Appearance of resistant organisms in a time scale of months or years, by the excessive use of antibiotics is an example of which of the following?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Evolution by anthropogenic action
Option (3) Evolution by anthropogenic action — Correct. When antibiotics are overused, the few resistant microbes survive and multiply, so resistant forms appear within months or years. Because human action drives this selection, it is evolution by anthropogenic action.
NCERT Extract:
What Are the Evidences for Evolution? – “… Remember that no variant is completely wiped out. 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.”