Immunity

Biology, HSSC-Punjab Second Year. This chapter is split into 26 topics and has 540 practice questions. The topics covered are listed below, followed by 10 free sample questions from the chapter.

Topics in this chapter

1. Autoimmune Diseases 20 questions
2. Protective Proteins: Complement System and Interferons 20 questions
3. Allergies and the Role of Histamines 20 questions
4. The Immune System and Lines of Defence 20 questions
5. First Line of Defence: The Skin 20 questions
6. Components of the Immune System: Monocytes, T Cells and B Cells 20 questions
7. Monoclonal Antibodies 20 questions
8. Transplant Rejection and Self-Proteins 20 questions
9. Temperature Response: Pyrogens and Fever 20 questions
10. Structure of an Antibody 20 questions
11. Vaccination, Immune Memory and Gene Therapy for Cancer 20 questions
12. Cell-Mediated Immunity 20 questions
13. Chapter Review: Immune System 20 questions
14. Antibody-Mediated (Humoral) Immunity 20 questions
15. The Inflammatory Response 20 questions
16. Second Line of Defence: Macrophages and Neutrophils 20 questions
17. Third Line of Defence and Types of Immunity 20 questions
18. Natural Killer Cells and Self-Proteins 20 questions
19. First Line of Defence: Digestive and Respiratory Tracts 20 questions
20. First-Line Barriers: Numbers, Analogies and Applied Reasoning 25 questions
21. Second Line of Defence: Cells, Proteins, Inflammation and Fever in Application 20 questions
22. T Cells, B Cells and Cell-Mediated Immunity in Application 24 questions
23. Antibody-Mediated Immunity, Antibody Molecule and Monoclonal Antibodies in Application 23 questions
24. Active and Passive Immunity: Case Classification, Vaccines and Tumour-Fighting Cells 24 questions
25. Allergy, Autoimmunity and Transplant Rejection: Case Studies and Reasoning 24 questions
26. Immunity: Assertion and Reason Questions 20 questions

Sample questions: Immunity

10 sample questions with the correct answer and an explanation. Try to answer each one before reading the explanation.

Q1. Which first-line site uses both a structural barrier and chemical secretions?

• A. The lining of the stomach
• B. The skin(correct answer)
• C. The bronchioles
• D. The ciliated nasal epithelium

Answer: B.Skin has tough keratin cells (structural) plus an acidic film and lysozyme (chemical); the other sites rely on a single kind of action as described in the chapter.

Q2. In the complement cascade each protein activates the next one. If the third protein of the sequence were non-functional, what would result?

• A. The later proteins, including the membrane-attack complex, would not be activated(correct answer)
• B. All the complement proteins would be activated together at once instead
• C. The complement proteins would be produced by the pancreas instead of the liver
• D. Only the first two proteins would be activated, but the complex would still form

Answer: A.Because activation proceeds in a sequence, a break at the third step prevents activation of the following proteins and therefore the final five proteins of the complex.

Q3. Which sequence of events in the inflammatory response is correct?

• A. Macrophages clear debris, monocytes arrive, phagocytes migrate in, chemical signals are released afterwards
• B. Blood vessels widen and leak, macrophages clear debris, chemical signals released, phagocytes migrate in afterwards
• C. Phagocytes migrate in, chemical signals released, blood vessels widen and leak, macrophages clear debris afterwards
• D. Chemical signals released, blood vessels widen and leak, phagocytes migrate in, monocytes arrive, macrophages clear debris(correct answer)

Answer: D.Injured cells first release histamines and prostaglandins; vessels dilate and become permeable; phagocytes, then monocytes arrive; macrophages finally clean up.

Q4. Of the four main kinds of T cells, how many directly break the body cells infected by microbes?

• A. One (cytotoxic T cells)(correct answer)
• B. Three (helper, inducer and cytotoxic T cells)
• C. All four
• D. Two (helper and cytotoxic T cells)

Answer: A.Helper T cells initiate the response, inducer T cells supervise development in the thymus and suppressor T cells end the response; only cytotoxic T cells break infected cells.

Q5. Which order correctly leads from the entry of a microbe to the start of the specific immune response?

• A. Helper T cell is activated, macrophage engulfs microbe, special proteins are produced, receptors recognise them afterwards
• B. Special proteins are produced, helper T cell is activated, macrophage engulfs microbe, receptors recognise them afterwards
• C. Macrophage engulfs microbe, produces special proteins, helper T cell receptors recognise them, helper T cell is activated(correct answer)
• D. Receptors recognise proteins, macrophage engulfs microbe, helper T cell is activated, proteins are produced afterwards

Answer: C.A macrophage first engulfs the microbe and produces proteins for helper T cells; their receptors recognise these proteins and the helper T cells are activated.

Q6. A B cell has bound an antigen but no helper T cell recognises the antigen-bound B cell. What is the most likely result?

• A. The B cell becomes a cytotoxic T cell at once
• B. The B cell immediately changes into a memory T cell
• C. The B cell is ingested by a plasma cell in the lymph
• D. The B cell does not proliferate into many plasma cells(correct answer)

Answer: D.Helper T cells that bind the antigen-bound B cell release proteins that stimulate it to proliferate; without them, strong plasma cell production does not occur.

Q7. A patient has no functional B cells but normal T cells. The patient would be least able to deal with:

• A. A cancer cell in the early stage
• B. A virus-infected liver cell
• C. A cell lacking self-proteins that is met by an NK cell
• D. Toxic molecules released into the body fluids(correct answer)

Answer: D.B cells make the antibodies that mark and inactivate antigens and toxic molecules in body fluids; virus-infected and cancer cells are handled by T cells and NK cells.

Q8. A traveller is exposed to a dangerous infection. A doctor injects ready-made antibodies and also gives a vaccine. Which statement is correct?

• A. The antibodies give immediate protection and the vaccine gives long-term protection(correct answer)
• B. The vaccine gives immediate protection and the antibodies give long-term protection
• C. Both give long-term protection of equal length
• D. Both give only immediate and short-lived protection

Answer: A.Injected antibodies act at once but are short-lived (passive); the vaccine starts the body's own antibody and memory cell production (active), which takes longer but lasts.

Q9. Systemic lupus erythematosus is called 'systemic' because the antibodies attack:

• A. Only one joint at a time in the body of the patient
• B. Only the receptors of the skeletal muscle of the patient
• C. Connective tissues and major organs throughout the body(correct answer)
• D. Only the insulin-making cells of the pancreas of the patient

Answer: C.The disease involves antibodies against the patient's own connective tissues and major organs, so many body systems are affected (standard explanation of 'systemic').

Q10. Assertion (A): B cells do not travel to the thymus to mature. Reason (R): The thymus is a small grey gland located just above the heart. Which option is correct?

• A. The assertion is false but the reason is a true one
• B. Both are true but the reason is not the explanation(correct answer)
• C. Both are true and the reason explains the assertion
• D. The assertion is true but the reason is a false one

Answer: B.Both statements are true: B cells mature in the bone marrow, and the thymus lies above the heart, but the location of the thymus does not explain why B cells skip it.