QAL Laws & Regulation Practice Exam

What is an example of how a contact pesticide functions?

1. It absorbs into the soil to kill weeds

2. It travels through the vascular system of plants

3. It controls pests only on the part of the plant it touches

4. It binds to the pest's outer layer

The correct answer is: It controls pests only on the part of the plant it touches

A contact pesticide works by affecting the pests that come into direct contact with it. This means that its effectiveness is limited to the area where it is applied, as it targets only the pests that are physically exposed to the pesticide at the time of application. Once the pesticide is applied to a plant or surface, pests that land on or crawl over that area will be directly impacted, leading to their control or elimination. This method relies on the immediate physical interaction between the pesticide and the pest. The other options describe characteristics or functions that are not typical of contact pesticides. For instance, absorption into the soil to kill weeds pertains more to systemic herbicides, which can be taken up by roots and transported throughout the plant. Similarly, traveling through the vascular system of plants indicates a systemic action, which is not applicable to contact pesticides. Lastly, while binding to the pest's outer layer could describe some modes of action, it does not accurately convey the all-around technique of controlling pests through direct contact as effectively as the selected answer.