MDARD Michigan Core Pesticide Applicator Practice Exam

What critical enzyme do organophosphates interfere with?

1. Catalase

2. Cholinesterase

3. Cyclooxygenase

4. Amylase

The correct answer is: Cholinesterase

Organophosphates are a class of pesticides that operate by inhibiting the enzyme cholinesterase. This enzyme plays a vital role in the nervous system by breaking down the neurotransmitter acetylcholine after it has transmitted a nerve impulse. By preventing cholinesterase from functioning, organophosphates cause an accumulation of acetylcholine at nerve synapses, leading to overstimulation of the nerves. This overstimulation can result in various symptoms and can be detrimental to both pest species and non-target organisms, including humans. In contrast, the other enzymes listed do not play a role related to the mode of action of organophosphates. Catalase is involved in breaking down hydrogen peroxide into water and oxygen, cyclooxygenase plays a crucial role in the formation of prostaglandins and is more associated with inflammation and pain pathways, while amylase is primarily involved in the digestion of carbohydrates. Thus, the choice of cholinesterase correctly identifies the specific enzyme affected by organophosphates, highlighting the mechanism by which these pesticides exert their toxic effects.