NCERT Class 12 Biology: Chapter –8 Human Health and Diseases Part 7

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Question 8:

The following table shows certain diseases, their causative organisms and symptoms. Fill the gaps.

Chapter-8- Question -8- Table of Shows Certain Diseases

Name of the Disease

Causative organism









Appearance of dry, scaly lesions on various parts of the body




High fever, weakness, headache, stomach pain, constipation.



Streptococcus pneumoniae




Rhino viruses

Nasal congestion and discharge, sore throat, cough, headache




Inflammation in lower limbs


(i) Internal bleeding, muscular pain, anemia, fever, blockage of intestinal passage.

(ii) Ringworm

(iii) Salmonella typhi

(vi) Fluid in lungs, fever, difficulty in breathing

(v) Common cold

(vi) Wuchereria

Question 9:

The outline structure of a drug is given below.

a. Which group of drugs does this represent?

b. What are the modes of consumption of these drugs?

c. Name the organ of the body which is affected by consumption of these drugs.

Consumption of these drugs

Consumption of These Drugs

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(a) Cannabinoids

(b) Inhalation and oral ingestion

(c) Cardiovascular system

Question 10:

Give the full form of CT and MRI. How are they different from each other? Where are they used?


CT: Computed Tomography

MRI: Magnetic Resonance Imaging

Computed Tomography Magnetic Resonance Imaging



i. Computed tomography

i. Magnetic resonance imaging

ii. Uses X – ray for imaging

ii. Uses magnetic field and non-ionising radiations.

iii. It generates three – dimensional image of the internals of an object.

iii. It accurately detects pathological and physiological changes in living tissues.

Question 11:

Many secondary metabolites of plants have medicinal properties. It is their misuse that creates problems. Justify the statement with an example.


Many secondary metabolites of plants have medicinal properties but their misuse creates problems because they could be drugs like opium, heroin, LSD etc. which are the chemical compounds that act on receptor of the brain They make a person relax, improves their strength, free from pain, nausea and anxiety.

Question 12:

Why cannabinoids are banned in sports and games?

Answer:Cannabinoids are the chemical compounds that act on the Cannabinoid receptor of the brain irrespective of their origin. They make a person relax, improves their strength, free from pain, nausea and anxiety. Example: CBGA, THCA etc.

These drugs are banned in sports as they are known to enhance performance and have an adverse effect on the player’s health in a long run.

Question 13:

What is secondary metabolism?


These are small pathways or products that are not necessarily important for the growth or survival of an organisms hence are termed as secondary metabolites like antibiotics and pigments produced in bacteria, fungi etc.

Question 14:

Drugs and alcohol give short-term ‘high’ and long-term ‘damages’,


Answer:Drugs and alcohol give short-term ‘high’ and long-term ‘damages’ this statement holds true because:

1. Alcohol and drugs may irritate the lining of the stomach and can trigger nausea, vomiting and other gastric troubles.

2. As alcohol is a CNS (Central Nervous System) depressant it may slow down various bodily functions like breathing, heart rate etc.

3. The dependency on alcohol makes a person depressed.

4. The person may suffer from constant fatigue, sleepiness or sleeplessness.