Human Health and Disease Mock Test – Class 12 Biology

1. The increased HIV risk associated with sharing needles during intravenous drug abuse is best explained by

2. A person never smokes but uses chewing tobacco for many years. Which misconception is contradicted most directly by known tobacco effects?

3. An intravenous drug user shares needles and later tests positive for hepatitis B but not HIV. What does this outcome demonstrate?

4. In a family where one member has a respiratory infection spread through droplets and contaminated belongings, the most appropriate additional precaution is

5. A vaccinated individual has normal B-cell function but later develops a severe defect in T-lymphocyte function before encountering the pathogen again. Which statement best predicts the effect on acquired immunity?

6. Bone marrow function is severely impaired, but the thymus remains structurally normal. Which additional consequence is most directly supported biologically?

7. Substance abuse during pregnancy is especially concerning because

8. Two patients acquire intestinal infections after consuming contaminated vegetables. Patient P has abdominal cramps and stools containing excess mucus and blood clots. Patient Q develops anaemia and intestinal blockage. Which pairing is best supported biologically?

9. A community programme combines removal of stagnant water, mosquito nets, wire mesh, insecticides and introduction of Gambusia into suitable water bodies. The common biological objective of these measures is to

10. An adolescent who abuses anabolic steroids develops severe acne and stops gaining expected height earlier than anticipated. Which explanation best connects these findings?

11. Which table correctly distinguishes an acute consequence from a chronic consequence of substance abuse?

12. A person touches a keyboard contaminated by droplets from someone with common cold and then transfers the virus to the nose. Which route is illustrated?

13. After an infected female Anopheles mosquito introduces malarial parasites into a human, which sequence correctly describes the early human phase?

14. An HIV-positive patient begins antiretroviral treatment and remains clinically stable for a longer period. Which statement should not be inferred from this improvement?

15. A drug user consumes an excessive amount of a psychoactive substance together with alcohol. Which conclusion is most appropriate?

16. A severe drug overdose results in failure of a vital physiological system. Which fatal mechanisms are specifically listed?

17. The statement that both humans and mosquitoes are required for completion of the Plasmodium life cycle means that

18. A mosquito-borne helminthic infection produces slowly developing chronic inflammation but no intestinal blockage. Which site of pathology would most strongly support filariasis?

19. A patient's helper T-lymphocyte population declines progressively over time because of HIV infection. Which consequence is most directly expected?

20. A mutation prevents B lymphocytes from secreting antibodies, but T lymphocytes remain capable of performing their normal functions. Which combination is most likely?

21. An adolescent feels overwhelmed by academic stress and has begun experimenting with alcohol. Before the behaviour becomes more serious, which response is most appropriate?

22. Disease is best recognised as a condition in which

23. A pathogen is present mainly in tissue fluid and subsequently enters lymphatic vessels rather than circulating initially in blood. Which organ is especially suited to trap its antigens as the lymph passes through the lymphatic system?

24. Consider the following substances.
I. Atropa belladonna
II. Datura
III. Barbiturates
IV. Amphetamines
V. Benzodiazepines
Which statement best organises them?

25. A developmental defect severely disrupts the microenvironment required for normal T-lymphocyte maturation in the thymus. Which immune-cell population would be most directly affected?

26. Amoebiasis and ascariasis can both be associated with contaminated food or water, but they differ because

27. A public-health campaign provides safe blood screening, disposable needles, education about safer sexual behaviour and social-support programmes for people living with HIV. Why is this combination stronger than a campaign based only on isolation?

28. Three immune problems are described. Case P reacts excessively to pollen. Case Q attacks the person's own tissues. Case R damages a transplanted organ recognised as non-self. Which classification is correct?

29. An athlete uses a substance without medical need because it is believed to increase strength, body bulk or aggressiveness. Which broader category does this behaviour represent?

30. Consider the following disease-agent-site relations:
I. Typhoid — Salmonella typhi — small intestine
II. Pneumonia — Streptococcus pneumoniae — alveoli
III. Common cold — rhinoviruses — nose and respiratory passage
IV. Pneumonia — Haemophilus influenzae — large intestine
Which set contains only correctly matched relations?

31. Blood neutrophils and monocytes are severely depleted, but interferon production remains normal. Which innate defensive layer is most directly compromised?

32. The principal functional distinction between primary and secondary lymphoid organs is that

33. A stool sample contains mucus and blood clots from a patient with abdominal cramps, while epidemiological investigation finds frequent houseflies moving between exposed faecal material and uncovered food. Which disease and transmission mechanism fit best?

34. Normal cells may contain cellular oncogenes, also called proto-oncogenes. Their significance in cancer is that

35. A hormone-related drug is prescribed to treat a genuine medical condition in one person, while another person takes it without medical need solely to improve sporting performance. Which statement is most accurate?

36. Assertion: Natural killer cells and macrophages are both included among cellular components of innate immunity. Reason: Every cellular component of innate immunity protects the host through exactly the same mechanism.

37. Assertion: Both human and mosquito hosts are necessary for completion of the Plasmodium life cycle. Reason: Parasite development occurs partly in humans and partly in the female mosquito before infective sporozoites reach the mosquito salivary glands.

38. Another approach mentioned for cancer detection makes use of

39. Cocaine is obtained from the plant

40. Atropa belladonna and Datura are mainly cited as examples of

41. An intestinal pathogen becomes more successful after stomach acidity is experimentally reduced, while the person's skin and immune-cell numbers remain normal. Which inference is best supported?

42. A family's financial difficulties worsen as one member spends increasing amounts of money on drugs and becomes unable to maintain normal responsibilities. Which principle is illustrated?

43. A doctor suspects that a patient is allergic to a particular environmental substance. One approach for identifying the responsible allergen is to

44. Three disease-transmission relationships are listed. Which one differs fundamentally from the other two because the arthropod participates in parasite development rather than merely transferring infective material?

45. Four immune events occur in the same person.
I. Skin prevents microbial entry.
II. A second exposure to the same antigen produces a stronger response than the first.
III. Pollen triggers an IgE-associated exaggerated response.
IV. Immune cells attack the person's own tissues.
Which classification is correct?

46. A programme provides sterile disposable needles to reduce infection transmission among people who inject drugs. Which limitation of this intervention is most accurate?

47. Which integrated strategy most closely follows the recommended approach to preventing and controlling adolescent substance abuse?

48. A tumour is surgically removed, but microscopic malignant cells remain. Radiotherapy is directed to the affected region while surrounding normal tissue is protected as far as possible. What is the intended principle?

49. A drug produces pronounced CNS stimulation and euphoria. When the dose becomes excessive, hallucinations occur. Which molecular relation best supports identification of the drug?

50. A vaccination campaign leads to long-term population-level control of several infectious diseases. Which historical outcome most clearly demonstrates the potential power of immunisation?