The 'Widal Test' is a widely used clinical diagnostic tool for which disease?
- Cholera
- Tuberculosis
- Pneumonia
- Typhoid fever
Explanation: The Widal test detects antibodies against Salmonella typhi, the causative agent of typhoid fever, which typically enters the body through contaminated food.
The Human Immunodeficiency Virus (HIV) primarily attacks which specific cells in the body?
- Red blood cells
- Platelets
- B-lymphocytes
- Helper T-cells
Explanation: HIV replicates in TH cells, leading to a progressive decrease in their number and weakening the patient's immunity.
Which of the following genes, when activated, can transform normal cells into cancerous ones?
- Proto-oncogenes
- Regulatory genes
- Hox genes
- Structural genes
Explanation: Normal cells have genes called cellular oncogenes (c-onc) or proto-oncogenes which, if triggered, lead to oncogenic transformation.
A person with 'Type 1 Diabetes' is suffering from which category of disease?
- Infectious
- Autoimmune
- Communicable
- Allergic
Explanation: In Type 1 Diabetes, the body's immune system mistakenly attacks and destroys the insulin-producing beta cells in the pancreas.
In an HIV-infected person, which cells act as an 'HIV Factory' by continuously producing viral particles?
- Helper T-cells
- RBCs
- B-cells
- Macrophages
Explanation: Macrophages continue to produce virus particles for a long period, acting like a factory, while Helper T-cells are progressively destroyed.
Health is defined by the WHO as a state of complete physical, mental, and:
- Social well-being
- Genetic well-being
- Political well-being
- Financial well-being
Explanation: Health is not just the absence of disease; it includes a person's social health and interaction with the community.
Which physical barrier of the innate immune system prevents the entry of microorganisms into the body?
- Skin
- Stomach acid
- Tears in eyes
- Saliva in mouth
Explanation: Skin is the main physical barrier that prevents entry of microorganisms. Mucus coating of the respiratory and GI tracts also helps.
Which class of antibodies is primarily responsible for mediating allergic reactions?
Explanation: IgE antibodies are produced in response to allergens like pollen or dust, triggering the release of chemicals like histamine.
Which of the following is a common fungal disease in humans characterized by dry, scaly lesions?
- Filariasis
- Ascariasis
- Dengue
- Ringworm
Explanation: Fungi belonging to genera like Microsporum and Trichophyton cause ringworm, which is highly infectious.
The 'Physiological Barriers' of the innate immune system include which of the following?
- Interferons
- Acid in stomach
- Monocytes
- Natural killer cells
Explanation: Acid in the stomach, saliva in the mouth, and tears from the eyes all prevent microbial growth and are physiological barriers.
Regarding the common cold, which of the following symptoms is 'absent' in a typical case?
- Lung infection
- Nasal congestion
- Hoarseness
- Sore throat
Explanation: Rhinoviruses affect the upper respiratory tract; a lung infection (alveoli involvement) is characteristic of pneumonia, not the common cold.
The transmission of Chikungunya and Dengue is primarily through the bite of:
- Anopheles mosquito
- Tsetse fly
- Culex mosquito
- Aedes mosquito
Explanation: Aedes aegypti is the vector responsible for spreading both Dengue and Chikungunya viruses.
The genome of the HIV virus consists of:
- Single stranded DNA
- Single stranded RNA
- Double stranded RNA
- Double stranded DNA
Explanation: HIV is a retrovirus with an envelope enclosing two identical copies of single-stranded RNA (ssRNA).
The basic structural formula of an antibody molecule is represented as:
- $H_1L_1$
- $H_2L_1$
- $H_4L_4$
- $H_2L_2$
Explanation: Each antibody molecule has four peptide chains: two small light (L) chains and two longer heavy (H) chains.
Which category of 'Carcinogens' includes UV rays and X-rays?
- Biological agents
- Nutritional agents
- Chemical agents
- Physical agents
Explanation: Ionizing radiations (X-rays, gamma rays) and non-ionizing radiations (UV) cause DNA damage and are physical carcinogens.
A tumor that remains confined to its original location and does not spread is called:
- Metastatic
- Malignant
- Benign
- Neoplastic
Explanation: Benign tumors normally cause little damage compared to malignant tumors, which invade and damage surrounding healthy tissues.
Smoking increases the levels of which gas in the blood, reducing oxygen-carrying capacity?
- Nitrogen
- Methane
- Carbon monoxide
- Carbon dioxide
Explanation: Carbon monoxide (CO) binds to hemoglobin more strongly than oxygen, leading to oxygen deficiency in the body's tissues.
The transmission of 'Ringworm' infection most commonly occurs through:
- Contaminated soil
- Shared towels
- Mosquito bites
- Aerosol droplets
Explanation: Ringworms are fungal infections generally acquired from soil or by using towels, clothes, or even the comb of infected individuals.
Heroin, chemically known as diacetylmorphine, is extracted from the latex of:
- Cannabis sativa
- Erythroxylum coca
- Papaver somniferum
- Atropa belladonna
Explanation: Heroin is a depressant derived from the poppy plant and slows down body functions.
The graft rejection in organ transplantation is primarily due to which immune response?
- Passive immunity
- Humoral immunity
- Cell-mediated immunity
- Innate immunity
Explanation: The body is able to differentiate 'self' from 'non-self', and T-lymphocytes mediate the cell-mediated immune response responsible for graft rejection.
Virus-infected cells secrete proteins called 'Interferons' to protect non-infected cells from:
- Protozoan entry
- Bacterial growth
- Viral infection
- Fungal spores
Explanation: Interferons are cytokine barriers that prevent the further spread of viral infection to neighboring healthy cells.
The widely used diagnostic test for detecting AIDS is:
- Biopsy
- ELISA
- Widal test
- MRI
Explanation: ELISA (Enzyme-Linked Immuno-sorbent Assay) is the standard screening test for HIV antibodies.
Which of the following describes the nature of the malaria parasite's reproduction in the human liver?
- Sexual reproduction
- Budding
- Binary fission
- Asexual reproduction
Explanation: Plasmodium reproduces asexually in the liver cells and then in red blood cells; sexual stages (gametocytes) develop later in the RBCs.
Cannabinoids primarily interact with receptors located in which organ system?
- Skeletal system
- Digestive system
- Central nervous system
- Respiratory system
Explanation: Cannabinoids affect the brain and are also known for their effects on the cardiovascular system.
Where do T-lymphocytes originate and where do they mature, respectively?
- Thymus, Bone marrow
- Bone marrow, Thymus
- Spleen, Thymus
- Thymus, Spleen
Explanation: All blood cells originate in the bone marrow, but T-cells migrate to the thymus for maturation and differentiation.
An injection of 'Antitoxin' for Tetanus is an example of which type of immunity?
- Innate immunity
- Passive immunity
- Cellular immunity
- Active immunity
Explanation: Passive immunity involves the direct injection of pre-formed antibodies (antitoxin) to provide immediate protection against deadly pathogens.
The DPT vaccine provides combined protection against Diphtheria, Pertussis, and:
- Tetanus
- Tuberculosis
- Trachoma
- Typhoid
Explanation: DPT is a trivalent vaccine for three bacterial diseases: Diphtheria, Pertussis (Whooping cough), and Tetanus.
MALT (Mucosal Associated Lymphoid Tissue) constitutes approximately what percentage of lymphoid tissue in the body?
- 50 percent
- 10 percent
- 75 percent
- 25 percent
Explanation: MALT is located within the lining of the major tracts (respiratory, digestive, urogenital) and makes up half of the body's lymphoid tissue.
Practicing 'Yoga' has been recognized globally as an effective way to maintain:
- Only physical health
- Genetic structure
- Only mental health
- Physical/Mental health
Explanation: Yoga has been practiced since ancient times to achieve harmony between the body and mind, ensuring overall well-being.
In the malaria life cycle, where does the 'Sexual Stage' (gametocyte development) occur?
- Mosquito saliva
- Mosquito gut
- Human liver
- Human RBCs
Explanation: While fertilization occurs in the mosquito gut, the gametocytes (sexual stages) actually develop within the red blood cells of the human host.
Which of the following is a recognized primary symptom of 'Ascariasis', a disease caused by an intestinal endoparasite, as classified in standard biological literature?
- Scaly skin lesions
- Internal bleeding
- Fluid-filled alveoli
- Splenomegaly
Explanation: According to standard biological classifications (such as the Class 12 NCERT Biology curriculum), Ascaris (common roundworm) causes internal bleeding, muscular pain, fever, anemia, and blockage of the intestinal passage. Scaly lesions are associated with ringworm, fluid-filled alveoli with pneumonia, and splenomegaly with diseases like malaria or typhoid.
Which of the following serves as a mechanical carrier for the Amoebiasis pathogen?
- Female Culex
- Female Anopheles
- Houseflies
- Tsetse flies
Explanation: Houseflies act as mechanical carriers and serve to transmit the parasite from the feces of an infected person to food and food products.
Amoebic dysentery (Amoebiasis) is caused by the protozoan parasite:
- Entamoeba histolytica
- Plasmodium vivax
- Leishmania
- Trypanosoma
Explanation: Entamoeba histolytica is a protozoan parasite in the large intestine of humans which causes constipation, abdominal pain, and stools with excess mucus.
The 'Withdrawal Syndrome' characterized by anxiety and shakiness occurs when:
- Drug is stopped
- Drug dose increases
- Drug is pure
- Drug is cheap
Explanation: Withdrawal syndrome occurs when the regular dose of drugs/alcohol is abruptly discontinued in an addicted person.
Allergies involve the release of chemicals like 'Histamine' and 'Serotonin' from which cells?
- Macrophages
- Plasma cells
- Mast cells
- T-helper cells
Explanation: Allergens bind to IgE on mast cells, causing them to degranulate and release inflammatory mediators.
The disease 'Elephantiasis' or Filariasis is caused by which helminthic parasite?
- Ascaris
- Wuchereria
- Taenia
- Fasciola
Explanation: Wuchereria (W. bancrofti and W. malayi) causes chronic inflammation of the lymphatic vessels of the lower limbs.
The 'Spleen' is an important secondary lymphoid organ because it acts as a filter for:
- Lymph
- Blood
- Urine
- Cerebrospinal fluid
Explanation: The spleen contains lymphocytes and phagocytes. It filters the blood by trapping blood-borne microorganisms and worn-out RBCs.
Which specific group of viruses is responsible for causing the 'Common Cold' in humans?
- Retroviruses
- Flaviviruses
- Rhinoviruses
- Adenoviruses
Explanation: Rhinoviruses infect the nose and respiratory passage but do not infect the lungs, unlike the pathogens causing pneumonia.
Which of the following is an example of 'Passive Immunity'?
- Toxoid injection
- Natural infection
- Vaccination
- Colostrum
Explanation: Passive immunity involves giving pre-formed antibodies to the body. Colostrum contains IgA antibodies that protect the infant.
Chronic use of alcohol can lead to the severe damage of which organ, known as 'Cirrhosis'?
- Liver
- Spleen
- Kidney
- Heart
Explanation: Chronic alcohol intake causes the replacement of healthy liver tissue with scar tissue, leading to liver failure.
The 'Secondary' immune response is characterized by being highly:
- Non-specific
- Intensified
- Weak
- Slow
Explanation: The secondary (anamnestic) response is highly intensified because the immune system remembers the first encounter with the pathogen.
Which type of immunity is present from birth and consists of four types of barriers?
- Active immunity
- Innate immunity
- Acquired immunity
- Passive immunity
Explanation: Innate immunity is non-specific and includes physical, physiological, cellular, and cytokine barriers.
Which type of white blood cell is known as 'Polymorpho-nuclear Leucocytes' (PMNL)?
- Monocytes
- Neutrophils
- Macrophages
- Lymphocytes
Explanation: Neutrophils (PMNL) are cellular barriers of innate immunity that can phagocytose and destroy microbes.
The primary and secondary immune responses are carried out with the help of which two types of lymphocytes?
- Mast cells, Basophils
- Monocytes, Neutrophils
- Killer, Helper cells
- B-cells, T-cells
Explanation: B-lymphocytes produce antibodies, while T-lymphocytes help B-cells produce them and mediate cell-mediated immunity.
Morphine is clinically used as a very effective:
- Stimulant
- Hallucinogen
- Antibiotic
- Sedative/Painkiller
Explanation: Morphine is highly useful in patients who have undergone surgery due to its potent analgesic (pain-relieving) properties.
In the life cycle of Plasmodium, the infectious stage for humans is called:
- Merozoites
- Trophozoites
- Sporozoites
- Gametocytes
Explanation: Sporozoites are stored in the salivary glands of the female Anopheles mosquito and are injected into the human host during a bite.
Which of the following is a biological response modifier used in cancer treatment?
- Morphine
- Alpha-interferon
- Histamine
- Acetabulum
Explanation: Alpha-interferon activates the immune system and helps in destroying the tumor cells.
Which of the following organs is considered a 'Primary Lymphoid Organ'?
- Thymus
- Peyer's patches
- Spleen
- Lymph nodes
Explanation: Bone marrow and thymus are primary lymphoid organs where immature lymphocytes differentiate into antigen-sensitive lymphocytes.
Which disease was historically transmitted by the 'Rat Flea' (Xenopsylla)?
- Malaria
- Plague
- Tuberculosis
- Cholera
Explanation: Bubonic plague is caused by Yersinia pestis and is transmitted to humans by the bite of infected rat fleas.
The property of 'Contact Inhibition', which prevents uncontrolled growth, is lost in:
- Cancer cells
- Stem cells
- Nerve cells
- Normal cells
Explanation: Normal cells stop growing when they come into contact with other cells; cancer cells lose this property and form tumors.
The toxic substance 'Haemozoin', responsible for the recurring chills and high fever in malaria, is released from:
- Lymph nodes
- Salivary glands
- Liver cells
- Ruptured RBCs
Explanation: When RBCs rupture, they release haemozoin, a byproduct of hemoglobin digestion, which triggers the characteristic malarial paroxysms.
The principle of 'Vaccination' is based on which property of the immune system?
- Memory
- Discrimination
- Specificity
- Diversity
Explanation: Vaccines generate memory B and T-cells that recognize the pathogen quickly upon subsequent exposure and overwhelm the invaders.
Which of the following plants possesses hallucinogenic properties?
- Datura
- Cannabis sativa
- Atropa belladonna
- All of these
Explanation: Plants like Atropa belladonna and Datura are well-known for their hallucinogenic effects, as are some products from Cannabis.
The BCG vaccine is administered to provide lifelong protection against:
- Smallpox
- Cholera
- Tuberculosis
- Polio
Explanation: Bacille Calmette-Guérin (BCG) is the vaccine used to prevent TB, which primarily affects the lungs.
Which bacterium is primarily responsible for causing 'Pneumonia' by infecting the alveoli of the lungs?
- Salmonella typhi
- Streptococcus pneumoniae
- Haemophilus influenzae
- Both B and C
Explanation: Pneumonia is caused by bacteria like Streptococcus pneumoniae and Haemophilus influenzae, which lead to fluid-filled alveoli and severe breathing issues.
Cancer-causing agents, whether physical, chemical, or biological, are known as:
- Antigens
- Carcinogens
- Pathogens
- Antibiotics
Explanation: Carcinogens like X-rays, UV radiation, and tobacco smoke transform normal cells into cancerous neoplastic cells.
Cocaine (Coke or Crack) interferes with the transport of which neurotransmitter?
- Dopamine
- GABA
- Acetylcholine
- Serotonin
Explanation: Cocaine has a potent stimulating action on the CNS, producing a sense of euphoria and increased energy by blocking dopamine reuptake.
Rheumatoid arthritis is categorized as which type of immune system disorder?
- Allergic reaction
- Infectious disease
- Autoimmune disease
- Immunodeficiency
Explanation: Autoimmunity occurs when the body's immune system starts attacking self-cells, leading to damage to its own tissues.
Which enzyme allows HIV to convert its RNA genome into a DNA copy inside a host cell?
- DNA polymerase
- RNA polymerase
- Ligase
- Reverse transcriptase
Explanation: Retroviruses use reverse transcriptase to synthesize viral DNA from their RNA template after infecting a host cell.
The most feared property of malignant tumors is 'Metastasis', which refers to:
- The ability of tumor cells to evade the immune system
- The spread of tumor cells to distant sites to form secondary tumors
- The rapid and uncontrolled division of abnormal cells
- The loss of contact inhibition among cancer cells
Explanation: Metastasis is the pathogenic spread of cancer cells from the initial or primary site to distant organs or tissues in the body. While they often travel via the bloodstream or lymphatic system, the defining clinical feature is their ability to lodge in distant sites and establish secondary tumors.