Every Book Back multiple-choice question from Immunology (12th Standard Zoology, Samacheer Kalvi) — each with the correct option highlighted and a clear, worked explanation. Free to read in English and Tamil.
Q1
Colostrum provides
- A. Naturally acquired active immunity
- B. Naturally acquired passive immunityCorrect
- C. Artificially acquired active immunity
- D. Artificially acquired passive immunity
Explanation. Colostrum contains maternal antibodies, mainly IgA, which are transferred directly to the infant. This offers immediate, natural protective immunity without requiring the newborn's own immune system to generate a response.
Q2
Paratope is an
- A. Antibody binding site on variable regions
- B. Antibody binding site on heavy regions
- C. Antigen binding site on variable regionsCorrect
- D. Antigen binding site on heavy regions
Explanation. The paratope is the specific antigen-binding site of an antibody. It is located in the variable regions of the heavy and light chains, where it structurally recognizes and fits the epitope of an antigen.
Q3
Allergy involves
- A. IgECorrect
- B. IgG
- C. IgA
- D. IgM
Explanation. Allergic reactions represent immediate hypersensitivity responses that are primarily mediated by IgE antibodies. These immunoglobulins bind to the surface of mast cells, triggering the release of inflammatory chemical mediators like histamine.
Q4
Anaphylactic shock is due to
- A. Allergic reactionCorrect
- B. Secretion of toxins
- C. Secretion of histamines
- D. All the above
Explanation. Anaphylactic shock is a severe, life-threatening systemic allergic reaction. It represents a classical immediate hypersensitivity response caused by rapid, generalized degranulation of mast cells and release of vasoactive mediators.
Q5
Spread of cancerous cells to distant sites is termed as
- A. MetastasisCorrect
- B. Oncogenes
- C. Proto-oncogenes
- D. Malignant neoplasm
Explanation. Metastasis is the process by which malignant cancer cells detach from the primary tumor, migrate through blood or lymphatic vessels, and colonize distant healthy tissues to form secondary tumors.
Q6
AIDS virus has
- A. Single stranded RNACorrect
- B. Double stranded RNA
- C. Single stranded DNA
- D. Double stranded DNA
Explanation. The Human Immunodeficiency Virus, which causes AIDS, is an enveloped retrovirus carrying its genetic information in the form of two identical molecules of single-stranded RNA along with reverse transcriptase enzymes.
Q7
All are peripheral lymphoid organs except
- A. Lymph nodes
- B. Spleen
- C. Mucosa associated lymphoid tissue
- D. ThymusCorrect
Explanation. The thymus is a primary lymphoid organ responsible for the selection and maturation of T-lymphocytes. In contrast, lymph nodes, spleen, and mucosa-associated lymphoid tissues are peripheral lymphoid organs where immune responses are initiated.
Q8
Which is a macrophage?
- A. MonocyteCorrect
- B. Erythrocyte
- C. Thrombocyte
- D. Lymphocyte
Explanation. Monocytes are a type of white blood cell circulating in the blood. When they migrate into body tissues, they undergo maturation and differentiate into large, highly phagocytic cells known as macrophages.
Q9
True about interferon is that
- A. It is synthetic antiviral agent
- B. It inhibits viral replication in cellsCorrect
- C. It is specific for a particular virus
- D. It causes infection
Explanation. Interferons are natural glycoprotein signaling molecules produced by virally infected mammalian cells. They stimulate neighboring, uninfected cells to synthesize antiviral enzymes, thereby actively inhibiting the replication of viruses.
Q10
Cell mediated immunity is carried out by______________ while humoral immunity is mainly carried out by
- A. B cells/T cells
- B. Epitopes/antigens
- C. T cells/B cellsCorrect
- D. antibodies/antigens
Explanation. Cell-mediated immunity is directly executed by T-lymphocytes, which destroy damaged or infected cells. Humoral immunity is mediated by B-lymphocytes, which differentiate into plasma cells that secrete specific antibodies into body fluids.
Q11
B Cells are activated by
- A. Complement
- B. Antibody
- C. Interferon
- D. AntigenCorrect
Explanation. B-lymphocytes are activated when their membrane-bound antigen receptors bind directly to a specific foreign antigen. This binding event, typically assisted by cytokine signals, initiates cell division and differentiation into plasma cells.
Q12
In agglutination and precipitation reactions, the antigen is a ______________ and ____________ respectively
- A. Whole cell/soluble moleculeCorrect
- B. Soluble molecule/whole cell
- C. Bacterium/virus
- D. Protein/Antibody
Explanation. Agglutination is a cross-linking reaction occurring between antibodies and particulate or whole-cell antigens. Precipitation occurs when antibodies react with soluble antigen molecules, forming an insoluble lattice that settles out of solution.
Q13
B cells that produce and release large amounts of antibody are called
- A. Memory cells
- B. Basophils
- C. Plasma cellsCorrect
- D. killer cells
Explanation. Upon antigen activation and clonal selection, B-lymphocytes differentiate into effector cells called plasma cells. These specialized cells serve as factories that actively synthesize and secrete large quantities of soluble antibodies.
Q14
Raja is injured and got swelling. The swelling is due to the infection of tissue is an example of
- A. Mechanical barrier
- B. Physiological barrier
- C. Phagocytosis
- D. InflammationCorrect
Explanation. Tissue injury or infection triggers an inflammatory response. Chemical alarm signals cause increased local blood flow and vascular permeability, resulting in fluid accumulation in the surrounding tissues, which manifests as swelling.
About these Immunology questions
These are the Book Back multiple-choice questions for Immunology from the Tamil Nadu State Board (Samacheer Kalvi) 12th Standard Zoology syllabus. Each question shows the correct option and an original, step-by-step explanation so you understand the method, not just the answer. Use the answer key above to jump to any question, then take the practice test to check yourself under exam-like conditions.
Frequently asked questions
How many MCQs are there in Immunology?
This chapter has 14 book-back multiple-choice questions, each with the correct answer and a step-by-step explanation.
Are these 12th Standard Zoology MCQs free to practise online?
Yes. Every question, answer and explanation here is free, and you can also take them as a timed practice test.
Where can I find the Immunology book-back answers?
The correct option for each question is highlighted on this page with a worked explanation, plus a quick answer-key summary at the top.
