3．一般人对苯硫脲感觉味苦，由基因B控制，也有人对其无味觉，叫味盲，由基因b控制。若三对夫妇的子女味盲各是25%、50%和100%。则这三对夫妇的基因型最大可能是

　　 ①BBXBB　 ②bbxbb　 ③BBXbb　 ④Bb×Bb　 ⑤Bb×bb　 ⑥BB×Bb

　　 A．①②③　　 　　　　　　 B．④⑤⑥　　 　　　　　　 C．④②⑤　　 　　　　　 D．④⑤②

2．下列各杂交组合的所有后代中，与双亲具有相同表现型的是

　　 A．BbSsXbbss　 　　　　 B．BbSs×bbSs　 　　　 C．BbSS~BBSs　 　　　 D．BBSs×bbss

1．基因型为AA的牛与杂种公牛表现有角，杂种母牛与基因型为aa的牛表现为无角，现在一对有角牛交配，生下一只无角牛，这只小牛的性别是

　　 A．雄牛　　 　　　　　　　 B．雌牛　　 　　　　　　　　 C．雌、雄牛都可　　 D．无法确定

8.(★★★★★)In this passage the author mainly discusses ________.

A.how Western school systems mirror the value of individualism

B.the advantages and disadvantages of the two educational systems

C.what Asian schools should do to make students more creative

D.the differences in culture, religion, etc. between the East and West

7.(★★★★★)The main purpose of the passage is to ________.

A.list today’s standards of some food and nutrition

B.introduce what should be eaten and what not

C.explain what is helpful to your health and what is not

D.test our nutrition IQ by judging the problems listed

H

In a society such as the United States or Canada, which has many national, religious and cultural differences, people highly value individualism-the differences among people. Teachers place a lot of importance on the qualities that make each student special. The educational systems in these countries show these values. Students do not memorize information. Instead, they work on their own and find answers themselves. There is often discussion in the classroom. At an early age, students learn to form their own ideas and opinions.

In most Asian societies, by contrast, the people have the same language, history and culture. Perhaps for this reason, the educational system in these Asian countries reflects society’s belief in group goals and purposes rather than individualism. Children in China, Japan, and Korea often work together and help one another on assignments(作业).

There are advantages and disadvantages to both of these systems of education. For example, one advantage to the system in Japan is that students there learn much more math and science than American students learn by the end of high school. They also study more hours each day and more days each year than North Americans do. The system is difficult, but it prepares students for a society that values discipline(纪律)and self-control.There is,however, a disadvantage. Memorization is an important learning method in Japanese schools, yet many students say that after an exam, they forget much of the information that they have memorized.

The advantage of the educational system in North America, on the other hand, is that students learn to think for themselves. The system prepares them for a society that values creative ideas. There is, however, a disadvantage. When students graduate from high school, they haven’t memorized as many basic rules and facts as students in other countries have.

7.Food grown in poor soil is lower in vitamins than food grown in rich soil.

False.The vitamins in our foods are made by the plants themselves.They don’t come from the soil.However,the minerals in a plant depend on the minerals in the soil.

If you have answered these questions correctly,you can say you know much about food and nutrition by today’s standards.But remember that nutrition is growing science and that it may be aged as new information is obtained.

6.Older people need the same amount of vitamins as younger people.

True.Older people need the same quantity of vitamins as younger people although they need fewer calories.Certain illnesses raise the requirements for some vitamins,but that is true for the young as well as the old.

5.Natural vitamins are better supplements(补充) for the diet than synthetic vitamins.

False.There is no difference.A vitamin has the same properties(性质) and specific chemical structure whether made in a laboratory or taken from plant or animal parts.

4.Taking extra vitamins beyond the recommended daily allowances won’t give you more energy.

True.It’s widely believed that extra vitamins provide more energy.But taking more than the body needs doesn’t make if function better,just as overfilling your gas tank doesn’t make your car run better.

3.Food eaten between meals can be just as good for health as food eaten at regular meals.

True.Nutritional value depends on what types of food you eat,not when you eat them.Eating an egg or an orange between meals can contribute to a good diet.