Class 12/Question Bank/Competency Based
Created by Titas Mallick
Biology Teacher • M.Sc. Botany • B.Ed. • CTET (CBSE) • CISCE Examiner
Created by Titas Mallick
Biology Teacher • M.Sc. Botany • B.Ed. • CTET (CBSE) • CISCE Examiner
Competency Based Questions on Human Health and Diseases
1. Diagnose the Patient: A patient presents with sustained high fever (39°C - 40°C), stomach pain, constipation, headache, and loss of appetite. The doctor prescribes a Widal test. What is the most likely diagnosis if the test is positive? a) Malaria b) Pneumonia c) Typhoid d) Amoebiasis Answer: c) Typhoid Explanation: These are the classic clinical symptoms of Salmonella typhi infection. The Widal test is specifically used to diagnose Typhoid (Enteric fever).
2. Analyze the Immune Response: A person is infected with a virus. Which of the following innate immune responses will be the first line of defense to prevent the virus from infecting neighboring healthy cells? a) Production of IgG antibodies b) Secretion of Interferons c) Activation of Memory B-cells d) Release of Histamine Answer: b) Secretion of Interferons Explanation: Interferons are cytokine barriers produced by virus-infected cells. They signal neighboring uninfected cells to produce antiviral proteins, protecting them from the virus.
3. Identify the Vector: A sudden outbreak of a disease characterized by severe joint pain and high fever occurs in a town. The local health department finds high breeding of Aedes aegypti mosquitoes. Which disease is this likely to be? a) Malaria b) Filariasis c) Chikungunya d) Typhoid Answer: c) Chikungunya Explanation: Severe, debilitating joint pain is the hallmark of Chikungunya. The Aedes mosquito is the primary vector for both Chikungunya and Dengue.
4. Assertion (A): The use of vaccines leads to the production of antibodies and memory cells. Reason (R): Vaccines introduce pre-formed antibodies into the body for immediate protection. a) Both A and R are true and R is the correct explanation of A. b) Both A and R are true but R is not the correct explanation of A. c) A is true but R is false. d) A is false but R is true. Answer: c) A is true but R is false. Explanation: Vaccines introduce Antigens (weakened/killed pathogens), which trigger the body's own immune system to make antibodies and memory cells (Active Immunity). Introducing pre-formed antibodies is Passive Immunity.
5. Predict the Outcome: If a person's thymus gland is removed at birth (thymectomy), which part of their immune system will be most severely affected? a) Humoral Immunity only b) Cell-Mediated Immunity (CMI) c) Innate Immunity d) Phagocytosis Answer: b) Cell-Mediated Immunity (CMI) Explanation: The Thymus is where T-lymphocytes mature. T-cells are responsible for CMI. Without a thymus, T-cells cannot mature, leading to severe deficiency in CMI.
6. Mechanism of Action: How does the HIV virus specifically cause immunodeficiency in the host? a) By destroying red blood cells. b) By attacking the liver cells. c) By destroying Helper T-lymphocytes (TH cells). d) By inhibiting antibody production directly. Answer: c) By destroying Helper T-lymphocytes (TH cells). Explanation: HIV infects and kills TH cells (CD4+ cells). Since TH cells are needed to activate both B-cells (for antibodies) and Cytotoxic T-cells, their loss collapses the entire adaptive immune system.
7. Evaluate the Drug: Morphine is a very effective sedative and painkiller. However, it is strictly regulated. Why? a) It causes severe allergic reactions. b) It is ineffective in most patients. c) It has a high potential for addiction and abuse. d) It causes kidney failure immediately. Answer: c) It has a high potential for addiction and abuse. Explanation: Morphine is an opioid that provides euphoria and powerful pain relief, but it leads to rapid physiological and psychological dependence (addiction).
8. Differentiate: Which of the following features distinguishes a Malignant tumor from a Benign tumor? a) Uncontrolled cell division. b) Absence of contact inhibition. c) Metastasis. d) Presence of blood vessels. Answer: c) Metastasis. Explanation: Both tumor types show uncontrolled growth. Only malignant tumors have the ability to shed cells into the blood/lymph and start new tumors in distant organs (Metastasis).
9. Immunology Application: A newborn baby receives IgA antibodies from the mother's milk (colostrum). What type of immunity is this? a) Natural Active Immunity b) Artificial Active Immunity c) Natural Passive Immunity d) Artificial Passive Immunity Answer: c) Natural Passive Immunity Explanation: It is Passive because the baby is receiving ready-made antibodies. It is Natural because it occurs through a biological process (breastfeeding), not a medical procedure.
10. Lifecycle Analysis: In the life cycle of Plasmodium, where does sexual reproduction (fertilization) occur? a) In the human liver. b) In the human RBCs. c) In the mosquito's gut. d) In the mosquito's salivary glands. Answer: c) In the mosquito's gut. Explanation: Gametocytes are taken up by the mosquito from human blood. They mature and fertilize in the mosquito's gut, forming a zygote.
11. Identify the Mismatch: a) Salmonella typhi - Bacteria - Typhoid b) Microsporum - Fungi - Ringworm c) Wuchereria bancrofti - Protozoa - Filariasis d) Rhinovirus - Virus - Common Cold Answer: c) Wuchereria bancrofti - Protozoa - Filariasis Explanation: Wuchereria bancrofti is a Helminth (specifically a Nematode or roundworm), not a protozoan.
12. Critical Thinking: Why are organ transplant patients given immunosuppressant drugs like Cyclosporin-A? a) To prevent bacterial infection of the new organ. b) To suppress Cell-Mediated Immunity (CMI) and prevent graft rejection. c) To stimulate antibody production. d) To reduce pain. Answer: b) To suppress Cell-Mediated Immunity (CMI) and prevent graft rejection. Explanation: The recipient's T-cells recognize the transplanted organ as "non-self" and attack it (Cell-Mediated response). Immunosuppressants block this attack to allow the organ to survive.
13. Diagnosis: A child has an itchy, dry, scaly lesion on the scalp. The doctor advises not to share the child's comb or towel. What is the causative organism likely to be? a) Ascaris b) Entamoeba c) Trichophyton d) Haemophilus Answer: c) Trichophyton Explanation: These are the symptoms of Ringworm, which is a fungal infection caused by genera like Microsporum, Trichophyton, or Epidermophyton.
14. Prevention Strategy: To prevent the spread of Amoebiasis and Ascariasis, which public health measure is most effective? a) Use of mosquito nets. b) Improvement of sanitation and hygiene (fecal-oral route). c) Vaccination campaigns. d) Wearing masks. Answer: b) Improvement of sanitation and hygiene. Explanation: Both diseases are transmitted when food or water is contaminated by the feces of an infected person containing eggs (Ascaris) or cysts (Entamoeba).
15. Concept Check: What is the primary function of "Memory cells" in the immune system? a) To produce antibodies immediately upon first exposure. b) To engulf pathogens. c) To launch a faster and stronger secondary response upon re-exposure. d) To differentiate into T-cells. Answer: c) To launch a faster and stronger secondary response... Explanation: Memory cells persist after an infection. Upon a second encounter with the same pathogen, they recognize it instantly and multiply rapidly to eliminate it before symptoms develop.
Mr. Kumar returned from a trip to a forest area. A few days later, he started experiencing high fever which recurred every 3 days (48-hour cycle), accompanied by severe chills and shivering. His blood report showed a lower than normal RBC count.
16. Identify: What disease is Mr. Kumar likely suffering from? a) Typhoid b) Malaria c) Dengue d) Pneumonia Answer: b) Malaria Explanation: Recurring cycles of chills and high fever are characteristic of Malaria. The forest trip suggests mosquito exposure.
17. Analyze: What causes the characteristic "chills and recurring fever"? a) Release of histamine by mast cells. b) Rupture of RBCs and release of the toxin Hemozoin. c) Bacterial toxins in the blood. d) The bite of the mosquito itself. Answer: b) Rupture of RBCs and release of the toxin Hemozoin. Explanation: When Plasmodium multiplies in RBCs, the cells eventually burst, releasing Hemozoin. This chemical triggers the massive inflammatory response (fever/chills).
18. Prevention: Which vector control measure would have best prevented this infection? a) Using Gambusia fish in ponds. b) Wearing a mask. c) Drinking boiled water. d) Avoiding crowded places. Answer: a) Using Gambusia fish in ponds. Explanation: Gambusia fish eat mosquito larvae. Since Malaria is transmitted by mosquitoes (Anopheles), controlling the vector population prevents the disease.
A 50-year-old woman discovers a hard, painless lump in her breast. She ignores it for months. Later, she notices swelling in her armpit lymph nodes. A biopsy confirms breast cancer.
19. Evaluate: The fact that the cancer has reached the lymph nodes suggests which property of the tumor? a) It is Benign. b) Contact Inhibition. c) Metastasis. d)Differentiation. Answer: c) Metastasis. Explanation: Metastasis is the spread of cancer cells from the primary site (breast) to other parts of the body (lymph nodes).
20. Treatment: Her doctor recommends a combination of Surgery, Radiotherapy, and Chemotherapy. How does Chemotherapy specifically work to kill cancer cells? a) It surgically removes the tissue. b) It burns the cells with radiation. c) It uses drugs to target and kill rapidly dividing cells. d) It activates the immune system. Answer: c) It uses drugs to target and kill rapidly dividing cells. Explanation: Chemotherapy drugs interfere with DNA replication or cell division. Since cancer cells divide very fast, they are killed preferentially.
21. Side Effects: Why might she experience hair loss and anemia during treatment? a) The cancer eats the hair follicles. b) Chemotherapy drugs affect all rapidly dividing cells, including hair roots and bone marrow. c) It is a symptom of breast cancer. d) Due to lack of appetite. Answer: b) Chemotherapy drugs affect all rapidly dividing cells... Explanation: Normal cells that divide fast (hair, skin, blood-forming bone marrow) are caught in the crossfire of chemotherapy, leading to hair loss and low RBC counts (anemia).
Little Rohan goes to a park to play. Suddenly, he starts sneezing violently, his eyes become watery, and he has difficulty breathing (wheezing). His mother gives him an anti-histamine tablet, and he feels better.
22. Mechanism: Which antibody isotype is responsible for triggering this reaction? a) IgG b) IgA c) IgM d) IgE Answer: d) IgE Explanation: IgE is the immunoglobulin produced in response to environmental allergens.
23. Cellular Level: Which cells released the chemicals (like Histamine) that caused these symptoms? a) Macrophages b) Mast Cells and Basophils c) Helper T-cells d) Red Blood Cells Answer: b) Mast Cells and Basophils Explanation: IgE binds to the surface of Mast cells. When the allergen (pollen) attaches to this IgE, the mast cell "degranulates," releasing Histamine and Serotonin.
24. Critical Analysis: Why did the anti-histamine work? a) It killed the pollen grains. b) It blocked the action of histamine on body tissues. c) It increased IgE production. d) It acted as a vaccine. Answer: b) It blocked the action of histamine on body tissues. Explanation: Histamine causes sneezing/inflammation. Anti-histamines block the histamine receptors, stopping the symptoms.
25. Designing a Campaign: You are the Health Officer for a city facing a Dengue outbreak.
26. Visualizing Immunity: Draw a flowchart or describe the sequence of events in the Humoral Immune Response when a pathogen enters the blood. Answer:
27. Formulating a Hypothesis: Observation: HIV cases are higher in populations with high rates of drug abuse.
28. Debating Addiction: Topic: "Addiction is a disease, not a choice."
29. Scenario Analysis (Cancer): Two patients have tumors. Patient A has a Benign lipoma. Patient B has a Malignant sarcoma.
30. Creating a Public Health Advisory: Draft a short advisory for a high school notice board regarding "Adolescence and Drug/Alcohol Abuse." Answer:
31. Analyzing Data: Data: A graph shows antibody levels in blood.
/Class-12/Question-Bank/Competency-Based/Unit_3_Chapter_1_Human_Health_and_Diseases_Competency_Questions.mdx