Human Health and Disease

What you'll learn

Master NEET's Human Health and Disease — common pathogens and their vectors, innate vs acquired immunity, active vs passive immunity, antibodies, allergies and vaccination, with worked examples.

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Human Health and Disease — solved practice questions

8 NEET Biology questions with step-by-step solutions. Attempt each, then reveal the answer.

1. Q1easy

   The malignant form of malaria in humans, which can be fatal, is caused by which species of Plasmodium?

   • APlasmodium vivax
   • BPlasmodium malariae
   • CPlasmodium falciparum
   • DPlasmodium ovale
   Show answer & solution

   Correct answer: (C) Plasmodium falciparum

   Plasmodium falciparum causes malignant (cerebral) malaria, the most severe and potentially fatal form; P. vivax and P. malariae cause milder forms.

2. Q2medium

   In the life cycle of Plasmodium, the rupture of red blood cells and release of a toxic substance responsible for the recurring chill and high fever of malaria is caused by:

   • ASporozoites
   • BMerozoites entering liver cells
   • CGametocytes
   • DHaemozoin
   Show answer & solution

   Correct answer: (D) Haemozoin

   When infected RBCs rupture they release the toxin haemozoin, which is responsible for the characteristic recurring chill and high fever every three to four days in malaria.

3. Q3hard

   Which class of antibody (immunoglobulin) is the first to be produced during the primary immune response and is also found on the surface of B cells as a receptor?

   • AIgM
   • BIgG
   • CIgA
   • DIgE
   Show answer & solution

   Correct answer: (A) IgM

   IgM is the first antibody produced in the primary immune response and is present as a monomer on the B-cell surface acting as an antigen receptor, while it circulates as a pentamer in plasma.

4. Q4medium

   The primary lymphoid organs in humans where lymphocytes originate and/or mature into antigen-sensitive cells are:

   • ASpleen and lymph nodes
   • BBone marrow and thymus
   • CTonsils and Peyer's patches
   • DSpleen and thymus
   Show answer & solution

   Correct answer: (B) Bone marrow and thymus

   The bone marrow and thymus are the primary lymphoid organs where lymphocytes originate (bone marrow) and mature (B cells in bone marrow, T cells in thymus); the spleen and lymph nodes are secondary lymphoid organs.

5. Q5medium

   HIV, the causative agent of AIDS, primarily attacks and progressively destroys which type of immune cells in the human body?

   • AB lymphocytes
   • BNeutrophils
   • CHelper T lymphocytes
   • DRed blood cells
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   Correct answer: (C) Helper T lymphocytes

   HIV enters helper T lymphocytes (TH cells), replicates within them and progressively destroys them, causing a fall in helper T-cell numbers that cripples the immune response.

6. Q6medium

   Passive immunity is best exemplified by which of the following?

   • AInjection of a live attenuated vaccine
   • BRecovery from chickenpox
   • CInjection of the tetanus toxoid vaccine
   • DTransfer of antibodies from mother to foetus via placenta
   Show answer & solution

   Correct answer: (D) Transfer of antibodies from mother to foetus via placenta

   In passive immunity, ready-made antibodies are given directly to protect against a pathogen; the transfer of antibodies from mother to foetus through the placenta (and colostrum) is a natural example.

7. Q7medium

   Which of the following diseases is correctly matched with its causative organism?

   • ATyphoid — Salmonella typhi
   • BPneumonia — Wuchereria bancrofti
   • CAmoebiasis — Trichophyton
   • DRingworm — Entamoeba histolytica
   Show answer & solution

   Correct answer: (A) Typhoid — Salmonella typhi

   Typhoid is caused by the bacterium Salmonella typhi, which spreads through contaminated food and water and can be confirmed by the Widal test.

8. Q8hard

   The interferons produced by virus-infected cells provide protection by:

   • ADirectly killing the viruses in blood
   • BProtecting non-infected cells from further viral infection
   • CProducing antibodies against the virus
   • DEngulfing the viruses by phagocytosis
   Show answer & solution

   Correct answer: (B) Protecting non-infected cells from further viral infection

   Interferons are proteins secreted by virus-infected cells that protect neighbouring non-infected cells from further viral infection; they are part of the innate (non-specific) immune defence.

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