DDT was sprayed on some insects as an experiment. Among them, some died and some survived. A second generation was created by mating the survived ones. Again, DDT was sprayed. This process was repeated on five generations. The result is given in the table. Analyse it and answer the following questions.
Generations Percentage of survived insects
1 10
2 20
3 30
4 40
5 50
(a) Interpret the result given in the table.
(b) What scientific explanation can you give for this result?
(c) What may be the result if the experiment is continued?

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Solution

(a) After each generation, the insect's resistance to the pesticide DDT increases which means the insect has undergone mutation.
(b) This is an example of Darwin's theory of Natural selection which states that an organism with better traits will be selected over the one with inferior traits. This is because the surviving organism has adapted to the changing environmental conditions. These changes are transmitted to the succeeding generations.
(c) If the experiment is continued, the complete population of insects may become resistant to DDT.

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