Answer

(d) An antiseptic is an antimicrobial drug. It tends to destroy/prevent development or inhibit the pathogenic action of microbes. Antiseptics are applied to the living tissues such as wounds, cuts, ulcers and diseased skin surfaces e.g., soframicine.

Bithionol the compound is also called bithional is added to soaps to impart antiseptic properties.

Dilute solutions of some disinfectants can be used as antiseptic e.g., 0.2 per cent solution of phenol is an antiseptic while its one per cent solution is disinfectant. But, antiseptic medicines can not be ingested like antibiotics.

• (a) Some antiseptics can be added to soaps: This statement is correct. Antiseptics like bithionol are added to soaps to impart antiseptic properties.

• (b) Dilute solutions of some disinfectants can be used as antiseptic: This statement is correct. For example, a 0.2 percent solution of phenol is an antiseptic, while a 1 percent solution is a disinfectant.

• (c) Disinfectants are antimicrobial drugs: This statement is incorrect. Disinfectants are chemical agents used to destroy or inhibit the growth of harmful microorganisms on inanimate objects and surfaces, not drugs.

Answer

(c) Chemical substances which are used to check pregnancy in women are called birth control pills. Birth control pills essentially contain a mixture of synthetic estrogen and progesterone derivatives, both of these are sex hormones. It is known that progesterone suppresses ovulation and estrogen control the menstrual cycle.

Some of the commonly used pills contain a mixture of norethindrone (a progesterone derivative) and novestrol (an estrogen).

• (a) Contain estrogen only: This option is incorrect because birth control pills typically contain a combination of both estrogen and progesterone derivatives, not just estrogen alone. The combination is necessary to effectively prevent ovulation and regulate the menstrual cycle.

• (b) Contain progesterone only: This option is incorrect because, while some birth control methods may use progesterone-only formulations, the most common and effective birth control pills contain a combination of both estrogen and progesterone derivatives. The combination helps to better regulate the menstrual cycle and prevent ovulation.

• (d) Progesterone enhances ovulation: This option is incorrect because progesterone actually suppresses ovulation rather than enhancing it. Progesterone works by inhibiting the release of eggs from the ovaries, thereby preventing pregnancy.

Answer

(a) Aspirin can be prepared as follows

Aspirin inhibits the synthesis of compounds known as prostaglandins which stimulate inflammation in the tissues and cause pain. So, it is effective in relieving pain.

Beside this, aspirin has many other effects such as reducing fever (antipyretic) and preventing blood platelet coagulation. Because of this anti-blood clotting action, it is widely used to prevent heart attacks. It does not make a person addictive as it is non-narcotic drug.

• (b) It is effective in relieving pain: This statement is true because aspirin inhibits the synthesis of prostaglandins, which are compounds that stimulate inflammation and cause pain. Therefore, aspirin is effective in relieving pain.

• (c) It has antiblood clotting action: This statement is true because aspirin prevents blood platelet coagulation, which is why it is widely used to prevent heart attacks.

• (d) It is a neurologically active drug: This statement is true because aspirin affects the central nervous system by inhibiting the synthesis of prostaglandins, which are involved in the transmission of pain signals.

Answer

(c) Drugs can be classified in the following ways

(a) On the basis of chemical structure Drugs have been classified on the basis of their chemical structures because drugs having common structural features often have similar pharmacological activity. e.g., all sulphonamides having the common structural feature as given below are mostly antibacterial.

Structural feature of sulphonamide

(b) On the basis of drug action This classification is based on the action of a drug on a particular biochemical process.

(c) On the basis of molecular target Drugs usually interact with the biomolecules or biological macromolecules such as proteins, nucleic acids and lipids. These are called drug targets.

Drugs possessing some common structural features may have the same mechanism of action on a specific drug target. This classification is most useful for the medicinal chemists.

(d) On the basis of pharmacological effect This classification is based upon the pharmacological effects of the drugs. It is more useful for the doctors because it provides them the whole range of drugs available for the treatment of a particular disease. e.g., analgesics reduce or kill pain while antiseptic either kill or arrest the growth of microorganisms.

• (a) On the basis of chemical structure: While this classification is useful because drugs with common structural features often have similar pharmacological activities, it is not the most useful for medicinal chemists. This is because it does not necessarily provide information about the drug’s mechanism of action or its interaction with specific biological targets.

• (b) On the basis of drug action: This classification is based on the action of a drug on a particular biochemical process. However, it does not provide detailed information about the molecular targets or the specific interactions at the molecular level, which are crucial for medicinal chemists in designing and optimizing drugs.

• (d) On the basis of pharmacological effect: This classification is more useful for doctors as it provides a range of drugs available for treating a particular disease. However, it does not offer detailed insights into the molecular interactions and mechanisms of action, which are essential for medicinal chemists in drug development and research.

Answer

(a) Tranquilizers are used for the treatment of stress, fatigue, mild and severe mental diseases. They relieve anxiety, stress, irritability or excitement by inducing a sense of well-being. Noradrenaline is one of the several neurotransmitters which play an important role in mood changes.

If the level of noradrenaline in the body is low for some reasons, then the message transfer process becomes slow and the person suffer from depression. In such cases, antidepressant drugs are used. These drugs inhibits the enzymes which catalyse the degradation of noradrenaline.

If the enzyme is inhibited, then the neurotransmitter noradrenaline is slowly metabolised and can thus activate the receptor for longer periods there by counteracting the effect of depression. Tranquilizers form an essential component of sleeping pills.

• (b) Tranquilizers are not narcotic drugs. Narcotic drugs are substances that can dull the senses, relieve pain, and induce sleep, but they often have a high potential for addiction and abuse. Tranquilizers, on the other hand, are primarily used to reduce anxiety and tension without necessarily inducing sleep or having a high potential for addiction.

• (c) Tranquilizers do affect the message transfer from nerve to receptor. They work by altering the chemical balance in the brain, often by enhancing the effect of neurotransmitters like GABA (gamma-aminobutyric acid), which helps to calm the nervous system.

• (d) Tranquilizers are not primarily used to relieve pain and fever. Analgesics and antipyretics are the classes of drugs used for pain relief and fever reduction, respectively. Tranquilizers are mainly used to treat anxiety, stress, and other mental health conditions.

Answer

(a) Syphilis is an acute and chronic infections disease caused by the bacterium Treponema pallidum. It is a sexually transmitted infection. The primary route of transmission is through sexual contact but it may also be transmitted from mother to foetus during pregnancy or at birth.

Paul Ehrlich investigated arsenic based structures in order to produce less toxic substances for the treatment of syphilis as he got Nobel prize for medicine in 1908 for this discovery. Salvarsan was the first effective medicine discovered for syphilis. Although salvarsan is toxic to human beings, its effect on bacteria is much greater than on human being. Structure of salvarsan is -

• (b) Typhoid: Typhoid is a bacterial infection caused by Salmonella typhi. It is typically spread through contaminated food and water. Salvarsan was not developed for the treatment of typhoid; other antibiotics such as chloramphenicol, ampicillin, and ciprofloxacin are used for this purpose.

• (c) Meningitis: Meningitis is an inflammation of the protective membranes covering the brain and spinal cord, known as the meninges. It can be caused by various pathogens, including bacteria, viruses, and fungi. Salvarsan was not intended for the treatment of meningitis; treatments for bacterial meningitis include antibiotics like penicillin, ceftriaxone, and vancomycin.

• (d) Dysentery: Dysentery is an infection of the intestines resulting in severe diarrhea with the presence of blood and mucus in the feces. It can be caused by bacteria (such as Shigella) or amoebas (such as Entamoeba histolytica). Salvarsan was not used for the treatment of dysentery; appropriate treatments include antibiotics or antiparasitic medications depending on the cause.

Answer

(a) Antibiotics are now defined as chemical substances which in low concentration, either kill or inhibit the growth of microorganisms by intervening in their metabolic processes. The full range of microorganisms attacked by an antibiotic is called its spectrum.

Broad spectrum antibiotics are effective against several different types of harmful bacteria i.e., a wide range of gram-positive and gram-negative bacteria. These effective mainly against gram-positive or gram-negative bacteria are narrow spectrum antibiotics.

Chloramphenicol is a broad spectrum antibiotic penicillin-G has a narrow spectrum. If an antibiotic is effective against a single organism or disease then it is limited spectrum antibiotic.

• (b) Narrow spectrum antibiotics are not limited to gram-negative bacteria only; they can be effective against either gram-positive or gram-negative bacteria, but not both.

• (c) If an antibiotic is effective against a single organism or one disease, it is referred to as a limited spectrum antibiotic, not a narrow spectrum antibiotic.

• (d) Antibiotics that are effective against both gram-positive and gram-negative bacteria are classified as broad spectrum antibiotics, not narrow spectrum antibiotics.

Answer

(b) Analgesics reduces or abolish pain without causing impairment of consciousness, mental confusion, incordination or paralysis or some other disturbances of nervous system. Analgesics are non-narcotic or narcotic. Narcotic analgesics when administered in small doses relieve pain and produce sleep.

Tranquilisers are a class of chemical compounds used for the treatment of stress, and mild or even severe mental diseases.

Histamine is a substance which on release produce hypersensitivity to dust, some drugs etc (i.e., allergy). Antihistamines are the drugs which interfere with the natural action of histamine by competing with histamine for binding sites of receptor where histamine exerts its effect. They are anti-allergy drugs.

• Analgesics reduce or abolish pain without causing impairment of consciousness, mental confusion, incoordination, or paralysis or some other disturbances of the nervous system. They are not primarily used for general antirepressant action on the central nervous system.

• Narcotic analgesics, when administered in small doses, relieve pain and produce sleep. They are not primarily used for general antirepressant action on the central nervous system.

• Antihistamines are drugs that interfere with the natural action of histamine by competing with histamine for binding sites of receptors where histamine exerts its effect. They are primarily used as anti-allergy drugs and not for general antirepressant action on the central nervous system.

Answer

(d) Basically, all soaps are made by boiling fats or oils with suitable hydroxide. Variations are made by adding different raw materials. Sodium laurylsulphate and sodium dodecylbenzenesulphonate are anionic detergents.

A gum rosin added to soap to make it lather well. Bithional is added to soaps to impart antiseptic properties to soap.

• Sodium laurylsulphate and sodium dodecylbenzenesulphonate are anionic detergents, not antiseptic agents.
• Rosin is added to soap to make it lather well, not to impart antiseptic properties.

Answer

(b) Equanil is a tranquilizer.

(Also, refer to Q. 5)

• (a) artificial sweetener: Equanil is not an artificial sweetener. Artificial sweeteners are chemical compounds used to replace sugar in food and drinks, providing sweetness without the calories. Examples include aspartame, saccharin, and sucralose.

• (c) antihistamine: Equanil is not an antihistamine. Antihistamines are drugs used to treat allergic reactions by blocking histamine receptors in the body. Examples include diphenhydramine, loratadine, and cetirizine.

• (d) antifertility drug: Equanil is not an antifertility drug. Antifertility drugs are used to prevent pregnancy by interfering with the normal function of reproductive hormones. Examples include oral contraceptives like estrogen-progestin combinations.

Answer

(b) Shaving soaps contain glycerol to prevent rapid drying. While preparing this soaps, a gum called rosin is added to them. It forms sodium rosinate which lathers well. Laundary soaps contain fillers like sodium rosinate, sodium silicate, borax and sodium carbonate.

Trisodium polyphosphate is an important filler added to detergent powders and liquid detergents.

• Sodium carbonate: Sodium carbonate is primarily used as a water softener in soaps and detergents. It does not significantly enhance the lathering property of soap.

• Sodium stearate: Sodium stearate is a common soap ingredient that acts as a surfactant and helps in cleansing. However, it does not specifically enhance the lathering property of soap.

• Trisodium phosphate: Trisodium phosphate is used as a cleaning agent and a builder in detergents. It does not contribute to the lathering property of soap.

Answer

(c) Glycerol is added to shaving soap to prevent rapid drying while to enhance the leathering property of soap, a gum called rosin is added to them. It forms sodium rosinate which lathers well. Soap granules are dried miniature soap bubbles.

Builders/fillers make the soap act more rapidly. Builder or filler (e.g. sodium tripolyphosphate) is added to detergent powder. Its main function is to act as water softener by removing $\mathrm{Mg}^{2+}$ and $\mathrm{Ca}^{2+}$ ions from hard water by forming stable soluble complexes.

• (a) Fillers are added to soap to make it act more rapidly, not to prevent rapid drying. Fillers like sodium tripolyphosphate are used in detergent powders to soften water by removing $\mathrm{Mg}^{2+}$ and $\mathrm{Ca}^{2+}$ ions.

• (b) To increase lathering, a gum called rosin is added to soap, forming sodium rosinate which lathers well. Glycerol is not used for this purpose.

• (d) Soap granules are dried miniature soap bubbles, and glycerol is not used to make soap granules.

Answer

(b) Liquid dishwashing detergents are non-ionic type. Non-ionic detergents do not contain any ion in their constitution. Mechanism of cleansing action of this type of soaps. These remove grease and oil by micelle formation.

Other two classes of detergents are anionic detergents and cationic detergents. Anionic detergents are sodium salts of sulphonated long chain alcohols or hydrocarbons.

Anionic detergent (sodium lauryl sulphate)

They are mostly used for household work.

Cationic detergents are quaternary ammonium salts of amines with acetates, chlorides or bromides as anions. Cetyltrimethylammonium bromide is a popular cationic detergent and is used in hair conditioners.

• Option (a) is incorrect because it represents an anionic detergent, which is a sodium salt of sulphonated long chain alcohols or hydrocarbons. These are not typically used as liquid dishwashing detergents.

• Option (c) is incorrect because it represents a cationic detergent, which is a quaternary ammonium salt of amines with acetates, chlorides, or bromides as anions. These are commonly used in hair conditioners, not as liquid dishwashing detergents.

Answer

(c) Polyethyleneglycols are used in the preparation of non-ionic detergents. Non-ionic detergents do not contain any ion in their constitution.

Reaction is as follow

• (a) Cationic detergents: Cationic detergents contain a positively charged ion (cation) in their structure, which is typically derived from quaternary ammonium compounds. Polyethyleneglycols do not contribute to the formation of cationic detergents as they do not provide the necessary cationic group.

• (b) Anionic detergents: Anionic detergents contain a negatively charged ion (anion) in their structure, often derived from sulfonates or sulfates. Polyethyleneglycols do not provide the anionic group required for the formation of anionic detergents.

• (d) Soaps: Soaps are typically made from the saponification of fats and oils with an alkali, resulting in the formation of fatty acid salts. Polyethyleneglycols are not involved in this saponification process and do not contribute to the formation of soaps.

Answer

(c) Drugs usually interact with biomolecules such as carbohydrates, lipids, proteins and nucleic acids. These are called drug targets. Vitamins are not a target molecule for drug function in body.

• Carbohydrates: Carbohydrates can serve as drug targets because they play crucial roles in various biological processes, including cell recognition and signaling. Drugs can interact with carbohydrates to inhibit or modify these processes.

• Lipids: Lipids are essential components of cell membranes and can be targeted by drugs to alter membrane fluidity, signaling pathways, or to disrupt the integrity of microbial cell membranes.

• Proteins: Proteins are common drug targets because they are involved in nearly all cellular processes, including enzymatic activity, signal transduction, and structural functions. Drugs can bind to proteins to inhibit or modulate their activity.

Answer

(c) Drugs can block the binding site of the enzyme and present the binding of substrate, or can inhibit the catalytic activity of the enzyme. Such drugs are called enzyme inhibitors. Drugs inhibit the attachment of substrate on active site of enzyme in two different ways.

(i) Drugs which compete with natural substrate for their attachment on the active sites of enzymes are called competitive inhibitors.

Competitive inhibitors (Drug and substrate competing for active site)

(ii) However, some drugs do not bind to the active site but bind to a different site of enzyme i.e., allosteric site which changes the shape of the active site of the enzyme in such a way that the natural substrate cannot recognize it. Such enzymes are called non-competitive inhibitors.

Generally, a weak bond such as hydrogen bonding, van der, Waals’ interactions etc., is formed between the enzyme and inhibitor.

Non-competitive inhibitor changes the active site of enzyme after binding at allosteric site

• (a) Inhibit the catalytic activity of the enzyme: This statement is true because enzyme inhibitors can indeed inhibit the catalytic activity of the enzyme by binding to it and preventing it from catalyzing reactions.

• (b) Prevent the binding of substrate: This statement is true because enzyme inhibitors can prevent the binding of the substrate to the enzyme, either by competing with the substrate for the active site (competitive inhibition) or by binding to a different site and altering the enzyme’s shape (non-competitive inhibition).

• (d) Inhibitors can be competitive or non-competitive: This statement is true because enzyme inhibitors can be classified as competitive or non-competitive based on their mechanism of action. Competitive inhibitors compete with the substrate for the active site, while non-competitive inhibitors bind to a different site and change the enzyme’s shape.

Answer

(d) Sucrose and glucose are natural sweetening agent while aspartame and sucralose are artificial sweetening agent.

Aspartame is roughly 100 times as sweet as cane sugar. It is methyl ester of dipeptide formed from aspartic acid and phenylalanine. Use of aspartame is limited to cold foods and soft drinks because it is unstable at cooking temperature.

Sucralose is trichloro derivative of sucrose. Its appearance and taste are like sugar. It is stable at cooking temperature. It does not provide calories.

• Sucrose and glucose are natural sweetening agents and provide calories.
• Aspartame is unstable at cooking temperature and is limited to use in cold foods and soft drinks.

Answer

(b) Vitamins and minerals are essential nutrients because they perform hundred of roles in the body. They help shore up bones, heal wounds, and bolster immune system. They also convert food into energy, and repair cellular damage.

Artificial sweeteners are non-caloric substitutes for sugar. They are often intensly more sweet than sugar but do not enhance nutritional value of food.

Amino acids are the monomers of proteins. Proteins require for the growth and maintenance of the body. Therefore, amino acids will also enhance the nutritional value of food.

• Minerals and vitamins are essential nutrients because they perform hundreds of roles in the body. They help shore up bones, heal wounds, and bolster the immune system. They also convert food into energy and repair cellular damage.
• Amino acids are the monomers of proteins. Proteins are required for the growth and maintenance of the body. Therefore, amino acids will also enhance the nutritional value of food.

Answer

$(b, d)$

Receptors are proteins that are crucial to body’s communication process. Majority of these are embedded in cell membranes. They are embedded in the cell membrane in such a way that their small part possessing active site projects out of the surface of the membrane and opens on the outside region of the cell membrane.

In the body, message between two neurons and that between neuron to muscles is communicated through certain chemicals. These chemicals, known as chemical messengers are received at the binding site of receptors proteins.

To accommodate a messenger, shape of the receptor site changes. This brings about the transfer of message into the cell. Thus, chemical messenger gives message to the cell without entering the cell.

• (a) This statement is correct. Majority of receptor proteins are indeed embedded in the cell membranes.
• (c) This statement is correct. Chemical messengers are received at the binding sites of receptor proteins.

Answer

$(b, c)$

Food preservatives prevent spoilage of food due to microbial growth. The most commonly used preservatives include table salt, sugar, vegetable oils and sodium benzoate. Sodium hydrogen carbonate and cane sugar are not used as food preservatives.

• Table salt is used as a food preservative because it inhibits the growth of bacteria by drawing out moisture through the process of osmosis.
• Benzoic acid is used as a food preservative because it has antimicrobial properties that prevent the growth of mold, yeast, and some bacteria.

Answer

$(b, c)$

Antiseptics are the chemical substances which either kill or prevent the growth of microorganisms.

(a) $\mathrm{CHCl}_{3}$ (chloroform) was used as an anaesthesia in surgery but now it is used in the production of the freon refrigerant $\mathrm{R}-22$.

(b) lodoform $\left(\mathrm{CHI}_{3}\right)$ produces iodine on coming in contact with skin, so it is used as an antiseptic for wounds.

(c) Boric acid $\left(\mathrm{H} _{3} \mathrm{BO} _{3}\right)$ in dilute aqueous solution is a weak antiseptic for eyes. Thus, chemical messenger gives messagle to the all without entering the cell.

(d) Chlorine in the concentration of 0.2 to $0.4 \mathrm{ppm}$ in aqueous solution and sulphur dioxide in very low concentrations, are disinfectants.

• (a) $\mathrm{CHCl}_{3}$ (chloroform): Chloroform was historically used as an anaesthetic in surgery but is not used as an antiseptic. Its primary modern use is in the production of the freon refrigerant $\mathrm{R}-22$.

• (d) $0.3 \mathrm{ppm}$ aqueous solution of $\mathrm{Cl}_{2}$: Chlorine in the concentration of 0.2 to $0.4 \mathrm{ppm}$ in aqueous solution is considered a disinfectant, not an antiseptic. Disinfectants are used to kill microorganisms on non-living surfaces, whereas antiseptics are used on living tissues.

Answer

$(a, b)$

Barbituric acid and its derivatives such as veronal, luminal, seconal, amytal and nembutal constitute an important class of tranquilizers called barbiturates. They are used as hypnotics i.e., sleep producing agents.

• (c) Non-narcotic analgesics: Barbiturates are not classified as non-narcotic analgesics. Non-narcotic analgesics are drugs that relieve pain without causing sedation or sleep, whereas barbiturates are primarily used as sedatives and hypnotics.

• (d) Pain reducing without disturbing the nervous system: Barbiturates do affect the nervous system as they act on the central nervous system to produce their sedative and hypnotic effects. They do not specifically reduce pain without affecting the nervous system.

Answer

$(a, b)$

Sulpha drugs kills bacteria and fungi by interfering with their metabolism.

(a) Sulphapyridine is a sulphonamide antibacterial drug. It is no longer prescribed for the treatment of infections in humans. It is a good antibacterial drug, but its water solubility is very $\mathrm{pH}$ dependent. Thus, there is a risk of crystallisation within the bladder or urethra, which could lead to pain or blockage.

(b) Prontosil is also called sulphamidochrysoidine. It is used in the treatment of general bacterial infection in humans

(c) Salvarsan is arsenic based antibacterial drug. It is used in the treatment of syphilis.

(d) Nardil is an antidepressant drug.

• (c) Salvarsan is an arsenic-based antibacterial drug. It is used in the treatment of syphilis.
• (d) Nardil is an antidepressant drug.

Answer

$(a, b, c)$

Antidepressants are the substances which correct chemical imbalances of neurotransmitters in the brain and probably cause changes in mood and behaviour.

Iproniazid is a hydrazine drug used as an antidepressant. Phenelzine is also known as Nardil. It is used in the treatment of major depressive disorder. Equanil is used in controlling depression and hypertension.

Salvarsan is an antibacterial drug. It is used in the treatment of Syphilis.

• Salvarsan is an antibacterial drug. It is used in the treatment of Syphilis.

Answer

(c, $d)$

Penicillin is a group of antibiotics derived from Penicillium fungi. Ampicillin and Amoxycillin are synthetic modifications of penicillin. Pencillin destroys bacteria by destroying the cell wall of the microorganism or kill the bacteria so, it has bacteriocidal effect.

Penicillin as a class of antibiotics are generally narrow spectrum but when used in the combination with other antibiotics, it can make up a part of broad spectrum antibiotics.

• (c) It has bacteriostatic effect: This statement is incorrect because penicillin has a bactericidal effect, meaning it kills bacteria by destroying their cell walls, rather than merely inhibiting their growth.

• (d) It is a broad spectrum antibiotic: This statement is incorrect because penicillin is generally considered a narrow spectrum antibiotic. It is effective against a specific range of bacteria, although it can be part of a broad spectrum antibiotic regimen when combined with other antibiotics.

Answer

$(b, d)$

Antacid is a substance which neutralizes excess of acid in stomach.

The chemical formula of sodium hydrogen carbonate is $\mathrm{NaHCO}_{3}$. It is often used as an antacid because it neutralises excess of $\mathrm{HCl}$ secreted from the walls of stomach

$$ \mathrm{NaHCO} _{3}(\mathrm{~s})+\mathrm{HCl}(\mathrm{aq}) \rightarrow \mathrm{NaCl}(\mathrm{aq})+\mathrm{H} _{2} \mathrm{O}(l)+\mathrm{CO} _{2} $$

However, excessive hydrogen carbonate can make the stomach alkaline and trigger the production of even more acid.

Milk of magnesia, which is an aqueous solution of magnesium hydroxide is also used as an antacid.

• Sodium carbonate (Na2CO3) is not typically used as an antacid because it is a strong base and can cause a rapid increase in pH, leading to potential side effects such as alkalosis.

• Aluminium carbonate (Al2(CO3)3) is not used as an antacid because it is not very effective in neutralizing stomach acid and can cause constipation as a side effect.

Thinking Process

This question is based on the inter-relation between the antihistamines and antacids. Antihistaminies drugs are used in the treatment of hyperacidity came through the discovery accordig to which a chemical, histamine, stimulates the secreation of pepsin and hydrochloric acid in the stomach.

Answer

$(a, d)$

Histamine is a substance that stimulates the secretion of pepsin and hydrochloric acid. There are some antacids like cimetidine were designed to prevent the interaction of histamine with the receptors present in the stomach wall. As a result less $\mathrm{HCl}$ is released and the cause of hyperacidity is controlled/cured.

Ranitidine is also fall in the category of antihistamine. It is used to cure hyperacidity.

Brompheniramine is an antihistamine. It is used to treat runny nose, sneezing, itching and watery eyes caused by allergy.

Terfenadine, an antihistamine, was used for allergy.

• Brompheniramine is an antihistamine used to treat symptoms of allergy such as runny nose, sneezing, itching, and watery eyes. It is not an antacid and does not have any role in reducing stomach acid or treating hyperacidity.

• Terfenadine is an antihistamine that was used to treat allergic conditions. It does not have antacid properties and is not used to reduce stomach acid or treat hyperacidity.

Answer

$(a, d)$

Derivatives of barbituric acid viz., veronal and luminal are called barbiturates. These barbiturates constitute an important class of tranquilizers.

Tranquilizers are a class of chemical compounds used for the treatment of stress and mild or severe mental diseases. Tranquilizers are neurologically active drugs. These drugs affect the message transfer mechanism from nerve to receptor.

• (b) non-narcotic analgesic: Non-narcotic analgesics are drugs that relieve pain without causing sedation or sleep. Barbiturates, such as veronal and luminal, are not primarily used for pain relief but for their sedative and tranquilizing effects.

• (c) anti-allergic drugs: Anti-allergic drugs are used to treat allergic reactions by counteracting the effects of histamines. Barbiturates do not have anti-allergic properties and are not used to treat allergies.

Answer

$(a, d)$

Detergents are cleansing agents which have all the properties of soap, but which actually do not contain any soap. They are of three types which given below

1. Anionic detergents These are sodium salts of sulphonated long chain alcohols or hydrocarbons.

2. Cationic detergents These are quarternary ammonium salts of amines with acetates chlorides or bromides as anions e.g.,

3. Non-ionic detergents It is formed by the reaction of stearic acid with polyethylene glycol.

• Option (b): Ester of stearic acid and polyethylene glycol is incorrect because it describes a non-ionic detergent, not an anionic detergent. Non-ionic detergents are formed by the reaction of stearic acid with polyethylene glycol.

• Option (c): Quarternary ammonium salt of amine with acetate ion is incorrect because it describes a cationic detergent, not an anionic detergent. Cationic detergents are quarternary ammonium salts of amines with acetates, chlorides, or bromides as anions.

Answer

$(a, c, d)$

(a) Cationic detergents are quarternary ammonium salts of amines with acetates, chlorides or bromides as anions. These detergents have germicidal properties. Hence, option (a) is correct.

(b) Bacteria can not degrade the detergents containing highly branched chains, therefore, in most of the detergents used these days, the branching is kept to a minimum so that the detergents become easily biodegradable. Hence, option (b) is incorrect.

(c) Some synthetic detergents can give foam even in ice cold water. Hence, option (c) is correct.

(d) Synthetic detergents are cleansing agents which have all the properties of soaps, but which actually do not contain any soap. Hence, option (d) is correct.

• Bacteria can not degrade the detergents containing highly branched chains, therefore, in most of the detergents used these days, the branching is kept to a minimum so that the detergents become easily biodegradable. Hence, option (b) is incorrect.

Answer

Drugs are the chemicals of low molecular masses i.e., $(\sim 100-500 \mathrm{u})$. They interact with macromolecular targets and produce a biological response. When the biological response is therapeutic and useful, these chemicals are called medicines.

Answer

Chemical substances which are used in diagnosis, prevention and treatment of diseases which are called medicines.

Medicines are used in diagnosis, prevention and treatment of diseases.

Note If drugs taken in doses higher than those recommended, most of the drugs used as medicines are potential poisons. Use of chemicals for therapeutic effect is called chemotherapy.

Answer

Antiseptics are the antimicrobes. Antiseptics are the chemical which either kill or prevent the growth of microorganism and are safe to be applied to the living tissues e.g., soframicine. They can not be taken orally like antibiotics.

Answer

Disease in human beings and animals may be caused by a variety of microorganisms such as bacteria, virus, fungi and other pathogens.

An antimicrobial tends to destroy/prevent development or inhibit the pathogenic action of microbes such as bacteria (antibacterial drugs), fungi (antifungal agents), virus (antiviral agents), or other parasites (antiparasitic drugs) selectively. Antiseptic, disinfectants, antibiotics and sulpha drugs are antimicrobial drugs.

Answer

Receptors are proteins that are crucial to body’s communication process. Receptors are embedded on the outer surface of the cell membrane in such a way that their small part possessing active site projects out of the surface of the membrane and opens on the outside region of the cell membrane.

Answer

Hyperacidity produces sudden stomach pain. It may lead to vomiting, loss of appetite, flatulence and heart burn. It is also responsible for chronic indigestion and in severe cases cause gastric ulcers.

Answer

Sites different from active site of enzyme where a molecule can bind and change the shape of the active site is called allosteric site.

(Also, refer to $Q .16$ )

Answer

During the catalytic action of an enzyme, enzyme hold the substrate for a chemical reaction. Active sites of enzymes holds the substrate molecule in a suitable position, so that it can be attacked by the reagent effectively.

Substrate bind to the active site of the enzyme through a variety of interactions. These forces are van der Waals’ interactions, ionic bonding, hydrogen bonding or dipole-dipole interaction.

Answer

Arsphenamine is also known as salvarsan. It is a synthetic organic arsenic compound that was previously used for treating syphilis. Arsphenamine possess - As = As - linkage.

Azo dyes are used to promote epithelial growth in the treatment of ulcers, burns, and other wounds. Many azodyes have anticoagulation action. Azo dyes possess $-\mathrm{N}=\mathrm{N}-$ linkage like arsphenamine which possess - As $=\mathrm{As}$ - linkage .

Answer

Tranquilizers are essential components of sleeping pills. It is the class of chemical compounds used for the treatment of stress and mild or even severe mental diseases. These relieve anxiety stress, irritability or excitement by inducing a sense of well beings.

Answer

Aspirin is 2- acetoxybenzoic acid. It is very effective in reducing or abolishing pain without causing impairment of consciousness, mental confusion, incordination or paralysis or some other disturbance or disorder of the nervous system. It reduces fever (antipyretics) and prevents platelet coagulation.

Due to, it has anti blood clotting action and, therefore, it is widely used to prevent heart attack.

Answer

Histamine is a chemical substance that stimulates the secretion of pepsin and hydrochloric acid in stomach. Antacids are designed to prevent the interaction of histamine with the receptors present in the stomach wall. As a result, less $\mathrm{HCl}$ is released in stomach.

Histamine contracts the smooth muscles in the bronchi and gut and relaxes other muscles in walls of fine blood vessels. As a result, histamine causes allergy. Antihistamines interfere with the natural action of histamine by competing with histamine for binding sites of receptor where histamine exerts its effect.

Since, antiallergic and antacids drugs work on different receptors, therefore, antihistamines remove allergy while antacids remove acidity.

Answer

Chemical substances which concentrates at the surface of the solution or interfaces, from surface films, reduces surface tension of the solution and help in removing dirt and dust by emulsifying grease are called surfactants i.e., soap and detergents.

Soaps are sodium or potassium salts of long chain fatty acids such as palmitic acid $\left(\mathrm{C} _{15} \mathrm{H} _{31} \mathrm{COOH}\right)$, stearic acid $\left(\mathrm{C} _{17} \mathrm{H} _{3} \mathrm{COOH}\right)$ and linolic acid $\left(\mathrm{C} _{17} \mathrm{H} _{31} \mathrm{COOH}\right)$

Potassium salts of fatty acids such as palmitic acid, stearic acid and oleic acid are called soft soap.

Generally, potassium soap are soft to the skin so, they are named as soft soap.

Answer

A solution of soap is titrated with standard hydrochloric acid. It is an acid-base titration. In this titration, phenolphthalein is used as an indicator. During the preparation of soap, fat (i.e., glyceryl ester of fatty acid) is heated with aqueous sodium hydroxide

Thus, the source of this excess alkali (which irritates skin) is the alkali left unused when the soap is prepared by hydrolysis of fat.

Answer

Detergents have long hydrocarbon chains. If their hydrocarbon chain is highly branched, then bacteria cannot degrade this easily. Such detergents are non-biodegradable. Slow degradation of detergents leads to their accumulation.

These non-biodegradable detergents persist in water even after sewage treatment and cause foaming in rivers, ponds and their water get polluted. In order to overcome this issue branching of the hydrocarbon chain is controlled and kept to minimum.

Answer

Anionic detergents such as sodium lauryl sulphate, sodium dodecylbenzenesulphonate etc are used in toothpaste. They are responsible to clean the teeth and to provide a foam that helps to carry away the debris.

Further, sodium lauryl sulphates have significant antibacterial properties, and can penetrate as well as dissolve the plaque.

Answer

Hair shampoos are made up of cationic detergents. These are quarternary ammonium salts of amines with acetates, chlorides or bromides as anions, e.g., cetyltrimethyl ammonium bromide.

Answer

Dishwashing soaps are non-ionic detergents. It can be prepared by the reaction of stearic acid with polyethylene glycol.

$$ \begin{aligned} & \underset{\text { Stearic acid }}{\mathrm{CH} _{3}-(\mathrm{CH}) _{16} \mathrm{COOH}}+\mathrm{HO}-\left(\mathrm{CH} _{2} \mathrm{CH} _{2} \mathrm{O}\right) _{n}-\underset{\text { Polyethylene glycol }}{\mathrm{CH} _{2} \mathrm{CH} _{2} \mathrm{OH}} \xrightarrow{-\mathrm{H} _{2} \mathrm{O}} \\ & \mathrm{CH} _{3}-\left(\mathrm{CH} _{2}\right) _{16} \mathrm{COO}\left(\mathrm{CH} _{2} \mathrm{CH} _{2} \mathrm{O}\right) _{n} \mathrm{CH} _{2} \mathrm{CH} _{2} \mathrm{OH} \end{aligned} $$

Since, non-ionic detergents do not contain any ion in their constitution, it is neutral in nature.

Answer

Sodium lauryl sulphate, $\mathrm{CH} _{3}\left(\mathrm{CH} _{2}\right) _{10} \mathrm{CH} _{2} \mathrm{OSO} _{3}^{-} \stackrel{+}{\mathrm{N}}$ a is an example of anionic detergent.

When added to water, it dissociates as follows

$$ \mathrm{CH} _{3}-\left(\mathrm{CH} _{2}\right) _{10}-\mathrm{CH} _{2} \mathrm{OSO}^{-}{ } _{3} \stackrel{+}{\mathrm{Na}} \stackrel{+\mathrm{H} _{2} \mathrm{O}}{\longrightarrow} \mathrm{CH} _{3}-\left(\mathrm{CH} _{2}\right) _{10} \mathrm{CH} _{2}-\mathrm{OSO}^{-}{ } _{3}+\stackrel{+}{\mathrm{Na}} $$

These anions are present on the surface with their $-\mathrm{OSO}_{3}^{-}$groups in water and hydrocarbon part staying away from it and remain at the surface.

At higher concentration, these anions are pulled into the bulk of the solution and form an aggregate of spherical shape with their hydrocarbon part pointing towards the centre and $\mathrm{OSO}_{3}^{-}$part outwards on the surface of the sphere.

An aggregate thus formed is known as micelle.

Answer

Detergents having highly branched hydrocarbon chains cause pollution in rivers. The reason being that side chains stop bacteria from attacking and breaking the chains.

Thus, lesser the branching more is the biodegradability i.e., detergents with long straight hydrocarbon chains are more easily degraded than those having branched hydrorcarbon chains.

Since, unbranched (i.e., straight) chains are more prone to attack by bacteria, therefore, in most of the detergents used these days, the branching is kept to be minimum, so that the detergents become easily biodegradable.

Answer

Soaps are biodegradable while detergents containing branched hydrocarbon chains are quite stable, i.e., they are not degraded by the action of microorganism and therefore it cause water pollution in rivers and other water ways.

Answer

Analgesics reduce or abolish pain without causing impairment of consciousness, mental confusion, incoordination or paralysis or some other disturbances of nervous system.

These are classified in two groups

(i) Non-narcotic analgesics These are non-addictive analgesics e.g., aspirin.

(ii) Narcotic analgesics Morphine is an example of narcotic analgesics.

Answer

Noradrenaline is a neuro-transmitter which plays an crucial role in mood changes. If any person has low level of noradrenaline, then the message transfer process becomes slow and the person feeling of depression.

Answer

Antiseptics and disinfectants both are antimicrobials. Antiseptics prevent or destroy development or inhibit the pathogenic action of microbes. They are safe to be applied on living tissues.

On the other hand, disinfectants also kill microorganisms but are not safe to be applied on living tissues. They are generally applied on non-living objects such as drains, toilets, floors and living rooms infected with bacteria and disease carrying germs.

Answer

Magnesium hydroxide $\left[\mathrm{Mg}(\mathrm{OH})_{2}\right]$ is a better antacid because being insoluble it does not allow the $\mathrm{pH}$ to increase above neutrality. On the other hand, sodium hydrogen carbonate being soluble and its excess amount can make the stomach alkaline and trigger the production of even more acid.

Answer

Analgesics reduce or abolish pain without causing impairment of consciousness, mental confusion, incoordination or paralysis or some other disturbances of nervous system. These are classifieds in two categories

(i) Non-narcotic (non-addicitive) analgesics - Aspirin and paracetamol belong to the class of non-narcotic analgesics.

(ii) Narcotic analgesics-Morphine and many of its homologues, when administered in medicinal doses, relieve pain and produce sleep. In poisonous doses, these produce stupor, coma, convulsions and ultimately death. Morphine narcotics are sometimes referred to as opiates, since they are obtained from the opium poppy.

Answer

Narcotic analgesics (morphine and many of its homologous) when administered in medicinal doses, relieve pain and produce sleep. Since, these drugs relieve pain and produce sleep, therefore are chiefly used for the relief of postoperative pain, cardian pain and pains of terminal cancer, and in child birth.

Answer

Drugs that bind to the receptor site and inhibit its natural function are called antagonist, drugs e.g., cimetidine is an antagonist drug because it binds to the receptor site in stomach otherwise histamine will bind to the receptor site and induce the secretion of $\mathrm{HCl}$ in stomach.

Thus, this antacid blocks the receptor site and hence, the secretion of $\mathrm{HCl}$ is reduced thereby reducing/removing hyperacidity.

Answer

An antimicrobes tend to destroy/prevent development or inhibit the pathogenic action of microbes such as bacteria, fungi, virus or other parasites selectively. Thus, antimicrobial are drugs which cure diseases caused by microorganisms.

Answer

Soaps are sodium or potassium salts of long chain fatty acids such as stearic acid, oleic acid and palmitic acid. Soaps containing sodium salts are formed by heating fat (i.e., glyceryl ester of fatty acid) with aqueous sodium hydroxide

Show Answer

Answer

This reaction is known as saponification. In this reaction, esters of fatty acids are hydrolysed and the soap obtained remains in colloidal form. It is precipitated from the solution by adding $\mathrm{NaCl}$. The solution left after removing the soap contains glycerol as side product.

61. What is the difference between bathing soap and washing soaps?

62. How are transparent soaps manufactured?

63. What is the advantage of using antihistamines over antacids in the treatment of acidity?

64. What are the functions performed by histamine in the body?

65. With the help of an example explain how do tranquilizers control the feeling of depression?

66. Why are certain drugs called enzyme inhibitors?

Answer

Substances which are added to soaps to change their properties in order to make them more useful for a particular application, are called fillers. Some important examples are given below

(i) Sodium rosinate, sodium silicate, borax and sodium carbonate are added to laundary soaps to increase their lather forming ability.

(ii) Glycerol is added to shaving soaps to prevent them from rapid drying.

(iii) In medicated soaps, substances of medicinal values are added.

Answer

Natural sweetners e.g., sucrose add to calorie intake. Due to occurrence of more cases of diabetes and obesity among young and old people, these days people usually take low calorie drinks. These are artificial sweetening agents as given below

Saccharin It is 550 times as sweet as cane sugar. It is excreted from the body through urine.

Aspartame It is 100 times as sweet as cane sugar. Its use is limited to cold foods and soft drinks because it is unstable at cooking temperature.

Alitame It is more stable than aspartame but the control of sweetners of food is difficult while using it.

Sucralose It is stable at cooking temperature. It does not provide calories.

These artificial sweetening agents do not metabolize and hence do not produce any energy.

Answer

Plenty of salt and cover of oil act as preservatives. These food preservatiues prevent spoilage of food due to microbial growth. Salt and oil do not allow moisture and air to enter the material and hence bacteria cannot thrive on them. Therefore, pickles do not get spoiled for months together.

Answer

Saccharin is an artificial sweetening agent. It is about 550 times as sweet as cane sugar. It is excreted from the body in urine unchanged. It appears to be entirely inert and harmless when taken. Its use is of great value to diabetic people who need to control intake of calories.

On the other hand, saccharic acid, is a dibasic acid obtained by the bacterial oxidation of glucose in the mouth or by conc. $\mathrm{HNO}_{3}$ in the laboratory.

Answer

Sucralose is trichloro derivative of the sucrose. Its appearance and taste are like sugar. It is stable at cooking temperature. Sucralose contributes zero calories to the diet, compared with sucrose, which contributes 16 calories per teaspoon. Structure of sucralose is

Answer

Aspartame is the most successful and widely used artificial sweetener. It is methyl ester of dipeptide formed from aspartic acid and phenylalanine. Its use is limited to cold foods and soft drinks because it is unstable at cooking temperature.

Structure of aspartame is

Answer

Aspartame is used in cold foods and soft drinks. It is an artifical sweetening agent. (Also, refer to $Q .72$ )

Answer

A preservative is naturally occuring or synthetically produced substance that is added to foods to prevent decomposition by microbial growth or by undesirable chemical changes. Sodium salts of same acids are very useful as food preservatives. Some examples of such acids are as follows

(i) Benzoic acid in the form of its sodium salt, constitutes one of the most common food preservative. Sodium benzoate is a common preservative in acid or acidified foods such as fruit, juices, pickles etc. Yeasts are inhibited by benzoate to a greater extent than are moulds and bacteria.

(ii) Sorbic acid and its salts (sodium, potassium and calcium) also have preservative activities but the applications of sodium sorbate $\mathrm{C} _{6} \mathrm{H} _{7} \mathrm{NaO} _{2}$ are limited compared to that for potassium salt.

(iii) Sodium erythorbate $\mathrm{C} _{6} \mathrm{H} _{7} \mathrm{NaO} _{6}$ is a food additive used predominate in meats, poultry and soft drinks.

(iv) Sodium propanoate $\mathrm{Na}\left(\mathrm{C} _{2} \mathrm{H} _{5} \mathrm{COO}\right)$ is used in bakery products as mold inhibitor.

Answer

Some drugs do not bind to the active site of enzymes to inhibit their activities. These bind to a different site of enzyme. This binding of inhibitor (drug) changes the shape of the active site in such a way that substrate cannot recognise it.

The site different from active site of an enzyme where a drug molecule can bind is called the allosteric site.

Non-competitive inhibitor changes the active site of enzyme after binding at allosteric site.

Non-competitive inhibitor changes the active site of

enzyme after binding at allosteric site

Answer

Receptor proteins are embedded in the cell membrane in such a way that their small part possessing active site projects out of the surface of the it membrane and opens on the outside region of the cell membrane.

Receptor protein embedded in the cell membrane, the active site of the receptor opens on the outside region of the cell

Answer

Generally, a weak bond such as H-bonding, van der Waals’ interactions, etc., is formed between the enzyme and inhibitor. If a strong covalent bond is formed between the enzyme and the inhibitor which cannot be broken easily, then the enzyme is blocked permanently. The body then degrades the enzyme-inhibitor complex and synthesises the new enzyme.

Answer

A. $\rightarrow(3)$

B. $\rightarrow(4)$

C. $\rightarrow(1)$

D. $\rightarrow(2)$

A. Ranitidine It prevents the interaction of histamine with the receptors present in the stomach wall. Thus, it controls the secretion of $\mathrm{HCl}$ and pepsin in stomach.

B. Furacine Furacine is an antiseptic. It can be applied to the living tissues to kill or to prevent the growth of microorganisms.

C. Phenelzine It is also known as Nardil. Its structure is

It is used to treat depression.

D. Chloramphenicol it is a broad spectrum antibiotic. It can be given orally in case of typhoid, acute fever, dysentary, certain urinary infections, meningitis and pneumonia.

Answer

A. $\rightarrow(2)$

B. $\rightarrow(1)$

C. $\rightarrow(4)$

D. $\rightarrow(3)$

A. Soap chips are made by running a thin sheet of melted soap into a cool cylinder and scraping off the soaps in small broken pieces.

B. Soap granules are dried miniature soap bubbles.

C. Soap powders contain soap powder and builders like sodium carbonate and trisodium phosphate. Builders make the soap act more rapidly.

D. Scouring soaps contain soap powder, a scouring agent (abrasive) such as powdered pumice or finely divided sand and builders.

Answer

A. $\rightarrow$ (3)

B. $\rightarrow(4)$

C. $\rightarrow(2)$

D. $\rightarrow(1)$

Non-ionic detergent - $\mathrm{CH} _{3}\left(\mathrm{CH} _{2}\right) _{16} \mathrm{COO}\left(\mathrm{CH} _{2} \mathrm{CH} _{2} \mathrm{O}\right) _{n}, \mathrm{CH} _{2} \mathrm{CH} _{2} \mathrm{OH}$

Soap $-\mathrm{C} _{17} \mathrm{H} _{35} \mathrm{COO}^{-} \mathrm{Na}^{+}$

Anionic detergent $-\mathrm{CH} _{3}-\left(\mathrm{CH} _{2}\right) _{10} \mathrm{CH} _{2} \mathrm{SO} _{3}^{-} \mathrm{Na}^{+}$

Cationic detergent $-\left[\mathrm{CH} _{3}\left(\mathrm{CH} _{2}\right) _{15}-\left.\right| _{\mathrm{CH} _{3}} ^{\mathrm{N}}-\mathrm{CH} _{3}\right]^{+} \mathrm{Br}^{-}$

Answer

A. $\rightarrow$ (3)

B. $\rightarrow(4)$

C. $\rightarrow(2)$

D. $\rightarrow(1)$

A. Hair shampoos/conditioners are made up of cationic detergents. These are quarternary ammonium salts of amines with chlorides, bromides or acetates, e.g., cetyltrimethyl ammonium bromide.

B. Anionic detergents are used in toothpaste e.g., sodium dodecyl benzene sulphonate. It can be prepared as follows

C. Laundary soaps contain fillers like soidum rosinate. Sodium silicate, borax and sodium carbonate. Sodium rosinate makes the soap to lather well.

D. Dishwashing powder are non-ionic detergents

$$ \mathrm{H} _{3} \mathrm{C}-\left(\mathrm{CH} _{2}\right) _{16} \mathrm{COO}\left(\mathrm{CH} _{2} \mathrm{CH} _{2} \mathrm{O}\right) _{n} \mathrm{CH} _{2} \mathrm{CH} _{2} \mathrm{OH} $$

Answer

A. $\rightarrow(2)$

B. $\rightarrow(4)$

C. $\rightarrow(1)$

D. $\rightarrow(5)$

E. $\rightarrow$ (3)

A. Antagonist drugs are used when blocking of message is required. e.g., dopamine antagonist is a drug which blocks the dopamine receptors by receptor antagonism.

B. Agonist drugs are useful when there is lack of chemical messenger. e.g., heroin.

C. These chemical messengers are received at the binding sites of receptor. These communicate message between two neurons and that between neurons to muscles.

D. Inhibitors block the binding site of the enzyme and prevent the binding of the substrate, or inhibit the catalytic activity of the enzyme.

E. Receptors are proteins that are crucial to body’s communication. They are embedded in the cell membrane in such a way that their small part possessing active site projects out of the surface of the membrane and opens on the outside region of the cell membrane.

Answer

A. $\rightarrow(5)$

B. $\rightarrow(6)$

C. $\rightarrow(4)$

D. $\rightarrow(7)$

E. $\rightarrow(2) \quad$

F. $\rightarrow(1)$

G. $\rightarrow(3)$

A. Analgesics reduce or abolish pain without causing impairment of consciousness, mental confusion, in coordination or paralysis or some other disturbances of nervous system, e.g., aspirin.

B. Antiseptics are the chemicals which either kill or prevent the growth of mircoorganisms. They are applied to living tissues such as wounds, cuts etc., e.g., tincture of iodine.

C. Antihistamines are anti-allergic drugs. These drugs interfere with the natural action of histamine by competing with histamine for binding sites of receptor where histamine exerts its effect. e.g., seldane.

D. Antacids are used to neutralise excess of acid released in stomach e.g., mixture of $\mathrm{Mg}(\mathrm{OH}) _{2}$ and $\mathrm{Al}(\mathrm{OH}) _{3}$.

E. Tranquilizers are used for the treatment of stress, and mild or even severe mental diseases e.g., equanil.

F Antibiotics are antimicrobial drugs. Antibiotics are used as drugs to treat infections because of their low toxicity for humans and animals e.g., chloramphenicol.

G. Disinfectants are the chemicals which either kill or prevent the growth of microorganisms but they can be applied on non-living objects e.g., 1 per cent solution of phenol.

Answer

(c) Both assertion and reason are wrong statements. Correct assertion Penicillin $(G)$ is an antibiotic.

Correct reason Penicillin is effective against some gram positive bacteria.

Answer

(d) Asssertion is correct statement reason is wrong statement. Correct reason Salvarsan is a antibacterial but does not contain sulphonamide group.

Answer

(a) Assertion and reason both are correct statements but reason does not explain assertion. Correct Explanation Neurotransmitters are small molecules which bind to the receptor for a very short time to transfer message to it and depart quickly unchanged after transferring the message. The receptor then forwards the message inside the cell.

Answer

(d) Assertion is correct statement reason is wrong statement Correct reason Drug compete with natural substrate by attaching by weak bonds such as hydrogen bond, van der Waals’, interaction and ionic bonding etc., to the active site of the enzyme.

Answer

(d) Assertion is correct statement reason is wrong statement. Correct reason Chemicals bind to the receptor sites present on the surface of the membrane or the cell. They give message to the cell without entering the cell.

Answer

(d) Assertion is correct statement reason is wrong statement. Correct reason Ethanol removes air and moisture which scatter light.

Answer

(b) Assertion and reason both are correct and reason explains the assertion. Sodium chloride is added to precipitate soap after saponification because hydrolysis of esters of long chain fatty acids by alkali produces soap in colloidal form.

Answer

(d) Assertion is correct statement reason is wrong statement. Correct reason In competitive inhibition, inhibitor binds to the active site of the enzyme.

Answer

(e) Assertion is wrong statement reason is correct statement. Correct assertion Non-competitive inhibitor inhibits the catalytic activity by binding the enzyme at allosteric site.

Answer

(b) Assertion and reason both are correct and reason explains the assertion. Chemical messenger gives message to the cell without entering the cell because it is received at the binding site of receptor proteins.

Answer

(d) Assertion is correct statement reason is wrong statement. Correct reason Chemical messenger binds the receptor site and gives the message to the cell without entering the cell.

Answer

(c) Both assertion and reason are wrong statements. Correct assertion Chemicals which are used to protect food against bacteria, yeasts and moulds are called food preservatives.

Correct reason Preservatives do not increase the nutritive values of food.

Answer

(b) Assertion and reason both are correct and reason explains the assertion. Preservatives are added to food items because it inhibit the growth of microorganisms

Answer

(b) Assertion and reason both are correct and reason explains the assertion. Aritificial sweeteners are added to the food to control the intake of calories because most of the artificial sweeteners are inert and do not metabolise in the body.

Answer

Prontosil, also called sulfamido chrysoidine, trade name of the first synthetic drug used in the treatment of general bacterial infections in humans.

Prontosil resulted from research, directed by German chemist and pathologist Gerhard Domagk, on the antibacterial action of azo dyes. A red azo dye of low toxicity, prontosil was shown by Domagk to prevent mortality in mice infected with Streptococcus bacteria.

The dye was also effective in controlling staphylococcus infections in rabbits. Within a relatively short period, it was demonstrated that prontosil was effective not only in combating experimental infections in animals but also against Streptococcal disease in humans, including meningitis and puerperal sepsis. Structural formula of prontosil is

From the structure of prontosil, it is very clear that it has $-\mathrm{N}=\mathrm{N}$ - linkage. It was discovered that the part of the structure of prontosil molecule shown in box, i.e., p-aminobenzenesulphonamide has antibacterial activity.

Salvarsan is also known as arsphenamine. It was introduced at the begining of 1910 s as the first effective treatment for syphilis. It is an organoarsenic molecule and has - As $=$ Asdouble bond.

Salvarsan and prontosil show similarity in their structure. Both of these drugs are antimicrobials. Salvarsan contains $-\mathrm{As}=\mathrm{As}-$ linkage whereas prontosil has $-\mathrm{N}=\mathrm{N}-$ linkage.

Prontosil (a red azo dye) and azo dye both have $-\mathrm{N}=\mathrm{N}-$ linkage.

Answer

In the catalytic activity, enzymes perform the following two major functions

(i) The first function of an enzyme is to hold the substrate molecule for a chemical reaction. the active sites of the enzymes hold the substrate molecule in a suitable position, so that it can be attacked by the reagent effectively.

The substrate molecules bind to the amino acid residues of the protein present the active site of the enzyme through a variety of interactions such as hydrogen bonding, dipole-dipole interactions, van der Waals’ interactions and ionic bonding.

These binding forces should be strong enough to hold the substrate long enough so that the enzyme can catalyse the reaction, but weak enough to allow the products to depart after their formation.

Active site of enzyme

Substrate

(ii) The second function of the enzyme is to provide functional groups which will attack the substrate to carry out the chemical reaction. This function is carried out by some other amino acid residues of protein present on the active site of the enzyme.

These provide free amino groups to attack the substrate and bring about the chemical reaction. If the amino acid serine is present nearby the substrate held on the active site, then its $-\mathrm{OH}$ group is free to act as a nucleophile in the enzyme catalysed reaction.

L-serine

The part of the amino acid which lies outside the box act as a nucleophile in enzyme catalysed reactions, but the part of the amino acid which is enclosed in the box is involved in the formation of peptide bond in protein molecule.

Answer

Synthetic detergents are cleansing agents which have all the properties of soaps, but which actually do not contain any soap. These can be used in soft as well as in hard water.

They are mainly classified into three categories

(1) Anionic Detergents

Anionic detergents are sodium salts of sulphonated long chain alcohols or hydrocarbons. Alkyl hydrogen sulphates formed by treating long chain alcohols with conc. $\mathrm{H} _{2} \mathrm{SO} _{4}$ are neutralised with alkali to form anionic detergents. Similarly alkyl benzene sulphonates are obtained by neutralising alkyl benzene sulphonic acids with alkali.

In these detergents, the anionic part of the molecule is involved in the cleansing action. They are mostly used for house hold work. They are also used in toothpaste.

(2) Cationic Detergents

They are quarternary ammonium salts of amines with acetates, chlorides or bromides as anions. Cationic part possess a long hydrocarbon chain and a positive charge on nitrogen atom. Cetyltrimethylammonium bromide is a popular cationic detergent and is used in hair conditioners.

Cationic detergents have germicidal properties and are expensive, therefore, these are of limited use.

(3) Non-ionic Detergents

Non-ionic detergents do not contain any ion in their constitution. One such detergent is formed when stearic acid reacts with polyethylene glycol.

$$ \begin{aligned} & \underset{\text { Stearic acid }}{\mathrm{H} _{3} \mathrm{C}-\left(\mathrm{CH} _{2}\right) _{16} \mathrm{COOH}}+\mathrm{HO}\left(\mathrm{CH} _{2} \mathrm{CH} _{2} \mathrm{O}\right) _{n} \mathrm{CH} _{2} \mathrm{CH} _{2} \mathrm{OH} \xrightarrow{\text {polyethyleneglycol }} \xrightarrow{-\mathrm{H} _{2} \mathrm{O}} \\ & \quad \underset{\substack{\text { Polyethyleneglycol stearate }}}{\mathrm{CH} _{3}\left(\mathrm{CH} _{2}\right) _{16} \mathrm{COO}\left(\mathrm{CH} _{2} \mathrm{CH} _{2} \mathrm{O}\right) _{n} \mathrm{CH} _{2} \mathrm{CH} _{2} \mathrm{OH}} \end{aligned} $$

Liquid dishwashing detergents are non-ionic type

Advantages of Synthetic Detergents over Soaps

(i) Synthetic detergents can be used in hard water without any wastage while some of the soaps gets wasted.

(ii) Synthetic detergents can be used in acidic medium while soaps get precipitated.

(iii) Synthetic detergents are more soluble in water and hence produce lather more easily than soaps. Some synthetic detergents produce lather even in ice cold water.

(iv) Synthetic detergents decrease the surface tension of water to greater extent and hence have a stronger cleansing action than soap.

Synthetic detergents have advantages over usual soaps but use of synthetic detergents over a long time creates environmental pollution because some detergents have highly branched hydrocarbon chains.

These branches or side chains stop bacteria from attacking and breaking the chains. This result in slow degradation of detergent molecule leading to their accumulation. Effluents containing these detergents reach the rivers, ponds etc. These persist in water even after sewage treatment and thus water gets polluted.

Since, unbranched (i.e., straight) chains are more prone to attack by bacteria, therefore, in most of the detergents used these days, the branching is kept to a minimum, so that the detergents become easily biodegradable and hence pollution is prevented.

Answer

Enzymes are responsible to hold the substrate molecule for a chemical reaction and they provide functional groups which will attack the substrate to carry out the chemical reaction. Drugs which inhibit any of the two activities of enzymes are called enzyme inhibitors.

Enzyme inhibitors can block the binding site thereby preventing the binding of the substrate to the active site and hence inhibiting the catalytic activity of the enzyme.

Drugs inhibit the attachment of natural substrate on the active site of enzymes in two different ways as explained below

(i) Drugs which compete with natural substrate for their attachment on the active sites of enzymes are called competitive inhibitors.

(ii) Some drugs, however, do not bind to the active site but bind to a different site of the enzyme which is called allosteric site. This binding of the drug at allosteric site changes the shape of the active site of the enzyme in such a way that the natural substrate cannot recognise it. Such enzymes are called non-competitive inhibitors.