Question

Five hundred cockroaches of one species were sprayed with a new insecticide. Twenty-four hours later nearly all the cockroaches were dead. A few, however, survived. This outcome illustrates which one of darwin’s key ideas about natural selection and variation?.

Answer 1

This shows that over time, some insects can become "pesticide-resistant" meaning that pesticides don't affect them anymore. And this only happens every few generations. Therefore, each generation is being naturally selected and accumulating variations that make them resist the chemicals. This shows that each cockroach's genes are changing to give them variation from the rest of the population.

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