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Human Health and Disease Class 12 NEET Notes and Important Questions

by PW Gulf
March 19, 2024

Human Health and Disease Class 12 NEET is an important chapter. Every year, NEET questions are asked from this chapter. To perform well in NEET, students must thoroughly cover Human Health and Diseases during the preparation phase. 

This NEET chapter includes topics such as different types of diseases, their causes, and treatment methods. In order to gain a solid understanding of Human Health and Diseases, students must regularly revise the expert notes provided by PW faculties. These notes offer an easy explanation of important topics to strengthen exam preparation.

Human Health and Disease Class 12 Important Topics

The Human Health and Diseases explain the fundamental concepts of the human body. The major topics covered in this chapter are as follows:

  • Meaning of health and disease

  • Different types of diseases

  • Diseases in humans

  • Plasmodium lifecycle

  • Immunity and its types

  • Allergies 

  • Autoimmunity 

  • AIDS

  • Cancer

Human Health and Disease Class 12 Notes

Once students complete a NEET chapter, they must keep revising the important topics to reinforce their knowledge and improve their recalling ability. Here are the detailed revision notes of class 12 Human Health and Disease to help students enhance their NEET preparation.

Types of Diseases

Human beings suffer from various diseases, including infection, genetic issues, etc. These diseases can be categorised into the following two types:

  • Acquired Diseases: These include the health issues humans acquire throughout their lifetime, such as allergies, infections, deficiency ailments, communicable diseases, and non-communicable diseases.

  • Congenital Diseases: These are genetic defects present in human beings by birth due to gene mutation. Such diseases are transmitted from one generation to the next generation. Examples of congenital diseases are colour blindness, haemophilia, Down syndrome, etc. 

Common Diseases in Humans

Diseases in human beings are typically caused by pathogens, such as bacteria, fungi, viruses, worms, and protozoans. Here are the details of common diseases in human beings, including their causing agent, symptoms and effects. 

  • Pneumonia

    • Pathogen: Streptococcus pneumoniae, Haemophilus influenzae (Bacteria)

    • Mode of Infection: Using infected utensils or inhaling droplets/aerosols released by an infected person.

    • Symptoms: Fever, cough, chills, and headache

    • Effects: Respiration problems due to fluid in the alveoli

  • Typhoid

  • Pathogen: Salmonella typhi (Bacteria)

  • Mode of Infection: Contaminated food and water

  • Symptoms: Continued high fever, stomachache, headache, loss of appetite, and constipation. 

  • Effects: Intestinal perforation in severe cases

  • Common cold

  • Pathogen: Rhinoviruses

  • Mode of Infection: Sneeze, Cough, and contaminated objects

  • Symptoms: Nasal congestion, runny nose, Cough, sore throat, headache

  • Effects: Nose and respiratory passage blockage

  • Malaria

  • Pathogen: Plasmodium falciparum, P. vivax (Protozoan)

  • Mode of Infection: Female anopheles mosquito

  • Symptoms: High fever with chills

  • Effects: Rupture of RBCs due to parasite that multiplies in liver cells

  • Amoebic dysentery

  • Pathogen: Entamoeba histolytica (Protozoan)

  • Mode of Infection: Houseflies

  • Symptoms: Constipation, mucous and blood in the stool, abdominal pain

  • Effects: Infection in the large intestine

  • Filariasis/ Elephantiasis

  • Pathogen: Wuchereria bancrofti, W. malayi (Helminthes)

  • Mode of Infection: Bloodsucking black flies and female mosquitos

  • Symptoms: Inflammation of the lower limb and genital organs

  • Effects: Blockage of Lymphatic vessels, specifically of the lower limbs

  • Ascariasis

  • Pathogen: Ascaris (Helimenthes)

  • Mode of Infection: Contaminated water, vegetables, fruits

  • Symptoms: Muscular pain, anaemia, internal bleeding, fever

  • Effects: Blockage of intestinal passage

  • Ringworms

  • Pathogen: Microsporum, Epidermophyton, Trichophyton(Fungi)

  • Mode of Infection: Spread from soil, using towel, clothes, or comb of infected person

  • Symptoms: Itchy skin, dry scaly lesions 

  • Effects: Effects skin, scalp, and nail

Plasmodium Lifecycle

Plasmodium is a parasitic protozoan that enters the human body through the saliva of female Anopheles mosquitoes. The infectious form of these mosquitoes' bite is sporozoites. After entering the human body, the infection multiplies in the liver cells. Further, they start to attack RBCs and rupture them. This results in the release of Hemozoin, a toxic substance.

When a female Anopheles bites an infected person, the gametocyte gets transferred to the mosquito through human blood. Further, sporozoites are formed, which migrate to mosquitoes' salivary glands, and this cycle repeats. 

Immunity and its Types

Immunity is the ability of the human body to fight and protect against foreign bodies. The immune system protects the body against infections. Broadly, immunity is divided into two types:

  • Innate Immunity: It is present in human beings by birth. These include four types of immunity barriers, namely:

    • Physiological barriers, such as tears, saliva, stomach acid.

    • Physical barriers include the skin and mucous lining of the gastrointestinal, urinary, and respiratory tract.

    • Cytokine barriers, such as interferons produced by infected cells.

    • Cellular barriers, such as monocytes, neutrophils, and lymphocytes.

  • Acquired Immunity: It includes the immunity people acquire during their lifecycle.


Allergies are exaggerated immune responses when human beings are exposed to certain antigen, such as dust, pollens, etc. During allergic reactions, IgE antibodies are produced, and mast cells produce serotonin and histamine. To reduce allergic symptoms, adrenalin, steroids, and antihistamines are used.

Auto Immunity

Autoimmunity is a disorder in which the body attacks its own cells. One example of autoimmune disorder is Rheumatoid arthritis.


AIDS is caused by HIV, which is a retrovirus having RNA as its genome. After entering the host, RNA releases viral DNA through the enzyme reverse transcriptase. The released DNA builds into the host genome, resulting in the multiplication of the virus. Further, the virus attacks T cells, which reduces the number of T lymphocytes. This weakens the immune system of the host.

AIDS is majorly transmitted by contaminated blood transfusion, sexual intercourse, mother to foetus, infected syringe. To diagnose AIDS, ELISA is widely used.


Cancer is caused by the uncontrolled growth of cells, resulting in tumours. Cancerous tumours are of two types: 

  • Malignant Tumour: It spreads and enters the human tissues very fast. These are the most dangerous types of cancerous tumours.

  • Benign Tumour: This tumour only affects the area where it starts. It does not spread to other parts of the body. Benign tumours are not harmful to human beings.

To detect cancer, histological examination and biopsy are performed. In some cases, CT scans and MRI is also used. To diagnose cancerous genes, molecular biology methods are employed.

Human Health and Disease Important Questions

Besides covering the Human Health and Disease chapter, candidates must also solve important questions to assess their knowledge and enhance their problem-solving skills. Here are Human Health and Disease important questions candidates must practise during their NEET preparation journey:

  1. What should you check if someone lacks disease-fighting antibodies?

A. Serum Globulins

B. Serum Albumin

C. Fibrinogen

D. Haemocytes

  1. Which type of immunoglobulins is most abundant in human breast milk?

A. IgM

B. IgD

C. IgA

D. IgE

  1. What do polio drops contain?

A. Weakened pathogens

B. Harvested antibodies

C. Gamma globulin

D. Activated pathogens 

  1. In some cases, the immune system can't differentiate between the body's own cells and foreign ones, which can lead to:

A. Increased immunity

B. Rejection of transplanted tissue

C. Autoimmune disease

D. No changes at all

  1. Which of the following leads to Asthma?

A. Lung infections caused by bacteria

B. Fluid buildup in the lungs

C. Swelling in the windpipe

D. Allergic reactions in the lungs' mast cells

  1. Which of the following diseases are caused by bacteria?

A. Typhoid and smallpox

B. Herpes and influenza

C. Tetanus and mumps

D. Cholera and tetanus

  1. Which disease is caused by tiny single-celled organisms called protozoa?

A. Syphilis 

B. Cancer

C. Influenza

D. Babesiosis

Realise your goal of clearing NEET with 700+ scores. Join PW Gulf NEET Coaching to prepare under the guidance of expert faculties and strengthen your exam preparation.

Human Health and Disease Class 12 NEET FAQs

Q1. How many questions come from Human Health and Disease in NEET?

Ans. 3-4 questions come from Human Health and Disease in the NEET exam.

Q2. Is Human Health and Disease important for NEET?

Ans. Yes, Human Health and Disease is a crucial chapter for NEET. It deals with the human body and different types of diseases that affect people.

Q3. Which chapter is most important in Biology class 12?

Ans. Chapters such as Genetics and Evolution, Human Reproduction, Human Health and Disease, Ecology, and Human Physiology are important in class 12 Biology.

Q4. Is NCERT enough to prepare for Human Health and Disease class 12?

Ans. All the topics covered in the Human Health and Disease chapter of the NCERT book are crucial for the NEET exam. However, students must refer to relevant sample papers and test series to enhance their exam preparation.

Q5. Which chapter is Human Health and Disease class 12?

Ans. Human Health and Disease is chapter 8 of class 12 Biology.

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