Pesticides Practice Questions

Correct answer: Killing or suppressing unwanted plants and weeds

Herbicides are a specific category of pesticides designed to target weeds. They work by interfering with plant-specific processes like photosynthesis or specific enzyme production.

Correct answer: Dichloro-diphenyl-trichloroethane

DDT was widely used in the mid-20th century to control malaria and typhus. Its use was later restricted globally due to its environmental persistence and negative impact on wildlife.

Correct answer: Biomagnification

Biomagnification occurs when persistent, fat-soluble chemicals like organochlorines are stored in the tissues of organisms. Top predators end up with much higher concentrations than the organisms at the bottom of the food chain.

Correct answer: Azadirachtin

Azadirachtin is the active compound found in Neem tree seeds. It acts as an antifeedant and growth regulator for insects while being relatively safe for humans and beneficial organisms.

Correct answer: Acetylcholinesterase

Acetylcholinesterase breaks down the neurotransmitter acetylcholine. When inhibited, acetylcholine builds up, leading to overstimulation of the nervous system, paralysis, and death of the target pest.

Correct answer: Systemic pesticides are absorbed and travel inside the plant

Systemic pesticides travel through the plant's sap, making the entire plant toxic to pests that feed on it. Contact pesticides only kill pests that come into direct physical contact with the chemical on the surface.

Correct answer: Warfarin

Warfarin interferes with Vitamin K recycling, which is essential for blood clotting. It causes internal bleeding in rodents, leading to their eventual death.

Correct answer: Copper sulfate and slaked lime

Developed in the 19th century, the Bordeaux mixture is used to control downy mildew and other fungi. The copper acts as the active fungicide, while the lime neutralizes the acidity to prevent plant damage.

Correct answer: Plants and many bacteria

The shikimate pathway is essential for synthesizing certain amino acids in plants but is absent in humans and other mammals. This is why glyphosate is generally considered to have lower acute toxicity to humans compared to other pesticides.

Correct answer: Molluscicides

Molluscicides target mollusks. Common active ingredients include metaldehyde or iron phosphate, which disrupt the mucus production or digestion of snails and slugs.

Correct answer: Chrysanthemum flowers

Natural pyrethrins are extracted from Chrysanthemum cinerariifolium. They are favored for home use because they degrade quickly in sunlight and have low toxicity to mammals.

Correct answer: Pests evolving to survive chemicals, forcing higher doses

Pesticide resistance is a classic example of natural selection. When a few resistant individuals survive a chemical application, they pass those traits to their offspring, eventually making the pesticide ineffective for the entire population.

Correct answer: Methyl bromide

Fumigants are pesticides that act in a gaseous state. Methyl bromide is highly effective at penetrating soil or grain stores, though its use is being phased out due to its role in ozone depletion.

Correct answer: Acute toxicity to test animals

LD50 stands for 'Lethal Dose, 50%'. A lower LD50 value indicates a more toxic substance, as a smaller amount is required to kill half of the experimental animals.

Correct answer: Pollinators like honeybees

Neonicotinoids are chemically similar to nicotine and are highly toxic to insects. Evidence suggests they can impair bee navigation and immune systems, leading to colony collapse disorders.

Correct answer: Pesticide residue

Pesticide residues are monitored by food safety authorities to ensure they stay below 'Maximum Residue Limits' (MRLs) that are considered safe for human consumption.

Correct answer: Ticks and mites

Acaricides (sometimes called miticides) target members of the subclass Acari, which includes ticks and mites. These are often used in both agricultural settings and for pet health.

Correct answer: A last resort when other methods fail

IPM focuses on long-term prevention using a combination of biological controls, habitat manipulation, and resistant varieties. Chemicals are used only as needed and with the goal of minimizing risks to human health and the environment.

Correct answer: Aldrin

Aldrin, like DDT, is an organochlorine that is highly persistent in the environment. These chemicals were targeted for bans because they do not break down easily and accumulate in animal fats.

Correct answer: Disrupt mating cycles or monitor populations

Pheromones are chemical signals used by insects to communicate. Synthetic pheromones can be used to lure insects into traps for monitoring or to confuse males so they cannot find females to mate with.