Q.1 Which organ is primarily responsible for the metabolism of most toxins in the body?
Kidney
Liver
Lungs
Spleen
Explanation - The liver contains enzymes, especially cytochrome P450, which metabolize most xenobiotics and toxins.
Correct answer is: Liver
Q.2 Which type of poisoning is characterized by a 'garlic breath' odor?
Arsenic poisoning
Mercury poisoning
Lead poisoning
Cyanide poisoning
Explanation - Acute arsenic poisoning can produce a garlic-like odor on the breath due to its metabolism.
Correct answer is: Arsenic poisoning
Q.3 Which heavy metal inhibits enzymes containing sulfhydryl groups and can cause neurological symptoms?
Lead
Mercury
Arsenic
Cadmium
Explanation - Mercury binds to sulfhydryl (-SH) groups in enzymes, disrupting their function, leading to neurological and renal symptoms.
Correct answer is: Mercury
Q.4 Which of the following is a common antidote for acetaminophen (paracetamol) overdose?
N-acetylcysteine
Atropine
Pralidoxime
Vitamin K
Explanation - N-acetylcysteine replenishes glutathione, which detoxifies the toxic metabolite of acetaminophen.
Correct answer is: N-acetylcysteine
Q.5 Which route of exposure generally leads to the fastest absorption of toxins?
Oral
Inhalation
Dermal
Intramuscular
Explanation - Inhaled substances reach the bloodstream quickly via alveolar-capillary transfer, leading to rapid systemic effects.
Correct answer is: Inhalation
Q.6 Which of the following is a classical symptom of organophosphate poisoning?
Bradycardia, miosis, salivation
Hypertension, mydriasis, dry skin
Tachycardia, hyperthermia, sweating
Hypotension, jaundice, confusion
Explanation - Organophosphates inhibit acetylcholinesterase, causing accumulation of acetylcholine and cholinergic symptoms.
Correct answer is: Bradycardia, miosis, salivation
Q.7 Which metal is commonly associated with microcytic anemia upon chronic exposure?
Lead
Mercury
Arsenic
Cadmium
Explanation - Lead interferes with heme synthesis, resulting in microcytic, hypochromic anemia.
Correct answer is: Lead
Q.8 Which type of toxin is produced by bacteria and can cause botulism?
Endotoxin
Exotoxin
Mycotoxin
Neurotoxin
Explanation - Clostridium botulinum produces botulinum toxin, a potent exotoxin causing flaccid paralysis.
Correct answer is: Exotoxin
Q.9 Which of the following is the main target organ of cadmium toxicity?
Liver
Kidney
Brain
Heart
Explanation - Chronic cadmium exposure accumulates in the renal cortex, causing tubular dysfunction and proteinuria.
Correct answer is: Kidney
Q.10 Which of these is a chelating agent used to treat lead poisoning?
Deferoxamine
Dimercaprol (BAL)
EDTA
Atropine
Explanation - EDTA binds to lead in the blood, forming a stable complex that is excreted in urine.
Correct answer is: EDTA
Q.11 Chronic alcohol consumption primarily affects which enzyme system in the liver?
Cytochrome P450
Monoamine oxidase
Acetylcholinesterase
Glutathione peroxidase
Explanation - Chronic ethanol induces CYP2E1, leading to altered drug metabolism and generation of reactive oxygen species.
Correct answer is: Cytochrome P450
Q.12 Which of the following is a typical feature of carbon monoxide poisoning?
Cherry-red skin color
Blue lips
Jaundice
Pale skin
Explanation - CO binds to hemoglobin forming carboxyhemoglobin, giving a characteristic cherry-red appearance.
Correct answer is: Cherry-red skin color
Q.13 Which of the following toxins is associated with liver failure and mushroom ingestion?
Amanitin
Tetrodotoxin
Saxitoxin
Botulinum toxin
Explanation - Amanitin, found in Amanita phalloides, inhibits RNA polymerase II, causing hepatocyte necrosis.
Correct answer is: Amanitin
Q.14 Which class of compounds is commonly responsible for allergic contact dermatitis?
Metals
Haptens
Neurotoxins
Endotoxins
Explanation - Small molecules (haptens) bind to skin proteins, triggering a T-cell mediated allergic reaction.
Correct answer is: Haptens
Q.15 Which of the following is a biomarker for arsenic exposure?
Urinary arsenic
Blood lead
Serum mercury
Urinary cadmium
Explanation - Urinary arsenic reflects recent exposure and is the standard biomarker for arsenic poisoning.
Correct answer is: Urinary arsenic
Q.16 Which of the following is the primary toxic effect of aflatoxins?
Neurotoxicity
Hepatotoxicity
Nephrotoxicity
Cardiotoxicity
Explanation - Aflatoxins, produced by Aspergillus species, cause liver damage and are potent hepatocarcinogens.
Correct answer is: Hepatotoxicity
Q.17 Which of these is the treatment of choice for methanol poisoning?
Fomepizole
N-acetylcysteine
Atropine
Dimercaprol
Explanation - Fomepizole inhibits alcohol dehydrogenase, preventing the formation of toxic formaldehyde and formic acid.
Correct answer is: Fomepizole
Q.18 Which type of chemical is primarily responsible for 'industrial asthma'?
Isocyanates
Organophosphates
Aflatoxins
Aminoglycosides
Explanation - Isocyanates are industrial chemicals that can induce asthma via sensitization of the airways.
Correct answer is: Isocyanates
Q.19 Which of the following describes a dose-response relationship?
The effect increases with dose
The effect decreases with dose
The effect is independent of dose
The effect fluctuates randomly
Explanation - A dose-response relationship shows that increasing the dose of a toxin generally increases its biological effect.
Correct answer is: The effect increases with dose
Q.20 Which of the following is an example of bioaccumulation?
Mercury concentration increasing up the food chain
Detoxification of alcohol by the liver
Absorption of water in the intestine
Rapid excretion of caffeine
Explanation - Bioaccumulation occurs when toxins accumulate in organisms faster than they are eliminated, often magnifying through food chains.
Correct answer is: Mercury concentration increasing up the food chain
Q.21 Which of the following substances is an example of a neurotoxin?
Tetrodotoxin
Aflatoxin
Carbon tetrachloride
Arsenic
Explanation - Tetrodotoxin blocks sodium channels in neurons, leading to paralysis.
Correct answer is: Tetrodotoxin
Q.22 Which of the following metals is most associated with Itai-Itai disease?
Cadmium
Lead
Mercury
Arsenic
Explanation - Cadmium exposure caused Itai-Itai disease in Japan, characterized by severe bone and kidney damage.
Correct answer is: Cadmium
Q.23 Which of the following is a common symptom of cyanide poisoning?
Cherry-red skin
Severe headache, confusion, and seizures
Blue lips and fingertips
Yellowing of skin
Explanation - Cyanide inhibits cytochrome oxidase, preventing cellular respiration and causing neurological symptoms.
Correct answer is: Severe headache, confusion, and seizures
Q.24 Which enzyme is inhibited by organophosphates?
Acetylcholinesterase
Monoamine oxidase
Glutathione peroxidase
Alcohol dehydrogenase
Explanation - Organophosphates bind irreversibly to acetylcholinesterase, causing accumulation of acetylcholine at synapses.
Correct answer is: Acetylcholinesterase
Q.25 Which of the following toxins is responsible for causing hemolysis after ingestion of fava beans in susceptible individuals?
Vicine and divicine
Aflatoxin
Botulinum toxin
Tetrodotoxin
Explanation - These compounds cause oxidative stress in red blood cells, especially in individuals with G6PD deficiency, leading to hemolysis.
Correct answer is: Vicine and divicine