问题 实验题

有些微生物能合成纤维素酶,通过对这些微生物的研究和应用,使人们能够利用秸秆等废弃物生产酒精,用纤维素酶处理服装面料等。纤维素酶可以通过微生物发酵生产,为了提高酶的产量,请你设计一个实验,利用诱变育种的方法,获得产生纤维素酶较多的菌株。

(1)写出实验步骤:

①.将培养好的生产菌株分成两组,___________。

②.制备含有___________________的固体培养基。

③._______________________________________。

④._______________________________________。

(2)预测实验结果及结论:

①.诱变组中菌落周围的透明圈比对照组_________,说明__________________。

②.诱变组中菌落周围的透明圈与对照组_________,说明__________________。

③.诱变组中菌落周围的透明圈比对照组小,说明_________________________。

(3)若获得纯净的高产菌株,需进行_________或_________操作。

答案

(1)①.一组用一定剂量的诱变剂处理,另一组不处理作为对照   ②.纤维素   ③.把诱变组的大量菌株接种到多个含有纤维素的固体培养基上,同时接种对照组(未处理)的菌株,把它们置于相同的适宜条件下培养   ④.一段时间后,取培养基用刚果红染色,观察记录菌落周围透明圈的大小情况

(2)①.大   诱变育种获得了高纤维素酶产量的菌株   ②.相同   诱变育种没有使菌株发生变化   ③.诱变育种获得了低纤维素酶产量的菌株

(3)平板划线   稀释涂布平板

阅读理解

In junior high school in America, kids study English, writing, math, science, biology, music and art.

At 12 o’clock, the students eat lunch at school. They have meat, vegetables, fruit, bread and a drink, but they like hot dogs and hamburgers best. American kids like sugar (糖), and after the meal they can have a small piece of cake.

Students sleep (睡觉) for a short time after lunch. They begin classes at 1:30 in the afternoon. They go to school on weekdays and have classes for six hours every day and then return home.

Parents let their kids play or watch TV until dinner at 6:00 p. m. After dinner, they do their homework. Sometimes kids and their parents have a family activity after dinner.

根据短文内容,选择正确答案。

小题1: What do the students like best for lunch at school?

A.Meat and fruit.

B.Hot dogs and hamburgers.

C.Hot dogs and sugar.

D.Bread and hamburgers.小题2:In America, students go to school __________ days a week.

A.4

B.5

C.6

D.7小题3:The American kids usually have dinner_____ in the evening.

A.at five o’clock

B.at six thirty

C.at six o’clock

D.at five thirty小题4:Which of the following is NOT true?

A.American students like hot dogs and hamburgers best.

B.After lunch students sleep for a short time.

C.The classes begin at 2:00 p. m.

D.Sometimes students have a family activity with their parents.小题5:The best title(标题)for the passage (短文) is ______.

A.Favorite food

B.Junior high school

C.Outdoor activities

D.School life in America

单项选择题