问题 问答题 论述题

论述马铃薯癌肿病的症状特点、病原菌形态特点;病害发生规律和流行条件;在国内的适生区域以及检疫检验方法。

答案

参考答案:

症状特点:主要为害块茎,地上部分症状多不明显。

病原菌形态特点:休眠孢子囊近球形,褐色,厚壁,萌发产生游动孢子;

原孢堆游动孢子侵入芽组织细胞内,使寄主细胞受刺激而膨大,菌体先发育形成的经细胞多次分裂,转而形成含有3-9隔夏孢子囊的夏孢子堆;

夏孢子囊壁薄淡色,多角形或卵形;

游动孢子卵圆形,鞭毛单生;

合子(游动孢子形成配子,并结合形成合子)两根鞭毛,游动;侵入寄主细胞形成休眠孢子囊。

病害发生规律和流行条件:1.气象因素-土壤水分饱和,温度12-24℃,pH4.5-7,最有利于发病。

2.海拔高度-3600—1680m,2500m以上发明面积大。

3.坡向和地势-阴坡病重,阳坡病轻。

4.轮作-连作地病重,轮作年限长的病轻。

5.自生马铃薯数量-自生马铃薯是土壤中重要的初侵染来源。

在国内的适生区域:山区和潮湿地带对此病最为有利,这些地区气候凉爽、雨日频繁、雾多、日照少、土壤湿度大及酸性土壤。如在云、贵、川高原区有发生。

检疫检验方法:1.土壤检验-漂浮法提取休眠孢子囊。

2.直接检查有无肿瘤物。

3.病原菌形态观察-夏孢子囊堆和休眠孢子囊。

4.染色检验-单鞭毛的游动孢子和双鞭毛的合子。

阅读理解

How would you like an easy way to earn 2,500 dollars? All you have to do is to sit around and wait for your meals.There’s catch, however.You have to stay in a chicken cage with a stranger for a whole week.There are no books or television or radio for amusement.You can’t leave until the week is up.And a camera will be recording your every move.

Two people actually took the job.The idea came from Rob Thompson, a video artist.He wanted to make a film about the way animals are treated.His goal was to raise people’s awareness of the living conditions of animals that are raised for food.He decided to pay $ 5000 out of his own savings to two people who were willing to lie like chicken for a week.

To Rob’s surprise, quite a few people answered his advertisement.He had interviews and selected Eric, a 24-year-old restaurant worker, and Pam, a 27-year-old chemist.The plan was for them to spend seven days together in a chicken cage that was six feet long and three feet wide.A camera would record their experience, which would take place in an art museum.

The week was long and difficult.They slept on a hard wooden floor.They couldn’t stand up without banging(重击)their heads.They ate vegetarian mash(土豆泥)and drank water from a garden hosepipe(水龙头软管).Their only privacy was a toilet surrounded by a curtain.There were no sinks, mirrors, or toothbrushes in the cage.Their only inspiration was the two framed checks that hung on the wall outside the cage.Visitors who came here were warned, “Do not food the humans.”

Finally it was over, Pam and Eric emerged from their cage.They had survived the week, and they each had a $2,500 check in their hands.When Rob Thompson opened the cage, Eric came out, changed into clean clothes, and ate a chocolate bar right away.“It’s great to be able to stand up,” he said.Pam just changed her clothes and left.After a week of visitors and reporters watching her, she didn’t want to talk to anyone.

小题1:What kind of person is Rob Thompson?

A.He is curious about people’s personal life.

B.He is kind-hearted to animals.

C.He hates people around.

D.He likes to help poor people.小题2:What made it most difficult for the two to stay in the cage?

A.They didn’t know each other.

B.They couldn’t lie down to sleep in the cage.

C.They didn’t have meat to eat.

D.They had to do almost everything under others’ eyes.小题3:Rob offered the money because he wanted________.

A.to see if there were any people who would like to live in a cage

B.to show the public how bitter animals’ life could be

C.to make more money by publishing the recorded video tapes

D.to improve housing conditions of working people like Eric小题4:Which of the following would be the best title for this passage?

A.Easy Way to Earn $ 2 500.

B.Do Not Feed the Humans.

C.Living Like a Chicken.

D.Getting Along Well Anyway.

单项选择题 共用题干题