Which statement best differentiates systemic and contact pesticides?

Which statement best differentiates systemic and contact pesticides?

• A. Systemic pesticides are absorbed and move through the plant; contact pesticides act on surfaces and pests without systemic movement.
• B. Systemic pesticides remain on the plant surface; contact pesticides are absorbed by roots.
• C. Systemic pesticides evaporate quickly; contact pesticides become part of the plant.
• D. Systemic pesticides target only mammals; contact pesticides target only insects.

Answer: (A)

The key idea is how these pesticides move and where they act in the plant. Systemic pesticides are absorbed by the plant and transported through its vascular system, so protection extends inside the plant to tissues you can’t see. Contact pesticides, on the other hand, stay on the surface where they’re applied and kill pests that touch or feed on those treated surfaces, without moving through the plant. That’s why the correct statement says systemic pesticides are absorbed and move through the plant, while contact pesticides act on surfaces and pests without systemic movement. This distinction also explains practical differences—systemic products can protect new growth after application, whereas contact products require thorough coverage and may be washed off by rain. The other ideas—systemic staying only on surfaces, systemic evaporating, or targeting mammals instead of insects—don’t reflect how movement and site of action actually work.

The key idea is how these pesticides move and where they act in the plant. Systemic pesticides are absorbed by the plant and transported through its vascular system, so protection extends inside the plant to tissues you can’t see. Contact pesticides, on the other hand, stay on the surface where they’re applied and kill pests that touch or feed on those treated surfaces, without moving through the plant.

That’s why the correct statement says systemic pesticides are absorbed and move through the plant, while contact pesticides act on surfaces and pests without systemic movement. This distinction also explains practical differences—systemic products can protect new growth after application, whereas contact products require thorough coverage and may be washed off by rain. The other ideas—systemic staying only on surfaces, systemic evaporating, or targeting mammals instead of insects—don’t reflect how movement and site of action actually work.