Health, Diseases and Immunity: Vaccines, Antibiotics, MCQs

Health is not just the absence of disease. The World Health Organization defines it as a state of complete physical, mental and social well-being. Our health is constantly challenged by tiny invaders – bacteria, viruses, protozoa, fungi and worms – and also by lifestyle problems like diabetes, heart disease and cancer. To protect us, the body has a powerful defence system called immunity, and science has given us two great weapons: vaccines that prevent disease and antibiotics that cure bacterial infections.

Health and diseases is one of the most frequently asked topics in the Biology section of SSC CGL, CHSL, MTS, GD, RRB NTPC, Group D, WBCS, WBPSC, Police, Banking and State PSC exams. Questions come on disease-causing organisms, carriers (vectors), vaccines, types of immunity, antibodies, antibiotics and their discoverers, India's immunisation programme and health days. This guide explains everything in simple language with diagrams, easy tables, memory tricks and 20 MCQs with answers.

➤ Communicable diseases: Spread from person to person – caused by bacteria, viruses, protozoa, fungi and worms
➤ Non-communicable diseases: Do not spread – diabetes, hypertension, heart disease, cancer, deficiency diseases
➤ Father of Immunology / first vaccine: Edward Jenner – smallpox vaccine (1796)
➤ First antibiotic: Penicillin – discovered by Alexander Fleming (1928)
➤ Immunity: Innate (by birth) and Acquired (develops later) · Active and Passive
➤ Antibodies: Y-shaped proteins made by B-lymphocytes · Most common: IgG · In mother's first milk (colostrum): IgA
➤ India milestones: Smallpox-free (1977) · Polio-free certified (27 March 2014) · Mission Indradhanush (25 December 2014)

Basic Terms of Health and Disease

Classification of Diseases

Diseases are broadly divided into two groups. Communicable (infectious) diseases are caused by pathogens and can spread from one person to another through air, water, food, touch, body fluids or vectors. Non-communicable diseases do not spread from person to person; they are caused by lifestyle, genes, nutritional deficiency or environmental factors (Figure 1).

Figure 1: Classification of diseases into communicable and non-communicable groups, with examples

Bacterial Diseases

Bacteria are single-celled organisms without a true nucleus (prokaryotes). Most bacteria are harmless or even useful, but some cause serious diseases. Bacterial diseases can usually be treated with antibiotics.

Viral Diseases

Viruses are extremely small particles made of genetic material (DNA or RNA) inside a protein coat. They are on the border between living and non-living – they can multiply only inside a living host cell. Antibiotics do not work against viruses; viral diseases are prevented mainly by vaccines and treated with antiviral drugs and supportive care. The study of viruses is called virology.

Protozoan Diseases

Protozoa are single-celled organisms with a true nucleus (eukaryotes). Many of them are spread by insect vectors.

Life Cycle of the Malaria Parasite

The malaria parasite needs two hosts. Humans are the intermediate host, where the parasite multiplies asexually, and the female Anopheles mosquito is the definitive (primary) host, where sexual reproduction takes place. Sir Ronald Ross proved in 1897 that mosquitoes transmit malaria (Figure 2).

Figure 2: Simplified life cycle of the malaria parasite (Plasmodium) between humans and the female Anopheles mosquito

Fungal and Helminthic (Worm) Diseases

Common Vectors and Diseases

Non-Communicable Diseases (NCDs)

Non-communicable diseases are now the leading cause of death in India and the world. They develop slowly, last long, and are linked to unhealthy diet, physical inactivity, tobacco, alcohol, stress, air pollution and genes.

Immunity – The Body's Defence System

Immunity is the body's ability to resist disease-causing organisms. The immune system recognises foreign substances, called antigens, and destroys them. It works in three lines of defence (Figure 3).

Figure 3: The three lines of defence of the human immune system

Types of Immunity

Lymphoid organs: B-lymphocytes mature in the bone marrow and T-lymphocytes mature in the thymus – both are primary lymphoid organs. The spleen, lymph nodes and tonsils are secondary lymphoid organs. HIV weakens immunity by destroying helper T-cells, which is why AIDS patients suffer from many infections.

Antibodies (Immunoglobulins)

An antibody is a Y-shaped protein made of four chains – two heavy chains and two light chains (H₂L₂). Each antibody fits a specific antigen like a lock and key.

Allergy: An exaggerated immune response to harmless substances (allergens) such as pollen, dust mites or certain foods. Mast cells release histamine, causing sneezing, itching and swelling. Antihistamine drugs give relief.

Vaccines – Preventing Disease

A vaccine contains a weakened, killed or partial form of a pathogen (or its genetic instructions). When given, it trains the immune system to produce antibodies and memory cells without causing the disease. If the real pathogen attacks later, the body responds quickly. Vaccination gives active acquired immunity. When most people in a community are immune, even unvaccinated people get protection – this is called herd immunity.

The word "vaccine" comes from the Latin vacca (cow). In 1796, Edward Jenner used material from cowpox to protect a boy against smallpox – the first vaccine. Louis Pasteur later developed vaccines for anthrax and rabies (1885).

Types of Vaccines

India's Universal Immunisation Programme (UIP)

India began the Expanded Programme on Immunisation in 1978, which became the Universal Immunisation Programme in 1985. It is one of the largest public health programmes in the world. Mission Indradhanush was launched on 25 December 2014 to vaccinate children and pregnant women who had been left out. The U-WIN portal digitally records every vaccination.

Indian vaccine milestones: India was declared smallpox-free in 1977. WHO certified India (with the South-East Asia region) polio-free on 27 March 2014 – the last wild polio case was reported from Howrah, West Bengal, in January 2011. India developed indigenous vaccines such as Rotavac (rotavirus), Covaxin (Bharat Biotech with ICMR) and Cervavac (Serum Institute of India's HPV vaccine against cervical cancer). The Serum Institute of India, Pune, is the world's largest vaccine maker by number of doses.

Antibiotics – Fighting Bacteria

An antibiotic is a chemical substance, originally produced by a microorganism, that kills or stops the growth of bacteria. The word means "against life". Antibiotics are effective only against bacteria – not against viruses such as those causing colds, flu or COVID-19.

In 1928, Alexander Fleming noticed that a mould, Penicillium notatum, had killed bacteria (Staphylococcus) growing in a dish. This led to penicillin, the first antibiotic. Howard Florey and Ernst Chain developed it into a medicine, and all three shared the Nobel Prize in 1945. Penicillin saved countless soldiers during the Second World War.

Antibiotics, Antiseptics and Other Drugs

Antimicrobial Resistance (AMR)

When antibiotics are overused or misused – taken without prescription, for viral illnesses, or stopped before the full course – bacteria can evolve to survive them. These "superbugs" make common infections hard to treat. WHO lists AMR among the top global public health threats. In India, prescription-only antibiotics carry a red vertical line on the pack under the "Red Line" campaign (2016) to warn against self-medication, and India launched a National Action Plan on AMR in 2017. Kerala was the first state to launch its own AMR action plan (KARSAP, 2018).

Great Discoveries in Medicine

Important Health Days

West Bengal Connection

Revise related topics in our guides on Biotechnology, Molecular Biology and Life Sciences, Carbon and Organic Chemistry, Light Reflection and Refraction (including eye defects) and Climatology and Climate Change – climate change is also linked with the spread of vector-borne diseases. For practice, try the CSIR NAL MTS Mock Test.

20 MCQs on Health, Diseases and Immunity

Q1. Which of the following is a bacterial disease?
(a) Malaria
(b) Tuberculosis
(c) Measles
(d) Ringworm

Answer: (b) – TB is caused by Mycobacterium tuberculosis. Malaria is protozoan, measles is viral and ringworm is fungal.

Q2. Who discovered the bacterium that causes tuberculosis?
(a) Robert Koch
(b) Louis Pasteur
(c) Alexander Fleming
(d) Edward Jenner

Answer: (a) – Robert Koch discovered Mycobacterium tuberculosis in 1882; World TB Day (24 March) marks the date of his announcement.

Q3. The Widal test is used to diagnose:
(a) Malaria
(b) AIDS
(c) Typhoid
(d) Tuberculosis

Answer: (c) – Typhoid is caused by Salmonella typhi. ELISA is used for HIV and the Mantoux test for TB.

Q4. Malaria is caused by:
(a) A virus
(b) A bacterium
(c) A fungus
(d) A protozoan (Plasmodium)

Answer: (d) – Plasmodium is spread by the bite of the female Anopheles mosquito; P. falciparum causes the most dangerous form.

Q5. Dengue is spread by which mosquito?
(a) Female Anopheles
(b) Aedes aegypti
(c) Culex
(d) Sandfly

Answer: (b) – Aedes also spreads chikungunya and Zika; Culex spreads filariasis and JE.

Q6. Kala-azar is transmitted by:
(a) Housefly
(b) Tsetse fly
(c) Rat flea
(d) Sandfly

Answer: (d) – Kala-azar is caused by Leishmania donovani; the tsetse fly spreads sleeping sickness and the rat flea spreads plague.

Q7. HIV, which causes AIDS, mainly destroys:
(a) Red blood cells
(b) Platelets
(c) Helper T-lymphocytes
(d) B-lymphocytes only

Answer: (c) – HIV attacks helper T-cells (CD4 cells), weakening the whole immune system.

Q8. Ringworm is caused by a:
(a) Fungus
(b) Worm
(c) Virus
(d) Protozoan

Answer: (a) – Despite its name, ringworm is a fungal skin infection.

Q9. Filariasis (elephantiasis) is caused by:
(a) Plasmodium vivax
(b) Wuchereria bancrofti
(c) Entamoeba histolytica
(d) Vibrio cholerae

Answer: (b) – A roundworm spread by the Culex mosquito, causing swelling of the legs.

Q10. Which of the following is a non-communicable disease?
(a) Cholera
(b) Chickenpox
(c) Diabetes
(d) Tuberculosis

Answer: (c) – Diabetes does not spread from person to person; it results from lack of insulin or insulin resistance.

Q11. Who developed the first vaccine, against smallpox, in 1796?
(a) Louis Pasteur
(b) Robert Koch
(c) Jonas Salk
(d) Edward Jenner

Answer: (d) – Jenner used cowpox material; smallpox was declared eradicated by WHO in 1980.

Q12. The rabies vaccine was developed by:
(a) Louis Pasteur
(b) Edward Jenner
(c) Albert Sabin
(d) Waldemar Haffkine

Answer: (a) – Pasteur developed it in 1885; World Rabies Day (28 September) marks his death anniversary.

Q13. The BCG vaccine protects against:
(a) Polio
(b) Tuberculosis
(c) Measles
(d) Hepatitis B

Answer: (b) – BCG (Bacillus Calmette–Guérin) is a live attenuated vaccine given at birth.

Q14. DPT vaccine gives protection against:
(a) Dengue, Polio, Typhoid
(b) Diphtheria, Pneumonia, TB
(c) Diphtheria, Pertussis, Tetanus
(d) Diarrhoea, Plague, Typhoid

Answer: (c) – Under UIP it is given as part of the pentavalent vaccine, which also covers hepatitis B and Hib.

Q15. Immunity obtained by a baby through mother's milk is an example of:
(a) Active natural immunity
(b) Innate immunity
(c) Active artificial immunity
(d) Passive natural immunity

Answer: (d) – Ready-made antibodies (mainly IgA in colostrum) are received from the mother, so the baby's body does not make them.

Q16. Which antibody is the most abundant in blood and can cross the placenta?
(a) IgG
(b) IgA
(c) IgM
(d) IgE

Answer: (a) – IgG protects the unborn baby; IgE is linked with allergies and IgM is the largest antibody.

Q17. Penicillin, the first antibiotic, was discovered by:
(a) Selman Waksman
(b) Alexander Fleming
(c) Joseph Lister
(d) Robert Koch

Answer: (b) – Fleming discovered it in 1928 from the mould Penicillium notatum; Waksman discovered streptomycin.

Q18. Antibiotics are NOT effective against:
(a) Typhoid
(b) Tuberculosis
(c) Cholera
(d) Common cold

Answer: (d) – The common cold is caused by viruses (rhinovirus); antibiotics act only on bacteria. Misusing them leads to antimicrobial resistance.

Q19. WHO certified India polio-free on:
(a) 27 March 2014
(b) 13 January 2011
(c) 25 December 2014
(d) 8 May 1980

Answer: (a) – The last wild polio case was reported from Howrah, West Bengal, in January 2011. Mission Indradhanush began on 25 December 2014.

Q20. Which Kolkata scientist discovered the cholera toxin in 1959?
(a) Upendranath Brahmachari
(b) Dilip Mahalanabis
(c) Sambhu Nath De
(d) Prafulla Chandra Ray

Answer: (c) – His discovery explained how cholera causes severe dehydration. Dilip Mahalanabis pioneered ORS use and Brahmachari discovered Urea Stibamine for kala-azar.

Want more practice? Try our Daily GK Quiz and Mock Tests.

Conclusion

Diseases may be caused by tiny pathogens or by lifestyle and genetic factors, but the body's immune system, vaccines and antibiotics together give us strong protection. Bacteria, viruses, protozoa, fungi and worms each cause typical diseases, often spread by specific vectors, while non-communicable diseases like diabetes and heart disease now cause most deaths. For exams, remember the pathogen and vector of each disease, the types of immunity and antibodies, vaccine types and the UIP, antibiotics and their discoverers, antimicrobial resistance, health days and Bengal's great contributions – from Ronald Ross to Dilip Mahalanabis. Revise the tricks above and practise the MCQs regularly.

Reference: NCERT Biology Class XII ("Human Health and Disease"); NCERT Science Class VIII ("Microorganisms: Friend and Foe") and Class IX ("Why Do We Fall Ill?"); Ministry of Health and Family Welfare; World Health Organization.