on international issues.

B.The U.N. asks the whole world to get used to China saying no on international issues.

C.CNN believed that China helped Syria to fight against the U.N.

D.All the member countries of the U.N. supported Susan Rice.