Given below are two statements:
Statement I: Microbes resistant to the antibiotics we employ against them are appearing in a time scale of centuries and not months or years.
Statement II: Excess use of herbicides and pesticides has resulted in selection of resistant varieties in a much lesser time scale.
In the light of the above statements, choose the most appropriate answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Statement I is false but Statement II is true
Human actions can also drive evolution. When we use chemicals against weeds, pests or microbes, the few resistant individuals survive and multiply, so resistant forms soon take over. Because pests and microbes reproduce fast, this happens within months or years.
Statement I: Microbes resistant to the antibiotics we employ against them are appearing in a time scale of centuries and not months or years. — False. The time scales are reversed. Resistant organisms appear in a time scale of months or years, not centuries.
Statement II: Excess use of herbicides and pesticides has resulted in selection of resistant varieties in a much lesser time scale. — True. Heavy use of herbicides and pesticides has only selected resistant varieties, and much faster than natural changes. These are examples of evolution by anthropogenic action.
NCERT Extract:
What are the Evidences for Evolution? – “Similarly, excess use of herbicides, pesticides, etc., has only resulted in selection of resistant varieties in a much lesser time scale. This is also true for microbes against which we employ antibiotics or drugs against eukaryotic organisms/cell. Hence, resistant organisms/cells are appearing in a time scale of months or years and not centuries. These are examples of evolution by anthropogenic action.”