Câu hỏi: Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer for each of the questions from 35 to 42.
In the 1960s, the World Health Organization (WHO) began a campaign to eradicate the mosquitoes that transmit the disease malaria. It was a noble goal, since malaria kills an estimated 3 million people each year in the world's tropical regions, predominantly southern Africa. WHO led an effort to spray the mosquitoes's habitat with a chemical pesticide- a poison used to kill insects- called DDT. Early results were promising, and the mosquito was eliminated from the adge of its native range. The effort soon faltered, however, and the eradication plan was dropped. How could a tiny mosquito thwart the best efforts of a large group of well- funded scienttists?
Situations like this one have occurred dozens of times in the last several decades. In a common scenario, whenevera a new type of oesticide is used to control agricultural pests, the early results are encouraging. A relatively small amount of the poison dusted onto a crop may kill 99% of the insects. However, the relatively few survivors of the first pesticide ware are insects with genes that somehow enable them to resist the chemical attack. The oison kills most members of the insect population, leaving only the resistant individuals to reproduce. And when they do, their offspring inherit the genes for pesticide resistance. In each generation, the proportion of pesticide-resistant individuals in the insect population increases, making subsequent sprayings less and less effective.
Since the widespread use of chemical pesticides began in the 1940s, scientists have documented pesticide resistance in more than 500 species of insects. The problem such insects pose-through their impact on agriculture and medicine-are just some of the many ways that evolution has a direct organisms are fine tuning adaptations to local environments through the evolutionary process of natural selection. Given the dynamics of Earth and its life, it is not surprising that even the kinds of organisms on the planet-the species-have changed over time.
The increase of pesticide-resistant insects____________.
A. makes later sprayings more expensive
B. makes it more convenient for future sprayings
C. makes laters sprayings less effective
D. makes subsequent sprayings impoppible
In the 1960s, the World Health Organization (WHO) began a campaign to eradicate the mosquitoes that transmit the disease malaria. It was a noble goal, since malaria kills an estimated 3 million people each year in the world's tropical regions, predominantly southern Africa. WHO led an effort to spray the mosquitoes's habitat with a chemical pesticide- a poison used to kill insects- called DDT. Early results were promising, and the mosquito was eliminated from the adge of its native range. The effort soon faltered, however, and the eradication plan was dropped. How could a tiny mosquito thwart the best efforts of a large group of well- funded scienttists?
Situations like this one have occurred dozens of times in the last several decades. In a common scenario, whenevera a new type of oesticide is used to control agricultural pests, the early results are encouraging. A relatively small amount of the poison dusted onto a crop may kill 99% of the insects. However, the relatively few survivors of the first pesticide ware are insects with genes that somehow enable them to resist the chemical attack. The oison kills most members of the insect population, leaving only the resistant individuals to reproduce. And when they do, their offspring inherit the genes for pesticide resistance. In each generation, the proportion of pesticide-resistant individuals in the insect population increases, making subsequent sprayings less and less effective.
Since the widespread use of chemical pesticides began in the 1940s, scientists have documented pesticide resistance in more than 500 species of insects. The problem such insects pose-through their impact on agriculture and medicine-are just some of the many ways that evolution has a direct organisms are fine tuning adaptations to local environments through the evolutionary process of natural selection. Given the dynamics of Earth and its life, it is not surprising that even the kinds of organisms on the planet-the species-have changed over time.
The increase of pesticide-resistant insects____________.
A. makes later sprayings more expensive
B. makes it more convenient for future sprayings
C. makes laters sprayings less effective
D. makes subsequent sprayings impoppible
Câu trả lời dựa vào thông tin "...the proportion of pesticide-resistant individuals in the insect population increases, making subsequent sprayings less and less effective"
Đáp án C.