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Human Health and Disease — Class 12 MCQs with Answers

Class 12 CBSE Biology · Chapter 7

90 practice questions · 30 Easy · 30 Medium · 30 Hard · Updated

Jump to the 6 solved questions

Practise the most important Class 12 CBSE Biology questions from Chapter 7, "Human Health and Disease". You get 9 timed quizzes made from 90 NCERT-based MCQs, with answers and explanations. The questions are split into 30 Easy, 30 Medium and 30 Hard. Warm up on the basics, then move on to the exam-level questions that top scorers in CBSE & Maharashtra HSC Board exams, MHT-CET and NEET UG get right.

To score well in "Human Health and Disease", focus on diagrams, key terms and knowing NCERT line by line. Each MCQ here is timed and uses exam-style marking (+4 correct, −1 wrong, 0 skipped). This helps you stay accurate when time is short, just as real papers need. Every question has a short explanation, so a wrong answer becomes a quick lesson. It is the fastest way to fix gaps before a test.

Use this chapter for focused revision. Start with the Easy set to check your basics on Human Health and Disease, then move to Medium and Hard to practise applying them. Your accuracy, streaks and XP save automatically. This chapter also adds to your overall Class 12 Biology mastery score. Try the 6 sample questions below: tap an option to see the answer and a worked explanation. Sign in free to start practising.

Human Health and Disease — important questions & MCQs with answers (Class 12 Biology)

6 solved questions from this chapter's difficulty levels, each with its answer and explanation. Tap an option to check yourself.

0 of 6 answered

  1. Q1 of 6Easy

    Malaria is caused by:

    Show answer

    Answer: Plasmodium (protozoan)

    Explanation: Plasmodium, a protozoan parasite, causes malaria; the female Anopheles mosquito is the vector, not the pathogen itself — don't confuse vector with cause.

  2. Q2 of 6Easy

    Vaccination provides:

    Show answer

    Answer: Active acquired immunity

    Explanation: Vaccination triggers the body's own B and T cells to make antibodies and memory cells — active acquired immunity — unlike antiserum, which is passive and ready-made.

  3. Q3 of 6Medium

    Pneumonia is caused by:

    Show answer

    Answer: Streptococcus pneumoniae

    Explanation: Streptococcus pneumoniae (and Haemophilus influenzae) infect the alveoli, filling them with fluid — a bacterial cause, unlike malaria's protozoan Plasmodium.

  4. Q4 of 6Medium

    Antibodies are:

    Show answer

    Answer: Y-shaped immunoglobulins

    Explanation: Antibodies are Y-shaped immunoglobulins (2 heavy + 2 light chains) secreted by plasma cells; the variable tip binds antigen, unlike the lipid/carbohydrate/steroid distractors.

  5. Q5 of 6Hard

    Cancer is essentially:

    Show answer

    Answer: Uncontrolled cell division and metastasis

    Explanation: Cancer is uncontrolled cell division from loss of contact inhibition; malignant cells go on to invade and metastasise to distant sites via blood or lymph.

  6. Q6 of 6Hard

    HIV preferentially infects:

    Show answer

    Answer: CD4 T-helper cells

    Explanation: HIV preferentially infects CD4-bearing helper T-lymphocytes via its envelope protein, depleting them and crippling cell-mediated immunity — not RBCs or platelets.

Human Health and Disease notes: key concepts (Class 12 Biology)

Human health and disease: pathogens and life cycles of malaria, amoebiasis, typhoid, pneumonia, ascariasis, filariasis and ringworm; the immune system — innate and acquired, active and passive immunity, antibody structure, B and T lymphocytes; AIDS and HIV; cancer and oncogenes; and drug and alcohol abuse.

Malaria
Caused by Plasmodium, spread by a female Anopheles mosquito bite; the sporozoite is infective and haemozoin toxin release causes the cyclic chill and fever.
The life cycle of Plasmodium as a loop between a human and a female Anopheles mosquito. In the human: a mosquito bite injects sporozoites into the blood; they multiply in liver cells; then they multiply in red blood cells, which burst and release the toxin haemozoin, causing the cycles of chill and fever (a looped arrow shows the RBC cycle repeating); gametocytes form in the blood. A female Anopheles biting the person takes up the gametocytes; fertilisation and development happen in the mosquito's gut; sporozoites form and move to its salivary glands, ready to enter the next human at a bite.
Common pathogens
Typhoid — Salmonella typhi (Widal test); pneumonia — Streptococcus; amoebiasis — Entamoeba; ascariasis — Ascaris; filariasis — Wuchereria; ringworm — fungi.
Innate immunity
Non-specific defence present from birth: physical barriers (skin), physiological (acid, saliva), cellular (phagocytes) and cytokine (interferon) barriers.
Acquired immunity
Pathogen-specific defence with memory; humoral (antibody-mediated, B-cells) and cell-mediated (T-cells) responses. Secondary response is faster and stronger.
Antibody structure
A Y-shaped protein of four chains — two light and two heavy (H₂L₂); variable regions form the antigen-binding sites. Also called immunoglobulins.
An antibody molecule drawn as a Y. It has four polypeptide chains: two long heavy chains, which form the stem and run up the inside of both arms, and two short light chains, one beside each arm, so it is written H₂L₂. Disulphide bonds join the two heavy chains at the hinge and each light chain to a heavy chain. The tips of the arms are the variable regions; the rest is the constant region. The two tips, between heavy and light chain, are the two antigen-binding sites.
Active vs passive immunity
Active — body makes its own antibodies after exposure/vaccine, slow but lasting. Passive — ready-made antibodies given (antiserum, colostrum), fast but temporary.
Vaccination
Introducing an antigen or weakened pathogen to generate memory cells, so a later infection meets a rapid, strong secondary response; the basis of immunisation.
AIDS / HIV
HIV, a retrovirus, uses reverse transcriptase and destroys helper T-cells, crippling immunity; spreads via blood, sex and mother-to-child. Diagnosed by ELISA.
Cancer
Uncontrolled division of cells that lose contact inhibition, forming tumours; malignant tumours metastasise. Caused by carcinogens activating oncogenes.
Oncogenes
Cancer-causing genes; normal cellular proto-oncogenes can be activated to transform cells. Inactivation of tumour-suppressor genes also causes cancer.
Allergy
Exaggerated immune response to allergens; mediated by IgE and release of histamine and serotonin from mast cells; relieved by antihistamines.
Autoimmunity
The immune system attacks the body's own cells and tissues; rheumatoid arthritis is a classic example.
Drugs of abuse
Opioids (heroin/morphine, from poppy) depress the CNS; cannabinoids (from Cannabis) affect the brain; cocaine (from coca) is a stimulant.
Addiction and dependence
Tolerance (needing higher doses) and withdrawal symptoms on stopping mark dependence; nicotine is the addictive agent in tobacco.
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Human Health and Disease — FAQs

What are the key concepts in Class 12 Biology Human Health and Disease?+

Human health and disease: pathogens and life cycles of malaria, amoebiasis, typhoid, pneumonia, ascariasis, filariasis and ringworm; the immune system — innate and acquired, active and passive immunity, antibody structure, B and T lymphocytes; AIDS and HIV; cancer and oncogenes; and drug and alcohol abuse. Key ideas include Malaria, Common pathogens, Innate immunity, Acquired immunity, Antibody structure, Active vs passive immunity.

What does Class 12 Biology Chapter 7 (Human Health and Disease) cover on XamBaaz?+

It has 90 NCERT-based MCQs on "Human Health and Disease": 30 Easy, 30 Medium and 30 Hard. Together they make 9 timed quizzes, and you never get the same set twice. Every question has an instant explanation. They help you prepare for CBSE & Maharashtra HSC Board exams, MHT-CET and NEET UG.

Are these "Human Health and Disease" questions free to practise?+

Yes. Sign in with Google to practise "Human Health and Disease" free. Full unlimited access is ₹1,999/year. One year from the day you pay. Class 12 is your last school year, so your class stays as it is. No chapter is charged separately.

How should I revise "Human Health and Disease" for the exam?+

Start with the Easy quiz to check your basics, then try Medium and Hard to practise applying them. There are 9 timed quizzes on this chapter, so you can come back for a fresh set instead of one you have seen. Read each explanation, retry the questions you miss, and track your accuracy until it stays high.

Are these "Human Health and Disease" MCQs available with answers?+

Yes. 6 sample questions are on this page with answers: tap an option, or "Show answer", to see the correct option and a step-by-step explanation. Sign in free with Google to start practising, with instant scoring.

Is there negative marking in the "Human Health and Disease" quizzes?+

Yes. The timed quizzes use exam-style marking: +4 for a right answer, −1 for a wrong one and 0 for a skip, the same negative marking as NEET UG. MHT-CET and CBSE board papers have no negative marking. Our mocks for those are scored their way.

What are the important questions from Human Health and Disease (Class 12 Biology)?+

The questions that matter most test Malaria, Common pathogens, Innate immunity, Acquired immunity, Antibody structure, Active vs passive immunity. This page shows 6 solved important MCQs with answers and explanations. Sign in to practise all 90 questions on the chapter as timed quizzes.

Is there an online quiz for Human Health and Disease?+

Yes — Class 12 Biology Human Health and Disease has timed online quizzes at Easy, Medium and Hard levels, with instant scoring and a worked explanation on every question. The first quiz on the chapter is free.

Are there question answers and extra questions for Human Health and Disease (Class 12 Biology)?+

Yes. This page has 6 solved questions on Human Health and Disease, each with the correct answer and a short explanation. Sign in to practise all 90 questions on the chapter as timed quizzes.

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