Question

A farmer uses triazine herbicide to control pigweed in his field. For the first few years, the triazine works well and almost all the pigweed dies; but after several years, the farmer sees more and more pigweed. Which of these explanations best describes this observation?
A. Pigweed wants to survive and so it mutates in response to triazine.
B. Only triazine-resistant weeds survived and reproduced, so each year more pigweed was triazine-resistant.
C. Triazine-resistant pigweed has less efficient photosynthesis metabolism.
D. Natural selection caused the pigweed to mutate, creating a new triazine-resistant species.

Answer 1

Answer:

The correct option is B) Only triazine-resistant weeds survived and reproduced, so each year more pigweed was triazine-resistant.

Explanation:

With time, the pigweed became resistant to triazine. As we know, according to the theory of natural selection only those species are able to survive and reproduce which are better adapted to live in an environment and adapt to the environmental changes. As the triazine- resistant weeds were better adapted survive and reproduce in the area, it began passing its resistant genes to offsprings. As a result, the population of the pigweed increases.