Chemistry Class 12 NCERT Solutions: Chapter 16 Chemistry in Everyday Life Part 1

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


The classification of drugs and the reasons for classification are as follows:

(i) On the basis of pharmacological effect:

This classification provides doctors the whole range of drugs available for the treatment of a particular type of problem. Hence, such a classification is very useful to doctors.

(ii) On the basis of drug action:

This classification is based on the action of a drug on a particular biochemical process. Thus, this classification is important.

(iii) On the basis of chemical structure:

This classification provides the range of drugs sharing common structural features and often having similar pharmacological activity.

(iv) On the basis of molecular targets:

This classification provides medicinal chemists the drugs having the same mechanism of action on targets. Hence, it is the most useful to medicinal chemists.

Q: 2. Explain the term target molecules or drug targets as used in medicinal chemistry.


In medicinal chemistry, drug targets refer to the key molecules involved in certain metabolic pathways that result in specific diseases. Carbohydrates, proteins, lipids, and nucleic acids are examples of drug targets.

Drugs are chemical agents designed to inhibit these target molecules by binding with the active sites of the key molecules.

Q: 3. Name the macromolecules that are chosen as drug targets.


The macromolecules chosen as drug targets are carbohydrates, lipids, proteins, and nucleic acids.

Q: 4. Why should not medicines be taken without consulting doctors?


A medicine can bind to more than one receptor site. Thus, a medicine may be toxic for some receptor sites. Further, in most cases, medicines cause harmful effects when taken in higher doses than recommended. As a result, medicines may be poisonous in such cases. Hence, medicines should not be taken without consulting doctors.

Q: 5. Define the term chemotherapy.


The use of chemicals for therapeutic effect is called chemotherapy. For example: the use of chemicals in the diagnosis, prevention, and treatment of diseases

Q 5 Meaning Of Chemotherapy

Q 5 Meaning of Chemotherapy

Q 5 Meaning Of Chemotherapy

Q: 6. Which forces are involved in holding the drugs to the active site of enzymes?


Either of the following forces can be involved in holding drugs to the active sites of enzymes.

(i) Ionic bonding

(ii) Hydrogen bonding

(iii) Dipole-dipole interaction

(iv) van der waals force

Q: 7. While antacids and antiallergic drugs interfere with the function of histamines, why do these not interfere with the function of each other?


Specific drugs affect particular receptors. Antacids and anti-allergic drugs work on different receptors. This is the reason why antacids and anti-allergic drugs do not interfere with each other’s functions, but interfere with the functions of histamines.

Q: 8. Low level of noradrenaline is the cause of depression. What types of drugs are needed to cure this problem? Name two drugs.


Anti-depressant drugs are needed to counteract the effect of depression. These drugs inhibit enzymes catalysing the degradation of the neurotransmitter, noradrenaline. As a result, the important neurotransmitter is slowly metabolised and then it can activate its receptor for longer periods of time.

Two anti-depressant drugs are:

(i) Iproniazid

(ii) Phenelzine

Q: 9. What is meant by the term ‘broad spectrum antibiotics’? Explain.


Antibiotics that are effective against a wide range of gram-positive and gram-negative bacteria are known as broad-spectrum antibiotics. Chloramphenicol is a broad spectrum antibiotic.

Q 9 Structure of Chloramphenicol

Q 9 Structure of Chloramphenicol

Q 9 Structure of Chloramphenicol

It can be used for the treatment of typhoid, dysentery, acute fever, pneumonia, meningitis, and certain forms of urinary infections. Two other broad-spectrum antibiotics are vancomycin and ofloxacin. Ampicillin and amoxicillin −synthetically modified from penicillin − are also broad-spectrum antibiotics.