Toxicology — MCQs Biology – T4Tutorials .PK

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1. Toxicology is the study of:
(A) Plant growth
(B) Human anatomy only
(C) Harmful effects of chemicals, toxins, and poisons on living organisms
(D) Microbial nutrition

2. A toxin is:
(A) A poisonous substance produced by living organisms
(B) A harmless compound
(C) A vitamin
(D) An essential mineral

3. A toxicant is:
(A) A harmless organic molecule
(B) A toxic substance of chemical origin
(C) A nutrient
(D) A hormone

4. Dose-response relationship in toxicology shows:
(A) Toxicity is independent of dose
(B) The effect of a substance depends on its dose
(C) Only lethal effects
(D) Only beneficial effects

5. LD50 refers to:
(A) Dose that causes no effect
(B) Dose for 50% survival
(C) Dose for beneficial effects
(D) Lethal dose that kills 50% of test population

6. LC50 refers to:
(A) Lethal concentration of a substance killing 50% of organisms
(B) Dose causing no effect
(C) Safe concentration
(D) Dose for 100% survival

7. Acute toxicity refers to:
(A) Long-term exposure only
(B) Harmful effects from a single or short-term exposure
(C) Genetic mutations only
(D) Chronic diseases only

8. Chronic toxicity refers to:
(A) Harmful effects from repeated or long-term exposure
(B) Single exposure only
(C) Immediate death only
(D) Infection only

9. Xenobiotics are:
(A) Nutrients only
(B) Endogenous hormones
(C) Foreign substances in the body
(D) Enzymes only

10. The main organs involved in detoxification are:
(A) Skin and bones
(B) Heart and lungs
(C) Brain and muscles
(D) Liver and kidneys

11. Biotransformation in toxicology refers to:
(A) Cell division
(B) Chemical modification of toxins in the body
(C) Protein synthesis
(D) DNA replication only

12. Phase I biotransformation reactions include:
(A) Oxidation, reduction, hydrolysis
(B) Conjugation with glucuronic acid
(C) Conjugation with sulfate
(D) Protein synthesis

13. Phase II biotransformation reactions include:
(A) Hydrolysis only
(B) Conjugation with glucuronic acid, sulfate, or glutathione
(C) Oxidation only
(D) Reduction only

14. Bioaccumulation refers to:
(A) Detoxification
(B) Immediate excretion of toxins
(C) Accumulation of chemicals in organisms over time
(D) Protein synthesis

15. Biomagnification refers to:
(A) Excretion
(B) Decrease of toxin concentration
(C) Detoxification only
(D) Increase of toxin concentration up the food chain

16. Neurotoxins affect:
(A) Liver only
(B) Nervous system
(C) Kidneys only
(D) Blood only

17. Hepatotoxins affect:
(A) Brain only
(B) Liver
(C) Heart only
(D) Lungs only

18. Nephrotoxins affect:
(A) Brain only
(B) Lungs only
(C) Kidneys
(D) Heart only

19. Hemotoxins affect:
(A) Liver only
(B) Skin only
(C) Blood and blood vessels
(D) Kidneys only

20. Cytotoxins affect:
(A) Tissues only
(B) Whole organs only
(C) Cells
(D) Nerves only

21. Carcinogens are substances that:
(A) Aid metabolism
(B) Reduce toxicity
(C) Cause cancer
(D) Repair DNA only

22. Mutagens are substances that:
(A) Cause immediate death only
(B) Enhance metabolism
(C) Aid digestion
(D) Cause genetic mutations

23. Teratogens are substances that:
(A) Aid bone formation
(B) Enhance growth only
(C) Cause hair growth
(D) Cause developmental defects in embryos

24. Carcinogenesis involves:
(A) Only initiation
(B) Initiation, promotion, progression of cancer
(C) Only promotion
(D) Only progression

25. Mechanism of toxicity can include:
(A) Only bone damage
(B) Only blood pressure changes
(C) Only muscle injury
(D) Enzyme inhibition, oxidative stress, receptor binding

26. Poisoning by organophosphates primarily inhibits:
(A) DNA polymerase
(B) Acetylcholinesterase
(C) Protein kinase
(D) Cytochrome P450

27. Carbon monoxide poisoning results from:
(A) Kidney damage
(B) Binding of CO to hemoglobin, reducing oxygen transport
(C) Liver failure
(D) Nerve injury only

28. Heavy metals like lead and mercury act as:
(A) Hepatotoxins
(B) Neurotoxins
(C) Nephrotoxins only
(D) Carcinogens only

29. Toxicology studies include:
(A) Only treatment
(B) Only detection
(C) Detection, analysis, treatment, and prevention of toxic effects
(D) Only prevention

30. Poisoning can occur via:
(A) Dermal only
(B) Oral only
(C) Inhalation only
(D) Oral, inhalation, dermal, or injection routes

31. LD50 value helps to:
(A) Determine nutritional value
(B) Compare toxicity of substances
(C) Determine color
(D) Measure enzyme activity

32. Toxic effects of chemicals can be:
(A) Local or systemic
(B) Only systemic
(C) Only local
(D) Only chronic

33. Synergistic effect occurs when:
(A) No effect
(B) Effect is less than sum
(C) Only individual effects matter
(D) Combined effect of two chemicals is greater than sum of individual effects

34. Antagonistic effect occurs when:
(A) Chemicals enhance each other
(B) One chemical reduces the effect of another
(C) Only one chemical acts
(D) No interaction

35. Detoxification of poisons can involve:
(A) Enzymatic metabolism and excretion
(B) Photosynthesis only
(C) Respiration only
(D) Protein synthesis only

36. Cyanide poisoning inhibits:
(A) Protein synthesis only
(B) Acetylcholinesterase only
(C) DNA replication only
(D) Cytochrome oxidase, halting cellular respiration

37. Methanol poisoning primarily affects:
(A) Kidneys only
(B) Liver only
(C) Eyes and CNS, causing blindness and coma
(D) Skin only

38. Alcohol toxicity mainly affects:
(A) Kidneys only
(B) Brain only
(C) Heart only
(D) Liver

39. Dose threshold in toxicology refers to:
(A) Only lethal dose
(B) Maximum safe dose only
(C) Minimum dose required to produce a detectable effect
(D) No-effect dose

40. Acute poisoning symptoms can include:
(A) Only rash
(B) Only fever
(C) Nausea, vomiting, convulsions, coma
(D) Only headache

41. Chronic poisoning symptoms may include:
(A) Only vomiting
(B) Only nausea
(C) Liver or kidney damage, neurological deficits, cancer
(D) Only headache

42. Poisoning diagnosis involves:
(A) Only physical exam
(B) Only laboratory analysis
(C) Clinical history, symptoms, and laboratory analysis
(D) Only imaging

43. Treatment of poisoning may include:
(A) Radiation therapy only
(B) Surgery only
(C) Antidotes, supportive care, decontamination
(D) Antibiotics only

44. Activated charcoal is used in poisoning to:
(A) Bind enzymes only
(B) Neutralize blood toxins only
(C) Bind DNA only
(D) Adsorb toxins in the gastrointestinal tract

45. Chelation therapy is used to treat:
(A) Alcohol poisoning only
(B) Heavy metal poisoning
(C) Cyanide poisoning only
(D) Pesticide poisoning only

46. Paracetamol overdose can cause:
(A) Kidney toxicity only
(B) Liver toxicity
(C) Heart failure only
(D) CNS toxicity only

47. Pesticide poisoning affects:
(A) Only skin
(B) Nervous system and can cause respiratory failure
(C) Only bones
(D) Only muscles

48. Toxicology testing can include:
(A) Tissues only
(B) Blood only
(C) Hair only
(D) Blood, urine, hair, tissues, and environmental samples

49. Toxicokinetics studies:
(A) Only absorption
(B) Only metabolism
(C) Only excretion
(D) Absorption, distribution, metabolism, and excretion of toxins

50. Toxicodynamics studies:
(A) Only excretion
(B) Only metabolism
(C) Biological effects of toxins and mechanism of action
(D) Only absorption