Chapter 8: Human Health and Disease – Case-Based Questions with Answers

CBSE Class 12 Biology Case-Based Questions (NCERT): Human Health and Disease

Course & Examination Details

Course: CBSE Class 12 Biology
Unit: Unit III – Biology and Human Welfare
Chapter: Chapter 8 – Human Health and Disease
Prescribed Textbook: NCERT Biology Class XII
Examination: CBSE Class 12 Board Examination
Question Type: Case-Based / Source-Based Questions
Syllabus Alignment: Strictly as per NCERT

Section A: Health and Its Significance

Case 1

A person is free from illness but suffers from stress and social isolation.
Q. Is this person healthy? Give reason.
Answer: No. Health includes physical, mental, and social well-being. Stress and social isolation indicate poor mental and social health.

Case 2

A village has poor sanitation and unsafe drinking water.
Q. How will this affect community health?
Answer: Poor sanitation increases spread of infectious diseases, affecting overall community health and productivity.

Case 3

Two individuals show different disease resistance under similar conditions.
Q. What factor may cause this difference?
Answer: Genetic variation and immune efficiency cause differences in disease resistance.

Section B: Common Human Diseases

Case 4

A patient shows prolonged fever, weakness, and abdominal pain after consuming contaminated water.
Q. Identify the disease.
Answer: Typhoid.

Case 5

A child develops cough, chest pain, and breathing difficulty after exposure to an infected person.
Q. Name the disease and mode of transmission.
Answer: Pneumonia; transmitted through inhalation of droplets.

Case 6

A person experiences periodic fever with chills after mosquito bites.
Q. Identify the disease and vector.
Answer: Malaria; transmitted by female Anopheles mosquito.

Case 7

A patient suffers from dysentery due to contaminated food.
Q. Name the disease and causative organism.
Answer: Amoebiasis caused by Entamoeba histolytica.

Section C: Pathogens and Parasites

Case 8

A disease spreads rapidly through air and requires host cells for reproduction.
Q. Identify the type of pathogen.
Answer: Virus.

Case 9

An organism lives inside the human intestine and derives nutrition from the host.
Q. What type of organism is this?
Answer: Endoparasite.

Case 10

Lice infest the scalp and cause irritation.
Q. What type of parasite is lice?
Answer: Ectoparasite.

Section D: Immunity

Case 11

Skin prevents entry of pathogens into the body.
Q. Which type of immunity is involved?
Answer: Innate immunity (physical barrier).

Case 12

Macrophages engulf and destroy pathogens.
Q. Name the type of defence mechanism.
Answer: Cellular barrier of innate immunity.

Case 13

A person recovers quickly from a second infection of the same pathogen.
Q. Which property of immunity is responsible?
Answer: Immunological memory of acquired immunity.

Case 14

Antibodies are transferred from mother to newborn.
Q. Identify the type of immunity.
Answer: Natural passive immunity.

Section E: Vaccination

Case 15

A vaccine introduces weakened pathogens to stimulate immunity.
Q. Name the type of immunity developed.
Answer: Artificial active immunity.

Case 16

A population shows reduced disease spread due to high vaccination coverage.
Q. What is this phenomenon called?
Answer: Herd immunity.

Case 17

A vaccine is produced using genetic engineering techniques.
Q. Identify the type of vaccine.
Answer: Recombinant vaccine (e.g., Hepatitis B).

Section F: Allergies

Case 18

A person develops sneezing and watery eyes on exposure to pollen.
Q. What condition is this?
Answer: Allergy.

Case 19

IgE antibodies trigger histamine release from mast cells.
Q. What is the result of this reaction?
Answer: Inflammation and allergic symptoms.

Case 20

An individual shows severe allergic reaction to peanuts.
Q. Name the causative agent.
Answer: Allergen (peanut proteins).

Section G: Autoimmune Diseases

Case 21

Immune cells attack joint tissues causing chronic inflammation.
Q. Identify the disease.
Answer: Rheumatoid arthritis.

Case 22

Insulin-producing cells are destroyed by immune response.
Q. Name the disorder.
Answer: Type 1 diabetes.

Section H: Drugs and Alcohol Abuse

Case 23

An adolescent begins drug use due to peer pressure and curiosity.
Q. Name two reasons for drug abuse.
Answer: Peer pressure and curiosity.

Case 24

A person consuming alcohol shows liver damage and impaired judgment.
Q. Identify the substance and its effect.
Answer: Alcohol; causes liver cirrhosis and nervous system depression.

Case 25

Sharing of syringes among drug users leads to disease spread.
Q. Name one disease transmitted this way.
Answer: HIV/AIDS.