Question

Toxicology

1) The toxicants pass through the cell membranes by what is known as, "passive diffusion" which depends on (a) pore size (b) concentration gradients across the membrane (c) lipid solubility (d) the diastolic and systolic blood pressure in the individual 2) In toxicokinetics the rate of elimination of administered substances is measured from the area plots of concentrations versus time. Among the following substances which one would you expect to be excreted out at the slowest rate? (a) glucose (b) sodium chloride (c) sodium carbonate (d) tetraethyl lead 3) Certain toxicants are engulfed by the cells. The specific term for such process involving engulfing of solid particles into the cells are known as: (a) pinocytosis (b) phagocytosis (c) endocytosis (d) swallowing 4) One of the following biotransformation processes involves a Phase II Conjugation reaction: (a) microsomal oxidation of an alcohol (b) non-microsomal reduction of a carboxylic acid (c) reaction with glucuronic acid (d) conversion of benzene into benzene epoxide 5) One of the following reactions is an example of N- hydroxylation: (a) (CHỊ) N = (CH, N=0 (b) C,H,NH,… CHÚNHOH (c) (CH), N H (CH) NES (d) (CH, NHOH - CH,NH, 6) Conversion of parathion into paraoxon is a Phase I reaction involving (a) N-oxidation (b) P-oxidation (c) S-oxidation (d) none of the above 7) One of the following enzyme catalyzed reactions is an example of Phase I hydrolysis: (a) conversion of carboxylic acids into alcohols (b) conversion of amides into amines (c) conversion of choline into cholinesterases (d) conversion of ethanol into acetic acid 8) In the GI tract in acid medium an amine may react with nitrite ion (NO, ) to form (a) nitrosamine (b) amino acid (c) ammonia (d) hydroxylamine 9) Many reactive epoxide metabolites bind to one of the following substances to form water-soluble conjugates and detoxify: (a) glucuronic acid (b) phenol (c) amino acid (d) glutathione 10) An example of immediate effect of poisoning is (a) liver cirrhosis (b) tumor formation (c) emphysema (d) cyanide

Answer 1

1. Option c

Explanation- Nonpolar or lipid-soluble materials pass through plasma membranes more easily than polar materials, allowing a faster rate of diffusion.

2. Option d

Explanation- Tetraethyl lead chronic exposure the main deposits (90%) are in the bone, with very slow elimination.

3. Option b

Explanation- engulfing of solid particles is phagocytosis and liquid particles is pinocytosis.

4. Option c

Explanation- In he biotransformation,the products of phase I metabolism can be conjugated with hydrophilic moieties (phase II metabolism) to form more readily excreted metabolites. Typical conjugation reactions involve glutathione, glucuronic acid, sulfate, and amino acids.

5. Option b

Explanation-The N hydroxylation reaction usually occurs on the alkyl side chain or on the aromatic ring but not directly on the carbamoyl nitrogen atom. The activity of hydroxylation reactions of N-alkyl groups decreases with increasing alkyl chain length.