问题 单项选择题

杂交水稻之父,袁隆平培育出高产的杂交水稻新品种,是利用了()。

A.基因的多样性

B.染色体的多样性

C.细胞的多样性

D.DNA的多样性

答案

参考答案:A

解析:本题考查生物多样性的内涵。生物多样性通常有三个层次的含义即生物种类的多样性,基因多样性,生态系统多样性。基因多样性是指物种的种内个体或者种群间的基因变化,不同物种(小麦与水稻)之间基因组成差别很大,同种生物之间(普通水稻与野生水稻)也有很大差别,每个物种都有独特的基因库,我国动物、植物及其野生亲缘种的基因多样性生分丰富。袁隆平用海南野生水稻与普通水稻杂交,培育出高产的杂交水稻,表明生物基因多样性是培育农作物新品种的基因库。故本题答案为A。

默写题
阅读理解

阅读理解。

     On a hill 600 feet above the surrounding land, we watch the lines of rain move across the scene, the

moon rise over the hills, and the stars appear in the sky. The views invite a long look from a comfortable

chair in front of the wooden house.

    Every window in our wooden house has a view, and the forest and lakes seldom look the same as the

hour before. Each look reminds us where we are.

    There is space for our three boys to play outside, to shoot arrows, collect tree seeds, build earth

houses and climb trees.

    Our kids have learned the names of the trees, and with the names have come familiarity and

appreciation. As they tell all who show even a passing interest, maple(枫树)makes the best fighting sticks

and white pines are the best climbing trees.

    The air is clean and fresh. The water from the well has a pleasant taste, and it is perhaps the healthiest

water our kids will ever drink. Though they have one glass a day of juice and the rest is water, they never

say anything against that.

    The seasons change just outside the door. We watch the maples turn every shade of yellow and red in

the fall and note the poplars'(杨树)putting out the first green leaves of spring. The rainbow smelt fills the

local steam as the ice gradually disappears, and the wood frogs start to sing in pools after being frozen for

the winter. A family of birds rules our skies and flies over the lake.

1. What can be learned from Paragraph 2?

A. The scenes are colorful and changeable.

B. There are many windows in the wooden house.

C. The views remind us that we are in a wooden house.

D. The lakes outside the windows are quite different in color.

2. By mentioning the names of the trees, the author aims to show that ______ .

A. the kids like playing in trees

B. the kids are very familiar with trees

C. the kids have learned much knowledge

D. the kids find trees useful learning tools

3. What does the underlined sentence in the last paragraph mean?

A. The change of seasons is easily felt.

B. The seasons make the scenes change.

C. The weather often changes in the forest.

D. The door is a good position to enjoy changing seasons.

4. What is the main purpose of the author writing the text?

A. To describe the beauty of the scene around the house.

B. To introduce her children's happy life in the forest.

C. To show that living in the forest is healthful.

D. To share the joy of living in the nature.