Category: Drug & Pharmaceutical Biotechnology Objective Questions

Drug Biotechnology Puzzles on “Drugs Biotransformation – Affecting Factors”.

1. What is enzyme induction?
a) The phenomenon of increased drug metabolizing ability of enzymes by drugs and chemicals
b) The phenomenon of increasing drug bioavailability drugs and chemicals
c) The phenomenon of increasing drug distribution drugs and chemicals
d) The phenomenon of increasing drug concentration for a particular tissue by drugs and chemicals
Answer: a
Clarification: The phenomenon of increased drug metabolizing ability of enzymes by drugs and chemicals is called as enzyme induction and the agents which helps to bring such changes are known as inducers.

2. Which of the following drugs has self -induction to stimulate their own metabolism?
a) Cortisol
b) Pentobarbital
c) Meprobamate
d) Contraceptives
Answer: c
Clarification: Drugs such as carbamazepine, Meprobamate, cyclophosphamide, rifampicin, etc. stimulate their own metabolism. This phenomenon is known as auto-induction or self -induction.

3. Alcohol is the inducer for which drug?
a) Cortisol
b) Pentobarbital
c) Meprobamate
d) Oral contraceptives
Answer: b
Clarification: Alcohol act as an inducer for pentobarbital, coumarins, and phenytoin. Meprobamate is self-inducing. Oral contraceptives are induced by barbiturates.

4. What is the name of the process where structurally same compounds compete for the same site on an enzyme to inhibit that?
a) Altered physiology
b) Repression
c) Non-competitive inhibition
d) Competitive inhibition
Answer: d
Clarification: Competitive inhibition results when structurally similar compounds compete for the same site on an enzyme. Such an inhibition due to substrate competition is reversible and can be overcome by a high concentration of one substrate. Methacholine inhibits the metabolism of acetylcholine by competing with it for cholinesterase.

5. What is the name of the process where structurally different compounds interact with the enzyme and prevent the metabolism of the drug?
a) Altered physiology
b) Repression
c) Non-competitive inhibition
d) Competitive inhibition
Answer: c
Clarification: Non-competitive inhibition happens when structurally different compounds interact with the enzyme and prevent the metabolism of the drug. This interaction is not structured specifically. So lead, mercury, arsenic, organophosphorus insecticides inhibit enzymes noncompetitively.

6. What is the name of the process where the enzyme amount is decreased due to a decrease in enzyme synthesis?
a) Altered physiology
b) Repression
c) Non-competitive inhibition
d) Competitive inhibition
Answer: b
Clarification: Repression is the process where the enzyme amount is decreased due to a decrease in enzyme synthesis. The synthesis of the enzyme can be affected by puromycin and actinomycin D. It can also happen by raising the rate of enzyme degradation such as carbon tetrachloride, carbon disulphide, disulfiram, etc.

7. What is the name of the process where due to nutritional deficiency an enzyme content is decreased?
a) Altered physiology
b) Repression
c) Non-competitive inhibition
d) Competitive inhibition
Answer: a
Clarification: Altered physiology is the process where due to nutritional deficiency an enzyme content is decreased. Thus decreasing the enzyme content, and decreasing the drug metabolizing time.

8. Which one of the following is not an environmental agent to decrease drug metabolizing ability?
a) DDT
b) Cigarette smoke
c) Organophosphate insecticides
d) Methacholine
Answer: d
Clarification: Methacholine inhibits the metabolism of acetylcholine by competing with it for cholinesterase. It is not an environmental factor. Halogenated pesticides e.g. DDT, polycyclic aromatic hydrocarbon e.g. cigarette smoke, organophosphate insecticides, heavy metals inhibit drug metabolizing of enzymes.

9. What is polygenic control of drugs?
a) Drug controlling seen in an individual
b) Drug controlling seen in twins
c) Drug controlling seen in between different species
d) Drug controlling seen in a particular population
Answer: b
Clarification: Polygenic control has been observed in twins. In identical twins that are monozygotic twins, there is very little or no difference in drug metabolism. It was detected that there was no difference in the metabolism of phenylbutazone, dicoumarol, and antipyrine. Although large variations were detected in dizygotic twins.

10. Differences observed in metabolism of drug among different races is known as ______________
a) Pharmacogenetics
b) Ethnic variations
c) Discontinues variation
d) Polygenic control
Answer: b
Clarification: Differences observed in the metabolism of the drug among different races is known as ethnic variation. Polygenic control is the control of drug metabolizing in the twins. Pharmacogenetics is the study of inter-subject variability in drug response.

11. Which age group is known as the neonates?
a) Up to 2 months
b) Up to 2 years
c) Up to 6 months
d) Up to 1 year
Answer: a
Clarification: Babies below the age of 2 months are called as neonates. Their microsomal enzymes are not fully developed. Thus takes much longer time to metabolize drugs.

12. Which age group metabolizes drugs faster than the adults?
a) Between 1-12 year
b) Between 1-15 year
c) Between 6-12 year
d) Between 12-18 year
Answer: a
Clarification: Children and older infant of the age group 1-12 year metabolize several drugs much more rapidly than adults. The rate of metabolism reaches a maximum somewhere between 6 months to 12 years of age. As a result, they require large mg/kg doses in comparison to adults.

13. Fat-free diet depresses cytochrome P-450 level.
a) True
b) False
Answer: a
Clarification: A fat-free diet decreases the phospholipid content. Phospholipids are important components of microsomes. When these become deficient, the cytochrome p-450 levels decrease.

14. Maternal drug metabolizing ability increases in the later stage of pregnancy.
a) True
b) False
Answer: b
Clarification: Maternal drug metabolizing ability decreases in the later stage of pregnancy. Due to high levels of steroid hormones in circulation during pregnancy, in women, the metabolism of promazine and pethidine decreases. Thus, maternal drug metabolizing ability decreases.

15. Enzyme activity is maximum during the early morning.
a) True
b) False
Answer: a
Clarification: By research, it has been observed that the enzyme activity is maximum during the early morning and minimum during the late afternoon. This also corresponds to high and low serum levels of corticosterone.

To practice all Puzzles on Drug Biotechnology,

Advanced Drug Biotechnology Questions and Answers on “Mechanism of Action of General Anesthetics”.

1. Which of the following will work as an anesthetic?
a) Pantoprazole
b) Amlodipine
c) Cocaine
d) Mannitol
Answer: c
Clarification: Pantoprazole is a proton pump inhibitor used to reduce peptic ulcer. Amlodipine is a 2nd line drug for hypertension. Cocaine be the potent anesthetics. But not in general purpose use because of it high demand for drug addiction. Mannitol is an osmotic diuretic. It is used in severe head injury to reduce blood loss.

2. In which of the stage of general anesthesia the movement of the diaphragm is the highest?
a) Plane 1 of stage III
b) Plane 2 of stage III
c) Plane 3 of stage III
d) Plane 4 of stage III
Answer: a
Clarification: The patient’s breath is normal in the 1st stage, then in the 2nd stage patient will have a problem in breathing thus will have scattered breathing, in the plane 1 of stage III The patient will breathe heavily, with slow and normal breathing in plane 2. Increase in the concentration of general anesthesia will cause the death of the patient thus in stage IV the patient breathing stops.

3. In which stage of general anesthesia the patient starts vomiting?
a) Stage I ending
b) Stage II ending
c) Stage III ending
d) Stage IV ending
Answer: b
Clarification: The patient starts vomiting by the end of stage II, thus the patient has to be given with anti-vomiting medicines.

4. What is the function of general anesthetics?
a) Render a specific portion of the body insensitive to pain
b) Render a full body of the patient insensitive to pain
c) Render a specific organ of the body insensitive to pain
d) Render a specific CNS of the body insensitive to pain
Answer: b
Clarification: General anesthesia is a drug that brings about a reversible loss of consciousness. These drugs are generally administered by an anaesthesiologist in order to induce or maintain general anesthesia to facilitate surgery. It helps to prevent the psychological and somatic adverse effect of surgical trauma and create a better condition for surgery.

5. Which of the following is not an inhaled anesthetics?
a) Haloethane
b) Enflurane
c) Isoflurane
d) Diflurane
Answer: d
Clarification: Examples of inhaled anesthetics are haloethane, enflurane, isoflurane, desflurane. They are a halogenated compound containing fluorine or bromide simple, small molecules. Inhalational anesthetics refers to the delivery of gases or vapours from the respiratory system to produce anesthesia. A special set of physical principles govern absorption, distribution, and elimination.

6. Which of the following order of inducing cardiac arrhythmias of inhaled anesthetics is correct?
a) F < Br < I < Cl
b) F < Cl < Br < I
c) F > Cl > Br > I
d) Br < I < F < Cl
Answer: b
Clarification: Although halogenations of hydrocarbons and ethers increase anesthetic potency, it also increases the potential for inducing cardiac arrhythmias in the following order F < Cl < Br < I. Halogenated methyl ethyl ethers (Enflurane and Isoflurane) are more stable, are more potent, and have better clinical profile than halogenated diethyl ethers.

7. Which of the following is incorrect if we are talking about the essential components of general anesthesia?
a) Analgesia
b) Hypnosis
c) Depression of spinal motor reflexes
d) Muscle contraction
Answer: d
Clarification: The most essential components of anesthesia are analgesia that is the perception of pain, hypnosis that is unconsciousness, Depression of spinal motor reflexes and muscle relaxation. These components altogether emphasize the role of immobility.

8. What does the lipid theory tell?
a) Lower the solubility of the anesthetic in water higher potency it has
b) Higher the solubility of the anesthetic in water higher potency it has
c) Higher the solubility of the anesthetic in oil higher potency it has
d) Lower the solubility of the anesthetic in oil higher potency it has
Answer: c
Clarification: The lipid theory states that higher the solubility of anesthetics is in oil greater is the potency of that anesthetics. It is based on the fact that anesthetic action is correlated with the oil/gas coefficients. The Protein (Receptor) theory states that based on the fact that anesthetic potency is correlated with the ability of anesthetics to inhibit enzymes activity of a pure, soluble protein. Also, attempts to explain the GABAA receptor is a potential target of anesthetics action.

9. What does the protein (receptor) theory tells us?
a) Anesthetic potency is related to the ability of anesthetic to inhibit enzyme activity
b) Higher the solubility of the anesthetic in water higher potency it has
c) Higher the solubility of the anesthetic in oil higher potency it has
d) Lower the solubility of the anesthetic in oil higher potency it has
Answer: a
Clarification: The Protein (Receptor) theory states that based on the fact that anesthetic potency is correlated with the ability of anesthetics to inhibit enzymes activity of a pure, soluble protein. Also, attempts to explain the GABAA receptor is a potential target of anesthetics action. The lipid theory states that higher the solubility of anesthetics is in oil greater is the potency of that anesthetics. It is based on the fact that anesthetic action is correlated with the oil/gas coefficients.

10. Administration of general anesthetics decreases the presynaptic Ca²⁺ entry.
a) True
b) False
Answer: a
Clarification: Administration of general anesthetics decreases the presynaptic Ca²⁺ entry, thus decreases the neurotransmitter release. It increases postsynaptic Cl^– entry and also increases postsynaptic K⁺ leakage from the cell. Local anesthetics help block conduction. It decreases the axonal Na+ entry thus prevents action potential propagation.

11. Local anesthetics increase the axonal Na+ entry.
a) True
b) False
Answer: b
Clarification: Local anesthetics help block conduction. It decreases the axonal Na+ entry thus prevents action potential propagation. Administration of general anesthetics decreases the presynaptic Ca²⁺ entry, thus decreases the neurotransmitter release. It increases postsynaptic Cl^– entry and also increases postsynaptic K+ leakage from the cell.

12. The lower the blood: gas ratio, the more anesthetics will arrive at the brain.
a) True
b) False
Answer: a
Clarification: Amount of anesthetics that reaches the brain can be indicated by oil: gas ratio (lipid solubility) and Partial Pressure of anesthetics. The lower the blood: gas ratio, the more anesthetics will arrive at the brain since more gas can dissolve in the blood.

13. Which option will be correct for the market place in the diagram shown below?

a) Alveoli
b) Arterial blood
c) Venous blood
d) Brain
Answer: d
Clarification: Partial Pressure in brain quickly equilibrates with partial pressure in arterial blood which has equilibrated with partial pressure perfused alveoli. Furthermore, the depth of anesthesia induced by an inhaled anesthetic depends on the partial pressure of the anesthetics in the brain, and the rate of induction and recovery from anesthesia depends on the rate of change of partial pressure in the brain. These drugs are small lipid-soluble molecules that can cross the alveolar membrane easily. Move into and out of the blood based on the partial pressure gradient.

14. Which option will be correct for the marked place in the diagram shown below?

a) Alveoli
b) Arterial blood
c) Venous blood
d) Brain
Answer: b
Clarification: Arterial blood is the fresh blood which has more amount of oxygen in it. After passing the alveolar wall the anesthetic can easily mix with the alveolar blood and then get pump back to the whole body. Furthermore, the depth of anesthesia induced by an inhaled anesthetic depends on the partial pressure of the anesthetics in the brain, and the rate of induction and recovery from anesthesia depends on the rate of change of partial pressure in the brain. These drugs are small lipid-soluble molecules that can cross the alveolar membrane easily. Move into and out of the blood based on the partial pressure gradient.

15. Which option will be correct for the marked place in the diagram shown below?

a) Alveoli
b) Arterial blood
c) Venous blood
d) Brain
Answer: a
Clarification: General anesthetics when allowed to inhaled 1st enter the lungs. Then they can readily pass through the alveolar walls and mix with the arterial blood. Furthermore, the depth of anesthesia induced by an inhaled anesthetic depends on the partial pressure of the anesthetics in the brain, and the rate of induction and recovery from anesthesia depends on the rate of change of partial pressure in the brain. These drugs are small lipid-soluble molecules that can cross the alveolar membrane easily. Move into and out of the blood based on the partial pressure gradient.

To practice advanced questions and answers on all areas of Drug Biotechnology,

Drug Biotechnology Multiple Choice Questions on “Controlled Release Medication – Prescription Writing – 1”.

1. What does the symbol Rx mean?
a) To take
b) Should date
c) How to take
d) What to take
Answer: a
Clarification: The Rx symbol means to take. It is written above of all the prescription meaning to take these medicines. It is a Greek symbol meaning to take.

2. The prescription should be clear enough to read.
a) True
b) False
Answer: a
Clarification: It is essential that the prescription is legible i.e. clear enough to read by the patients and by the shopkeepers. It is not allowed to scribble something in the prescription. It should be written in a perfect manner with all the information about the illness and the medicine.

3. Computer generated prescription is not acceptable.
a) True
b) False
Answer: b
Clarification: It is essential that the prescription is legible i.e. clear enough to read by the patients and by the shopkeepers. Most prescriptions in General Practice are now computer generated. Recently this has been introduced for some prescriptions written in hospital i.e. those written together with an electronic discharge summary.

4. Which one should be written on the top of a prescription?
a) Patient name
b) Patient address
c) Patient father’s name
d) Patient illness
Answer: a
Clarification: The name of the patient must be the 1^st thing written on a prescription followed by an address and the MCI registration number of a doctor. All three things must be clearly written on the prescription form. There is no need for a patient’s parent’s name. The illness should be described well.

5. What does the A on a prescription mean?
a) Adult
b) Under 16 years
c) Under 6 years of age
d) Script for oral contraceptive
Answer: a
Clarification: The A on the top of a prescription means adult. O means script for an oral contraceptive. J means the patient is under 16 years of age. Y means the prescription belongs to the patient under 6 years of age. All these must be carefully represented on a prescription. If not the age must be written on the prescription.

6. What does the O on a prescription mean?
a) Adult
b) Under 16 years
c) Under 6 years of age
d) Script for oral contraceptive
Answer: d
Clarification: O means script for an oral contraceptive. The A on the top of a prescription means adult. J means the patient is under 16 years of age. Y means the prescription belongs to the patient under 6 years of age. All these must be carefully represented on a prescription. If not, the age must be written on the prescription.

7. What does the J on a prescription mean?
a) Adult
b) Under 16 years
c) Under 6 years of age
d) Script for oral contraceptive
Answer: b
Clarification: J means the patient is under 16 years of age. The A on the top of a prescription means adult. O means script for an oral contraceptive. Y means the prescription belongs to the patient under 6 years of age. All these must be carefully represented on a prescription. If not the age must be written on the prescription.

8. What does the Y on a prescription mean?
a) Adult
b) Under 16 years
c) Under 6 years of age
d) Script for oral contraceptive
Answer: c
Clarification: Y means the prescription belongs to the patient under 6 years of age. J means the patient is under 16 years of age. The A on the top of a prescription means adult. O means script for an oral contraceptive. All these must be carefully represented on a prescription. If not, the age must be written on the prescription.

9. The 1^st part of a prescription contain the name of medicines.
a) True
b) False
Answer: a
Clarification: A prescription has 3 parts. The 1^st part contains the name of the medicine, formulation which is to be taken, strength of the medicine that is to be taken. The 2^nd part has the instructions that go on the label. And 3^rd part tells the quantity to be dispensed.

10. The 1^st part of the prescription will be having all the below-written information except ____________
a) How to take the medicines
b) Rx
c) Name of medicine
d) Type of administration
Answer: a
Clarification: A prescription has 3 parts. The 1^st part contains the name of the medicine, formulation which is to be taken, strength of the medicine that is to be taken. For example, if the prescription is for amoxicillin the 1^st part will be Rx Amoxicillin caps 500 mg. The 2^nd part has the instructions that go on the label. And 3^rd part tells the quantity to be dispensed.

11. Which of the following information should be on the 1^st part of the prescription?
a) Name of medicine
b) How to take the medicine
c) Quantity to be dispensed
d) Signature of the doctor.
Answer: a
Clarification: A prescription has 3 parts. The 1^st part contains the name of the medicine, formulation which is to be taken, strength of the medicine that is to be taken. For example, if the prescription is for amoxicillin the 1^st part will be Rx or recipe Amoxicillin caps 500 mg. in the 2^nd part more details of how to take the medicine will be given.

12. Which of the following information should be on the 2^nd part of the prescription?
a) Name of medicine
b) How to take the medicine
c) Quantity to be dispensed
d) Signature of the doctor.
Answer: b
Clarification: The 2^nd part of the prescription is the instructions that go on the label. It begins with the Sig which is the short of Signa which means a mark or write. For example, if any doctor is prescribing amoxicillin it may be written as Sig: i.t.i.p.o that means twice a day orally.

13. Which of the following information should be on the 3^rd part of the prescription?
a) Name of medicine
b) How to take the medicine
c) Quantity to be dispensed
d) Signature of the doctor.
Answer: c
Clarification: The 3^rd part of the prescription specifies the quantity to be dispersed. That is the dosage should be taken for how many days. Traditionally starts with M or Mitte. For example, M: 1 week’s supply. The largest quantity of dispensed is 3 months’ supply and for oral contraceptive which is 6 months’ supply.

14. Which one of the following should be there on a prescription to make it a legal one?
a) Name of medicine
b) How to take the medicine
c) Quantity to be dispensed
d) Signature of the doctor.
Answer: d
Clarification: A prescription is not legal unless it is signed and dated by the doctor himself. This prescription one patient should or grant and shopkeepers should not allow them to buy medicines without a signed prescription.

15. What does the abbreviation o.d? means on a prescription?
a) Name of medicine
b) How to take the medicine
c) Quantity to be dispensed
d) Once daily
Answer: d
Clarification: The abbreviations for o.d. is once a day, t.d.s. means twice a day, b.i.d. means twice a day, q.i.d. means for times a day. These abbreviations are used by a doctor on a prescription such that with short writing a lot of information can be put together.

Drug Biotechnology Multiple Choice Questions on “Drugs Absorption – Limitations of pH Partition Hypothesis”.

1. Which one of these options is not one of the limitations of pH-partition theory?
a) Presence if virtual membrane pH
b) Absorption of ionized drugs
c) Influence of GI surface area
d) Dissolution rate
Answer: d
Clarification: Some of the deviations of the pH-partition hypothesis are the presence of virtual membrane, absorption of the ionized drug, the influence of GI surface area and residence time, Presence of aqueous unstirred diffusion layer.

2. A microclimate pH, different from the luminal pH exists at the membrane surface.
a) True
b) False
Answer: a
Clarification: As shown in experiments, pH absorption curves are less steep and shift to left for basic drug and shift to the right for an acidic drug. This led to the hypothesis that a virtual pH also called a microclimate pH exists at the membrane surface.

3. According to the pH-partition theory which form of the drug gets absorbed mostly?
a) Hydrated form
b) Aggregated form
c) Ionised
d) Unionised
Answer: d
Clarification: According to the pH-partition theory, a unionized form of a drug gets absorbed mostly. Ionized drugs have low lipid solubility and poor permeability.

4. What helps the ionized drug molecules to pass through the cell membrane passively?
a) Different pH
b) Polar group
c) Large lipophilic group
d) Hydration
Answer: c
Clarification: Ionised drugs if attached with a large lipophilic group in their structure. This helps them in getting absorbed passively e.g. morphine derivatives.

5. Acidic drugs are best absorbed through the stomach and basic drugs are best absorbed through the intestine.
a) True
b) False
Answer: a
Clarification: According to the pH-partition theory, Acidic drugs are best absorbed through the stomach where the pH is low and basic drugs are best absorbed through the intestine where the pH is high. In this condition, the molecules will be unionized and this helps them to get absorbed better.

6. What could be the reason that irrespective of pH any drug gets absorbed mostly from the intestine?
a) More surface area
b) Long residence time
c) Large surface area and long residence time
d) Large surface area, long residence time, basic pH
Answer: c
Clarification: Experiments showed that irrespective of the GI pH and the degree of ionization, most of the acidic and basic drugs are more rapidly absorbed from the intestine. The 1st reason because of large surface area and second reason due to high residence time.

7. What will be in the place of ‘?’ in the given picture?

a) Plasma layer
b) Aqueous unstirred diffusion layer
c) Lipid membrane
d) Blood vessel
Answer: b
Clarification: The luminal fluid is not in direct contact with the membrane. There stands a barrier called as the aqueous unstirred diffusion layer which is interposed between the bulk fluid and the lipoidal membrane.

8. Drug having a small partition coefficient can rapidly penetrate the lipid membrane but diffusion through the unstirred water layer is a rate-limiting step.
a) True
b) False
Answer: b
Clarification: Drugs having a large partition coefficient can rapidly penetrate the lipid membrane but diffusion through the unstirred water layer is a rate-limiting step. This applies particularly to high molecular weight fatty acids and bile acids.

9. What are the major stability problems which result in poor bioavailability of any orally administered drugs?
a) Acidic degradation
b) Degradation by salivary amylase
c) Degradation of the drug in inactive form
d) Interaction with the excipients and degradation in an inactive form
Answer: d
Clarification: A drug for oral use may destabilize either during its shelf life or in the GIT. Thus giving up to two major destabilizing problems that give rise to bioavailability problems are degradation of the drug in inactive form and interaction with one or more different components of the formulation.

Drug Biotechnology Multiple Choice Questions on “Bioactivation and Tissue Toxicity”.

1. Which of the following statement rightly states “bioactivation”?
a) Formation of high reactive metabolites which interact with tissues to precipitate toxic compounds
b) Formation chelating agents
c) Formation of enzymes which can lyse toxic compounds
d) Stimulating the immune systems to initiate the formation of t cells
Answer: a
Clarification: Formation of highly reactive metabolites which can interact with the tissues and precipitate out various toxic compounds such as carcinogens, teratogens, etc. is known as bioactivation or toxicological activation.

2. Which of the following is an example of electrophiles?
a) Thalidomide
b) Aflatoxin
c) Epoxides
d) Benzopyrene
Answer: c
Clarification: Electrophiles are species deficient in electron pair. Important electrophiles are epoxides, hydroxylamines, nitroso, and azoxy derivatives, nitrenium ions, and elemental sulphur.

3. What is the body’s defence against electrophiles?
a) Their inactivation by conjugation with glucagon
b) Their inactivation by conjugation with glutamine
c) Their inactivation by conjugation with glucuronic acid
d) Their inactivation by conjugation with glutathione
Answer: d
Clarification: The body’s defence against electrophile is their inactivation by conjugation with glutathione, the most abundant cellular nucleophile wit –SH group. Example of tissue toxicity due to electrophiles is hepatotoxicity of paracetamol metabolites.

4. Electrophiles are deficient of pair of electrons and free radicals contain an odd number of electrons.
a) True
b) False
Answer: a
Clarification: Electrophiles are the species which are deficient in a pair of electron. These electrophiles in our body are generated through cytochrome P-450. Free radicals are species containing an odd number of electrons. These may be positively charged, negatively charged or neutral. Free radicals are formed via NADPH cytochrome P-450 reductase.

5. Which xenobiotics yield free radicles on metabolic activation?
a) Thalidomide
b) Aflatoxin
c) Quinones
d) Benzopyrene
Answer: c
Clarification: Quinones, arylamines, nitroaryls and carbon tetrachloride are some of the examples of xenobiotics which yields free radicals. Endogenous compounds such as epinephrine, DOPA can generate free radicals.

6. Which of the following will be an example of inorganic free radicle?
a) H₂O₂ and O₂^–
b) Aflatoxin
c) Quinones
d) Benzopyrene
Answer: a
Clarification: Most free radicles are organic. Some of the examples of inorganic free radicles are H₂O₂ and O₂ and O₂-. These oxidative moieties can cause tremendous tissue damage leading to mutations and cancer. The potential toxicity of free radicals is more than electrophiles.

7. How are electrophiles generated?
a) Through cytochrome P-450 system
b) NADPH cytochrome P-450 reductase
c) Different Flavin containing reductase
d) Through cytochrome P-350 system
Answer: a
Clarification: Electrophiles are species deficient in electron pair. The enzyme system through which they are generated is cytochrome-P450. Carbon, nitrogen, sulphur compounds can be metabolically activated to yield electrophiles.

8. How are free radicals generated in the human body?
a) Through cytochrome P-450 system
b) NADPH cytochrome P-450 reductase
c) NADPH reductase
d) Through cytochrome P-350 system
Answer: b
Clarification: Free radicles are formed via NADPH cytochrome P-450 reductase or other Flavin containing reductases. Quinones, arylamines, nitroaryls and carbon tetrachloride are some of the examples of xenobiotics which yields free radicals. Endogenous compounds such as epinephrine, DOPA can generate free radicals.

9. Free radicals are more dangerous than electrophiles.
a) True
b) False
Answer: a
Clarification: Some of the examples of inorganic free radicles are H₂O₂ and O₂^–. These oxidative moieties can cause tremendous tissue damage leading to mutations and cancer. The potential toxicity of free radicals is more than electrophiles.

10. Bioavailability of glutathione in the body doesn’t determine the threshold of a toxic response.
a) True
b) False
Answer: b
Clarification: The generation of reactive metabolites is indicated by modification in enzyme activities, the formation of glutathione conjugates and depletion of tissue levels of glutathione. Thus, the bioavailability of glutathione in the body determines the threshold of a toxic response.