CPA Pesticide Toxicology and Mode of Action 2

Question 1

Neonicotinoid insecticides such as imidacloprid act primarily on which receptor in insects?

Accepted Answer

Nicotinic acetylcholine receptor

Answer

Neonicotinoids bind to nicotinic acetylcholine receptors in insects, causing continuous nerve stimulation; they have much lower affinity for mammalian receptors.

Question 2

Which class of insecticides disrupts insect development by mimicking or interfering with juvenile hormone, preventing normal molting?

Accepted Answer

Insect growth regulators (IGRs)

Answer

Insect growth regulators mimic juvenile hormone or ecdysone, disrupting molting and metamorphosis without the same risks to mammals as conventional neurotoxins.

Question 3

A 'systemic' pesticide is one that:

Accepted Answer

Is absorbed by the plant and translocated throughout its tissues

Answer

Systemic pesticides are absorbed by plant roots or leaves and move within plant vascular tissue, protecting parts not directly sprayed.

Question 4

What is the primary mode of action of organochlorine pesticides such as DDT?

Accepted Answer

Voltage-gated sodium channel disruption

Answer

DDT and other organochlorines keep voltage-gated sodium channels open in nerve membranes, causing repetitive nerve firing similar to pyrethroids.

Question 5

Which EPA toxicity category requires both the signal word 'DANGER' and the word 'POISON' printed on the pesticide label?

Accepted Answer

Category I

Answer

Category I pesticides are the most acutely toxic and require 'DANGER' along with 'POISON' and a skull-and-crossbones symbol on the label.

(CPA) Certified Pesticide Applicator Practice Test

(CPA) Certified Pesticide Applicator Practice Test

CPA Pesticide Toxicology and Mode of Action 2