问题 实验题

5分(每空1分)请你利用遗传学知识分析下列现象并回答问题。

(1)一对夫妇的男方想要一个男孩,而女方却想要一个女孩,请问生男生女取决于男方还是女方?_________________。

(2)假如他们婚后想生一个孩子,这个孩子为男孩的机会是多大______。

A.0%

B.50%

C.80%

D.100%(3)假设父母双方都是双眼皮,(控制双眼皮的基因为A,单眼皮的基因为a)而生育了一个孩子却是单眼皮,请确定父母双方的基因型为____________,孩子的基因型为___________。

(4)假设父母双方的个子都矮,而他们的孩子却比父母双方都高,这种现象在遗传学上叫做_____________。

答案

(1)男方(2)B(3)Aa   aa(4)变异

题目分析:(1)人的体细胞内的23对染色体,有一对染色体与人的性别有关,叫做性染色体;男性的性染色体是XY,女性的性染色体是XX;在产生生殖细胞的过程中,女性产生的卵细胞仅含X染色体,男性产生的精子含X或Y染色体,当卵细胞X与精子Y结合的受精卵为XY时,受精卵发育为男孩;当卵细胞X与精子X结合的受精卵为XX时,该受精卵发育为女孩;可见,生男生女主要决定于男方的哪一种精子与女方的卵细胞相融合.(2)含X的精子和含Y的精子,哪种精子与卵细胞结合是随机的,一个母亲如果生一个孩子,生男生女的机会各占50%,因此他们婚后想生育一个小孩,这个小孩为男孩的机会是50%.(3)控制孩子的眼皮性状的一对基因来自于父母双方,父母都为双眼皮,而生育的这个孩子为单眼皮,说明单眼皮为隐性性状,这个孩子控制单眼皮的一对基因分别来自父方和母方,即父方和母方都含有一个控制单眼皮的基因和一个控制双眼皮的基因,故其基因组成是Aa,孩子的基因组成是aa。(4)变异指的是子代与亲代之间存在差异的现象。父母都比较矮,但是孩子却比较高,与父母存在差异,是变异的现象。

阅读理解
Hundreds of years ago, life was harder than it is today. People didn’t have modern machines. There was no medicine, either.
Life today brings new problems. One of the biggest is pollution. Water pollution has made our rivers and lakes dirty. It kills our fish and pollutes our drinking water. Noise pollution makes us talk louder and we become angry more easily. Air pollution is the most serious kind of pollution to all living things in the world.
Cars, planes and factories all pollute our air every day. Sometimes the polluted air is very thick. People cannot see the sky clearly.
Many countries are making rules to fight against pollution. Factories now must clean their water before they throw it away. And they mustn’t let dirty smoke go into the air.
There are many things we can do to fight against pollution. We should put waste things in dustbins and do not throw them on the ground. We should go to work by bike or on foot instead of taking a car or a bus. If there are fewer people driving, there will be less pollution.
Rules are not enough. We should do our best to fight against pollution.
小题1:Which of the following is NOT true about life in the past?
A.There were no modern machines.
B.There was no modern medicine.
C.There was much air pollution.
D.There were not many people.
小题2:What should people do to fight against pollution?
A.Always drive a car to work.
B.Throw waste things anywhere they like.
C.Put waste things in dustbins.
D.Always take a bus to go to school.
小题3:The most serious pollution is              .
A.water pollution
B.air pollution
C.noise pollution
D.light pollution
小题4:What should factories do to fight against pollution?
A.Let dirty smoke go into the air.
B.Throw dirty water away without cleaning it.
C.Close the factories.
D.Let dirty water go after cleaning it.
小题5:From the passage, we know that              .
A.a few years ago, there was no pollution at all.
B.people today don’t have to talk to each other loudly
C.we can drink water from the polluted rivers and lakes.
D.Everybody should try his or her best to fight against pollution
 
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