Bihar Board - Class 12 Chemistry - Chapter 16: Chemistry in Everyday Life Short Answer Question

                                Short Question Answer

Question. 1. Why do we need to classify drugs in different ways ?

Answer: Analgesics have pain killing effects, whereas antiseptic kills or arrests the growth of microorganisms.

Question. 2. Explain the term, target molecules or drug targets as used in medicinal chemistry.

Answer: Target molecules or drug targets : Drugs usually interact with biological macromolecules such as carbohydrates, lipids proteins and nucleic acids. These biological molecules are called targets. The correct choice of the molecular target for a drug is important to obtain its desired therapeutic effect.

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Question. 3. Name the macromolecules that are chosen as drug targets.

Answer: Macromolecules that are chosen as drug targets include carbohydrates, lipids, proteins and nucleic acids.

Question. 4. Define the term Chemotherapy.

Answer:  Use of chemicals in prescribed doses for – therapeutic effect is called Chemotherapy.

Question. 5. What is meant by the term ‘broad spectrum antibiotics’ ? Explain.

Answer: The full range of microorganisms attacked by an antibiotic is called its spectrum. Broad spectrum antibiotics are medicines effective against several different types of harmful microorganisms, e.g., tetracycline, chloramphenicol and a mixture of potent antibiotics.

Question. 6. Name a substance which can be used as an antiseptic as well as disinfectant.

Answer: 0.2 a percent solution of phenol is an antiseptic while its one percent solution is disinfectant.

Question. 7. What are the main constituents of dettol ?

Answer: Dettol is a mixture of chloroxylenol and terpineol in a suitable solvent.

Question. 8. What is tincture of iodine ? What is its use ?

Answer: It is 2-3 % solution of iodine in alcohol and water. It is a powerful antiseptic.

Question. 9. What are food preservatives ?

Answer: Food preservatives prevent spoilage of food due to microbial growth. Table salt, sugar and vegetable oils are class I preservatives. The most common preservative of class II is sodium benzoate (C6H5COONa) . It can be safely used in small quantities which are metabolized in the body.

Question. 10 . How are synthetic detergents better than soap ?

Answer: Soaps when used in hard water from curdy precipitate that separates as scum. These insoluble soaps are useless as a cleansing agent. Synthetic detergents, on the other hand, can be used in any sort of water because they form foam even in water containing mineral compounds. Some of them can give foam even in ice cold water.

Question. 11. Why do soaps not work in hard water?

Answer: Hard water contains calcium and magnesium ions. These form insoluble calcium and magnesium soaps respectively.

2 C17H35COONa + CaCl2 2 NaCl + (C17H35COO)2Ca

(Calcium chloride                                  Insoluble calcium

in hard water)                                            stearate (soap)

These insoluble soaps are useless as a cleansing agent. In fact these are hindrance to good washing because this precipitate adheres on to the fibers of the cloth as gummy mass.

Question. 12. Why do we require artificial sweetening agents ?

Answer: Natural sweeteners like glucose, sucrose etc. add to calorie intake and therefore many people prefer to use artificial sweeteners. They are of great value to diabetic persons and people who are calorie-conscious. They are excreted from the body in the urine unchanged.

Question. 13. How do antiseptics differ from disinfectants ? Give one example of each.

Answer: Antiseptics are the chemicals which either kill or prevent the growth of microorganisms without affecting the living human tissues. Disinfectants also kill the micro-organism and also affect the living human tissues. Example of :

(i) antiseptic : Dettol, iodoform
(ii) disinfectants : Chlorine, potassium permanganate.

Question. 14. What are artificial sweetening agents ? Give two examples.
Answer: The artificial sweeteners are food additives. They do not add calories. Examples are (i) Saccharine and (ii) aspartame.

Question.15. Name an alkaloid in each case used for the treatment of (i) hypertension, (ii) malaria fever, (iii) pain.

Answer: (i) Reserpine is the alkaloid used for treatment of hypertension.
(ii) Quinine is the alkaloid used for treatment of malaria.
(iii) Morphine is the alkaloid used for the treatment of pain.

Question. 16. Name the active chemotherapeutic agent in each of the following used medicines : (i) Brufen, (ii) Crocin, (iii) Disprin.

Answer: (i) Brufen:  p-Isobutylphenyl-2-propanoic acid.
(ii) Crocin : Paracetamol
(iii) Disprin : Acetylsalicylic acid.

Question. 17. What is an antibiotic ? Give the name of the first antibiotic discovered.

Answer: Antibiotics are chemical substances (Produced wholly or partially by chemical synthesis) which in low concentration, either kill or inhibit the growth of microorganisms by intervening in their metabolic process. Penicillin was the first antibiotics discovered.

Question. 18. Why are detergents preferred to soaps? How are detergents classified ?

Answer: Detergents are preferred to soaps because they work even in hard water as cleansing agents. Detergents are classified in the three categories : (i) Anionic detergents, (ii) Cationic detergents, (iii) Non-ionic detergents.

Question. 19. How do drugs interact with enzymes ?

Answer: Drugs inhibit the activity of enzymes. Such drugs are also called enzyme inhibitors. Enzyme inhibitors can block the binding site and prevent the binding of substrates or these can inhibit the catalytic activity of enzymes.

Question 20. Which forces are involved in holding the drugs to the active site of enzymes?

Answer: The following forces are involved in holding the drugs to the active site of enzymes:

(a) Hydrogen bonding

(b) Ionic bonding

(c) Dipole-dipole interactions

(d) van der Waals interactions

Question 21. Antacids and antiallergic drugs interfere with the function of histamines but do not interfere with the function of each other. Explain.

Answer: They don't interfere with the functioning of each other because they work on different receptors in the body.Histamine stimulates the secretion of pepsin and hydrochloric acid in the stomach. The drug cimetidine (antacid) was designed to prevent the interaction of histamine with the receptors present in the stomach wall. This resulted in the release of a lesser amount of acid. Antacid and antiallergic drugs work on different receptors.

Question.22. Why are cimetidine and ranitidine better antacids than sodium hydrogen carbonate or magnesium or aluminum hydroxide?

Answer: If excess of NaHCO3 or Mg(OH)2 or Al(OH)3 is used, it makes the stomach alkaline and thus triggers the release of even more HCl which may cause ulcer in the stomach. In contrast, cimetidine and ranitidine prevent the interaction of histamine with the receptor cells in the stomach wall and thus release of HCl  will be less as histamine stimulates the secretion of acid.

Question.23. If water contains dissolved calcium hydrogencarbonate, out of soaps and synthetic detergents, which one will you use for cleaning clothes?

Answer: Calcium hydrogen carbonate makes water hard. Therefore, soap cannot be used because it gets precipitated in hard water. On the other hand, a synthetic detergent does not precipitate in hard water because its calcium salt is also soluble in water. Therefore, synthetic detergents can be used for cleaning clothes in hard water.

Question.24. What is meant by the term broad spectrum antibiotics? Explain.

Answer: Broad spectrum antibiotics are effective against several different types or a wide range of harmful bacteria. For example, tetracycline, chloramphenicol and ofloxacin. Chloramphenicol can be used in case of typhoid, dysentery, acute fever, urinary infections, meningitis and pneumonia.

Question.25. Explain the following as used in medicinal chemistry

(a) Lead compounds

(b) Target molecules or drug targets.

Answer:

(a) Lead compounds are the compounds which are effective in different drugs. They have specific chemical formulas and may be extracted either from natural sources (plants and animals) or may be synthesized in the laboratory.

(b) Target molecules or drug targets. An enzyme (E) functions by combining with the reactant (called substrate) denoted as 'S' to form an activated complex known as enzyme-substrate complex (E-S) . The complex dissociates to form a product and releases the enzyme for carrying out further activity.

E + S   [E-S] P + E