CBSE Class 12 Biology Question Bank with Important Questions – Human Health & Disease Immunity 2026
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Introduction: Navigating Biology and Human Welfare in 2026
As we approach the 2026 board examination cycle, the CBSE Class 12 Biology syllabus continues to prioritize Unit VIII: Biology and Human Welfare. Within this unit, the chapter on "Human Health and Disease" stands out, carrying a significant weightage of approximately 9 to 12 marks. For students aiming for a medical career, this chapter bridges the gap between school-level biology and MBBS-level immunology.
The 2026 exam pattern is expected to lean heavily toward competency-based questions, moving away from rote memorization. This blog provides a comprehensive CBSE Class 12 Biology Question Bank 2026 tailored to the latest NCERT guidelines and official sample papers.
Core Concepts of Human Health and Disease Immunity
Understanding immunity is the core of this chapter. The 2026 curriculum emphasizes the distinction between innate and acquired immunity, the role of lymphoid organs, and the mechanism of vaccinations.
1. Innate vs. Acquired Immunity
Innate immunity is our "inborn" defense system, while acquired immunity is what we develop throughout our lives.
Physical Barriers: Skin and mucus coating.
Physiological Barriers: Acid in the stomach, saliva in the mouth, and tears.
Cellular Barriers: Polymorphonuclear leukocytes (PMNL-neutrophils) and Monocytes.
Cytokine Barriers: Interferons produced by virus-infected cells.
2. The Antibody Molecule
The structure of an antibody is a frequent 3-mark question. It consists of four peptide chains: two small light chains and two longer heavy chains, represented as H2L2.
CBSE Class 12 Biology Question Bank 2026: Important Questions
Analyzing previous years' papers (2015–2025), we have curated the most repeated and expected questions for the 2026 session.
Very Short Answer Questions (1 Mark)
Name the diagnostic test used to confirm Typhoid fever. (Ans: Widal Test)
Which type of antibodies are present in colostrum (mother's first milk)? (Ans: IgA)
Name the pathogen responsible for malignant malaria. (Ans: Plasmodium falciparum)
Define 'Metastasis' in the context of cancer.
What is the role of the Thymus in the immune system?
Short Answer Questions (2-3 Marks)
Differentiate between Active and Passive Immunity. > Tip: Active immunity is slow but long-lasting (e.g., vaccination), while passive immunity provides immediate relief (e.g., anti-tetanus serum).
Explain the 'lock and key' mechanism of antigen-antibody interaction.
Why are AIDS patients more susceptible to opportunistic infections like Mycobacterium and Toxoplasma?
Describe the life cycle of the Malarial parasite (Plasmodium) with a labeled flowchart.
Long Answer & Case-Based Questions (4-5 Marks)
The HIV Replication Cycle: Explain how the HIV virus acts as a 'factory' within Macrophages and Helper T-cells (TH cells).
Cancer Diagnosis and Treatment: Discuss the differences between Benign and Malignant tumors. Explain treatment modalities like Radiotherapy and Immunotherapy.
Drug and Alcohol Abuse: Analyze the reasons for drug addiction among adolescents and the withdrawal symptoms associated with it.
Formulae and Technical Terms
While Biology is largely descriptive, certain numerical and structural concepts are vital. In your CBSE Class 12 Biology Question Bank 2026, ensure you are familiar with:
Antibody Structure Formula Name: H2L2 (Two Heavy and Two Light chains).
Hardy-Weinberg Equilibrium Principle (often linked to disease resistance in populations).
BMI (Body Mass Index) Calculation Name (relevant for lifestyle diseases).
Official Links for CBSE Question Banks
To ensure you are practicing with the most authentic material, always refer to official government portals. The Central Board of Secondary Education (CBSE) updates its repository annually with additional practice questions.
CBSE Academic Website (Question Bank Section): https://cbseacademic.nic.in/
Direct Access to CBSE Question Bank: https://www.cbse.gov.in/cbsenew/question_bank.html
Conclusion
Mastering the "Human Health and Disease" chapter is non-negotiable for anyone looking to excel in the Class 12 boards and beyond. By focusing on the CBSE Class 12 Biology Question Bank 2026, students can systematically cover high-yield topics like immunity, cancer, and AIDS. Remember, consistency in practicing previous years' questions is the secret to a 95+ score.
FAQs on CBSE Class 12 Biology Question Bank 2026
Q1: How much weightage does the 'Immunity' section carry in the 2026 exam?
A: In the CBSE Class 12 Biology Question Bank 2026, the "Human Health and Disease" chapter typically carries 9 marks, with at least 4-5 marks dedicated specifically to Immunity and Vaccination questions.
Q2: Is NCERT sufficient for the 2026 Biology Board Exam?
A: Yes, over 95% of the board paper is based directly on the NCERT textbook. However, practicing from an updated CBSE Class 12 Biology Question Bank 2026 helps you tackle high-order thinking skills (HOTS) questions.
Q3: What are the most important diagrams in this chapter?
A: The most crucial diagrams are the Structure of an Antibody, the Replication of Retrovirus (HIV), and the Life Cycle of Plasmodium.
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