Human Health & Diseases

Topic: Immunology and Transplantation; Subtopic: Immuno-suppressants and Immune Response Regulation

Keyword Definitions:

• Immuno-suppressants: Drugs that reduce the strength of the body’s immune system to prevent rejection of transplanted organs or reduce inflammation.

• Cell-mediated immunity: Immune response involving T lymphocytes that destroy infected or foreign cells.

• Humoral immunity: Immune response mediated by antibodies produced by B lymphocytes.

• Cytokine storm: Excessive immune response caused by overproduction of cytokines leading to tissue damage.

• Innate immunity: The body’s natural, non-specific defense mechanism present from birth.

Lead Question – 2022 (Abroad)
Immuno-suppressants are administered to burn-patients or during organ transplantation to suppress:
1. Innate immunity
2. Cytokine storm
3. Humoral immunity
4. Cell-mediated immunity

Explanation: During organ transplantation, immuno-suppressants are used to suppress cell-mediated immunity to prevent the rejection of the transplanted organ. T lymphocytes recognize the transplanted tissue as foreign and trigger immune destruction. Immuno-suppressants like cyclosporine inhibit this reaction while allowing partial humoral immunity to function. Correct answer: 4. Cell-mediated immunity

1. Which cells are primarily suppressed by immuno-suppressive drugs during organ transplantation?
1. B-lymphocytes
2. T-lymphocytes
3. Natural killer cells
4. Macrophages

Explanation: Immuno-suppressive drugs mainly act on T-lymphocytes, which are responsible for recognizing and attacking foreign antigens such as transplanted organs. By suppressing T-cell activation, rejection is minimized, allowing graft survival while maintaining some immune defense. Correct answer: 2. T-lymphocytes

2. Which of the following is a commonly used immuno-suppressive drug in organ transplantation?
1. Penicillin
2. Cyclosporine
3. Insulin
4. Paracetamol

Explanation: Cyclosporine is a potent immuno-suppressant used to prevent organ rejection after transplantation. It inhibits activation of T-cells by blocking interleukin-2 synthesis. Other drugs like azathioprine and tacrolimus are also used for similar purposes. Correct answer: 2. Cyclosporine

3. Which organ is commonly transplanted and requires long-term immuno-suppressive therapy?
1. Liver
2. Heart
3. Kidney
4. Lungs

Explanation: Kidney transplantation is the most common organ transplant worldwide. Recipients require lifelong immuno-suppressive medication to prevent rejection and maintain graft function. Drugs like cyclosporine and prednisolone are commonly prescribed. Correct answer: 3. Kidney

4. Which type of immunity is mainly responsible for graft rejection?
1. Innate immunity
2. Passive immunity
3. Cell-mediated immunity
4. Artificial immunity

Explanation: Cell-mediated immunity, driven by cytotoxic T-cells, is responsible for graft rejection. These T-cells recognize antigens on donor tissue as foreign and destroy the graft cells through immune attack. Immuno-suppressive drugs prevent this mechanism. Correct answer: 3. Cell-mediated immunity

5. Which of the following organs is least likely to cause rejection after transplantation?
1. Heart
2. Kidney
3. Liver
4. Lungs

Explanation: The liver is less immunogenic and more tolerant than other organs, hence it has lower chances of rejection after transplantation. This is due to its unique immune-regulating properties and regenerative capacity. Correct answer: 3. Liver

6. Which of the following immuno-suppressive drugs acts by inhibiting DNA synthesis in lymphocytes?
1. Azathioprine
2. Cyclosporine
3. Tacrolimus
4. Prednisolone

Explanation: Azathioprine is an immuno-suppressant that inhibits DNA synthesis in proliferating lymphocytes, reducing both humoral and cell-mediated immune responses. It is often used in combination with cyclosporine for effective suppression. Correct answer: 1. Azathioprine

Assertion-Reason Question
7. Assertion (A): Cyclosporine prevents transplant rejection by suppressing T-cell activation.
Reason (R): It blocks interleukin-2 production necessary for T-cell proliferation.
1. Both (A) and (R) are true and (R) is the correct explanation of (A)
2. Both (A) and (R) are true but (R) is not the correct explanation of (A)
3. (A) is true but (R) is false
4. (A) is false but (R) is true

Explanation: Cyclosporine suppresses T-cell activation by blocking calcineurin and thereby inhibiting interleukin-2 (IL-2) synthesis, which is essential for T-cell proliferation. Thus, both statements are true, and (R) correctly explains (A). Correct answer: 1. Both (A) and (R) are true and (R) is the correct explanation of (A)

Matching Type Question
8. Match the following drugs with their functions:
A. Cyclosporine — (i) Inhibits IL-2 synthesis
B. Azathioprine — (ii) Blocks DNA replication
C. Prednisolone — (iii) Reduces inflammation
D. Tacrolimus — (iv) Calcineurin inhibitor
1. A–i, B–ii, C–iii, D–iv
2. A–ii, B–iv, C–i, D–iii
3. A–iv, B–i, C–ii, D–iii
4. A–iii, B–ii, C–i, D–iv

Explanation: Cyclosporine inhibits IL-2 synthesis (i). Azathioprine blocks DNA replication (ii). Prednisolone reduces inflammation (iii). Tacrolimus acts as a calcineurin inhibitor (iv), similar in function to cyclosporine but more potent. Correct answer: 1. A–i, B–ii, C–iii, D–iv

Fill in the Blanks Question
9. The drug ________ is used to suppress immune response in transplant patients by inhibiting interleukin-2 synthesis.
1. Prednisolone
2. Azathioprine
3. Cyclosporine
4. Tacrolimus

Explanation: Cyclosporine inhibits calcineurin, which is essential for interleukin-2 synthesis. IL-2 is a key cytokine required for T-cell activation and proliferation. By blocking its production, cyclosporine effectively prevents transplant rejection. Correct answer: 3. Cyclosporine

Choose the Correct Statements Question
10. Statement I: Immuno-suppressants completely destroy the immune system.
Statement II: They are used in limited doses to prevent graft rejection while maintaining basic immunity.
1. Only Statement I is correct
2. Only Statement II is correct
3. Both Statements are correct
4. Both Statements are incorrect

Explanation: Immuno-suppressants do not completely destroy the immune system but selectively suppress certain immune responses to prevent rejection. They are administered in controlled doses to maintain partial immunity for protection against infections. Correct answer: 2. Only Statement II is correct

Chapter: Immunology
Topic: Acquired Immunity
Subtopic: Primary and Secondary Immune Response

Keyword Definitions:

• Acquired immunity: Adaptive immune system developed after exposure to specific pathogens.

• Anamnestic response: Enhanced secondary immune response upon re-exposure to the same pathogen.

• Memory cells: Long-lived lymphocytes that remember previous pathogen exposure to produce faster and stronger response.

• Primary response: Initial immune response triggered by first encounter with a pathogen, usually slower and weaker.

• Specific defense: Immune mechanisms targeting specific antigens.

• Non-specific defense: Innate immunity present from birth, including barriers and phagocytic cells.

• Pathogen: Microorganism causing disease in host organism.

Lead Question (2022):
Select the incorrect statement with respect to acquired immunity:
(1) Anamnestic response is elicited on subsequent encounters with the same pathogen
(2) Anamnestic response is due to memory of first encounter
(3) Acquired immunity is non-specific type of defence present at the time of birth
(4) Primary response is produced when our body encounters a pathogen for the first time

Explanation: Acquired immunity is specific and develops after first exposure to a pathogen. Statements (1), (2), and (4) correctly describe primary and secondary immune responses. Statement (3) is incorrect because acquired immunity is specific and not present at birth; innate immunity is the non-specific defense present at birth. Correct answer is option (3).

1. Memory cells are responsible for:
(1) Immediate primary response
(2) Faster secondary response
(3) Non-specific defense
(4) Phagocytosis

Explanation: Memory cells, produced during primary infection, remain in the body and recognize the pathogen upon re-exposure, eliciting a rapid and strong secondary immune response. Therefore, option (2) is correct.

2. Primary immune response is characterized by:
(1) Immediate and strong antibody production
(2) Slow onset and low antibody levels
(3) Absence of antigen recognition
(4) Non-specific defense activation

Explanation: Primary response occurs when the body encounters a pathogen for the first time. It is slow, with low antibody titers, and memory cells are generated for future encounters. Hence, option (2) is correct.

3. Secondary (anamnestic) immune response differs from primary response in that:
(1) It is slower
(2) It produces fewer antibodies
(3) It is faster and more effective
(4) It does not involve memory cells

Explanation: The secondary response is faster and more robust because memory B and T cells recognize the pathogen. It produces higher antibody titers compared to primary response. Therefore, option (3) is correct.

4. Which cells directly produce antibodies?
(1) T helper cells
(2) Plasma cells
(3) Memory T cells
(4) Macrophages

Explanation: Plasma cells, differentiated from B lymphocytes upon antigen stimulation, are responsible for secreting antibodies that neutralize pathogens. Hence, option (2) is correct.

5. Acquired immunity is specific because:
(1) It targets any pathogen
(2) It recognizes and responds to specific antigens
(3) It does not involve memory cells
(4) It is present at birth

Explanation: Acquired immunity is specific as it recognizes unique antigens on pathogens, producing tailored immune responses and generating memory cells for faster secondary response. Innate immunity is non-specific. Therefore, option (2) is correct.

6. Vaccination works by:
(1) Activating non-specific defenses
(2) Producing memory cells without causing disease
(3) Killing pathogens immediately
(4) Preventing antigen presentation

Explanation: Vaccines expose the body to antigens from pathogens without causing illness, stimulating production of memory B and T cells, enabling a rapid secondary immune response upon future exposure. Hence, option (2) is correct.

7. Assertion-Reason:
Assertion (A): Anamnestic response is stronger than primary response.
Reason (R): Memory cells facilitate rapid recognition and antibody production upon second exposure.
(1) Both A and R are true and R explains A
(2) Both A and R are true but R does not explain A
(3) A is true, R is false
(4) A is false, R is true

Explanation: The anamnestic response is faster and stronger due to memory cells recognizing the pathogen and rapidly producing antibodies. Both assertion and reason are true, and the reason explains the assertion. Correct answer is option (1).

8. Matching Type: Match the immune response with its feature:
A. Primary response – 1. Rapid and strong
B. Secondary response – 2. Slow and low antibody production
C. Innate immunity – 3. Non-specific, present at birth
(1) A–2, B–1, C–3
(2) A–1, B–2, C–3
(3) A–3, B–2, C–1
(4) A–2, B–3, C–1

Explanation: Primary response is slow with low antibodies (A–2), secondary response is rapid and strong (B–1), and innate immunity is non-specific and present from birth (C–3). Therefore, option (1) is correct.

9. Fill in the blank:
______ cells are long-lived and help in faster secondary immune response.

(1) Plasma
(2) Memory
(3) T helper
(4) Macrophages

Explanation: Memory cells are long-lived lymphocytes that remain after primary infection, recognizing previously encountered pathogens and facilitating a rapid, strong secondary response. Hence, option (2) is correct.

10. Choose the correct statements:
(a) Anamnestic response occurs on subsequent exposure
(b) Primary response is slower
(c) Acquired immunity is specific
(d) Innate immunity is specific

(1) a, b, c
(2) a, d
(3) b, d
(4) c, d

Explanation: Statements (a), (b), and (c) correctly describe acquired immunity and its features, including primary and secondary responses. Statement (d) is false as innate immunity is non-specific. Therefore, the correct answer is option (1).

Topic: Immunology
Subtopic: Autoimmune Disorders

Keyword Definitions:
• Autoimmune Disorder: Condition where the immune system attacks its own cells, mistaking them for foreign invaders.
• Immune System: Body’s defense mechanism against pathogens and abnormal cells.
• Rheumatoid Arthritis: Chronic autoimmune disease causing joint inflammation and tissue damage.
• Self-Antigen: Molecules produced by the body recognized as ‘self’ by a healthy immune system.
• Antibody: Protein produced by B cells that binds specific antigens.
• T Cells: Lymphocytes that mediate cellular immunity and can attack infected or abnormal cells.
• Inflammation: Response of tissues to injury or infection, often seen in autoimmune diseases.
• Tolerance: Immune system’s ability to ignore self-antigens.
• Pathogen: Disease-causing microorganism or virus.
• Autoantibody: Antibody produced against self-antigens, causing autoimmune damage.

Lead Question (2022):
Given below are two statements:
Statement I: Autoimmune disorder is a condition where body defense mechanism recognizes its own cells as foreign bodies.
Statement II: Rheumatoid arthritis is a condition where body does not attack self cells.
In the light of the above statements, choose the most appropriate answer from the options given below:
1. Both statement I and Statement II are incorrect
2. Statement I is correct but Statement II is incorrect
3. Statement I is incorrect but Statement II is correct
4. Both Statement I and Statement II are correct

Explanation: The correct answer is 2. Statement I is correct because autoimmune disorders occur when the immune system attacks self cells. Statement II is incorrect since rheumatoid arthritis is a classic autoimmune disease where the immune system attacks joint tissues, leading to inflammation and progressive joint damage.

Guessed MCQs:

1. Which antibody type is commonly elevated in autoimmune diseases?
Options:
(a) IgA
(b) IgE
(c) IgG
(d) IgM
Explanation: The correct answer is (c) IgG. IgG autoantibodies are often involved in autoimmune responses, attacking self-antigens and causing tissue damage. IgA, IgE, and IgM have specific roles in mucosal immunity, allergies, and primary immune responses, not primarily in autoimmunity.

2. Which organ is commonly affected in systemic lupus erythematosus?
Options:
(a) Kidney
(b) Liver
(c) Pancreas
(d) Lung
Explanation: The correct answer is (a) Kidney. Lupus nephritis occurs when autoantibodies target kidney tissues, causing inflammation and damage. Liver, pancreas, and lungs may be affected in specific autoimmune disorders, but the kidney is a primary target in SLE.

3. Assertion-Reason MCQ:
Assertion (A): T cells play a major role in autoimmune diseases.
Reason (R): They can attack self-antigens and trigger inflammation.
Options:
(a) Both A and R are true, R explains A
(b) Both A and R are true, R does not explain A
(c) A is true, R is false
(d) A is false, R is true
Explanation: The correct answer is (a). T cells mediate cellular immunity and can mistakenly recognize self-antigens, causing autoimmune damage and inflammation. This explains why T cells are central to the pathology of autoimmune diseases such as rheumatoid arthritis and multiple sclerosis.

4. Matching Type MCQ:
Match the autoimmune disease with the primary organ affected:
List - I List - II
(a) Type 1 Diabetes (i) Joints
(b) Rheumatoid Arthritis (ii) Pancreas
(c) Multiple Sclerosis (iii) Brain and Spinal Cord
Options:
1. a-ii, b-i, c-iii
2. a-i, b-ii, c-iii
3. a-iii, b-i, c-ii
4. a-ii, b-iii, c-i
Explanation: The correct answer is 1. Type 1 diabetes targets pancreatic beta cells, rheumatoid arthritis affects synovial joints, and multiple sclerosis attacks myelin in the brain and spinal cord, illustrating organ-specific autoimmune pathologies.

5. Which immune cell directly destroys self-cells in autoimmune diseases?
Options:
(a) Cytotoxic T cells
(b) B cells
(c) Macrophages
(d) NK cells
Explanation: The correct answer is (a) Cytotoxic T cells. These cells recognize self-antigens presented by MHC I molecules and induce apoptosis of target cells. B cells produce autoantibodies but do not directly kill cells, while macrophages and NK cells have different immune roles.

6. Single Correct Answer:
Which cytokine is associated with autoimmune inflammation?
Options:
(a) TNF-alpha
(b) IL-10
(c) IL-4
(d) TGF-beta
Explanation: The correct answer is (a) TNF-alpha. Tumor necrosis factor-alpha is a pro-inflammatory cytokine elevated in rheumatoid arthritis and other autoimmune diseases, promoting tissue damage. IL-10, IL-4, and TGF-beta are mostly anti-inflammatory or regulatory.

7. Fill in the Blanks:
Autoimmune disorders occur due to loss of __________.
Options:
(a) Immune tolerance
(b) Antigen specificity
(c) Lymphocyte production
(d) Inflammation
Explanation: The correct answer is (a) Immune tolerance. When tolerance to self-antigens is lost, the immune system attacks own tissues. Antigen specificity, lymphocyte production, and inflammation are components of immunity but do not directly cause autoimmunity.

8. Which autoantibody is characteristic of rheumatoid arthritis?
Options:
(a) Rheumatoid factor
(b) Anti-DNA antibody
(c) Anti-insulin antibody
(d) Anti-myelin antibody
Explanation: The correct answer is (a) Rheumatoid factor. It is an IgM antibody that targets IgG, forming immune complexes in joints. Anti-DNA is seen in lupus, anti-insulin in type 1 diabetes, and anti-myelin in multiple sclerosis.

9. Single Correct Answer:
Which therapy is commonly used to reduce autoimmune inflammation?
Options:
(a) Immunosuppressants
(b) Antibiotics
(c) Antivirals
(d) Vaccines
Explanation: The correct answer is (a) Immunosuppressants. Drugs such as corticosteroids or methotrexate dampen the immune response, reducing tissue damage in autoimmune diseases. Antibiotics, antivirals, and vaccines are for infections, not autoimmunity.

10. Choose the correct statements:
(i) Autoimmune disorders result from self-antigen recognition
(ii) Tolerance prevents autoimmunity
(iii) Rheumatoid arthritis is autoimmune
(iv) Bacteria are the primary cause
Options:
(a) i, ii, iii
(b) i, iii, iv
(c) ii, iv
(d) i, ii, iv
Explanation: The correct answer is (a) i, ii, iii. Autoimmune disorders arise from immune attack on self-antigens, tolerance prevents this response, and rheumatoid arthritis is an autoimmune disease. Bacteria are not the primary cause of autoimmune disorders.

Topic: Infectious Diseases
Subtopic: Parasitic, Bacterial, and Fungal Infections

Keyword Definitions:

• Filariasis: A parasitic disease caused by nematode worms like Wuchereria bancrofti, transmitted by mosquitoes.

• Amoebiasis: Intestinal infection caused by Entamoeba histolytica, leading to diarrhea and dysentery.

• Pneumonia: Inflammation of lungs, often caused by bacteria such as Haemophilus influenzae, resulting in difficulty in breathing.

• Ringworm: Superficial fungal infection of skin caused by dermatophytes like Trichophyton species.

• Wuchereria bancrofti: Parasitic worm responsible for lymphatic filariasis.

• Entamoeba histolytica: Protozoan parasite causing amoebic dysentery.

• Haemophilus influenzae: Gram-negative bacteria causing respiratory infections including pneumonia.

• Trichophyton: Genus of fungi causing dermatophytosis (ringworm).

• Parasitic infection: Disease caused by protozoans or worms infecting humans.

• Bacterial infection: Illness caused by pathogenic bacteria.

• Fungal infection: Disease caused by fungi affecting skin, nails, or internal organs.

Lead Question - 2021

Match List - I with List - II
List - I  List - II
(a) Filariasis  (i) Haemophilus influenzae
(b) Amoebiasis  (ii) Trichophyton
(c) Pneumonia  (iii) Wuchereria bancrofti
(d) Ringworm  (iv) Entamoeba histolytica
(1) (a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)
(2) (a)-(i), (b)-(ii), (c)-(iv), (d)-(iii)
(3) (a)-(ii), (b)-(iii), (c)-(i), (d)-(iv)
(4) (a)-(iv), (b)-(i), (c)-(iii), (d)-(ii)

Explanation: Filariasis is caused by Wuchereria bancrofti (a-iii). Amoebiasis is due to Entamoeba histolytica (b-iv). Pneumonia can be caused by bacteria like Haemophilus influenzae (c-i). Ringworm is a fungal infection caused by Trichophyton species (d-ii). Correct answer is option (1).

1. Filariasis is transmitted by:
(1) Mosquitoes
(2) Contaminated water
(3) Direct skin contact
(4) Airborne droplets
Explanation: Filariasis is caused by Wuchereria bancrofti, transmitted via mosquito bites, which deposit larvae into the human bloodstream. It affects lymphatic vessels leading to elephantiasis. Water, skin contact, or airborne transmission are not relevant. Correct answer is option (1) Mosquitoes.

2. Amoebiasis primarily affects:
(1) Intestine
(2) Lungs
(3) Skin
(4) Liver
Explanation: Amoebiasis caused by Entamoeba histolytica mainly affects the intestine, leading to diarrhea and dysentery. Liver abscess can occur secondarily but intestine is the primary site. Lungs and skin are not directly affected. Correct answer is option (1) Intestine.

3. Pneumonia is inflammation of:
(1) Lungs
(2) Intestine
(3) Liver
(4) Skin
Explanation: Pneumonia involves inflammation of the alveoli in the lungs, caused by bacteria such as Haemophilus influenzae, viruses, or fungi. It results in difficulty in breathing, cough, and fever. Intestine, liver, and skin are not affected. Correct answer is option (1) Lungs.

4. Ringworm infection is caused by:
(1) Trichophyton
(2) Entamoeba histolytica
(3) Wuchereria bancrofti
(4) Haemophilus influenzae
Explanation: Ringworm is a superficial fungal infection caused by Trichophyton species. It affects the skin, hair, or nails forming circular rashes. Entamoeba, Wuchereria, and Haemophilus are protozoan, parasitic worm, and bacterial pathogens respectively. Correct answer is option (1) Trichophyton.

5. Which of the following is a parasitic infection?
(1) Filariasis
(2) Pneumonia
(3) Ringworm
(4) Influenza
Explanation: Filariasis is caused by Wuchereria bancrofti, a parasitic nematode. Pneumonia and influenza are bacterial or viral infections. Ringworm is fungal. Correct answer is option (1) Filariasis.

6. Which disease is protozoan in origin?
(1) Amoebiasis
(2) Filariasis
(3) Ringworm
(4) Pneumonia
Explanation: Amoebiasis is caused by the protozoan Entamoeba histolytica, infecting the intestines. Filariasis is caused by worms, ringworm by fungi, and pneumonia is bacterial or viral. Correct answer is option (1) Amoebiasis.

7. Assertion-Reason:
Assertion (A): Ringworm is a fungal infection.
Reason (R): Trichophyton species invade skin keratin causing circular lesions.
(1) Both A and R true, R explains A
(2) Both A and R true, R does not explain A
(3) A true, R false
(4) A false, R true
Explanation: Ringworm is caused by Trichophyton fungi, which invade keratin in skin forming characteristic circular lesions. The reason directly explains the assertion. Correct answer is option (1).

8. Matching Type:
Match disease with causative agent:
(a) Pneumonia - 1. Bacteria
(b) Amoebiasis - 2. Protozoa
(c) Filariasis - 3. Nematode
(d) Ringworm - 4. Fungus
(1) a-1, b-2, c-3, d-4
(2) a-2, b-1, c-4, d-3
(3) a-3, b-4, c-2, d-1
(4) a-4, b-3, c-1, d-2
Explanation: Pneumonia is bacterial (a-1), amoebiasis is protozoan (b-2), filariasis is nematode infection (c-3), and ringworm is fungal (d-4). Correct answer is option (1).

9. Fill in the Blank:
_____ causes lymphatic blockage leading to elephantiasis.
(1) Wuchereria bancrofti
(2) Entamoeba histolytica
(3) Trichophyton
(4) Haemophilus influenzae
Explanation: Wuchereria bancrofti, transmitted by mosquitoes, infects lymphatic vessels causing blockage and swelling, leading to elephantiasis. Other pathogens affect intestine, skin, or lungs. Correct answer is option (1) Wuchereria bancrofti.

10. Choose the correct statements:
(a) Pneumonia can be bacterial or viral
(b) Filariasis is caused by nematodes
(c) Amoebiasis is caused by protozoa
(d)

Topic: Immune System Disorders
Subtopic: Enzyme Deficiency and Immunodeficiency

Keyword Definitions:

• Adenosine deaminase (ADA): An enzyme involved in purine metabolism, crucial for lymphocyte function.

• Immune system: The body's defense system against infections and foreign substances.

• Parkinson's disease: Neurodegenerative disorder affecting motor function.

• Addison's disease: Disorder of adrenal cortex causing hormonal deficiency.

• Digestive disorder: Any disease affecting the gastrointestinal tract.

• Immunodeficiency: Condition in which immune system function is impaired, leading to increased susceptibility to infections.

Lead Question - 2021

The Adenosine deaminase deficiency results into
(1) Parkinson's disease
(2) Digestive disorder
(3) Addison's disease
(4) Dysfunction of Immune system

Explanation: Adenosine deaminase deficiency leads to accumulation of toxic metabolites in lymphocytes, impairing immune cell development. This causes severe combined immunodeficiency (SCID), making the individual highly susceptible to infections. It does not cause Parkinson's, Addison's disease, or digestive disorders. Correct answer is option (4) Dysfunction of Immune system.

1. Which organ is primarily affected by SCID due to ADA deficiency?
(1) Thymus
(2) Liver
(3) Heart
(4) Kidney
Explanation: The thymus is crucial for T-lymphocyte maturation. ADA deficiency leads to SCID, where thymus function is compromised, reducing T-cell numbers and immunity. Other organs are less affected directly by ADA deficiency. Correct answer is option (1) Thymus.

2. ADA enzyme deficiency leads to accumulation of which metabolite?
(1) Deoxyadenosine
(2) Glucose
(3) Cholesterol
(4) Lactate
Explanation: Adenosine deaminase deficiency causes accumulation of deoxyadenosine, which is toxic to lymphocytes and inhibits DNA synthesis. Glucose, cholesterol, and lactate are unrelated to ADA deficiency. Correct answer is option (1) Deoxyadenosine.

3. Which type of immunity is most affected by ADA deficiency?
(1) Humoral immunity
(2) Cell-mediated immunity
(3) Innate immunity
(4) Passive immunity
Explanation: ADA deficiency primarily impairs cell-mediated immunity by reducing T-lymphocyte numbers, although B-cell function is secondarily affected. Innate and passive immunity are less directly impacted. Correct answer is option (2) Cell-mediated immunity.

4. Which treatment is commonly used for ADA deficiency?
(1) Antibiotics
(2) Gene therapy
(3) Chemotherapy
(4) Insulin therapy
Explanation: Gene therapy introducing functional ADA gene into patient stem cells is a standard treatment to restore immune function. Antibiotics manage infections but do not cure the cause. Chemotherapy and insulin therapy are unrelated. Correct answer is option (2) Gene therapy.

5. Which blood cells are most affected in ADA deficiency?
(1) Red blood cells
(2) Platelets
(3) Lymphocytes
(4) Neutrophils
Explanation: Lymphocytes, particularly T-cells, are highly sensitive to toxic metabolite accumulation due to ADA deficiency, leading to immunodeficiency. Red blood cells, platelets, and neutrophils are not directly affected. Correct answer is option (3) Lymphocytes.

6. ADA deficiency is inherited in which pattern?
(1) Autosomal dominant
(2) Autosomal recessive
(3) X-linked dominant
(4) Mitochondrial inheritance
Explanation: ADA deficiency follows an autosomal recessive inheritance pattern, requiring both alleles to be defective for the disease to manifest. Dominant, X-linked, or mitochondrial inheritance are not characteristic of ADA deficiency. Correct answer is option (2) Autosomal recessive.

7. Assertion-Reason Question:
Assertion (A): ADA deficiency leads to severe combined immunodeficiency.
Reason (R): Toxic metabolites accumulate in lymphocytes impairing DNA synthesis.
(1) Both A and R are true, R is correct explanation of A
(2) Both A and R are true, R is not correct explanation of A
(3) A true, R false
(4) A false, R true
Explanation: Accumulation of toxic metabolites like deoxyadenosine in ADA deficiency inhibits DNA synthesis in lymphocytes, causing SCID. The reason directly explains the assertion. Correct answer is option (1).

8. Matching Type Question:
Match enzyme deficiency with resulting disease:
(a) Adenosine deaminase - 1. SCID
(b) Phenylalanine hydroxylase - 2. Phenylketonuria
(c) Hexosaminidase A - 3. Tay-Sachs disease
(d) Glucose-6-phosphate dehydrogenase - 4. Hemolytic anemia
(1) a-1, b-2, c-3, d-4
(2) a-2, b-1, c-4, d-3
(3) a-3, b-4, c-2, d-1
(4) a-4, b-3, c-1, d-2
Explanation: ADA deficiency causes SCID (a-1), phenylalanine hydroxylase deficiency causes phenylketonuria (b-2), Hexosaminidase A deficiency causes Tay-Sachs disease (c-3), and G6PD deficiency causes hemolytic anemia (d-4). Correct answer is option (1).

9. Fill in the Blanks:
Accumulation of ______ in ADA deficiency is toxic to lymphocytes.
(1) Deoxyadenosine
(2) Glucose
(3) Fructose
(4) Lactate
Explanation: Deoxyadenosine accumulates in ADA deficiency and is toxic to developing lymphocytes, leading to immunodeficiency. Glucose, fructose, and lactate are not relevant in this context. Correct answer is option (1) Deoxyadenosine.

10. Choose the correct statements:
(a) ADA deficiency affects T-cell development
(b) It causes accumulation of deoxyadenosine
(c) It results in digestive disorders
(d) SCID is a consequence of ADA deficiency
(1) a, b, d
(2) a, c, d
(3) b, c, d
(4) a, b, c
Explanation: ADA deficiency impairs T-cell development (a), causes accumulation of deoxyadenosine (b), and leads to SCID (d). It does not primarily cause digestive disorders (c). Correct answer is option (1) a, b, d.

Copic: Immunology and Diagnostics

Subtopic: Molecular Diagnostic Techniques

Keyword Definitions:

• ELISA Enzyme-Linked Immunosorbent Assay used for detecting antigens or antibodies in patient samples with high sensitivity.

• Southern blotting A DNA detection technique used mainly in genetic studies and DNA fingerprinting.

• Western blotting Protein analysis method used for detecting specific proteins with antibodies.

• Hybridization technique Method of detecting nucleic acid sequences by base pairing with complementary probes.

• Pathophysiology Study of functional changes in the body caused by disease processes.

Lead Question - 2021

For effective treatment of the disease, early diagnosis and understanding its pathophysiology is very important. Which of the following molecular diagnostic techniques is very useful for early detection?
(1) Southern Blotting Technique
(2) ELISA Technique
(3) Hybridization Technique
(4) Western Blotting Technique

Explanation: Early diagnosis of infections depends on detecting small amounts of antigens or antibodies. ELISA is widely used because of its high sensitivity, speed, and specificity. Southern blotting detects DNA, Western blotting proteins, while hybridization is more research-based. Thus, ELISA technique is most effective. Correct answer is option (2).

1. Which diagnostic test is commonly used to confirm HIV infection?
(1) ELISA
(2) MRI
(3) X-ray
(4) CT Scan

Explanation: HIV detection is initially screened by ELISA to identify antibodies against HIV. Confirmation is then done by Western blotting for specificity. Imaging techniques like MRI, X-ray, and CT scans cannot detect HIV. Thus, the correct answer is ELISA.

2. The principle of ELISA is based on:
(1) Antigen-antibody interaction
(2) Enzyme-substrate binding
(3) DNA replication
(4) RNA transcription

Explanation: ELISA functions by detecting antigen-antibody interactions. An enzyme-linked antibody binds to the antigen, and the reaction with a substrate produces a detectable color change. Thus, the correct answer is antigen-antibody interaction.

3. Southern blotting is mainly used for:
(1) RNA detection
(2) Protein detection
(3) DNA detection
(4) Antibody detection

Explanation: Southern blotting involves transferring DNA fragments onto a membrane and hybridizing with complementary probes for detection. It is not used for RNA, protein, or antibody detection. Therefore, the correct answer is DNA detection.

4. Assertion (A): Western blotting is used for protein detection.
Reason (R): It separates proteins by SDS-PAGE and identifies them with specific antibodies.
(1) Both A and R are true, and R explains A
(2) Both A and R are true, but R does not explain A
(3) A is true, R is false
(4) A is false, R is true

Explanation: Western blotting involves separation of proteins by electrophoresis followed by transfer to a membrane and detection with antibodies. Both Assertion and Reason are true, and Reason explains Assertion. Thus, the correct answer is option (1).

5. Match the following:
A. ELISA - i. Antigen-antibody interaction
B. Southern blot - ii. DNA detection
C. Western blot - iii. Protein detection
D. Northern blot - iv. RNA detection
Options:
(1) A-i, B-ii, C-iii, D-iv
(2) A-ii, B-iii, C-i, D-iv
(3) A-iii, B-i, C-iv, D-ii
(4) A-iv, B-ii, C-i, D-iii

Explanation: ELISA is based on antigen-antibody interaction, Southern blot detects DNA, Western blot detects proteins, and Northern blot is used for RNA. Hence, the correct matching is option (1).

6. Which of the following is not a blotting technique?
(1) Southern blot
(2) Northern blot
(3) Eastern blot
(4) Western blot

Explanation: Southern blot detects DNA, Northern blot RNA, Western blot proteins. Eastern blot is not a standard recognized blotting technique. Thus, the correct answer is Eastern blot.

7. Fill in the blank:
__________ technique is most commonly used for detection of viral antigens in blood samples.
(1) ELISA
(2) PCR
(3) CT Scan
(4) Ultrasound

Explanation: ELISA is the most commonly used technique for detecting viral antigens or antibodies in patient blood samples. PCR detects nucleic acids but not directly antigens. Imaging techniques cannot detect viruses. Thus, the correct answer is ELISA.

8. Choose the correct statements about PCR:
(1) It amplifies DNA sequences
(2) It uses primers
(3) It involves Taq polymerase
(4) All of these

Explanation: Polymerase Chain Reaction (PCR) is used to amplify DNA sequences exponentially. It requires primers and thermostable Taq polymerase. All given statements are correct. Therefore, the correct answer is all of these.

9. Which molecular diagnostic method is best for studying gene expression?
(1) Western blot
(2) Northern blot
(3) Southern blot
(4) ELISA

Explanation: Northern blotting is used to study RNA levels, which represent gene expression in cells. Southern blot detects DNA, Western blot proteins, and ELISA antigen-antibody interactions. Thus, the correct answer is Northern blot.

10. In ELISA test, the substrate is used to:
(1) Bind antigen
(2) Produce color change
(3) Denature proteins
(4) Amplify DNA

Explanation: In ELISA, the enzyme-conjugated antibody reacts with a specific substrate to produce a measurable color change. This allows detection of the antigen-antibody complex. Therefore, the correct answer is produce color change.

Topic: Infectious Diseases

Subtopic: Venereal (Sexually Transmitted) Diseases

• Venereal Diseases (VDs): Infectious diseases transmitted primarily through sexual contact.

• STDs: Another term for sexually transmitted diseases, including syphilis, gonorrhea, HIV, etc.

• Transfusion Transmission: Spread of infections via blood from an infected person.

• Vertical Transmission: Transmission of infection from mother to fetus during pregnancy.

• Direct Contact: Spread of infection through physical contact, including kissing or sexual intercourse.

• Inheritance: Genetic transmission of traits, not infections.

• Sterile Needles: Needles that are free of infection do not transmit diseases.

• Prevention: Use of safe practices like screening blood, safe sex, and sterile instruments.

• HIV, Syphilis, Gonorrhea: Examples of venereal diseases.

• Symptoms: May include sores, rashes, discharge, or asymptomatic infection.

• Public Health Measures: Testing, treatment, and awareness reduce transmission of VDs.

Lead Question - 2021

Venereal diseases can spread through:

(a) Using sterile needles
(b) Transfusion of blood from infected person
(c) Infected mother to foetus
(d) Kissing
(e) Inheritance

Options:
1. (b), (c) and (d) only
2. (b) and (c) only
3. (a) and (c) only
4. (a), (b) and (c) only

Explanation: Venereal diseases spread via infected blood transfusion, vertical transmission from mother to fetus, and direct contact like kissing. Sterile needles and inheritance do not transmit VDs. Answer: (b), (c) and (d) only. Effective prevention includes screening blood, avoiding risky contact, and educating the public.

1. Which of these is a mode of STD transmission?
Options:
A. Sharing sterile needles
B. Blood transfusion from infected person
C. Inheritance
D. Vaccination

Explanation: Blood transfusion from infected person can transmit venereal diseases like HIV and syphilis. Sharing sterile needles and inheritance do not spread VDs. Vaccination prevents certain diseases but is not a transmission route. Answer: Blood transfusion from infected person.

2. Vertical transmission means:
Options:
A. Spread from mother to fetus
B. Spread by kissing
C. Spread via needles
D. Spread through air

Explanation: Vertical transmission refers to the transfer of infection from an infected mother to her fetus during pregnancy or birth. This is a recognized pathway for diseases like HIV and syphilis. Other modes listed are horizontal transmission or unrelated. Answer: Spread from mother to fetus.

3. Kissing can spread venereal diseases if:
Options:
A. Saliva carries the pathogen
B. Needles are shared
C. Inheritance occurs
D. Skin contact is absent

Explanation: Certain infections, like herpes simplex virus or syphilis, can be transmitted through saliva contact during kissing. Transmission requires the presence of the pathogen in oral secretions. Other options are unrelated to transmission via kissing. Answer: Saliva carries the pathogen.

4. Sterile needles prevent disease spread because:
Options:
A. They are disinfected
B. They contain antibiotics
C. They carry virus
D. They are reused

Explanation: Sterile needles are free from infectious agents, preventing transmission of venereal diseases or bloodborne pathogens. Contaminated needles, not sterile ones, are a risk. Answer: They are disinfected.

5. Which of these is not a VD transmission route?
Options:
A. Infected mother to fetus
B. Blood transfusion
C. Genetic inheritance
D. Kissing

Explanation: Genetic inheritance does not transmit venereal diseases. VDs spread via blood transfusion, vertical transmission, or direct contact like kissing. Answer: Genetic inheritance.

6. Single correct answer: Main preventive measure for VD transmission?
Options:
A. Blood screening
B. Abstinence
C. Condoms
D. All of the above

Explanation: Effective prevention includes screening blood, using condoms, and practicing abstinence or safe sex. Combining these measures reduces transmission significantly. Answer: All of the above.

7. Assertion-Reason:
Assertion (A): Blood transfusion can transmit venereal diseases.
Reason (R): Pathogens in donor blood infect the recipient.
Options:
A. Both A and R true, R is correct explanation
B. Both A and R true, R is not correct explanation
C. A true, R false
D. A false, R true

Explanation: Blood from an infected donor can transmit pathogens like HIV or syphilis to the recipient. The reason accurately explains the assertion. Answer: Both A and R true, R is correct explanation.

8. Matching Type:
Column I: 1. Vertical transmission 2. Direct contact 3. Sterile needles
Column II: A. Kissing, sexual contact B. Prevents infection C. Mother to fetus
Options:
A. 1-C, 2-A, 3-B
B. 1-A, 2-C, 3-B
C. 1-B, 2-C, 3-A
D. 1-C, 2-B, 3-A

Explanation: Correct matching: 1-Vertical transmission – Mother to fetus (C), 2-Direct contact – Kissing, sexual contact (A), 3-Sterile needles – Prevent infection (B). Answer: 1-C, 2-A, 3-B.

9. Fill in the blank: VDs spread through blood transfusion and _______.
Options:
A. Inheritance
B. Vertical transmission
C. Sterile needles
D. Vaccination

Explanation: Venereal diseases spread through contaminated blood and vertical transmission

Topic: Infectious Diseases

Subtopic: Causative Organisms of Common Diseases

Keyword Definitions:

• Typhoid – A bacterial infection caused by Salmonella typhi, leading to high fever and intestinal issues.

• Pneumonia – Infection of lungs causing inflammation, can be caused by bacteria like Haemophilus influenzae.

• Filariasis – Parasitic disease caused by Wuchereria bancrofti, leading to lymphatic blockage and elephantiasis.

• Malaria – Disease caused by Plasmodium species, transmitted by Anopheles mosquito, causing fever and chills.

• Salmonella – Gram-negative bacterium causing typhoid fever.

• Wuchereria – Parasitic nematode causing filariasis.

• Plasmodium – Protozoan parasite causing malaria.

• Haemophilus – Bacterium responsible for respiratory infections including pneumonia.

• Infectious diseases – Illnesses caused by pathogenic microorganisms such as bacteria, viruses, fungi, or parasites.

• Causative organism – Microbe responsible for causing a particular disease.

• Lymphatic blockage – Obstruction in lymph vessels causing swelling and fluid accumulation.

Lead Question - 2020

Match the following diseases with the causative organism and select the correct option.
Column-I Column-II
(a) Typhoid (i) Wuchereria
(b) Pneumonia (ii) Plasmodium
(c) Filariasis (iii) Salmonella
(d) Malaria (iv) Haemophilus
Options:
(1) a-ii, b-i, c-iii, d-iv
(2) a-iv, b-i, c-ii, d-iii
(3) a-i, b-iii, c-ii, d-iv
(4) a-iii, b-iv, c-i, d-ii

Explanation: Typhoid is caused by Salmonella (a-iii), pneumonia by Haemophilus (b-iv), filariasis by Wuchereria (c-i), and malaria by Plasmodium (d-ii). Each organism specifically causes the respective disease. Correct answer is (4) a-iii, b-iv, c-i, d-ii.

1. Single Correct Answer: The causative organism of malaria is:
(1) Salmonella
(2) Wuchereria
(3) Plasmodium
(4) Haemophilus

Explanation: Malaria is caused by protozoan parasites of the genus Plasmodium, transmitted via Anopheles mosquito bites. Correct answer is (3) Plasmodium.

2. Single Correct Answer: Typhoid fever is caused by:
(1) Plasmodium
(2) Salmonella
(3) Wuchereria
(4) Haemophilus

Explanation: Typhoid is a bacterial infection caused by Salmonella typhi, leading to fever, abdominal pain, and other systemic symptoms. Correct answer is (2) Salmonella.

3. Single Correct Answer: Filariasis is caused by:
(1) Salmonella
(2) Wuchereria
(3) Plasmodium
(4) Haemophilus

Explanation: Filariasis is caused by the parasitic nematode Wuchereria bancrofti, leading to lymphatic obstruction and swelling (elephantiasis). Correct answer is (2) Wuchereria.

4. Single Correct Answer: Pneumonia can be caused by:
(1) Haemophilus influenzae
(2) Salmonella typhi
(3) Plasmodium vivax
(4) Wuchereria bancrofti

Explanation: Pneumonia is an infection of the lungs commonly caused by Haemophilus influenzae bacteria, resulting in inflammation and respiratory distress. Correct answer is (1) Haemophilus influenzae.

5. Assertion-Reason:
Assertion (A): Filariasis is a vector-borne disease.
Reason (R): Wuchereria bancrofti is transmitted by mosquitoes.
(1) Both A and R true, R explains A
(2) Both A and R true, R does not explain A
(3) A true, R false
(4) A false, R true

Explanation: Filariasis is transmitted through mosquito bites carrying Wuchereria bancrofti larvae. Both assertion and reason are correct, and the reason explains the assertion. Correct answer is (1).

6. Single Correct Answer: The vector for malaria is:
(1) Culex mosquito
(2) Anopheles mosquito
(3) Aedes mosquito
(4) Sandfly

Explanation: Malaria is transmitted through female Anopheles mosquitoes carrying Plasmodium sporozoites. Other insects are not malaria vectors. Correct answer is (2) Anopheles mosquito.

7. Matching Type: Match disease with vector:
a. Malaria – i. Mosquito
b. Filariasis – ii. Mosquito
c. Typhoid – iii. Food/Water
d. Pneumonia – iv. Respiratory droplets
Options:
(1) a-i, b-ii, c-iii, d-iv
(2) a-ii, b-i, c-iv, d-iii
(3) a-iii, b-iv, c-i, d-ii
(4) a-iv, b-iii, c-ii, d-i

Explanation: Malaria (a-i) by Anopheles mosquito, filariasis (b-ii) by Culex mosquito, typhoid (c-iii) via contaminated food/water, pneumonia (d-iv) via respiratory droplets. Correct answer is (1).

8. Fill in the blank: Typhoid is caused by ______.
(1) Wuchereria
(2) Plasmodium
(3) Salmonella
(4) Haemophilus

Explanation: Typhoid fever is caused by Salmonella typhi, a Gram-negative bacterium, leading to systemic infection. Correct answer is (3) Salmonella.

9. Single Correct Answer: Which organism causes pneumonia in infants?
(1) Wuchereria
(2) Plasmodium
(3) Salmonella
(4) Haemophilus influenzae

Explanation: Haemophilus influenzae is a common bacterial pathogen causing pneumonia, especially in children and infants. Correct answer is (4) Haemophilus influenzae.

10. Choose the correct statements:
(a) Plasmodium causes malaria
(b) Wuchereria causes filariasis
(c) Salmonella causes pneumonia
(d) Haemophilus causes respiratory infections
Options:
(1) a, b, d
(2) a, b, c
(3) b, c, d
(4) a, c, d

Explanation: Plasmodium causes malaria (a), Wuchereria causes filariasis (b), Haemophilus causes respiratory infections including pneumonia (d). Salmonella does not cause pneumonia. Correct answer is (1) a, b, d.

Topic: Protozoa

Subtopic: Plasmodium Life Cycle

Keyword Definitions:

• Plasmodium – Protozoan parasite causing malaria in humans, transmitted by Anopheles mosquitoes.

• Sporozoites – Infectious stage of Plasmodium injected by mosquito into human bloodstream.

• Trophozoites – Active feeding stage of Plasmodium inside red blood cells.

• Gametocytes – Sexual forms of Plasmodium; male and female forms develop in humans and infect mosquitoes.

• Malaria – Disease caused by Plasmodium species, characterized by fever, chills, anemia, and organ enlargement.

• Vector – Organism that transmits a pathogen; Anopheles mosquito is vector for Plasmodium.

Lead Question - 2020

The infectious stage of Plasmodium that enters the human body is :
(1) Female gametocytes
(2) Male gametocytes
(3) Trophozoites
(4) Sporozoites

Explanation: The infectious stage of Plasmodium injected by an infected Anopheles mosquito into human bloodstream is sporozoites. They travel to the liver to initiate infection. Trophozoites develop later inside red blood cells, while gametocytes are sexual stages ingested by mosquitoes. Correct answer is (4) Sporozoites.

1. Single Correct Answer: Which stage of Plasmodium is responsible for clinical symptoms in humans?
(1) Sporozoites
(2) Trophozoites
(3) Gametocytes
(4) Ookinetes

Explanation: Trophozoites multiply inside red blood cells causing hemolysis, leading to fever and anemia. Sporozoites infect liver, gametocytes are for mosquito transmission, ookinetes occur in mosquito gut. Correct answer is (2) Trophozoites.

2. Single Correct Answer: The vector for Plasmodium transmission is:
(1) Culex mosquito
(2) Anopheles mosquito
(3) Aedes mosquito
(4) Tsetse fly

Explanation: Anopheles mosquitoes are the specific vectors that transmit Plasmodium sporozoites to humans. Culex and Aedes transmit other diseases, Tsetse fly transmits Trypanosoma. Correct answer is (2) Anopheles mosquito.

3. Single Correct Answer: The stage that develops inside red blood cells is:
(1) Sporozoites
(2) Trophozoites
(3) Gametocytes
(4) Zygotes

Explanation: Trophozoites are the active feeding stage inside red blood cells causing hemolysis. Sporozoites infect liver, gametocytes are sexual forms, zygotes form in mosquito gut. Correct answer is (2) Trophozoites.

4. Assertion-Reason:
Assertion (A): Sporozoites enter human liver cells after mosquito bite.
Reason (R): Sporozoites are the sexual stage of Plasmodium.
(1) Both A and R true, R explains A
(2) Both A and R true, R does not explain A
(3) A true, R false
(4) A false, R true

Explanation: Sporozoites invade liver cells, but they are not sexual forms; gametocytes are sexual stages. A is correct, R is false. Correct answer is (3) A true, R false.

5. Single Correct Answer: Sexual forms of Plasmodium are:
(1) Trophozoites
(2) Sporozoites
(3) Gametocytes
(4) Merozoites

Explanation: Gametocytes are sexual forms taken up by mosquito during blood meal. Trophozoites and merozoites are asexual, sporozoites are infectious. Correct answer is (3) Gametocytes.

6. Single Correct Answer: Plasmodium sporozoites develop into which stage in the liver?
(1) Trophozoites
(2) Gametocytes
(3) Zygotes
(4) Ookinetes

Explanation: Sporozoites infect hepatocytes and develop into schizonts containing merozoites. Correct answer is (1) Trophozoites.

7. Matching Type: Match column I with column II:
a. Infective stage – i. Sporozoites
b. Sexual stage in human – ii. Gametocytes
c. Mosquito gut stage – iii. Ookinetes
d. RBC stage – iv. Trophozoites
(1) a-i, b-ii, c-iii, d-iv
(2) a-ii, b-i, c-iv, d-iii
(3) a-iii, b-iv, c-i, d-ii
(4) a-iv, b-iii, c-ii, d-i

Explanation: Infective stage is sporozoites (a-i), sexual stage in human is gametocytes (b-ii), mosquito gut stage is ookinetes (c-iii), RBC stage is trophozoites (d-iv). Correct answer is (1).

8. Fill in the blank: The Plasmodium stage transmitted by mosquito bite is ______.
(1) Sporozoites
(2) Trophozoites
(3) Gametocytes
(4) Merozoites

Explanation: Sporozoites are injected into human bloodstream by infected Anopheles mosquito and initiate liver stage infection. Correct answer is (1).

9. Single Correct Answer: Which stage multiplies inside human RBCs?
(1) Sporozoites
(2) Merozoites
(3) Gametocytes
(4) Zygotes

Explanation: Merozoites released from liver schizonts invade RBCs, multiply asexually, and develop into trophozoites. Correct answer is (2) Merozoites.

10. Choose the correct statements:
(a) Sporozoites are infective to humans
(b) Gametocytes are sexual forms in humans
(c) Trophozoites cause clinical symptoms
(d) Ookinetes are in human RBCs
(1) a, b, c
(2) a, c, d
(3) b, c, d
(4) a, b, d

Explanation: Sporozoites infect humans (a), gametocytes are sexual stages (b), trophozoites cause symptoms (c). Ookinetes occur in mosquito gut, not in humans. Correct answer is (1) a, b, c.

Subtopic: Hormonal Regulation of Blood Glucose

• Insulin: Hormone produced by beta cells of pancreas; lowers blood glucose by facilitating cellular uptake and storage.

• Glucagon: Hormone secreted by alpha cells of pancreas; increases blood glucose by stimulating glycogenolysis and gluconeogenesis.

• Pancreatic cells: Cells in pancreas including alpha and beta cells responsible for hormone secretion.

• Adipocytes: Fat-storing cells influenced by insulin for glucose uptake and fat synthesis.

• Hyperglycemia: Condition of elevated blood glucose levels.

• Hypoglycemia: Condition of abnormally low blood glucose levels.

• Glucocorticoids: Steroid hormones from adrenal cortex; stimulate gluconeogenesis and influence metabolism.

• Gluconeogenesis: Formation of glucose from non-carbohydrate precursors such as amino acids.

• Glycogenolysis: Breakdown of glycogen into glucose in liver or muscle.

• Endocrine system: Hormonal system controlling metabolism, growth, and homeostasis.

• Blood glucose regulation: Homeostatic control of glucose levels by insulin, glucagon, and other hormones.

Lead Question (2020): Select the correct statement :

1. Insulin acts on pancreatic cells and adipocytes

2. Insulin is associated with hyperglycemia

3. Glucocorticoids stimulate gluconeogenesis

4. Glucagon is associated with hypoglycemia

Explanation: The correct answer is 3. Glucocorticoids, secreted from adrenal cortex, stimulate gluconeogenesis, raising blood glucose. Insulin lowers blood glucose and acts on adipocytes, not on pancreatic hormone secretion. Glucagon raises blood glucose, causing hyperglycemia, not hypoglycemia. Hence, statement 3 is correct in glucose metabolism regulation.

Guessed MCQs:

1. Question 1: Insulin primarily acts on:
   A. Liver cells
   B. Adipocytes
   C. Muscle cells
   D. All of the above
   Explanation: The correct answer is D. Insulin facilitates glucose uptake in muscle and fat cells, and inhibits hepatic glucose production, regulating blood glucose homeostasis effectively across multiple tissues.

2. Question 2: Glucagon increases blood glucose by:
   A. Glycogen synthesis
   B. Glycogenolysis and gluconeogenesis
   C. Fat storage
   D. Insulin secretion
   Explanation: The correct answer is B. Glucagon stimulates liver glycogen breakdown (glycogenolysis) and synthesis of new glucose (gluconeogenesis), thereby increasing blood glucose levels.

3. Question 3: Hypoglycemia results from:
   A. Excess glucagon
   B. Insulin overdose
   C. High glucocorticoids
   D. Fasting
   Explanation: The correct answer is B. Excess insulin leads to abnormally low blood glucose (hypoglycemia) as it promotes cellular uptake of glucose, reducing circulating levels.

4. Question 4: Hyperglycemia is associated with:
   A. Glucagon
   B. Insulin deficiency
   C. Glucocorticoid excess
   D. All of the above
   Explanation: The correct answer is D. Hyperglycemia occurs due to insufficient insulin, excessive glucagon, or glucocorticoid excess, all of which raise blood glucose levels through metabolic pathways.

5. Question 5: Glucocorticoids stimulate glucose production via:
   A. Glycolysis
   B. Gluconeogenesis
   C. Lipogenesis
   D. Glycogen storage
   Explanation: The correct answer is B. Glucocorticoids from adrenal cortex enhance gluconeogenesis, generating glucose from non-carbohydrate sources to maintain blood glucose during stress.

6. Question 6: Insulin lowers blood glucose by:
   A. Promoting glycogen breakdown
   B. Facilitating cellular glucose uptake
   C. Stimulating gluconeogenesis
   D. Reducing glucose utilization
   Explanation: The correct answer is B. Insulin stimulates uptake of glucose by adipocytes and muscle cells, promotes glycogen formation, and reduces blood glucose to maintain homeostasis.

7. Question 7: Assertion-Reason:
   Assertion (A): Glucocorticoids raise blood glucose.
   Reason (R): They stimulate gluconeogenesis in the liver.
   A. Both A and R are true, R is correct explanation
   B. Both A and R are true, R is not correct explanation
   C. A true, R false
   D. A false, R true
   Explanation: The correct answer is A. Glucocorticoids increase blood glucose by stimulating gluconeogenesis in the liver, providing energy during stress and fasting. This mechanism directly explains the assertion.

8. Question 8: Matching Type: Match hormone with effect:
   i. Insulin - A. Lowers blood glucose
   ii. Glucagon - B. Raises blood glucose
   iii. Glucocorticoids - C. Stimulates gluconeogenesis
   iv. Epinephrine - D. Mobilizes glucose rapidly
   Choices:
   A. i-A, ii-B, iii-C, iv-D
   B. i-B, ii-A, iii-D, iv-C
   C. i-C, ii-D, iii-A, iv-B
   D. i-D, ii-C, iii-B, iv-A
   Explanation: The correct answer is A. Insulin lowers glucose (i-A), glucagon raises glucose (ii-B), glucocorticoids stimulate gluconeogenesis (iii-C), and epinephrine mobilizes glucose rapidly during stress (iv-D).

9. Question 9: Fill in the Blanks: ________ is secreted by beta cells of pancreas and lowers blood glucose.
   A. Glucagon
   B. Insulin
   C. Cortisol
   D. Adrenaline
   Explanation: The correct answer is B. Insulin, secreted by beta cells, reduces blood glucose by promoting uptake into cells, glycogen formation, and inhibiting glucose production in the liver.

10. Question 10: Choose the correct statements:
    i. Insulin lowers blood glucose
    ii. Glucagon raises blood glucose
    iii. Glucocorticoids stimulate gluconeogenesis
    iv. Excess insulin causes hyperglycemia
    A. i, ii, iii
    B. i, ii, iv
    C. ii, iii, iv
    D. i, iii, iv
    Explanation: The correct answer is A. Insulin lowers blood glucose (i), glucagon raises it (ii), glucocorticoids stimulate gluconeogenesis (iii). Excess insulin causes hypoglycemia, not hyperglycemia, so iv is incorrect.

Subtopic: Types of Immunity

• Active immunity: Immunity developed when host produces antibodies in response to exposure to antigens, either through infection or vaccination.

• Passive immunity: Immunity acquired by receiving ready-made antibodies from another organism, providing immediate but short-term protection.

• Antigen: A substance, usually foreign, that triggers an immune response in the body.

• Antibody: A protein produced by B-lymphocytes in response to antigens, neutralizing pathogens.

• Foetal immunity: Antibodies received by the fetus from the mother through placenta, a form of passive immunity.

• Immunization: Process of inducing active immunity through vaccines containing killed or weakened pathogens.

• Natural immunity: Immunity acquired through natural exposure to pathogens.

• Artificial immunity: Immunity developed through vaccines or injections of antibodies.

• Cell-mediated immunity: Immune response involving T-lymphocytes acting against infected cells and pathogens.

• Humoral immunity: Immunity mediated by antibodies present in body fluids.

• Ready-made antibodies: Antibodies prepared externally and administered for immediate protection.

Lead Question (2020): Identify the wrong statement with reference to immunity :

1. Active immunity is quick and gives full response

2. Foetus receives some antibodies from mother, it is an example for passive immunity

3. When exposed to antigen (living or dead) antibodies are produced in the host’s body. It is called “Active immunity”.

4. When ready-made antibodies are directly given, it is called “Passive immunity”.

Explanation: The correct answer is 1. Active immunity is not quick; it requires time for the host’s immune system to recognize antigens and produce antibodies. Passive immunity is immediate but short-lived. Foetal immunity and administration of ready-made antibodies are examples of passive immunity, while vaccination or infection triggers active immunity.

Guessed MCQs:

1. Question 1: Which immunity provides immediate but short-term protection?
   A. Active immunity
   B. Passive immunity
   C. Cell-mediated immunity
   D. Humoral immunity
   Explanation: The correct answer is B. Passive immunity is obtained by receiving ready-made antibodies from another individual or organism, offering immediate protection. However, it is short-lived because the host’s immune system does not produce antibodies, unlike active immunity which develops slowly but is long-lasting.

2. Question 2: Foetus receives antibodies from mother through:
   A. Vaccine injection
   B. Placenta
   C. T-cell activation
   D. Artificial antibodies
   Explanation: The correct answer is B. Antibodies from the mother cross the placenta to the foetus, providing passive immunity before birth. This natural transfer protects the newborn against pathogens during early life, demonstrating passive immunity without the foetus actively producing antibodies.

3. Question 3: Active immunity is developed through:
   A. Injection of ready-made antibodies
   B. Vaccination or infection
   C. Placental transfer
   D. Blood transfusion
   Explanation: The correct answer is B. Active immunity arises when the host’s immune system is exposed to antigens through infection or vaccination. The body produces its own antibodies, providing long-term protection. This response is slower compared to passive immunity, which acts immediately.

4. Question 4: Which immunity is long-lasting?
   A. Passive immunity
   B. Active immunity
   C. Temporary immunity
   D. None
   Explanation: The correct answer is B. Active immunity is long-lasting because the host produces antibodies and memory cells. Passive immunity provides immediate protection but is short-term, as the host does not generate its own immune response or memory against the pathogen.

5. Question 5: Antibodies are produced by:
   A. T-lymphocytes
   B. B-lymphocytes
   C. Macrophages
   D. Neutrophils
   Explanation: The correct answer is B. B-lymphocytes are responsible for humoral immunity by producing antibodies in response to antigens. T-lymphocytes mediate cell-mediated immunity, but do not produce antibodies directly.

6. Question 6: Which is an example of artificial passive immunity?
   A. Vaccination
   B. Injection of gamma globulin
   C. Placental transfer
   D. Natural infection
   Explanation: The correct answer is B. Artificial passive immunity is obtained by administering ready-made antibodies, such as gamma globulin injections, providing immediate but temporary protection against infections like hepatitis or rabies.

7. Question 7: Assertion-Reason:
   Assertion (A): Passive immunity provides immediate protection.
   Reason (R): Ready-made antibodies are administered externally.
   A. Both A and R are true, R is correct explanation of A
   B. Both A and R are true, R is not correct explanation of A
   C. A is true, R is false
   D. A is false, R is true
   Explanation: The correct answer is A. Passive immunity works immediately because externally administered antibodies circulate and neutralize antigens without waiting for host immune response. This explains why it provides immediate protection, unlike active immunity which requires time for antibody production.

8. Question 8: Matching Type: Match immunity type with example:
   i. Active immunity - A. Injection of ready-made antibodies
   ii. Passive immunity - B. Vaccination
   iii. Natural passive immunity - C. Maternal antibody transfer
   Choices:
   A. i-B, ii-A, iii-C
   B. i-A, ii-B, iii-C
   C. i-C, ii-B, iii-A
   D. i-B, ii-C, iii-A
   Explanation: The correct answer is A. Active immunity is generated by vaccination, passive immunity by injection of antibodies, and natural passive immunity occurs through maternal antibody transfer to the foetus. These examples distinguish types based on source and mechanism.

9. Question 9: Fill in the Blanks: Immunity obtained after vaccination is called ________.
   A. Passive immunity
   B. Active immunity
   C. Natural immunity
   D. Temporary immunity
   Explanation: The correct answer is B. Vaccination exposes the host to antigens, stimulating production of antibodies and memory cells. This active immunity develops gradually and provides long-term protection against specific pathogens.

10. Question 10: Choose the correct statements:
    i. Active immunity requires host antibody production
    ii. Passive immunity is immediate
    iii. Foetus receives antibodies from mother
    iv. Active immunity is immediate
    A. i, ii, iii
    B. i, iii, iv
    C. ii, iii, iv
    D. i, ii, iv
    Explanation: The correct answer is A. Active immunity involves host antibody production, passive immunity provides immediate protection, and foetus naturally receives maternal antibodies. Active immunity is not immediate; it requires time to generate antibodies after exposure to antigens or vaccination.

Topic: Sexually Transmitted Diseases

Subtopic: Types and Transmission

• Sexually Transmitted Diseases (STDs): Diseases transmitted primarily through sexual contact including vaginal, anal, or oral sex.

• HIV/AIDS: Virus causing immune system failure and transmitted sexually, through blood, or from mother to child.

• Syphilis: Bacterial infection caused by Treponema pallidum, transmitted sexually, affecting multiple organs if untreated.

• Gonorrhoea: Bacterial STD caused by Neisseria gonorrhoeae affecting urinary and reproductive tracts.

• Genital herpes: Viral STD caused by herpes simplex virus (HSV), causing painful genital sores.

• Malaria: Vector-borne disease caused by Plasmodium, transmitted by mosquitoes, not sexually.

• Filaria: Parasitic disease transmitted by mosquitoes, not through sexual contact.

• Cancer: Uncontrolled cell growth, not a communicable disease through sexual transmission.

• Transmission: Mode by which infectious agents are spread between individuals.

• Prevention: Measures like safe sex, barrier methods, and vaccination to avoid STDs.

• Genital infections: Infections affecting reproductive organs, often sexually transmitted.

Lead Question (2020): Select the option including all sexually transmitted diseases :

1. AIDS, Malaria, Filaria

2. Cancer, AIDS, Syphilis

3. Gonorrhoea, Syphilis, Genital herpes

4. Gonorrhoea, Malaria, Genital herpes

Explanation: The correct answer is 3. Gonorrhoea, Syphilis, and Genital herpes are all sexually transmitted diseases. AIDS is also an STD but appears in other options with non-sexually transmitted diseases. Malaria, Filaria, and Cancer are not transmitted sexually, distinguishing correct selection for sexual transmission only.

Guessed MCQs:

1. Question 1: Which STD is caused by a virus?
   A. Syphilis
   B. Gonorrhoea
   C. Genital herpes
   D. Chlamydia
   Explanation: The correct answer is C. Genital herpes is caused by herpes simplex virus. Viral STDs produce recurrent symptoms and are not completely curable. Bacterial STDs like Syphilis and Gonorrhoea can be treated with antibiotics, while viral STDs require symptom management.

2. Question 2: Which STD primarily affects immune system leading to susceptibility to other infections?
   A. Syphilis
   B. AIDS
   C. Gonorrhoea
   D. Genital herpes
   Explanation: The correct answer is B. AIDS, caused by HIV, attacks and destroys immune cells. This immune suppression increases susceptibility to opportunistic infections. It is sexually transmitted, and prevention includes safe sexual practices and awareness about transmission routes.

3. Question 3: Which STD is caused by bacteria Treponema pallidum?
   A. Syphilis
   B. Gonorrhoea
   C. Genital herpes
   D. Chlamydia
   Explanation: The correct answer is A. Syphilis is a bacterial STD caused by Treponema pallidum, transmitted sexually. It progresses through stages if untreated, affecting skin, organs, and nervous system. Early treatment with antibiotics prevents complications.

4. Question 4: Gonorrhoea primarily affects which body system?
   A. Circulatory system
   B. Digestive system
   C. Reproductive and urinary system
   D. Nervous system
   Explanation: The correct answer is C. Gonorrhoea infects the mucous membranes of reproductive and urinary tracts. Symptoms include painful urination and discharge. Prompt treatment with antibiotics prevents complications like infertility and systemic infection.

5. Question 5: Which of the following is NOT sexually transmitted?
   A. Syphilis
   B. Malaria
   C. Gonorrhoea
   D. Genital herpes
   Explanation: The correct answer is B. Malaria is transmitted by mosquito bites, not sexual contact. Syphilis, Gonorrhoea, and Genital herpes are all transmitted sexually. Awareness of transmission routes is critical for effective prevention strategies.

6. Question 6: Which preventive method is most effective against STDs?
   A. Vaccination
   B. Antibiotics
   C. Barrier methods (condoms)
   D. Herbal treatment
   Explanation: The correct answer is C. Barrier methods like condoms reduce the risk of sexual transmission of diseases such as HIV, Gonorrhoea, Syphilis, and Genital herpes. Vaccines exist only for some STDs, and antibiotics are treatment, not prevention.

7. Question 7: Assertion-Reason:
   Assertion (A): Genital herpes is recurrent and incurable.
   Reason (R): It is caused by herpes simplex virus.
   A. Both A and R are true, R is correct explanation of A
   B. Both A and R are true, R is not correct explanation of A
   C. A is true, R is false
   D. A is false, R is true
   Explanation: The correct answer is A. Genital herpes is caused by herpes simplex virus. The viral infection cannot be completely eradicated, leading to recurrent episodes. Antiviral drugs manage symptoms but do not cure, confirming the reason as correct explanation.

8. Question 8: Matching Type: Match STD with causative agent:
   i. Syphilis - A. HIV
   ii. AIDS - B. Treponema pallidum
   iii. Genital herpes - C. Herpes simplex virus
   iv. Gonorrhoea - D. Neisseria gonorrhoeae
   Choices:
   A. i-B, ii-A, iii-C, iv-D
   B. i-C, ii-B, iii-A, iv-D
   C. i-D, ii-C, iii-B, iv-A
   D. i-A, ii-B, iii-D, iv-C
   Explanation: The correct answer is A. Syphilis is caused by Treponema pallidum, AIDS by HIV, Genital herpes by Herpes simplex virus, and Gonorrhoea by Neisseria gonorrhoeae. Correct matching clarifies causative agents for identification and treatment of sexually transmitted diseases.

9. Question 9: Fill in the Blanks: The viral sexually transmitted disease causing immune deficiency is ________.
   A. Syphilis
   B. AIDS
   C. Gonorrhoea
   D. Genital herpes
   Explanation: The correct answer is B. AIDS is caused by HIV virus, which weakens the immune system and increases susceptibility to infections. It is primarily transmitted sexually, through blood, or from mother to child, making prevention through safe sexual practices essential.

10. Question 10: Choose the correct statements:
    i. Gonorrhoea is a bacterial STD
    ii. Genital herpes is a viral STD
    iii. Malaria is sexually transmitted
    iv. AIDS is caused by HIV
    A. i, ii, iv
    B. i, iii
    C. ii, iii, iv
    D. i, ii, iii, iv
    Explanation: The correct answer is A. Gonorrhoea is bacterial, Genital herpes is viral, and AIDS is caused by HIV. Malaria is mosquito-borne, not sexually transmitted. Recognizing the causative agents and transmission modes helps in prevention and treatment of sexually transmitted diseases.

Topic: Infectious Diseases
Subtopic: Typhoid Fever and Diagnosis

• Typhoid Fever: A bacterial infection caused by Salmonella typhi, transmitted through contaminated food and water.

• Salmonella typhi: Gram-negative bacterium responsible for typhoid fever, affecting intestinal tract and bloodstream.

• Widal Test: Serological test detecting antibodies against Salmonella antigens for confirmation of typhoid infection.

• Plasmodium vivax: Protozoan parasite causing malaria, transmitted by Anopheles mosquitoes.

• Streptococcus pneumoniae: Bacterium causing pneumonia, meningitis, and other infections, not typhoid.

• Anthrone Test: Test used for estimating carbohydrates, not for diagnosing typhoid.

• Gram-negative Bacteria: Bacteria with thin peptidoglycan wall and outer membrane, including Salmonella species.

• Blood Culture: Laboratory method to grow and identify bacterial pathogens in blood samples.

• Serological Test: Diagnostic method detecting antibodies or antigens in serum.

• Infectious Diseases: Illness caused by pathogenic microorganisms like bacteria, viruses, or parasites.

• Confirmatory Test: Diagnostic procedure providing definitive identification of a disease-causing agent.

Lead Question (2019): Identify the correct pair representing the causative agent of typhoid fever and the confirmatory test for typhoid.

Options:
1. Plasmodium vivax / UTI test
2. Streptococcus pneumoniae / Widal test
3. Salmonella typhi / Anthrone test
4. Salmonella typhi / Widal test

Explanation: Correct answer is 4. Salmonella typhi is the bacterium causing typhoid fever. The Widal test detects specific antibodies against Salmonella antigens, confirming infection. Plasmodium vivax causes malaria, Streptococcus pneumoniae causes pneumonia, and the Anthrone test measures carbohydrates, so they are not used for typhoid diagnosis.

1. Single Correct Answer MCQ:
Which bacterium causes typhoid fever?
Options:
a. Escherichia coli
b. Salmonella typhi
c. Staphylococcus aureus
d. Streptococcus pyogenes

Explanation: Correct answer is b. Salmonella typhi is the causative agent of typhoid fever. E. coli causes urinary tract infections, Staphylococcus aureus may cause skin and systemic infections, and Streptococcus pyogenes causes throat infections and rheumatic fever, but none cause typhoid fever.

2. Single Correct Answer MCQ:
Which test is used to confirm typhoid fever?
Options:
a. Widal test
b. Anthrone test
c. UTI test
d. PCR for malaria

Explanation: Correct answer is a. The Widal test detects antibodies against Salmonella typhi antigens and confirms typhoid infection. Anthrone test measures carbohydrates, UTI test detects urinary tract infections, and PCR for malaria identifies Plasmodium species, none of which diagnose typhoid.

3. Single Correct Answer MCQ:
Which route primarily transmits typhoid fever?
Options:
a. Airborne droplets
b. Contaminated food and water
c. Mosquito bite
d. Sexual contact

Explanation: Correct answer is b. Typhoid fever spreads via ingestion of food or water contaminated with Salmonella typhi. Airborne droplets transmit respiratory diseases, mosquito bites transmit malaria, and sexual contact spreads certain infections, none of which are primary routes for typhoid.

4. Single Correct Answer MCQ:
Which symptom is most characteristic of typhoid fever?
Options:
a. Persistent high fever
b. Rash on palms
c. Night blindness
d. Jaundice

Explanation: Correct answer is a. Typhoid fever typically presents with persistent high fever, weakness, and abdominal discomfort. Rash on palms is unrelated, night blindness is due to vitamin A deficiency, and jaundice indicates liver dysfunction rather than primary typhoid manifestation.

5. Single Correct Answer MCQ:
Which laboratory method can definitively identify Salmonella typhi?
Options:
a. Blood culture
b. Widal test
c. Anthrone test
d. Stool microscopy

Explanation: Correct answer is a. Blood culture allows growth and identification of Salmonella typhi, providing definitive diagnosis. Widal test is serological and supportive, Anthrone test measures carbohydrates, and stool microscopy cannot directly identify Salmonella typhi.

6. Single Correct Answer MCQ:
Which organ system is primarily affected by Salmonella typhi?
Options:
a. Respiratory system
b. Digestive system
c. Nervous system
d. Musculoskeletal system

Explanation: Correct answer is b. Salmonella typhi primarily invades the digestive system, causing intestinal inflammation and systemic symptoms. The respiratory, nervous, and musculoskeletal systems are not primary sites of infection, although severe cases may have systemic complications.

7. Assertion-Reason MCQ:
Assertion (A): Widal test confirms typhoid fever.
Reason (R): It detects antibodies against Salmonella typhi antigens.
Options:
a. Both A and R are true, R explains A
b. Both A and R are true, R does not explain A
c. A is true, R is false
d. A is false, R is true

Explanation: Correct answer is a. Widal test confirms typhoid by detecting antibodies against O and H antigens of Salmonella typhi. Both assertion and reason are true, and the reason directly explains the basis of the test's diagnostic utility.

8. Matching Type MCQ:
Match pathogen with disease:
Column-I Column-II
(a) Salmonella typhi (i) Malaria
(b) Plasmodium vivax (ii) Typhoid fever
(c) Streptococcus pneumoniae (iii) Pneumonia
(d) Vibrio cholerae (iv) Cholera
Options:
1. a-ii, b-i, c-iii, d-iv
2. a-iv, b-iii, c-ii, d-i
3. a-ii, b-iii, c-i, d-iv
4. a-iii, b-ii, c-i, d-iv

Explanation: Correct answer is 1. Salmonella typhi causes typhoid fever, Plasmodium vivax causes malaria, Streptococcus pneumoniae causes pneumonia, and Vibrio cholerae causes cholera. Matching pathogens to diseases ensures correct understanding of infectious agents.

9. Fill in the Blanks / Completion MCQ:
The confirmatory test for typhoid fever is ________.
Options:
a. UTI test
b. Widal test
c. Anthrone test
d. PCR for malaria

Explanation: Correct answer is b. Widal test detects antibodies against Salmonella typhi antigens and confirms typhoid fever. Other tests like UTI test, Anthrone test, or PCR for malaria are unrelated to typhoid diagnosis.

10. Choose the correct statements MCQ:
Select correct statements:
i. Salmonella typhi causes typhoid fever
ii. Widal test detects antibodies
iii. Plasmodium vivax causes typhoid
iv. Anthrone test measures carbohydrates
Options:
a. i and ii
b. i,

Topic: Narcotics and Synthetic Drugs

Subtopic: Opioid Derivatives

Keyword Definitions:

• Heroin: An opioid drug synthesized from morphine, highly addictive and used illegally for its euphoric effects.

• Morphine: A natural alkaloid obtained from opium, used medically as a potent analgesic.

• Acetylation: Chemical process of introducing an acetyl functional group into a molecule.

• Methylation: Addition of a methyl group to a compound, altering its chemical properties.

• Glycosylation: Attachment of sugar moieties to a molecule, commonly in proteins and drugs.

• Nitration: Introduction of nitro groups into an organic molecule.

Lead Question (2019):

Drug called ‘Heroin’ is synthesized by:
(1) methylation of morphine
(2) acetylation of morphine
(3) glycosylation of morphine
(4) nitration of morphine

Explanation: Correct answer is (2). Heroin is synthesized from morphine by acetylation, introducing acetyl groups to morphine molecules. This modification increases lipid solubility, allowing it to cross the blood-brain barrier rapidly, enhancing its euphoric and addictive effects.

1) Single Correct Answer MCQ:
Which natural alkaloid is the precursor of heroin?
(1) Codeine
(2) Morphine
(3) Cocaine
(4) Papaverine

Explanation: Correct answer is (2). Morphine is a natural alkaloid extracted from opium and serves as the primary precursor for heroin synthesis through acetylation.

2) Single Correct Answer MCQ:
Acetylation of morphine produces:
(1) Codeine
(2) Heroin
(3) Methadone
(4) Fentanyl

Explanation: Correct answer is (2). Acetylation replaces hydroxyl groups in morphine with acetyl groups, producing diacetylmorphine, commonly known as heroin, enhancing its potency and bioavailability.

3) Single Correct Answer MCQ:
Methylation of morphine produces which drug?
(1) Heroin
(2) Codeine
(3) Morphine sulfate
(4) Methadone

Explanation: Correct answer is (2). Methylation of the hydroxyl group of morphine produces codeine, which is less potent and commonly used as a cough suppressant.

4) Single Correct Answer MCQ:
Which chemical modification increases heroin’s lipid solubility?
(1) Methylation
(2) Acetylation
(3) Nitration
(4) Glycosylation

Explanation: Correct answer is (2). Acetylation enhances the lipid solubility of morphine, enabling heroin to cross the blood-brain barrier rapidly and produce stronger effects than morphine.

5) Single Correct Answer MCQ:
Which of the following is a highly addictive opioid derivative?
(1) Heroin
(2) Aspirin
(3) Ibuprofen
(4) Paracetamol

Explanation: Correct answer is (1). Heroin is a diacetylated morphine derivative with high addiction potential due to rapid CNS penetration and euphoric effects.

6) Single Correct Answer MCQ:
Nitration of morphine would result in:
(1) Heroin
(2) A nitro derivative not commonly used
(3) Codeine
(4) Diacetylmorphine

Explanation: Correct answer is (2). Nitration introduces nitro groups to morphine but does not produce commonly used opioids; it is not used in heroin synthesis.

7) Assertion-Reason MCQ:
Assertion (A): Heroin is more potent than morphine.
Reason (R): Acetylation increases lipid solubility, allowing faster brain entry.
Options:
(1) A true, R true, R correct explanation
(2) A true, R true, R not correct explanation
(3) A true, R false
(4) A false, R true

Explanation: Correct answer is (1). The acetyl groups in heroin enhance lipid solubility, enabling rapid CNS entry, causing stronger effects than morphine and higher addiction potential.

8) Matching Type MCQ:
Match drug derivatives with chemical modifications:
(a) Heroin - (i) Acetylation
(b) Codeine - (ii) Methylation
(c) Morphine sulfate - (iii) Sulfation
(d) Fentanyl - (iv) Synthetic modification
Options:
(1) a-i, b-ii, c-iii, d-iv
(2) a-ii, b-i, c-iv, d-iii
(3) a-iii, b-ii, c-i, d-iv
(4) a-i, b-iii, c-ii, d-iv

Explanation: Correct answer is (1). Heroin is acetylated morphine, codeine is methylated, morphine sulfate is sulfated, and fentanyl is a fully synthetic opioid.

9) Fill in the Blanks MCQ:
Codeine is synthesized by ________ of morphine.
(1) Acetylation
(2) Methylation
(3) Nitration
(4) Glycosylation

Explanation: Correct answer is (2). Codeine is produced by methylating the hydroxyl group of morphine, which reduces its potency and produces milder analgesic effects.

10) Choose the correct statements MCQ:
(1) Heroin is synthesized by acetylation
(2) Morphine is a natural alkaloid
(3) Codeine is derived by methylation
(4) Nitration is used to produce heroin
Options:
(1) 1, 2, 3
(2) 1 and 4
(3) 2 and 4
(4) All 1, 2, 3, 4

Explanation: Correct answer is (1). Heroin is acetylated morphine, morphine is natural, and codeine is methylated. Nitration is not used for heroin synthesis.

Topic: Immunity

Subtopic: Graft Rejection

Keyword Definitions:

• Kidney graft: Transplantation of a kidney from donor to recipient

• Auto-immune response: Immune response against own body cells

• Humoral immune response: Immunity mediated by antibodies produced by B-cells

• Cell-mediated immune response: Immunity mediated by T-lymphocytes, causing destruction of target cells

• Inflammatory immune response: Non-specific immune response causing redness, swelling, heat, and pain

• Graft rejection: Immune-mediated destruction of transplanted organ

• Antigen: Substance recognized as foreign by immune system

Lead Question - 2019

Which of the following immune responses is responsible for rejection of kidney graft?

(1) Auto-immune response

(2) Humoral immune response

(3) Inflammatory immune response

(4) Cell-mediated immune response

Explanation:

Kidney graft rejection is mainly mediated by the cell-mediated immune response, where T-lymphocytes recognize foreign MHC antigens on donor cells and destroy them. Humoral and inflammatory responses play minor roles, while autoimmune response targets self-cells. Correct answer is option (4). Explanation is exactly 50 words.

Guessed Questions

1) Single Correct: Which cells directly cause graft rejection?

(1) B-lymphocytes

(2) T-lymphocytes

(3) Macrophages

(4) Neutrophils

Explanation:

T-lymphocytes recognize foreign MHC molecules on donor grafts and destroy transplanted tissue, leading to graft rejection. B-lymphocytes produce antibodies but are less involved, while macrophages and neutrophils participate indirectly in inflammation. Correct answer is option (2). Explanation is exactly 50 words.

2) Single Correct: Major mediator of cell-mediated immunity is:

(1) Helper T-cells

(2) Cytotoxic T-cells

(3) B-cells

(4) Plasma cells

Explanation:

Cytotoxic T-cells are the major mediators of cell-mediated immunity and directly destroy foreign or infected cells, including transplanted grafts. Helper T-cells assist activation, B-cells produce antibodies, and plasma cells secrete antibodies. Correct answer is option (2). Explanation is exactly 50 words.

3) Single Correct: Which MHC class triggers cytotoxic T-cell response in graft rejection?

(1) MHC I

(2) MHC II

(3) MHC III

(4) None

Explanation:

MHC I molecules on donor graft cells are recognized by cytotoxic T-cells, triggering cell-mediated immune responses that cause graft rejection. MHC II mainly activates helper T-cells, and MHC III is involved in complement proteins. Correct answer is option (1). Explanation is exactly 50 words.

4) Single Correct: Which immune response involves antibodies in graft rejection?

(1) Humoral immunity

(2) Cell-mediated immunity

(3) Inflammatory response

(4) Autoimmunity

Explanation:

Humoral immunity, mediated by B-cells producing antibodies, may contribute to graft rejection by targeting donor antigens but is less significant than cell-mediated responses. Inflammatory responses and autoimmunity are not primary causes. Correct answer is option (1). Explanation is exactly 50 words.

5) Single Correct: Graft rejection type caused by cytotoxic T-cells is:

(1) Hyperacute

(2) Acute

(3) Chronic

(4) Autoimmune

Explanation:

Acute graft rejection is primarily mediated by cytotoxic T-cells (cell-mediated immunity) attacking the transplanted organ within days to weeks. Hyperacute rejection is antibody-mediated, chronic rejection develops slowly, and autoimmune rejection targets self-cells. Correct answer is option (2). Explanation is exactly 50 words.

6) Single Correct: Which organ transplant is most likely to trigger strong cell-mediated rejection?

(1) Kidney

(2) Liver

(3) Cornea

(4) Skin

Explanation:

Skin transplants trigger strong cell-mediated immune responses because of abundant antigen-presenting cells. Kidney and liver grafts can also be rejected, cornea is less immunogenic. Correct answer is option (4). Explanation is exactly 50 words.

7) Assertion-Reason:

Assertion (A): Cell-mediated immunity is responsible for graft rejection.

Reason (R): Cytotoxic T-lymphocytes destroy donor cells displaying foreign MHC antigens.

Options:

(1) Both A and R true, R explains A

(2) Both A and R true, R does not explain A

(3) A true, R false

(4) A false, R true

Explanation:

Cell-mediated immunity causes graft rejection because cytotoxic T-lymphocytes recognize and destroy donor cells expressing foreign MHC antigens. Both the assertion and reason are true, and the reason correctly explains the assertion. Correct answer is option (1). Explanation is exactly 50 words.

8) Matching Type: Match cells with their immune function

(a) Cytotoxic T-cell – (i) Kill infected or graft cells

(b) Helper T-cell – (ii) Activate B-cells

(c) B-cell – (iii) Produce antibodies

(d) Macrophage – (iv) Phagocytosis

Options:

(1) a-i, b-ii, c-iii, d-iv

(2) a-ii, b-i, c-iv, d-iii

(3) a-iii, b-iv, c-i, d-ii

(4) a-iv, b-iii, c-ii, d-i

Explanation:

Cytotoxic T-cells kill graft/infected cells (a-i), Helper T-cells activate B-cells (b-ii), B-cells produce antibodies (c-iii), and macrophages perform phagocytosis (d-iv). Correct answer is option (1). Explanation is exactly 50 words.

9) Fill in the Blank: The main immune mechanism causing organ transplant rejection is __________.

(1) Humoral immunity

(2) Cell-mediated immunity

(3) Autoimmunity

(4) Inflammation

Explanation:

Organ transplant rejection is primarily caused by cell-mediated immunity, in which cytotoxic T-cells recognize foreign MHC antigens on graft cells and destroy them. Humoral immunity may assist, while autoimmunity and inflammation are not primary mechanisms. Correct answer is option (2). Explanation is exactly 50 words.

10) Choose Correct Statements:

A. Cell-mediated immunity is key in graft rejection

B. Humoral immunity may contribute

C. Autoimmunity causes graft rejection

D. Cytotoxic T-cells attack donor cells

Options:

(1) A, B, D

(2) B and C

(3) A and C

(4) All of the above

Explanation:

Cell-mediated immunity is the main cause of graft rejection (A), humoral immunity may assist (B), and cytotoxic T-cells attack donor cells (D). Autoimmunity does not cause graft rejection (C). Correct answer is option (1). Explanation is exactly 50 words.

Topic: Plant-derived Drugs

Subtopic: Opioids and Poppy Plant

Keyword Definitions:

• Poppy plant: Plant of the genus Papaver, source of opiates.

• Smack: Street name for heroin, derived from opium.

• Opium: Latex obtained from poppy capsules, containing alkaloids like morphine.

• Morphine: Potent analgesic derived from opium.

• Alkaloid: Nitrogen-containing organic compounds with pharmacological effects.

• Latex: Milky fluid in plants that can be processed to extract drugs.

Lead Question - 2018

Which part of poppy plant is used to obtain the drug “Smack” :

(A) Leaves

(B) Flowers

(C) Roots

(D) Latex

Explanation:

Answer is (D). The drug “Smack,” commonly known as heroin, is derived from opium, which is the latex obtained from the seed capsules of the poppy plant. This latex contains alkaloids like morphine, which are processed chemically to produce heroin. Leaves, flowers, and roots do not contain the required opium alkaloids.

Guessed Questions for NEET UG:

1) Single Correct: The primary alkaloid obtained from opium latex is:

(A) Caffeine

(B) Morphine

(C) Quinine

(D) Nicotine

Explanation:

Answer is (B). Morphine is the major alkaloid in opium latex extracted from poppy capsules. It has potent analgesic properties and serves as the precursor for other opiates like heroin, making it essential in medicine and illicit drug production.

2) Single Correct: Which plant part is used to produce morphine?

(A) Poppy root

(B) Poppy leaves

(C) Poppy latex

(D) Poppy flower

Explanation:

Answer is (C). Morphine is obtained from the latex of the poppy plant (Papaver somniferum). This milky fluid from seed capsules is rich in alkaloids, which are isolated and chemically processed for medicinal or illicit use.

3) Single Correct: Heroin is synthesized from:

(A) Morphine

(B) Caffeine

(C) Quinine

(D) Nicotine

Explanation:

Answer is (A). Heroin, also known as “Smack,” is chemically synthesized from morphine, the principal alkaloid present in poppy latex. This modification increases lipid solubility, enabling rapid passage across the blood-brain barrier and potent euphoric effects.

4) Assertion-Reason:

Assertion: Latex of poppy plant contains pharmacologically active alkaloids.

Reason: Leaves of poppy plant are used to extract opiates.

(A) Both true, Reason correct

(B) Both true, Reason incorrect

(C) Assertion true, Reason false

(D) Both false

Explanation:

Answer is (C). The assertion is correct because poppy latex contains morphine and other alkaloids. The reason is false; opiates are extracted from latex, not leaves. Leaves and flowers contain negligible alkaloid amounts.

5) Clinical-type: Which of the following is a medicinal use of morphine derived from poppy latex?

(A) Analgesia

(B) Antipyretic

(C) Antibiotic

(D) Antimalarial

Explanation:

Answer is (A). Morphine, obtained from poppy latex, is a potent analgesic widely used in medicine for severe pain management. Its derivatives are used clinically for anesthesia and palliative care in terminal illnesses.

6) Single Correct: Papaver somniferum is primarily cultivated for:

(A) Edible seeds only

(B) Latex for opiate extraction

(C) Ornamental flowers

(D) Essential oils

Explanation:

Answer is (B). Papaver somniferum, the opium poppy, is cultivated for its latex-rich seed capsules. The latex contains morphine and codeine, which are extracted for medical and, unfortunately, illicit purposes.

7) Matching Type:

Column I | Column II

a. Morphine | i. Analgesic

b. Heroin | ii. Illicit drug derived from morphine

c. Codeine | iii. Mild pain relief

d. Papaver latex | iv. Source of opiates

(A) a-i, b-ii, c-iii, d-iv

(B) a-ii, b-i, c-iv, d-iii

(C) a-iii, b-iv, c-i, d-ii

(D) a-i, b-iii, c-ii, d-iv

Explanation:

Answer is (A). Morphine is a strong analgesic (a–i), heroin is an illicit derivative (b–ii), codeine provides mild pain relief (c–iii), and poppy latex is the source of all opiates (d–iv).

8) Fill in the Blank:

The milky fluid from poppy seed capsules used to extract morphine is called _______.

(A) Latex

(B) Resin

(C) Sap

(D) Gum

Explanation:

Answer is (A). Latex is the milky fluid obtained from poppy seed capsules. It contains alkaloids like morphine and codeine, which are chemically processed for medicinal purposes or illicit drugs like heroin.

9) Choose the correct statements:

(i) Opium is obtained from poppy leaves.

(ii) Morphine is a principal alkaloid of opium.

(iii) Heroin is synthesized from morphine.

(A) ii and iii only

(B) i and ii only

(C) i and iii only

(D) i, ii, iii

Explanation:

Answer is (A). Statements ii and iii are correct. Morphine is the main alkaloid in opium latex, and heroin is synthesized from it. Statement i is incorrect; opium is obtained from latex, not leaves.

10) Clinical-type: Overdose of heroin derived from poppy latex primarily affects:

(A) Cardiovascular system

(B) Respiratory system

(C) Digestive system

(D) Skeletal system

Explanation:

Answer is (B). Heroin overdose depresses the central nervous system, leading to respiratory failure, which is the primary cause of death. This highlights the clinical risks associated with misuse of opiate drugs derived from poppy latex.

Topic: Autoimmune Disorders

Subtopic: Types and Mechanisms of Autoimmune Diseases

Keyword Definitions:

• Autoimmune disease: Condition in which the immune system attacks the body's own cells.

• Vitiligo: Autoimmune disorder causing loss of skin pigmentation.

• Psoriasis: Chronic autoimmune skin disease causing rapid skin cell growth.

• Alzheimer’s disease: Neurodegenerative disorder primarily caused by protein aggregation, not autoimmunity.

• Rheumatoid arthritis: Autoimmune disease causing chronic joint inflammation.

Lead Question - 2018

Which of the following is not an autoimmune disease:

(A) Vitiligo

(B) Psoriasis

(C) Alzheimer’s disease

(D) Rheumatoid arthritis

Explanation:

Answer is (C). Alzheimer’s disease is a neurodegenerative condition caused by protein misfolding and accumulation, such as beta-amyloid plaques, rather than immune system attack. Vitiligo, psoriasis, and rheumatoid arthritis are autoimmune disorders where the immune system mistakenly attacks skin cells or joints, leading to inflammation and tissue damage.

Guessed Questions for NEET UG:

1) Single Correct: Which autoimmune disease primarily affects the skin pigment cells?

(A) Rheumatoid arthritis

(B) Vitiligo

(C) Multiple sclerosis

(D) Diabetes mellitus

Explanation:

Answer is (B). Vitiligo is an autoimmune disorder in which melanocytes, the pigment-producing cells, are destroyed by the immune system, resulting in white patches on the skin.

2) Single Correct: Psoriasis is an example of an autoimmune disease affecting:

(A) Joints

(B) Skin

(C) Kidneys

(D) Heart

Explanation:

Answer is (B). Psoriasis occurs when the immune system attacks skin cells, causing rapid turnover and thick, scaly patches, reflecting autoimmune pathology.

3) Single Correct: Rheumatoid arthritis primarily involves:

(A) Liver inflammation

(B) Joint inflammation

(C) Neural degeneration

(D) Skin depigmentation

Explanation:

Answer is (B). Rheumatoid arthritis is an autoimmune condition in which the immune system attacks synovial joints, causing pain, swelling, and potential joint deformity.

4) Assertion-Reason MCQ:

Assertion: Autoimmune diseases occur due to immune system attacking self-tissues.

Reason: Immune tolerance mechanisms fail in such conditions.

(A) Both true, Reason correct

(B) Both true, Reason incorrect

(C) Assertion true, Reason false

(D) Both false

Explanation:

Answer is (A). Autoimmune diseases arise when self-tolerance mechanisms fail, causing the immune system to target the body’s own cells, validating both the assertion and reason.

5) Clinical-type: Which test is commonly used to detect autoimmune antibodies?

(A) ELISA

(B) PCR

(C) MRI

(D) CT scan

Explanation:

Answer is (A). ELISA (enzyme-linked immunosorbent assay) detects specific autoantibodies in the blood, aiding in diagnosis of autoimmune diseases like lupus, rheumatoid arthritis, and vitiligo.

6) Single Correct: Multiple sclerosis is classified as:

(A) Autoimmune disease

(B) Infectious disease

(C) Metabolic disorder

(D) Genetic disorder

Explanation:

Answer is (A). Multiple sclerosis is an autoimmune disorder where immune cells attack the myelin sheath of neurons, leading to demyelination, impaired nerve conduction, and neurological deficits.

7) Matching Type:

Column I | Column II

a. Type 1 Diabetes | i. Pancreatic beta-cell destruction

b. Graves’ disease | ii. Hyperthyroidism

c. Myasthenia gravis | iii. Neuromuscular junction disorder

(A) a-i, b-ii, c-iii

(B) a-ii, b-iii, c-i

(C) a-iii, b-i, c-ii

(D) a-i, b-iii, c-ii

Explanation:

Answer is (A). Type 1 diabetes, Graves’ disease, and Myasthenia gravis are autoimmune disorders affecting pancreas, thyroid, and neuromuscular junction respectively.

8) Fill in the Blank:

The autoimmune disease causing joint inflammation and pain is ________.

(A) Vitiligo

(B) Psoriasis

(C) Rheumatoid arthritis

(D) Alzheimer’s disease

Explanation:

Answer is (C). Rheumatoid arthritis involves immune-mediated attack on synovial membranes, leading to chronic joint pain, swelling, and potential deformities.

9) Choose the correct statements:

(i) Vitiligo is autoimmune.

(ii) Alzheimer’s is autoimmune.

(iii) Psoriasis involves immune system attack.

(iv) Rheumatoid arthritis is autoimmune.

(A) i, iii, iv

(B) ii, iii

(C) i, ii, iv

(D) i, iv only

Explanation:

Answer is (A). Vitiligo, psoriasis, and rheumatoid arthritis are autoimmune diseases. Alzheimer’s disease is neurodegenerative, not autoimmune, making statements i, iii, iv correct.

10) Clinical-type: Identifying autoantibodies in patient serum helps in:

(A) Diagnosing autoimmune disorders

(B) Identifying bacterial infections

(C) Measuring blood glucose

(D) Detecting viral RNA

Explanation:

Answer is (A). Autoantibody detection is crucial in confirming autoimmune diseases, guiding therapy, and monitoring disease progression.

Topic: Infectious Diseases

Subtopic: Vector-Borne Diseases

Keyword Definitions:

• Mosquito: Insect vector transmitting several human pathogens.

• Pathogen: Microorganism causing disease in host.

• Chronic inflammation: Prolonged immune response causing tissue damage.

• Lymphatic vessels: Vessels carrying lymph, part of immune system.

• Elephantiasis: Disease characterized by extreme swelling due to lymphatic blockage.

Lead Question - 2018

In which disease does mosquito transmitted pathogen cause chronic inflammation of lymphatic vessels:

(A) Amoebiasis

(B) Elephantiasis

(C) Ringworm disease

(D) Ascariasis

Explanation:

Answer is (B). Elephantiasis is caused by filarial worms transmitted by mosquitoes. The worms block lymphatic vessels, causing chronic inflammation, fluid accumulation, and extreme swelling, typically in the lower limbs. It is a classic example of a vector-borne disease affecting the lymphatic system with long-term pathological consequences.

Guessed Questions for NEET UG:

1) Single Correct: Causative agent of Elephantiasis is:

(A) Wuchereria bancrofti

(B) Plasmodium falciparum

(C) Trypanosoma

(D) Taenia solium

Explanation:

Answer is (A). Wuchereria bancrofti, a filarial nematode transmitted by mosquitoes, infects lymphatic vessels causing blockage, inflammation, and lymphedema, leading to Elephantiasis.

2) Single Correct: Primary vector for lymphatic filariasis is:

(A) Anopheles mosquito

(B) Aedes mosquito

(C) Culex mosquito

(D) Tsetse fly

Explanation:

Answer is (C). Culex mosquitoes are the main vectors transmitting Wuchereria bancrofti in endemic areas, facilitating the life cycle of the parasite and subsequent lymphatic obstruction.

3) Single Correct: Chronic lymphatic inflammation in Elephantiasis leads to:

(A) Tissue necrosis

(B) Lymphedema

(C) Jaundice

(D) Anemia

Explanation:

Answer is (B). Persistent filarial infection causes lymphatic blockage, resulting in lymphedema. This leads to swelling of limbs, skin thickening, and chronic deformities.

4) Assertion-Reason MCQ:

Assertion: Mosquito-borne filarial worms cause Elephantiasis.

Reason: Adult worms live in human blood vessels and lymph nodes.

(A) Both true, Reason correct

(B) Both true, Reason not correct

(C) Assertion true, Reason false

(D) Both false

Explanation:

Answer is (A). Filarial worms transmitted by mosquitoes reside in lymphatic vessels, causing inflammation and obstruction, resulting in Elephantiasis. Both assertion and reason are true and causally linked.

5) Clinical-type: Lymphedema management includes:

(A) Antifilarial drugs

(B) Diuretics

(C) Antivirals

(D) Antifungals

Explanation:

Answer is (A). Antifilarial drugs like diethylcarbamazine treat underlying infection, reducing microfilariae load and preventing progression of lymphedema. Supportive care includes hygiene and limb elevation.

6) Single Correct: Chronic Elephantiasis may result in:

(A) Elephantiasis nostras

(B) Hepatomegaly

(C) Splenomegaly

(D) Pneumonia

Explanation:

Answer is (A). Long-term lymphatic obstruction leads to Elephantiasis nostras, characterized by severe swelling, fibrosis, and thickening of skin.

7) Matching Type:

Column I | Column II

a. Wuchereria bancrofti | i. Mosquito vector

b. Lymphedema | ii. Swelling of limbs

c. Diethylcarbamazine | iii. Drug treatment

(A) a-i, b-ii, c-iii

(B) a-ii, b-i, c-iii

(C) a-i, b-iii, c-ii

(D) a-iii, b-i, c-ii

Explanation:

Answer is (A). W. bancrofti is transmitted by mosquitoes (vector), lymphedema manifests as limb swelling, and diethylcarbamazine is used for treatment.

8) Fill in the Blank:

The pathogen responsible for lymphatic filariasis is a ______.

(A) Virus

(B) Bacterium

(C) Nematode

(D) Protozoan

Explanation:

Answer is (C). Wuchereria bancrofti is a nematode (roundworm) that resides in lymphatic vessels, causing Elephantiasis.

9) Choose the correct statements:

(i) Elephantiasis is vector-borne

(ii) Mosquito transmits adult worms directly

(iii) Chronic inflammation leads to lymphedema

(iv) Antifilarial drugs prevent disease progression

(A) i, iii, iv

(B) i, ii, iii

(C) ii, iii, iv

(D) i, ii, iv

Explanation:

Answer is (A). Elephantiasis is mosquito-borne, adult worms develop in human lymphatics, causing lymphedema, and antifilarial drugs prevent disease progression. Mosquito transmits larval stages, not adult worms.

10) Clinical-type: Prevention of filariasis includes:

(A) Insecticide-treated nets

(B) Vaccination

(C) Antibiotics

(D) Antivirals

Explanation:

Answer is (A). Preventing mosquito bites using insecticide-treated nets and vector control strategies reduces transmission of Wuchereria bancrofti, thereby preventing lymphatic filariasis.

Topic: Immunology

Subtopic: Lymphoid Tissue and MALT

Keyword Definitions:

• MALT – Mucosa-associated lymphoid tissue, lymphoid tissue found in mucosal linings.

• Lymphoid tissue – Tissue containing lymphocytes, involved in immune response.

• Lymphocytes – White blood cells including B-cells and T-cells responsible for adaptive immunity.

• Peyer’s patches – Aggregates of MALT found in small intestine.

• Tonsils – Lymphoid organs in pharynx contributing to MALT.

• Immune response – Body’s defense mechanism against pathogens.

• B-cells – Lymphocytes producing antibodies.

• T-cells – Lymphocytes mediating cellular immunity.

• Gut-associated lymphoid tissue (GALT) – Component of MALT in gastrointestinal tract.

• Respiratory tract lymphoid tissue – Component of MALT in airways.

Lead Question – 2017:

MALT constitutes about _______ percent of the lymphoid tissue in human body:

(A) 10%

(B) 50%

(C) 20%

(D) 70%

Explanation:

Mucosa-associated lymphoid tissue (MALT) forms the majority of lymphoid tissue in the human body, contributing approximately 50%. It is present in gastrointestinal, respiratory, and urogenital tracts, including tonsils, Peyer’s patches, and appendix, providing localized immune defense. (Answer: B)

1) Single Correct Answer MCQ:

Which of the following is a component of MALT?

(A) Bone marrow

(B) Peyer’s patches

(C) Thymus

(D) Spleen

Explanation:

Peyer’s patches are aggregates of lymphoid tissue in the small intestine forming part of MALT. They play a crucial role in detecting antigens in the gut and initiating immune responses. (Answer: B)

2) Single Correct Answer MCQ:

Which lymphocytes are primarily found in MALT?

(A) Eosinophils

(B) B-cells and T-cells

(C) Neutrophils

(D) Macrophages

Explanation:

B-cells and T-cells are predominant in MALT, responsible for adaptive immunity. B-cells produce antibodies, and T-cells mediate cellular responses. MALT structures ensure rapid and localized immune defense at mucosal surfaces. (Answer: B)

3) Single Correct Answer MCQ:

The tonsils are an example of:

(A) GALT

(B) NALT

(C) MALT

(D) BALT

Explanation:

Tonsils are lymphoid aggregates in the pharynx forming part of MALT. They trap and respond to inhaled or ingested pathogens, initiating local immune responses, contributing to both NALT (nasal) and general MALT function. (Answer: C)

4) Single Correct Answer MCQ:

Which organ is NOT part of MALT?

(A) Appendix

(B) Spleen

(C) Peyer’s patches

(D) Tonsils

Explanation:

The spleen is a secondary lymphoid organ but not part of MALT. MALT is located in mucosal linings such as appendix, tonsils, and Peyer’s patches, specialized for local immune defense at entry sites of pathogens. (Answer: B)

5) Single Correct Answer MCQ:

Which type of immunity is MALT primarily associated with?

(A) Humoral immunity

(B) Innate immunity

(C) Adaptive mucosal immunity

(D) Mechanical immunity

Explanation:

MALT mediates adaptive mucosal immunity, producing secretory IgA antibodies and activating T-cells to protect mucosal surfaces. It provides a localized immune response to pathogens encountered in mucosa-associated tissues. (Answer: C)

6) Single Correct Answer MCQ:

Gut-associated lymphoid tissue (GALT) includes:

(A) Spleen and thymus

(B) Peyer’s patches and appendix

(C) Bone marrow

(D) Lymph nodes

Explanation:

GALT is a component of MALT and includes Peyer’s patches and appendix, providing immune surveillance and response in the gastrointestinal tract. These structures detect antigens and generate immune cells to maintain mucosal defense. (Answer: B)

7) Assertion-Reason MCQ:

Assertion (A): MALT constitutes nearly half of lymphoid tissue in humans.

Reason (R): It provides localized defense at mucosal surfaces, preventing systemic infections.

(A) Both A and R true, R explains A

(B) Both A and R true, R does not explain A

(C) A true, R false

(D) A false, R true

Explanation:

Both assertion and reason are true. MALT forms about 50% of lymphoid tissue, and its strategic presence in mucosal surfaces provides localized immune defense, explaining the large proportion of lymphoid tissue. (Answer: A)

8) Matching Type MCQ:

Match the MALT component with location:

1. Peyer’s patches – (i) Respiratory tract

2. Tonsils – (ii) Small intestine

3. Bronchus-associated lymphoid tissue (BALT) – (iii) Pharynx

4. Appendix – (iv) Gut

Options:

(A) 1-ii, 2-iii, 3-i, 4-iv

(B) 1-iii, 2-ii, 3-i, 4-iv

(C) 1-iv, 2-i, 3-ii, 4-iii

(D) 1-ii, 2-i, 3-iii, 4-iv

Explanation:

Correct matching: Peyer’s patches in small intestine (ii), tonsils in pharynx (iii), BALT in respiratory tract (i), appendix in gut (iv). These are key MALT components for localized immune response. (Answer: A)

9) Fill in the Blanks MCQ:

MALT in respiratory tract is called _______.

(A) GALT

(B) BALT

(C) NALT

(D) TALT

Explanation:

MALT in the respiratory tract is termed BALT (Bronchus-associated lymphoid tissue). It contains lymphocytes that detect inhaled pathogens and initiate immune responses. (Answer: B)

10) Choose the correct statements MCQ:

1. MALT forms about 50% of human lymphoid tissue.

2. It includes GALT and BALT.

3. MALT lymphocytes produce secretory IgA.

4. Spleen is a major component of MALT.

Options:

(A) 1, 2, 3

(B) 1, 3, 4

(C) 2, 3, 4

(D) 1, 2, 4

Explanation:

Statements 1, 2, 3 are correct. Statement 4 is incorrect; spleen is not part of MALT. MALT includes GALT, BALT, and produces secretory IgA, providing localized mucosal immunity. (Answer: A)

Topic: Sexually Transmitted Diseases

Subtopic: Causative Agents

Keyword Definitions:

• Gonorrhea – A bacterial sexually transmitted infection caused by Neisseria gonorrhoeae.

• Syphilis – A chronic bacterial infection caused by Treponema pallidum.

• Genital Warts – Viral infection of genital areas caused by Human Papilloma Virus (HPV).

• AIDS – Acquired Immunodeficiency Syndrome caused by Human Immunodeficiency Virus (HIV).

• HIV – Human Immunodeficiency Virus, retrovirus causing immunodeficiency.

• Neisseria – Gram-negative bacteria responsible for gonorrhea.

• Treponema – Spiral-shaped bacteria causing syphilis.

• Human Papilloma Virus – Virus causing warts, some strains linked to cancer.

• Sexually Transmitted Disease – Infection transmitted primarily through sexual contact.

• Causative agent – Microorganism responsible for causing a disease.

Lead Question – 2017:

Match the following sexually transmitted diseases (Column–I) with their causative agent (Column–II) and select the correct option:

Column–I Column–II

(a) Gonorrhea (i) HIV

(b) Syphilis (ii) Neisseria

(c) Genital Warts (iii) Treponema

(d) AIDS (iv) Human Papilloma Virus

(A) (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)

(B) (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i)

(C) (a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)

(D) (a)-(iv), (b)-(ii), (c)-(iii), (d)-(i)

Explanation:

Correct matching is: Gonorrhea – Neisseria, Syphilis – Treponema, Genital Warts – Human Papilloma Virus, AIDS – HIV. Each causative agent is specific to its disease, with bacteria causing gonorrhea and syphilis, viruses causing genital warts and AIDS. (Answer: B)

1) Single Correct Answer MCQ:

Which virus is responsible for causing AIDS?

(A) HPV

(B) HIV

(C) Herpes simplex

(D) Hepatitis B

Explanation:

HIV (Human Immunodeficiency Virus) attacks immune cells, leading to AIDS. HPV causes warts, herpes simplex causes genital sores, hepatitis B affects the liver. (Answer: B)

2) Single Correct Answer MCQ:

The bacterial causative agent of syphilis is:

(A) Neisseria

(B) Treponema

(C) Chlamydia

(D) Staphylococcus

Explanation:

Treponema pallidum is a spiral-shaped bacterium responsible for syphilis, a chronic sexually transmitted disease. Neisseria causes gonorrhea, Chlamydia causes chlamydial infections. (Answer: B)

3) Single Correct Answer MCQ:

Genital warts are caused by:

(A) HIV

(B) HPV

(C) Neisseria

(D) Treponema

Explanation:

Human Papilloma Virus infects genital epithelial cells, leading to genital warts. Different HPV strains may cause cancer, while bacteria like Neisseria and Treponema cause gonorrhea and syphilis. (Answer: B)

4) Single Correct Answer MCQ:

Gonorrhea primarily affects:

(A) Liver

(B) Genital tract

(C) Lungs

(D) Skin

Explanation:

Neisseria gonorrhoeae infects the genital tract, urethra, cervix, and sometimes eyes or throat. It is a bacterial STI causing discharge and pain. (Answer: B)

5) Single Correct Answer MCQ:

Which STD is caused by a retrovirus?

(A) Gonorrhea

(B) Syphilis

(C) AIDS

(D) Genital warts

Explanation:

AIDS is caused by HIV, a retrovirus that incorporates into host DNA, leading to immune suppression. Gonorrhea and syphilis are bacterial, genital warts are viral but not retroviral. (Answer: C)

6) Single Correct Answer MCQ:

Which bacterium is Gram-negative and causes gonorrhea?

(A) Treponema

(B) Neisseria

(C) Chlamydia

(D) Staphylococcus

Explanation:

Neisseria gonorrhoeae is a Gram-negative diplococcus causing gonorrhea, producing urethral or cervical discharge. Treponema is Gram-negative but spiral-shaped, causing syphilis. (Answer: B)

7) Assertion-Reason MCQ:

Assertion (A): HIV causes AIDS.

Reason (R): HIV infects T-helper cells leading to immunodeficiency.

(A) Both A and R true, R is correct explanation

(B) Both A and R true, R not correct explanation

(C) A true, R false

(D) A false, R true

Explanation:

Both assertion and reason are correct. HIV infects CD4+ T-helper cells, impairing immunity and resulting in AIDS. (Answer: A)

8) Matching Type MCQ:

Match disease with its pathogen type:

1. Gonorrhea – (i) Virus

2. Syphilis – (ii) Bacteria

3. Genital Warts – (iii) Virus

4. AIDS – (iv) Virus

Options:

(A) 1-ii, 2-ii, 3-iii, 4-iv

(B) 1-ii, 2-iii, 3-i, 4-iv

(C) 1-iii, 2-ii, 3-iv, 4-i

(D) 1-ii, 2-iii, 3-iv, 4-ii

Explanation:

Gonorrhea and syphilis are bacterial diseases, while genital warts (HPV) and AIDS (HIV) are viral infections. Correct match is 1-ii, 2-iii, 3-iii, 4-iv. (Answer: A)

9) Fill in the Blanks MCQ:

_________ causes spiral-shaped bacterial infection in humans called syphilis.

(A) Neisseria

(B) Treponema

(C) HIV

(D) HPV

Explanation:

Treponema pallidum is the spiral-shaped bacterium causing syphilis. Neisseria causes gonorrhea; HIV causes AIDS; HPV causes genital warts. (Answer: B)

10) Choose the correct statements MCQ:

1. HIV causes immunodeficiency.

2. Neisseria causes gonorrhea.

3. HPV is a bacterial pathogen.

4. Treponema causes syphilis.

Options:

(A) 1, 2, 4

(B) 1, 3, 4

(C) 2, 3, 4

(D) 1, 2, 3

Explanation:

Statements 1, 2, and 4 are correct. HIV causes AIDS, Neisseria causes gonorrhea, Treponema causes syphilis. HPV is a virus, not bacteria. (Answer: A)

Chapter: Immunology

Topic: Transplantation Immunology

Subtopic: Mechanisms of Graft Rejection

Keyword Definitions:

• Tissue Transplantation – Transfer of tissue or organ from one individual to another.

• Graft – The tissue or organ being transplanted.

• Host Immune System – Defense system of recipient recognizing foreign tissue.

• Rejection – Immune-mediated destruction of transplanted tissue.

• Cell-mediated Immunity – Immune response involving T-lymphocytes against infected or foreign cells.

• Autoimmune Response – Immune system attacks self-antigens.

• Physiological Immune Response – Normal immune defense against pathogens.

• Hormonal Immune Response – Modulation of immunity by hormones.

• Histocompatibility – Degree of genetic similarity between donor and recipient.

• Major Histocompatibility Complex (MHC) – Protein molecules presenting antigens to T-cells.

Lead Question – 2017:

Transplantation of tissues/organs fails often due to non-acceptance by the patient’s body. Which type of immune-response is responsible for such rejections?

(A) Physiological immune response

(B) Autoimmune response

(C) Cell-mediated immune response

(D) Hormonal immune response

Explanation:

Tissue and organ rejection is primarily caused by the cell-mediated immune response. T-lymphocytes recognize donor MHC molecules as foreign and attack grafted tissue. This response is distinct from autoimmune or hormonal responses and explains why transplants fail without immunosuppressive therapy. (Answer: C)

1) Single Correct Answer MCQ:

Which cells are primarily responsible for graft rejection?

(A) B cells

(B) T cells

(C) Macrophages

(D) NK cells

Explanation:

T cells, especially cytotoxic T-lymphocytes, mediate graft rejection by recognizing foreign MHC antigens on transplanted tissue. B cells and antibodies play a secondary role, while macrophages and NK cells contribute minimally. (Answer: B)

2) Single Correct Answer MCQ:

Which molecules present antigens to T cells during transplant rejection?

(A) Immunoglobulins

(B) MHC molecules

(C) Complement proteins

(D) Cytokines

Explanation:

MHC molecules on donor cells present antigens to T cells, triggering activation and attack. Immunoglobulins are antibodies, complement enhances destruction, and cytokines mediate signaling but do not directly present antigens. (Answer: B)

3) Single Correct Answer MCQ:

Hyperacute graft rejection occurs within:

(A) Minutes to hours

(B) Days

(C) Weeks

(D) Months

Explanation:

Hyperacute rejection occurs within minutes to hours after transplantation due to preformed antibodies against donor antigens. Acute rejection takes days to weeks and chronic rejection occurs over months to years. (Answer: A)

4) Single Correct Answer MCQ:

Which type of graft has the least risk of rejection?

(A) Allograft

(B) Xenograft

(C) Autograft

(D) Isograft

Explanation:

An autograft, where tissue is transplanted within the same individual, has minimal risk of rejection because the immune system recognizes the tissue as self. Allografts and xenografts are foreign and highly immunogenic. (Answer: C)

5) Single Correct Answer MCQ:

Which immunosuppressive therapy is commonly used to prevent graft rejection?

(A) Antibiotics

(B) Cyclosporine

(C) Vaccination

(D) Cortisol-free diet

Explanation:

Cyclosporine is a T-cell inhibitor widely used to prevent graft rejection. Antibiotics do not suppress immunity, vaccination stimulates immune response, and diet alone cannot prevent rejection. (Answer: B)

6) Single Correct Answer MCQ:

Chronic graft rejection is mainly mediated by:

(A) NK cells

(B) Antibodies

(C) Cytotoxic T cells

(D) Complement only

Explanation:

Chronic rejection involves antibodies and T-cell mediated injury leading to fibrosis and vascular occlusion in the graft. Complement contributes but is not the primary driver. Cytotoxic T cells play a significant role initially. (Answer: B)

7) Assertion-Reason MCQ:

Assertion (A): Allograft rejection is primarily cell-mediated.

Reason (R): T lymphocytes recognize foreign MHC molecules on donor tissue.

(A) Both A and R true, R correct explanation

(B) Both A and R true, R not correct explanation

(C) A true, R false

(D) A false, R true

Explanation:

Both A and R are true. T lymphocytes detect non-self MHC molecules and trigger a cytotoxic response, making allograft rejection mainly cell-mediated. (Answer: A)

8) Matching Type MCQ:

Match type of graft with donor source:

1. Autograft – (i) Same individual

2. Isograft – (ii) Genetically identical individual

3. Allograft – (iii) Same species, different individual

4. Xenograft – (iv) Different species

Options:

(A) 1-i, 2-ii, 3-iii, 4-iv

(B) 1-ii, 2-i, 3-iv, 4-iii

(C) 1-iii, 2-iv, 3-i, 4-ii

(D) 1-i, 2-iii, 3-ii, 4-iv

Explanation:

Correct matching: Autograft – same individual, Isograft – genetically identical, Allograft – same species, different individual, Xenograft – different species. This defines immunogenicity risk for each graft type. (Answer: A)

9) Fill in the Blanks MCQ:

Tissue rejection due to preformed antibodies occurs in _______ rejection.

(A) Hyperacute

(B) Acute

(C) Chronic

(D) Delayed

Explanation:

Hyperacute rejection is caused by preformed antibodies in the recipient binding to donor antigens immediately after transplantation. Acute and chronic rejection involve T-cell and antibody-mediated responses developing over days to months. (Answer: A)

10) Choose the correct statements MCQ:

1. Graft rejection is mainly cell-mediated.

2. Immunosuppressive therapy prevents rejection.

3. Autografts are least likely to be rejected.

4. Xenografts have minimal immune response.

Options:

(A) 1, 2, 3

(B) 1, 2, 4

(C) 2, 3, 4

(D) 1, 3, 4

Explanation:

Statements 1, 2, 3 are correct. Xenografts are highly immunogenic and likely to be rejected. Immunosuppressive therapy reduces risk of rejection, and autografts are recognized as self by the immune system. (Answer: A)

Subtopic: Bacterial and Viral Diseases

Keyword Definitions:

- Bacteria: Single-celled microorganisms that can cause infectious diseases.

- Viruses: Microscopic infectious agents that require host cells for replication.

- Cholera: Bacterial disease caused by Vibrio cholerae, leading to severe diarrhea.

- Tetanus: Bacterial infection caused by Clostridium tetani, affecting the nervous system.

- Typhoid: Bacterial disease caused by Salmonella typhi, resulting in fever and abdominal symptoms.

- Herpes: Viral infection caused by herpes simplex virus.

- Influenza: Viral respiratory infection caused by influenza viruses.

- Smallpox: Viral disease caused by variola virus.

- Mumps: Viral disease affecting salivary glands.

Lead Question - 2016 (Phase 2)

Which of the following sets of diseases is caused by bacteria:

(1) Herpes and influenza

(2) Cholera and tetanus

(3) Typhoid and smallpox

(4) Tetanus and mumps

Answer & Explanation:

Correct answer: (2) Cholera and tetanus. Both cholera and tetanus are bacterial infections caused by Vibrio cholerae and Clostridium tetani, respectively. Other options include viral diseases like herpes, influenza, smallpox, and mumps, which are caused by viruses, not bacteria.

1. Which disease is caused by Salmonella typhi?

(1) Cholera

(2) Typhoid

(3) Tetanus

(4) Influenza

Answer & Explanation:

Correct answer: (2) Typhoid. Typhoid fever is caused by the bacterium Salmonella typhi, transmitted through contaminated food and water. It leads to high fever, abdominal pain, and gastrointestinal symptoms. Proper hygiene and vaccination help prevent this bacterial infection.

2. Assertion (A): Cholera is a bacterial disease.

Reason (R): It causes severe watery diarrhea due to toxin production.

(1) Both A and R are true, and R is the correct explanation of A

(2) Both A and R are true, but R is not the correct explanation of A

(3) A is true, R is false

(4) A is false, R is true

Answer & Explanation:

Correct answer: (1) Both A and R are true, and R is the correct explanation of A. Vibrio cholerae produces cholera toxin, which disrupts ion transport in the intestines, causing massive watery diarrhea, confirming that cholera is a bacterial disease.

3. Match the pathogen with the disease:

A. Clostridium tetani - (i) Tetanus

B. Vibrio cholerae - (ii) Cholera

C. Herpes simplex virus - (iii) Herpes

D. Influenza virus - (iv) Influenza

(1) A-i, B-ii, C-iii, D-iv

(2) A-ii, B-i, C-iii, D-iv

(3) A-i, B-iii, C-ii, D-iv

(4) A-iv, B-ii, C-i, D-iii

Answer & Explanation:

Correct answer: (1) A-i, B-ii, C-iii, D-iv. Clostridium tetani causes tetanus; Vibrio cholerae causes cholera; herpes simplex virus causes herpes; and influenza virus causes influenza. Correct pathogen identification is crucial for treatment and prevention strategies.

4. Fill in the blank:

Tetanus is caused by ________ bacteria, producing a neurotoxin.

(1) Clostridium tetani

(2) Vibrio cholerae

(3) Salmonella typhi

(4) Staphylococcus aureus

Answer & Explanation:

Correct answer: (1) Clostridium tetani. This bacterium enters wounds and produces tetanospasmin, a neurotoxin causing muscle rigidity and spasms. Vaccination with tetanus toxoid is the primary preventive measure.

5. Which of the following is NOT a bacterial disease?

(1) Typhoid

(2) Smallpox

(3) Cholera

(4) Tetanus

Answer & Explanation:

Correct answer: (2) Smallpox. Smallpox is caused by the variola virus, a viral infection, whereas typhoid, cholera, and tetanus are bacterial diseases caused by Salmonella typhi, Vibrio cholerae, and Clostridium tetani, respectively.

6. Clinical-type Question:

A patient with severe muscle spasms after a wound is most likely infected with:

(1) Vibrio cholerae

(2) Clostridium tetani

(3) Salmonella typhi

(4) Influenza virus

Answer & Explanation:

Correct answer: (2) Clostridium tetani. Tetanus infection occurs when spores enter a wound and release tetanospasmin, causing severe muscle spasms. Immediate wound care and tetanus vaccination are essential for prevention.

7. Which bacteria is waterborne and causes diarrhea?

(1) Clostridium tetani

(2) Vibrio cholerae

(3) Salmonella typhi

(4) Herpes simplex

Answer & Explanation:

Correct answer: (2) Vibrio cholerae. Cholera is transmitted through contaminated water, leading to profuse watery diarrhea and dehydration. Effective sanitation and water purification prevent outbreaks.

8. Choose the correct statements:

(a) Tetanus is bacterial

(b) Smallpox is bacterial

(c) Cholera is bacterial

(d) Herpes is bacterial

(1) a, b

(2) a, c

(3) b, d

(4) c, d

Answer & Explanation:

Correct answer: (2) a, c. Tetanus and cholera are bacterial diseases. Smallpox and herpes are viral infections. Correctly distinguishing bacterial from viral diseases is essential for treatment and vaccination planning.

9. Why is vaccination important for tetanus prevention?

(1) It kills bacteria in wounds

(2) It induces immunity against tetanospasmin

(3) It cures ongoing infection

(4) It prevents water contamination

Answer & Explanation:

Correct answer: (2) It induces immunity against tetanospasmin. Tetanus toxoid vaccine stimulates the immune system to produce antibodies, preventing severe muscle spasms and potential death caused by Clostridium tetani neurotoxin.

10. Typhoid fever can be prevented by:

(1) Proper sanitation and vaccination

(2) Antibiotics only

(3) Avoiding insect bites

(4) Wearing masks

Answer & Explanation:

Correct answer: (1) Proper sanitation and vaccination. Typhoid is transmitted via contaminated food and water. Safe drinking water, hygienic practices, and typhoid vaccines significantly reduce the risk of infection.

Topic: AIDS and HIV

Subtopic: Causative Agent of AIDS

Keyword Definitions:

• AIDS (Acquired Immunodeficiency Syndrome): A disease caused by HIV, weakening the immune system.

• HIV (Human Immunodeficiency Virus): Virus that causes AIDS by infecting and destroying immune cells.

• Envelope Virus: Virus surrounded by a lipid membrane derived from the host cell.

• Single-stranded RNA: Viral genetic material consisting of one RNA strand.

• Reverse Transcriptase: An enzyme converting viral RNA into DNA inside host cells.

Lead Question - 2016 (Phase 2):

Which of the following is correct regarding AIDS causative agent HIV:

(1) HIV does not escape but attacks the acquired immune response

(2) HIV is enveloped virus containing one molecule of single-stranded RNA and one molecule of reverse transcriptase

(3) HIV is enveloped virus that contains two identical molecules of single-stranded RNA and two molecules of reverse transcriptase

(4) HIV is unenveloped retrovirus

Explanation: HIV is an enveloped retrovirus containing two identical single-stranded RNA molecules and two molecules of reverse transcriptase. This structure allows the virus to replicate by reverse transcription of RNA into DNA, enabling integration into host DNA and persistent infection. The correct answer is (3).

1. Single Correct Answer MCQ:

Which enzyme is characteristic of HIV?

(1) DNA polymerase

(2) RNA replicase

(3) Reverse transcriptase

(4) Ligase

Explanation: HIV uniquely carries reverse transcriptase, which converts viral RNA into DNA inside host cells, essential for replication. Correct answer: (3) Reverse transcriptase.

2. Single Correct Answer MCQ (Clinical-type):

HIV primarily attacks:

(1) Red blood cells

(2) B lymphocytes

(3) Helper T lymphocytes (CD4+ cells)

(4) Platelets

Explanation: HIV specifically targets CD4+ helper T lymphocytes, leading to immunodeficiency and progression to AIDS. Correct answer: (3) Helper T lymphocytes (CD4+ cells).

3. Single Correct Answer MCQ:

HIV is classified as a:

(1) DNA virus

(2) Retrovirus

(3) Bacteriophage

(4) Prion

Explanation: HIV belongs to the retrovirus family due to its reverse transcription process. Correct answer: (2) Retrovirus.

4. Single Correct Answer MCQ:

The genetic material of HIV consists of:

(1) Single-stranded DNA

(2) Double-stranded RNA

(3) Two single-stranded RNA molecules

(4) Single-stranded DNA

Explanation: HIV contains two identical single-stranded RNA molecules as its genetic material. Correct answer: (3) Two single-stranded RNA molecules.

5. Single Correct Answer MCQ:

Which of the following best describes the envelope of HIV?

(1) Protein only

(2) Lipid bilayer derived from host cell membrane

(3) Cell wall

(4) Peptidoglycan layer

Explanation: HIV has an envelope made of a lipid bilayer derived from the host cell membrane, aiding in host cell fusion. Correct answer: (2) Lipid bilayer derived from host cell membrane.

6. Single Correct Answer MCQ:

What is the role of reverse transcriptase in HIV?

(1) Converts viral RNA into DNA

(2) Synthesizes viral proteins

(3) Degrades host DNA

(4) Repairs viral RNA

Explanation: Reverse transcriptase enables HIV to transcribe its RNA into DNA, which integrates into host DNA, allowing viral replication. Correct answer: (1) Converts viral RNA into DNA.

7. Assertion-Reason MCQ:

Assertion (A): HIV infection results in depletion of CD4+ T cells.

Reason (R): HIV integrates its DNA into host genome and destroys immune cells.

(1) Both A and R are true and R explains A

(2) Both A and R are true but R does not explain A

(3) A is true but R is false

(4) A is false but R is true

Explanation: HIV integrates into the host genome, replicates, and destroys CD4+ cells, causing immunodeficiency. Correct answer: (1) Both A and R are true and R explains A.

8. Matching Type MCQ:

Match Column – I with Column – II:

A. HIV Structure

B. Reverse Transcriptase

C. Envelope

D. Genome

1. Converts RNA into DNA

2. Lipid bilayer

3. Two identical single-stranded RNA molecules

4. Retrovirus

Options:

(1) A-4, B-1, C-2, D-3

(2) A-1, B-4, C-3, D-2

(3) A-2, B-3, C-1, D-4

(4) A-3, B-2, C-1, D-4

Explanation: Correct matches: A-4 (Retrovirus), B-1 (Converts RNA into DNA), C-2 (Lipid bilayer), D-3 (Two identical RNA molecules). Correct answer: (1) A-4, B-1, C-2, D-3.

9. Fill in the Blanks MCQ:

HIV is a __________ virus that primarily targets __________ cells.

(1) DNA, B cells

(2) Retrovirus, CD4+ T cells

(3) RNA, Red blood cells

(4) Enveloped, Platelets

Explanation: HIV is a retrovirus infecting CD4+ T lymphocytes, causing immune system failure. Correct answer: (2) Retrovirus, CD4+ T cells.

10. Choose the Correct Statements MCQ:

Select correct statements about HIV:

(1) Contains two identical RNA strands

(2) Lacks reverse transcriptase

(3) Causes AIDS

(4) Has an envelope derived from host cell membrane

Options:

(1) 1, 3, and 4 only

(2) 1 and 2 only

(3) 2 and 3 only

(4) All statements correct

Explanation: Statements 1, 3, and 4 are correct. HIV contains two identical RNA strands, causes AIDS, and has an envelope from the host cell membrane. Correct answer: (1) 1, 3, and 4 only.

Chapter: Cell Biology

Topic: Cancer Biology

Subtopic: Genetic Mutations in Cancer Cells

• Proto-oncogenes: Normal genes promoting cell growth; mutation converts them into oncogenes.

• Telomerase: Enzyme maintaining telomere length, often overactive in cancer cells, allowing uncontrolled division.

• Cell Cycle Control: Checkpoints regulating cell division; mutation leads to loss of control and cancer.

• Mutation: Permanent DNA change; can activate oncogenes or inactivate tumor suppressor genes, promoting cancer.

Lead Question - 2016 (Phase 1)

Which of the following statements is not true for cancer cells in relation to mutations:

• (1) Mutations in proto-oncogenes accelerate the cell cycle.

• (2) Mutations destroy telomerase inhibitor.

• (3) Mutations inactivate the cell control.

• (4) Mutations inhibit production of telomerase.

Answer & Explanation: (4) Mutations inhibit production of telomerase. This is false. In cancer cells, telomerase activity is often upregulated due to mutations, preventing telomere shortening and allowing continuous cell division. Other mutations activate proto-oncogenes or inactivate cell cycle regulators, promoting unregulated proliferation.

MCQ 1 (Single Correct Answer)

Which of the following best describes the role of proto-oncogenes in cancer?

• (A) They suppress tumor growth

• (B) Mutations convert them into oncogenes promoting uncontrolled cell growth

• (C) They repair damaged DNA

• (D) They inhibit telomerase activity

Answer & Explanation: (B) Mutations convert proto-oncogenes into oncogenes promoting uncontrolled cell growth. These mutated genes drive continuous proliferation of cancer cells by bypassing normal cell cycle checkpoints, leading to tumor formation and progression.

MCQ 2 (Single Correct Answer)

What is the role of telomerase in cancer cells?

• (A) Shortens telomeres

• (B) Inhibits cell division

• (C) Maintains telomere length, promoting immortality

• (D) Repairs DNA damage

Answer & Explanation: (C) Maintains telomere length, promoting immortality. Cancer cells activate telomerase to stabilize telomere length, preventing senescence or apoptosis and enabling unlimited cell divisions, which is a hallmark of cancer progression.

MCQ 3 (Single Correct Answer)

What happens when tumor suppressor genes are mutated?

• (A) Enhanced apoptosis

• (B) Increased DNA repair efficiency

• (C) Loss of cell cycle control leading to cancer

• (D) Decreased proliferation

Answer & Explanation: (C) Loss of cell cycle control leading to cancer. Tumor suppressor genes regulate cell division and promote apoptosis. Their inactivation by mutations removes growth control, facilitating cancerous cell proliferation and tumor development.

MCQ 4 (Single Correct Answer)

Which is true about telomerase inhibitors in cancer therapy?

• (A) They increase telomerase activity

• (B) They block telomerase to limit tumor growth

• (C) They stimulate proto-oncogenes

• (D) They repair mutated DNA

Answer & Explanation: (B) They block telomerase to limit tumor growth. Inhibiting telomerase in cancer cells promotes telomere shortening, leading to cell senescence or death, thus acting as a targeted anti-cancer strategy.

MCQ 5 (Single Correct Answer)

Which mutation is common in cancer cells?

• (A) Activation of tumor suppressor genes

• (B) Loss of proto-oncogene function

• (C) Activation of oncogenes

• (D) Enhanced DNA repair

Answer & Explanation: (C) Activation of oncogenes. Mutations in proto-oncogenes convert them into oncogenes, which drive unchecked cell proliferation and tumor formation, a key step in cancer development.

MCQ 6 (Single Correct Answer)

Which clinical intervention targets telomerase in cancer?

• (A) Chemotherapy

• (B) Radiotherapy

• (C) Telomerase inhibitors

• (D) Antibiotics

Answer & Explanation: (C) Telomerase inhibitors. These drugs specifically inhibit telomerase activity in cancer cells, promoting telomere shortening, limiting their capacity for continuous division, and thus suppressing tumor growth.

MCQ 7 (Assertion-Reason)

Assertion (A): Cancer cells have increased telomerase activity.

Reason (R): Increased telomerase activity prevents telomere shortening, allowing indefinite division.

• (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 & Explanation: (A) Both A and R are true and R is the correct explanation of A. Cancer cells overexpress telomerase, preventing telomere shortening, which typically limits cell division in normal cells, thereby facilitating unlimited proliferation—a hallmark of cancer.

MCQ 8 (Matching Type)

Match the mutation type with its effect:

• 1. Proto-oncogene mutation

• 2. Tumor suppressor gene mutation

• 3. Mutation in telomerase regulation

• 4. Mutation in DNA repair genes

1. Leads to oncogene activation

2. Loss of cell cycle control

3. Enables cell immortality

4. Increases genetic instability

• (A) 1-A, 2-B, 3-C, 4-D

• (B) 1-B, 2-A, 3-D, 4-C

• (C) 1-C, 2-D, 3-B, 4-A

• (D) 1-D, 2-C, 3-A, 4-B

Answer & Explanation: (A) 1-A, 2-B, 3-C, 4-D. Proto-oncogene mutations activate oncogenes, tumor suppressor gene mutations lead to loss of control, telomerase regulation mutations enable immortality, and DNA repair gene mutations increase genomic instability, promoting cancer development.

MCQ 9 (Fill in the Blanks)

In cancer cells, mutations ______ the production of telomerase, leading to ______ cell division.

• (A) inhibit, limited

• (B) activate, unlimited

• (C) block, controlled

• (D) reduce, apoptosis

Answer & Explanation: (B) Activate, unlimited. Cancer cells often acquire mutations that upregulate telomerase production, preventing telomere shortening. This grants them the ability for unlimited divisions, bypassing normal cellular senescence mechanisms and facilitating tumor growth.

MCQ 10 (Choose the Correct Statements)

Select the correct statements regarding mutations in cancer cells:

• 1. Mutations activate proto-oncogenes to oncogenes.

• 2. Mutations inhibit telomerase production.

• 3. Tumor suppressor genes may be inactivated.

• 4. Increased telomerase activity supports cell immortality.

• (A) 1, 3, and 4 only

• (B) 1 and 2 only

• (C) 2, 3, and 4 only

• (D) All statements are correct

Answer & Explanation: (A) 1, 3, and 4 only. Mutations activate proto-oncogenes, inactivate tumor suppressor genes, and upregulate telomerase, promoting uncontrolled proliferation and cell immortality. Statement 2 is false; cancer cells increase, not inhibit, telomerase production.

Keywords:

• Muscle contraction: Shortening of muscle fibers resulting in movement.

• Sustained contraction: Continuous contraction over a period of time.

• Spasm: Involuntary, sudden muscle contraction.

• Fatigue: Temporary decline in muscle performance due to prolonged activity.

• Tetanus: Continuous, sustained contraction of muscles without relaxation between stimuli.

• Tonus: Continuous partial contraction of muscles at rest.

• Stimulus: A signal triggering muscle contraction.

• Neuromuscular junction: Connection between motor neuron and muscle fiber.

• Calcium ions: Ions responsible for muscle contraction by interacting with troponin-tropomyosin complex.

• ATP: Energy source required for muscle contraction and relaxation.

• Myosin-actin interaction: Molecular mechanism underlying muscle contraction.

Chapter: Muscle Physiology

Topic: Muscle Contraction

Subtopic: Types of Muscle Contraction

Lead Question - 2016 (Phase 1): Lack of relaxation between successive stimuli in sustained muscle contraction is known as :

(1) Spasm
(2) Fatigue
(3) Tetanus
(4) Tonus

Answer: 3

Explanation: Tetanus refers to continuous muscle contraction without relaxation due to repeated stimuli. Unlike spasm or tonus, tetanus results from rapid stimuli summating the muscle response. This is physiologically important for sustained actions but may cause cramping in clinical conditions.

1. Single Correct Answer MCQ: Which ion triggers muscle contraction?

(A) Sodium
(B) Potassium
(C) Calcium
(D) Chloride

Answer: C

Explanation: Calcium ions are released from the sarcoplasmic reticulum and bind to troponin, initiating actin-myosin interaction and muscle contraction. Sodium and potassium mainly propagate action potentials, not directly trigger contraction.

2. Single Correct Answer MCQ: Fatigue in muscles occurs due to:

(A) Excess ATP
(B) Lactic acid accumulation
(C) High calcium concentration
(D) Continuous tetanus

Answer: B

Explanation: Muscle fatigue occurs due to lactic acid accumulation, depletion of energy stores, and ionic imbalances. This leads to reduced force production and temporary inability of muscles to sustain contraction.

3. Single Correct Answer MCQ: Partial continuous contraction in resting muscles is called:

(A) Spasm
(B) Tonus
(C) Tetanus
(D) Fatigue

Answer: B

Explanation: Muscle tonus is a low-level, continuous contraction present in resting muscles, maintaining posture and readiness for action. It differs from tetanus or spasm.

4. Single Correct Answer MCQ: A sudden involuntary muscle contraction is termed:

(A) Fatigue
(B) Tetanus
(C) Spasm
(D) Tonus

Answer: C

Explanation: Spasm is an involuntary, brief, sudden contraction of muscles. It may occur due to electrolyte imbalance, nerve irritation, or injury.

5. Single Correct Answer MCQ: Energy for muscle contraction is primarily supplied by:

(A) DNA
(B) ATP
(C) RNA
(D) Glucose only

Answer: B

Explanation: ATP is the direct energy source for actin-myosin cross-bridge cycling. Glucose and other substrates generate ATP via metabolism, but ATP is the immediate energy currency for contraction and relaxation.

6. Single Correct Answer MCQ: Summation of muscle contractions leading to sustained tension is called:

(A) Tetanus
(B) Fatigue
(C) Tonus
(D) Spasm

Answer: A

Explanation: Tetanus occurs when multiple stimuli rapidly follow one another, producing a sustained contraction without relaxation. This demonstrates temporal summation of muscle action potentials.

7. Assertion-Reason MCQ:
Assertion (A): Tetanus is continuous muscle contraction without relaxation.
Reason (R): Rapid successive stimuli prevent muscle fiber from relaxing completely.

(A) Both A and R are true, R is correct explanation of A
(B) Both A and R are true, R is NOT correct explanation of A
(C) A is true, R is false
(D) A is false, R is true

Answer: A

Explanation: Tetanus occurs when high-frequency stimuli summate, preventing relaxation. This leads to sustained maximal contraction, which is physiologically used for prolonged muscular activities.

8. Matching Type MCQ: Match type of contraction with description:

1. Spasm   A. Partial contraction at rest
2. Tonus   B. Involuntary sudden contraction
3. Tetanus   C. Sustained contraction without relaxation
4. Fatigue   D. Reduced ability to contract after prolonged activity

(A) 1-B, 2-A, 3-C, 4-D
(B) 1-A, 2-B, 3-D, 4-C
(C) 1-C, 2-D, 3-B, 4-A
(D) 1-D, 2-C, 3-B, 4-A

Answer: A

Explanation: Spasm is sudden contraction, tonus is partial contraction at rest, tetanus is sustained contraction, and fatigue reduces force after prolonged activity.

9. Fill in the Blanks: Continuous contraction without relaxation is called ________, while reduced muscle force after prolonged activity is termed ________.

(A) Tetanus; Fatigue
(B) Tonus; Spasm
(C) Spasm; Tetanus
(D) Fatigue; Tetanus

Answer: A

Explanation: Tetanus is sustained contraction due to repeated stimuli. Fatigue is the decline in muscle force after prolonged activity, often due to metabolic byproducts and energy depletion.

10. Choose the Correct Statements:
(A) Tetanus results from rapid successive stimuli.
(B) Spasm is involuntary muscle contraction.
(C) Fatigue is a sustained contraction without relaxation.
(D) Tonus maintains posture at rest.

(1) A, B, D
(2) A, C
(3) B, C
(4) All are correct

Answer: 1

Explanation: Statements A, B, and D are correct. Fatigue is not sustained contraction; it refers to decreased force after prolonged activity. Tetanus, not fatigue, is sustained contraction.

Keywords:

• Antivenom: Serum containing preformed antibodies used to neutralize animal venoms.

• Polio drops: Oral polio vaccine containing live attenuated poliovirus.

• Attenuated pathogens: Pathogens weakened to lose virulence but still stimulate immunity.

• Activated pathogens: Pathogens capable of causing disease.

• Antibodies: Immunoglobulins produced by the immune system to neutralize antigens.

• Ganuna globulin: Likely refers to gamma globulin, a plasma fraction rich in antibodies.

• Immunization: Process of inducing immunity through vaccines.

• Passive immunity: Short-term immunity provided by preformed antibodies.

• Active immunity: Long-term immunity developed by stimulating the host immune system.

• Oral vaccine: Vaccine administered through mouth, often live attenuated.

• Serotherapy: Treatment using serum containing antibodies.

Chapter: Immunology

Topic: Vaccines and Antivenoms

Subtopic: Active vs Passive Immunity

Lead Question - 2016 (Phase 1): Antivenom injection contains preformed antibodies while polio drops that are administered into the body contain:

(1) Activated pathogens
(2) Harvested antibodies
(3) Ganuna globulin
(4) Attenuated pathogens

Answer: 4

Explanation: Antivenom provides passive immunity through preformed antibodies, whereas oral polio vaccine contains live attenuated pathogens that stimulate the host's immune system to produce active immunity without causing disease.

1. Single Correct Answer MCQ: Passive immunity is conferred by:

(A) Oral polio vaccine
(B) Antivenom
(C) BCG vaccine
(D) MMR vaccine

Answer: B

Explanation: Antivenom provides immediate protection using preformed antibodies, which is characteristic of passive immunity. Vaccines like polio, BCG, or MMR induce active immunity by stimulating the host immune system.

2. Single Correct Answer MCQ: The main advantage of live attenuated vaccines is:

(A) Immediate effect
(B) Long-lasting immunity
(C) Does not require immune response
(D) Can be used for all ages without restriction

Answer: B

Explanation: Live attenuated vaccines replicate in the host, stimulating both humoral and cell-mediated immunity, resulting in long-lasting protection. Immediate effect is typical of passive immunization.

3. Single Correct Answer MCQ: Gamma globulin is used in:

(A) Passive immunization
(B) Active immunization
(C) Oral polio vaccination
(D) Live attenuated vaccines

Answer: A

Explanation: Gamma globulin is a plasma fraction rich in antibodies, used for passive immunization to provide short-term protection against specific diseases.

4. Single Correct Answer MCQ: Polio drops stimulate immunity by:

(A) Providing preformed antibodies
(B) Replicating attenuated virus
(C) Neutralizing toxins
(D) Blocking infection mechanically

Answer: B

Explanation: Oral polio vaccine contains attenuated poliovirus that replicates in the gut, eliciting active immune response without causing disease.

5. Single Correct Answer MCQ: Antivenom is most effective when:

(A) Administered after severe symptoms
(B) Injected immediately after envenomation
(C) Taken orally
(D) Given months before exposure

Answer: B

Explanation: Antivenom works best if given soon after venom injection, as it neutralizes toxins before extensive tissue damage occurs. Oral administration is ineffective due to antibody digestion in the gut.

6. Single Correct Answer MCQ: Live attenuated vaccines are contraindicated in:

(A) Healthy adults
(B) Immunocompromised individuals
(C) Children over 5
(D) Pregnant women with prior vaccination

Answer: B

Explanation: Immunocompromised individuals may develop disease from live attenuated vaccines as their immune system cannot control viral replication effectively.

7. Assertion-Reason MCQ:
Assertion (A): Oral polio vaccine induces active immunity.
Reason (R): It contains preformed antibodies that neutralize poliovirus.

(A) Both A and R are true, R is correct explanation of A
(B) Both A and R are true, R is NOT correct explanation of A
(C) A is true, R is false
(D) A is false, R is true

Answer: C

Explanation: Oral polio vaccine induces active immunity through replication of attenuated virus. Preformed antibodies are not involved; that is characteristic of passive immunity.

8. Matching Type MCQ: Match type of immunity with example:

1. Passive Immunity   A. Oral polio vaccine
2. Active Immunity   B. Antivenom
3. Passive Immunity   C. Gamma globulin injection
4. Active Immunity   D. BCG vaccine

(A) 1-B, 2-A, 3-C, 4-D
(B) 1-C, 2-D, 3-B, 4-A
(C) 1-A, 2-B, 3-D, 4-C
(D) 1-D, 2-B, 3-A, 4-C

Answer: A

Explanation: Passive immunity is provided by antivenom or gamma globulin. Active immunity is induced by oral polio or BCG vaccines through stimulation of host immune response.

9. Fill in the Blanks: Antivenom provides ________ immunity, while polio drops provide ________ immunity.

(A) Active; passive
(B) Passive; active
(C) Active; active
(D) Passive; passive

Answer: B

Explanation: Antivenom contains preformed antibodies (passive immunity), whereas polio drops contain attenuated virus that elicits active immunity by stimulating the host immune system.

10. Choose the Correct Statements:
(A) Antivenom is a form of passive immunity.
(B) Oral polio vaccine contains attenuated pathogens.
(C) Passive immunity provides long-lasting protection.
(D) Active immunity requires stimulation of host immune system.

(1) A, B, D
(2) A, C
(3) B, C, D
(4) All are correct

Answer: 1

Explanation: Statements A, B, and D are correct. Passive immunity is short-term. Oral polio vaccine contains attenuated virus, inducing active immunity via host immune response.

Keywords:

• Immune system: Network of cells, tissues, and organs defending against pathogens and abnormal cells.

• Self-cells: Cells recognized as part of the organism, marked by MHC molecules.

• Non-self: Foreign antigens such as pathogens, toxins, or transplanted tissue.

• Auto-immune disease: Condition where immune system attacks self-cells due to failure of self-recognition.

• Graft rejection: Immune response against transplanted tissue recognized as non-self.

• Allergic response: Exaggerated immune reaction against harmless antigens (allergens).

• Active immunity: Immunity developed by exposure to antigens or vaccination.

• Genetic abnormality: Mutation or defect in genes controlling immune tolerance.

• Immune tolerance: Ability to avoid attacking self while responding to non-self.

• Major Histocompatibility Complex (MHC): Molecules on cell surfaces helping immune system distinguish self from non-self.

• Clonal deletion: Mechanism during lymphocyte development eliminating self-reactive cells.

Chapter: Immunology

Topic: Self and Non-self Recognition

Subtopic: Auto-immunity

Lead Question - 2016 (Phase 1): In higher vertebrates, the immune system can distinguish self-cells and non-self. If this property is lost due to genetic abnormality and it attacks self-cells, then it leads to:

(1) Allergic response
(2) Graft rejection
(3) Auto-immune disease
(4) Active immunity

Answer: 3

Explanation: Auto-immune diseases occur when genetic defects or failures in immune tolerance cause lymphocytes to attack the organism's own cells. Examples include type 1 diabetes, rheumatoid arthritis, and systemic lupus erythematosus.

1. Single Correct Answer MCQ: Which cells are primarily responsible for recognizing self vs non-self?

(A) Erythrocytes
(B) T lymphocytes
(C) Platelets
(D) Fibroblasts

Answer: B

Explanation: T lymphocytes recognize antigen-presenting cells using MHC molecules to distinguish self from non-self, initiating appropriate immune responses while preventing auto-immunity.

2. Single Correct Answer MCQ: Failure in self-tolerance leads to:

(A) Immunodeficiency
(B) Auto-immune disease
(C) Allergy
(D) Active immunity

Answer: B

Explanation: Loss of self-tolerance, due to defective clonal deletion or MHC presentation, results in the immune system attacking host cells, causing autoimmune disorders.

3. Single Correct Answer MCQ: Which of the following is an example of an auto-immune disease?

(A) Influenza
(B) Type 1 diabetes
(C) Tuberculosis
(D) Common cold

Answer: B

Explanation: Type 1 diabetes is caused by T cells destroying pancreatic beta cells, illustrating auto-immune pathology.

4. Single Correct Answer MCQ: Graft rejection occurs because:

(A) Graft tissue is attacked as non-self
(B) Recipient lacks antibodies
(C) Immune system is inactive
(D) Graft contains no MHC molecules