每日一练：职称英语考试卫生类每日一练(2018/7/31)
【单选题】
Plants, like animals, are subject todiseases of various kinds. It has been estimated that some 30,000 differentdiseases attack out economic plants: forty are known to attack corn, and aboutas many attack wheat. The results of unchecked plant disease are all tooobvious in countries which have marginal food supplies. The problem will soonbe more widespread as the population of the world increases at its frighteningrate. Even in countries which are now amply fed by their agricultural productsthere could soon be critical food shortages. It is easy to imagine theconsequences of some disastrous attack on one of the major crops; the resultingfamines could kill millions of people, and the resulting hardship on othermillions could cause political upheavals disastrous to the order of the world.
Some plants have relative immunity to a greatmany diseases, while others have a susceptibility to them. The tolerance of aparticular plant changes as the growing conditions change. A blight may be buta local infection easily controlled, on the other hand it can attack particularplants in a whole region or nation. An example is the blight which killedvirtually every. chestnut tree in North American. Another is the famous potatoblight in Ireland in the last century. As a result of that, it was estimatedthat one million people died of starvation and related aliments.
Plant pathologists have made remarkable stridesin identifying the pathogens of the various diseases. Bacteria may invade aplant through an infestation of insect parasites carrying the pathogen. A plantcan also be inoculated by man. Other diseases might be caused by fungus whichattacks the plant in the form of a mold or smut or rust. Frequently such aprimary infection will weaken the plant so that a secondary infection mayresult from its lack of tolerance. The symptoms shown may cause an error in diagnosis,so that treatment may be directed toward bacteria which could be the result ofa susceptibility caused by a primary virus infection.
1. How many diseases are known to attack wheat?
A) Around 30,000
B) Around 140
C) Around 29,960
D) Around 40
2. According to this passage, which of thefollowing would a plant disease result in if left unchecked?
A) A world war.
B) Border conflicts.
C) Rations of grain and meat.
D) Social upheavals.
3. What is the main idea of the secondparagraph?
A) Some plants have relative immunity to agreat many diseases, while others have a
susceptibility to them.
B) The tolerance of a particular plant changesas the growing condition change.
C) A blight killed virtually every chestnuttree in North American.
D) A blight may be a national infection.
4. According to the passage, some plantdiseases can be prevented by
A) killing parasites.
B) inoculation
C) Killing insects
D) improving growing conditions
5. Which of the following statements is nottrue?
A) Some plant diseases may be caused bybacteria.
B) Some plant diseases may be caused bypathogens.
C) Some plant diseases may be caused by fungus.
D) Symptoms are always helpful in identifying diseases在下面提交答题后即可查看答案与试题解析
发布评论 查看全部评论