NCERT Solutions Class 12 Chemistry Chapter 16 Chemistry in Everyday Life
1. Why do we need to classify drugs in different ways ?
Answer:
The reason for the drug’s classification is as follows:
(i) The pharmacological impact is based on:
To physicians this definition is helpful. It provides a whole array of drugs to classify drugs to different diseases.
(ii) Based on action on the drugs:
This is based on a drug’s action on a specific biochemical process.
(iii) Building on chemical structure:
The range of drugs that share common structural characteristics and have similar pharmacological activity.
(iv) Building on molecular objectives:
Many medications have the same action function on targets. In such cases this distinction is useful.
2. Explain the term, target molecules or drug targets as used in medicinal chemistry.
Answer:
The drug targets are the key molecule responsible for some metabolic pathways that can cause specific diseases. The drug targets are proteins, nucleic acids, carbohydrates and lipids.
Chemical agents used to block those target molecules are called drugs by fusing with the active sites of key molecules.
3. Name the macromolecules that are chosen as drug targets.
Answer:
Carbohydrates, lipids, proteins and nucleic acids are the macromolecules selected as targets for the drugs.
4. Why should medicines not be taken without consulting doctors?
Answer:
Medicines should not be taken without consulting a doctor because it can bind to more than one receptor site. Thus it can be harmful to some receptor sites. Medicines, when taken in higher doses, can cause harmful effects. So medicines can be poisonous.
5. Define the term chemotherapy.
Answer:
Chemotherapy is the use of chemicals for medicinal effects. Sources are the use of chemical agents for disease prevention, diagnosis and treatment.
6. Which forces are involved in holding the drugs to the active site of enzymes ?
Answer:
The forces responsible are
(1) Hydrogen bonding
(2) Ionic bonding
(3) van der Waals force
(4) Dipole-dipole interaction
7. While antacids and antiallergic drugs interfere with the function of histamines, why do these not interfere with the function of each other?
Answer:
Certain drugs only affect specific receptors. Antacids and antiallergic drugs do not interfere, as they work on different receptors. That is why antacids and antiallergic drugs interfere with histamine function but not with each other.
8. Low level of noradrenaline is the cause of depression. What type of drugs are needed to cure this problem ? Name two drugs.
Answer:
Antidepressant drugs are used to lessen the depression effect. These drugs contain enzymes that catalyze the degradation of the neurotransmitter, noradrenaline. The neurotransmitter is therefore slowly metabolized and can activate the receptor for a longer period of time.
The two anti-depressant drugs are:
1. Phenelzine
2. Iproniazid
9. What is meant by the term ‘broad spectrum antibiotics’ ? Explain.
Answer:
Antibiotics are known as broad-spectrum antibiotics, which are effective against a wide range of gram-negative and gram-positive bacteria. Eg: Chloramphenicol
This is used to treat acute fever, typhoid, meningitis, dysentery, tuberculosis and certain types of urinary tract infection. The other 2 broad-spectrum antibiotics are vancomycin and ofloxacin. Amoxicillin and ampicillin −synthetically derived from penicillin-, are also antibiotics of broad-spectrum.
10. How do antiseptics differ from disinfectants? Give one example of each.
Answer:
Disinfectants and antiseptics against micro-organisms are really successful. Antiseptics are used to treat living tissues such as cuttings, wounds, diseased skin surfaces and ulcers, while disinfectants are used for objects such as floors, drainage systems, instruments, etc. Disinfectants damage living tissues.
Iodine is a potent antiseptic. The iodine tincture is applied to wounds. One percent phenol solution is used as a disinfectant.
11. Why are cimetidine and ranitidine better antacids than sodium hydrogencarbonate or magnesium or aluminium hydroxide?
Answer:
The antacids that neutralize excess hydrochloric acid in the stomach are magnesium hydroxide, sodium hydrogen carbonate, and aluminium hydroxide. However, the motive for releasing excess acid remains untreated.
Cimetidine and ranitidine are good antacids because they control the acidity cause. These drugs prevent histamine from interacting with the receptors with the present in the walls of the stomach, and can, therefore, reduce the amount of acid released by the stomach.
12. Name a substance which can be used as an antiseptic as well as a disinfectant.
Answer:
Phenol is the substance which can be used as an antiseptic and as a disinfectant. 0.2 percent phenol solution can be used as an antiseptic and 1 percent of the solution should be used for disinfectant.
13. What are the main constituents of Dettol?
Answer:
Dettol’s principal constituents are chloroxylenol and α−terpineol.
14. What is tincture of iodine ? What is its use?
Answer:
For alcohol-water mixtures, 2-3 percent of iodine is referred to as iodine tincture and is primarily added to wounds.
15. What are food preservatives ?
Answer:
Chemicals that prevent microbial growth are referred to as preservatives for food. They cut back on spoilage. Some food preservatives are sugar, table salt, vegetable oil, propanoic acid salts and sodium benzoate(C6H5COONa).
