Structure and uses of DDT MCQs With Answer

Understanding the structure and uses of DDT is essential for B.Pharm students studying pesticide chemistry, toxicology, and environmental pharmacology. This set of concise, exam-focused MCQs covers DDT’s chemical structure (molecular formula, isomers, synthesis), physicochemical properties (lipophilicity, persistence), mode of action on insect nervous systems, metabolism to DDE/DDD, environmental fate, bioaccumulation, human toxicity, therapeutic responses, analytical detection (GC-MS), and regulatory status. Questions are crafted to deepen conceptual knowledge and clinical relevance, linking molecular structure to biological effects, resistance mechanisms, and public health applications such as malaria control. Ideal for revision and viva preparation. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which of the following is the correct molecular formula of DDT?

• C14H9Cl5
• C14H10Cl4
• C12H8Cl6
• C15H11Cl4

Correct Answer: C14H9Cl5

Q2. DDT belongs to which class of insecticides?

• Organophosphates
• Carbamates
• Organochlorines
• Pyrethroids

Correct Answer: Organochlorines

Q3. The primary biologically active isomer of technical DDT is:

• m,p’-DDT
• o,p’-DDT
• p,p’-DDT
• o,o’-DDT

Correct Answer: p,p’-DDT

Q4. Which reagents are commonly used in the classical synthesis of DDT?

• Chloral and chlorobenzene in acidic medium
• Benzoyl chloride and benzene with AlCl3
• Chloroform and phenol with NaOH
• Trichloroethylene and aniline with H2SO4

Correct Answer: Chloral and chlorobenzene in acidic medium

Q5. DDT exerts its insecticidal effect primarily by targeting:

• Acetylcholinesterase enzyme
• Voltage-gated sodium channels
• GABA-gated chloride channels
• Monoamine oxidase

Correct Answer: Voltage-gated sodium channels

Q6. The major environmental metabolites of DDT are:

• DDE and DDD
• DDU and DDF
• DDG and DDH
• DDX and DDY

Correct Answer: DDE and DDD

Q7. High lipophilicity of DDT contributes mainly to:

• High aqueous solubility
• Rapid biodegradation
• Bioaccumulation in fatty tissues
• High volatility at room temperature

Correct Answer: Bioaccumulation in fatty tissues

Q8. Which analytical technique is most commonly used for detection and quantification of DDT and metabolites in environmental and biological samples?

• UV-Vis spectrophotometry
• Gas chromatography–mass spectrometry (GC-MS)
• Infrared spectroscopy (IR)
• Atomic absorption spectroscopy (AAS)

Correct Answer: Gas chromatography–mass spectrometry (GC-MS)

Q9. Which property of DDT explains its long persistence in soil and sediments?

• High water solubility
• Weak adsorption to organic matter
• Resistance to microbial degradation and strong sorption to organic matter
• Rapid hydrolysis in neutral pH

Correct Answer: Resistance to microbial degradation and strong sorption to organic matter

Q10. DDE, a metabolite of DDT, is particularly implicated in which environmental effect?

• Ozone depletion
• Eggshell thinning in birds
• Acid rain formation
• Algal blooms in freshwater

Correct Answer: Eggshell thinning in birds

Q11. The log P (octanol-water partition coefficient) of DDT is generally:

• Very low (less than 0)
• Moderate (around 1–2)
• High (greater than 5)
• Undefined due to instability

Correct Answer: High (greater than 5)

Q12. Which mechanism is NOT a common basis for insect resistance to DDT?

• Increased metabolic detoxification enzymes
• Target site mutations in sodium channels
• Behavioral avoidance
• Increased cuticular absorption of DDT

Correct Answer: Increased cuticular absorption of DDT

Q13. In vertebrates, acute high-dose DDT poisoning primarily manifests as:

• Hepatic necrosis without neurological signs
• Neuroexcitation, tremors, and possible seizures
• Renal failure with anuria
• Profound hypotension and bradycardia only

Correct Answer: Neuroexcitation, tremors, and possible seizures

Q14. Which statement correctly links DDT structure to its persistence?

• Presence of multiple chlorine atoms reduces susceptibility to enzymatic attack
• High hydrogen content makes it highly degradable
• The aromatic rings make it water soluble and short-lived
• The tertiary amine prevents breakdown

Correct Answer: Presence of multiple chlorine atoms reduces susceptibility to enzymatic attack

Q15. Which public health use of DDT remains a global exception despite many bans?

• Use as a food preservative
• Indoor residual spraying for malaria vector control
• Disinfection of drinking water
• Crop treatment for cereal storage

Correct Answer: Indoor residual spraying for malaria vector control

Q16. Which factor enhances human exposure to DDT through diet?

• High consumption of fatty animal products from contaminated areas
• Drinking bottled water from clean sources
• Consuming only plant-based oils refined at high temperatures
• Exposure to sunlight while outdoors

Correct Answer: High consumption of fatty animal products from contaminated areas

Q17. Which occupational safety measure is most relevant when handling technical DDT formulations?

• Use of lipid-rich creams to increase dermal absorption
• Wearing appropriate PPE including gloves and respirators
• Heating formulations to increase volatility for faster action
• Ingesting small doses to build tolerance

Correct Answer: Wearing appropriate PPE including gloves and respirators

Q18. In pharmacokinetic terms, DDT is best described as:

• Highly hydrophilic with rapid renal excretion
• Weakly bound to plasma proteins and rapidly eliminated
• Lipophilic with accumulation in adipose tissue and slow elimination
• Rapidly metabolized to water-soluble conjugates and excreted

Correct Answer: Lipophilic with accumulation in adipose tissue and slow elimination

Q19. Which metabolite is mainly associated with persistent biological activity similar to DDT?

• DDE
• DDU
• DDX
• DDZ

Correct Answer: DDE

Q20. Which regulatory instrument restricts persistent organic pollutants like DDT internationally?

• Montreal Protocol
• Stockholm Convention
• Kyoto Protocol
• Rotterdam Convention

Correct Answer: Stockholm Convention

Q21. The primary physicochemical reason DDT concentrates in food chains is:

• High vapor pressure leading to atmospheric accumulation
• Specific binding to blood cells only
• High lipophilicity and low metabolic clearance
• Strong electrolyte nature in aqueous systems

Correct Answer: High lipophilicity and low metabolic clearance

Q22. Which laboratory animal endpoint is commonly used to assess acute DDT toxicity?

• ED50 for behavioral sedation
• LD50 for mortality
• Minimum inhibitory concentration (MIC)
• Mutagenicity index

Correct Answer: LD50 for mortality

Q23. Which statement about DDT’s solubility is correct?

• DDT is highly soluble in water
• DDT is practically insoluble in organic solvents
• DDT is poorly soluble in water but soluble in organic solvents
• DDT is a strong acid, fully ionized in water

Correct Answer: DDT is poorly soluble in water but soluble in organic solvents

Q24. How does DDT cause neurotoxicity at the molecular level?

• Inhibition of serotonin receptors causing depression
• Prolongation of sodium channel opening leading to repetitive neuronal firing
• Direct DNA intercalation in neurons
• Blockade of NMDA receptors causing paralysis

Correct Answer: Prolongation of sodium channel opening leading to repetitive neuronal firing

Q25. Which environmental compartment tends to act as a long-term sink for DDT?

• Surface water with high flow
• Sandy soil with low organic matter
• Marine and freshwater sediments rich in organic carbon
• Atmospheric gaseous phase only

Correct Answer: Marine and freshwater sediments rich in organic carbon

Q26. A common method to reduce human DDT body burden is:

• Promote consumption of high-fat traditional foods
• Avoid all fruits and vegetables
• Reduce intake of contaminated fatty animal products
• Increase dermal exposure to sunlight

Correct Answer: Reduce intake of contaminated fatty animal products

Q27. Which spectrometric feature helps identify chlorinated aromatic rings like DDT in mass spectrometry?

• Characteristic isotope pattern due to multiple chlorine atoms
• High nitrogen adduct peak
• Absence of molecular ion peak
• Strong OH stretching band in IR

Correct Answer: Characteristic isotope pattern due to multiple chlorine atoms

Q28. In the context of DDT pharmacology, enzyme induction in the liver may lead to:

• Decreased metabolism of other drugs leading to toxicity
• Increased metabolic clearance of co-administered drugs
• No interaction with drug-metabolizing enzymes
• Immediate renal elimination of DDT

Correct Answer: Increased metabolic clearance of co-administered drugs

Q29. Which therapeutic measure is most appropriate for seizure control in acute severe DDT poisoning?

• Opioid analgesics as first-line
• Benzodiazepines to control seizures
• High-dose aspirin therapy
• Immediate dialysis only

Correct Answer: Benzodiazepines to control seizures

Q30. Which characteristic differentiates o,p’-DDT from p,p’-DDT?

• o,p’-DDT has chlorine atoms at para positions only
• o,p’-DDT is usually less insecticidally active and more toxic to mammals
• They are identical in biological activity and environmental fate
• o,p’-DDT is not chlorinated

Correct Answer: o,p’-DDT is usually less insecticidally active and more toxic to mammals

Q31. Which diagnostic sample is most informative for recent DDT exposure in humans?

• Hair analysis only
• Breast milk and adipose tissue for bioaccumulation
• Urine for unmetabolized DDT exclusively
• Saliva for high sensitivity detection

Correct Answer: Breast milk and adipose tissue for bioaccumulation

Q32. The presence of DDE in wildlife most likely indicates:

• Recent application of fresh DDT only
• Historical use or long-term degradation of DDT
• Use of an unrelated pesticide
• Complete mineralization of DDT to CO2

Correct Answer: Historical use or long-term degradation of DDT

Q33. Which statement about DDT and endocrine disruption is accurate?

• DDT has no known endocrine effects
• Some DDT metabolites can interact with hormone receptors and disrupt endocrine function
• DDT acts solely as a thyroid hormone agonist with no other effects
• DDT enhances insulin secretion directly causing hypoglycemia

Correct Answer: Some DDT metabolites can interact with hormone receptors and disrupt endocrine function

Q34. Which property of DDT formulations improved residual efficacy when used for indoor spraying?

• High volatility to maintain airborne concentrations
• Formulation adherence to wall surfaces and low degradation rates
• Rapid photodegradation to non-toxic products
• Complete solubility in water for easy wash-off

Correct Answer: Formulation adherence to wall surfaces and low degradation rates

Q35. Which metabolic pathway in mammals converts DDT to DDE?

• Reductive dechlorination via anaerobic bacteria only
• Dehydrochlorination leading to formation of DDE
• Complete oxidation to carbon dioxide
• Hydrolytic cleavage to produce DDA

Correct Answer: Dehydrochlorination leading to formation of DDE

Q36. In environmental monitoring, which matrix is often prioritized to assess long-term DDT contamination?

• Tap water sampled weekly
• Topsoil and sediment cores reflecting historical deposition
• Freshly washed vegetables only
• Indoor air samples exclusively

Correct Answer: Topsoil and sediment cores reflecting historical deposition

Q37. Which physical state and appearance best describes technical DDT at room temperature?

• Colorless gas
• White crystalline solid
• Viscous aqueous solution
• Bright red liquid

Correct Answer: White crystalline solid

Q38. Resistance to DDT may confer cross-resistance to which class of insecticides due to shared target-site changes?

• Organophosphates
• Neonicotinoids
• Pyrethroids
• Biopesticides like Bt only

Correct Answer: Pyrethroids

Q39. Which factor is least likely to accelerate degradation of DDT in the environment?

• Anaerobic microbial activity in sediments
• Photodegradation under sunlight
• High organic carbon content in soil
• Frequent ploughing and aeration increasing microbial action

Correct Answer: High organic carbon content in soil

Q40. WHO guidance on DDT allows limited public health use primarily because:

• It is the only effective insecticide for all pests
• Its long residual action can reduce malaria transmission where alternatives are less effective
• It has no environmental or human health concerns
• It is inexpensive to produce for agriculture

Correct Answer: Its long residual action can reduce malaria transmission where alternatives are less effective

Q41. Which cultural practice can reduce environmental release of DDT from agricultural stocks?

• Open burning of old DDT containers near fields
• Safe disposal and destruction following regulatory guidelines
• Dilution and discharge into nearby streams
• Dumping in residential areas

Correct Answer: Safe disposal and destruction following regulatory guidelines

Q42. Which is a common analytical challenge when measuring DDT in biological samples?

• Interference from abundant polar metabolites only
• Low volatility preventing GC analysis
• Matrix effects due to lipid-rich samples requiring cleanup and extraction
• Immediate decomposition upon sampling at room temperature

Correct Answer: Matrix effects due to lipid-rich samples requiring cleanup and extraction

Q43. Which of the following best describes the global trend in DDT agricultural use since the 1970s?

• Wide increase in agricultural use worldwide
• Near elimination for agriculture with restricted public health exemptions
• Complete worldwide ban with no exceptions
• Unregulated rise in manufacturing only

Correct Answer: Near elimination for agriculture with restricted public health exemptions

Q44. In terms of molecular polarity, DDT is:

• Highly polar due to multiple chlorine atoms
• Nonpolar and hydrophobic due to aromatic rings and chlorine substitution
• Ionic in neutral solution
• Amphoteric with pKa around 7

Correct Answer: Nonpolar and hydrophobic due to aromatic rings and chlorine substitution

Q45. Which guideline is essential for B.Pharm students when discussing DDT in clinical toxicology?

• Recommend DDT use for all household pest control
• Emphasize evidence-based risks, exposure routes, clinical signs, and supportive management
• Ignore environmental legislation and focus only on chemistry
• Advocate ingestion of DDT to develop immunity

Correct Answer: Emphasize evidence-based risks, exposure routes, clinical signs, and supportive management

Q46. Which metabolic enzyme family is often implicated in enhanced detoxification of DDT in resistant insects?

• Digestive proteases only
• Glutathione S-transferases and cytochrome P450 monooxygenases
• DNA polymerases
• ATP synthase complexes

Correct Answer: Glutathione S-transferases and cytochrome P450 monooxygenases

Q47. A pharmacology student should associate DDT exposure with which chronic human health concern?

• Acute hypovolemia only
• Potential endocrine disruption and possible carcinogenicity concerns from long-term exposure
• Immediate and irreversible blindness in all exposed individuals
• Guaranteed immunity to mosquito-borne diseases

Correct Answer: Potential endocrine disruption and possible carcinogenicity concerns from long-term exposure

Q48. For environmental remediation of DDT-contaminated soils, which approach is promising scientifically?

• Phytoremediation combined with microbial degradation strategies
• Adding more DDT to neutralize the contamination
• Permanent burial without containment
• Release into groundwater to dilute concentrations

Correct Answer: Phytoremediation combined with microbial degradation strategies

Q49. Which criterion is least important when selecting an insecticide alternative to DDT for indoor residual spraying?

• Residual efficacy and duration on wall surfaces
• Human safety profile and environmental impact
• Cost and local acceptability
• Color of the packaging only

Correct Answer: Color of the packaging only

Q50. Which educational emphasis is most relevant for B.Pharm students learning about DDT?

• Only memorizing chemical names without clinical context
• Integrating chemical structure, mechanism of action, toxicokinetics, environmental fate, and public health implications
• Promoting unchecked use in agriculture
• Ignoring analytical and regulatory aspects

Correct Answer: Integrating chemical structure, mechanism of action, toxicokinetics, environmental fate, and public health implications

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