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 explains what happened?

A. The herbicide company lost its triazine formula and started selling poor-quality triazine.
B. Triazine-resistant weeds were more likely to survive and reproduce
C. Natural selection caused the pigweed to mutate, creating a new triazine-resistant species
D. Triazine-resistant pigweed has less efficient photosynthesis metabolism.

Answer 1

Answer:

B. Triazine-resistant weeds were more likely to survive and reproduce

Explanation:

According to darwin's theory of evolution, variation is already present in some members of a population and this variation lets them survive in the adverse condition and those who do not have that variation which helps in survival are lost with time.

So as before using triazine herbicide the major population of the weed were not resistant to this herbicide so in the first few years the nonresistant weeds were lost and only resistant weed which was very less in number survived.

So after several years these resistant weeds reproduced and transferred their gene to their offsprings and became predominant in the field. Therefore the correct answer is B.

Answer 2

Answer: Option B and C

Explanation:

A farmer used triazine herbicide to control the pig weed in his field. Because of this all the pig weeds died.

But after several years the pig weeds again reappeared on the field. This happened because the mutant species of the pigweeds were selected and they started to reproduce.

The population evolved were mutant species and they are more likely to survive and reproduce.