GK (Biology)

The 1984 Bhopal gas tragedy was caused by methyl isocyanate (MIC) gas leakage from a Union Carbide pesticide plant. Option C says 'methyl isocynide' which appears to be a typo for methyl isocyanate. This was one of the world's worst industrial disasters, exposing over 500,000 people to toxic gas. The other options (carbon dioxide, sulfur dioxide, ozone) are incorrect - they are common gases but not involved in this specific disaster.

BCG (Bacillus Calmette-Guérin) vaccine is used to prevent tuberculosis. It contains attenuated Mycobacterium bovis and provides protection against severe forms of TB in children, especially tuberculous meningitis and miliary TB. Typhoid, mumps, and measles have their own specific vaccines (typhoid: Vi polysaccharide/typhoid conjugate; mumps: MMR; measles: MMR). BCG has no protective effect against these diseases.

The pineal gland secretes melatonin, the hormone that regulates circadian rhythms (sleep-wake cycles), earning it the name 'biological clock'. Melatonin production increases in darkness and decreases in light, synchronising our internal body clock with the external day-night cycle. The adrenal gland secretes cortisol and catecholamines (stress response), pituitary is the 'master gland' controlling other endocrine glands, and thyroid regulates metabolism - none are the biological clock.

Skin is the largest sense organ in the human body, covering approximately 1.5-2 square meters in adults. It contains sensory receptors for touch, pressure, pain, temperature, and vibration - making it our largest sensory interface with the external environment. The eye (vision), ear (hearing/balance), and nose (smell) are specialised sense organs but much smaller in surface area. Skin also has additional functions: protection, thermoregulation, vitamin D synthesis, and immune surveillance.

The medulla oblongata is the most vital part of the brain because it contains centres controlling essential autonomic functions: respiratory centre (breathing), cardiovascular centre (heart rate, blood pressure), vomiting centre, and reflex centres like coughing, sneezing, and swallowing. Damage to the medulla is incompatible with life. The cerebrum (conscious thought, voluntary movement) and cerebellum (coordination, balance) are important but not immediately vital. The thalamus is a sensory relay station, not a vital centre.

Correct answer is (2). 

Radioactive cobalt (Co-60) and radium (Ra-226) are used in radiotherapy for cancer treatment. Cobalt-60 units deliver high-energy gamma rays for external beam radiotherapy. Radium was historically used in brachytherapy (internal radiation) - radium needles or implants placed directly in/near tumours. Both emit ionising radiation that damages cancer cell DNA, preventing replication. They are NOT used for typhoid (antibiotics), mumps (supportive care/vaccine), or tuberculosis (antitubercular drugs). Radiation therapy is a cornerstone of cancer treatment.

ECG (Electrocardiogram) records the electrical activity of the heart from electrodes placed on the skin. It shows the cardiac cycle (P wave, QRS complex, T wave) and is essential for diagnosing arrhythmias, myocardial infarction, conduction defects, and electrolyte imbalances. EEG (Electroencephalogram) is for brain electrical activity. Kidney function tests (creatinine, BUN) and liver function tests assess those organs. ECG is exclusively cardiac.

Correct Answer: Homo Sapiens

Diphtheria is a bacterial infection that primarily affects the throat and respiratory tract. The bacteria Corynebacterium diphtheriae produces toxins that damage throat tissues, creating a characteristic membrane. Blood, liver, and brain are not the primary sites of diphtheria infection.

Oviparous animals are those that lay eggs, with embryos developing and hatching outside the mother's body. Birds are oviparous, but 'birds' is too specific - reptiles, fish, and amphibians also lay eggs. Mammals generally give live birth, and viviparous specifically means giving live birth.

Cataract is a condition where the lens of the eye becomes cloudy, causing blurred vision and eventual vision loss. The lens is located in the eye, making 'eye' the correct answer. Skin, ear, and nose are not affected by cataracts.

Correct answer is (2). 

The ELISA (Enzyme-Linked Immunosorbent Assay) and Western Blot tests are the primary diagnostic tests for HIV/AIDS. ELISA screens for HIV antibodies, and Western Blot confirms the positive results. These are not standard tests for cancer, leprosy, or meningitis diagnosis.

The pancreas produces insulin in special cells called beta cells of the islets of Langerhans. Insulin regulates blood sugar levels. The pituitary gland is the 'master gland' that controls other glands, pineal regulates sleep cycles, and adrenal produces stress hormones like cortisol.

Influenza (flu) is caused by the influenza virus, not bacteria or other pathogens. The virus attacks the respiratory system. Fungi cause different infections, and amoebae are protozoa causing diseases like amoebic dysentery.

Measles is caused by the measles virus, a highly contagious RNA virus. It causes fever, rash, and respiratory symptoms. Like influenza, it is viral in origin, not bacterial, fungal, or protozoan.

Blood cancer (leukemia) involves uncontrolled proliferation of white blood cells (WBCs) in bone marrow. This crowds out healthy blood cells. RBCs carry oxygen, platelets help clotting, and hemoglobin is the oxygen-carrying protein in RBCs - none are the primary cancer source.

Normal human body temperature is 98.6°F (37°C), approximately 98.4°F as given in the option. 44°F and 96°F are too low, while 38°F is near room temperature. The narrow range around 98.6°F maintains optimal enzyme function.

The pituitary gland is called the 'master gland' because it controls other endocrine glands through hormone secretion. Pineal regulates sleep, adrenal produces stress hormones, and pancreas produces insulin - but they're controlled by pituitary signals.

Cirrhosis is late-stage liver disease where healthy liver tissue is replaced by scar tissue, impairing liver function. It affects the liver specifically. Heart disease affects the cardiovascular system, lungs handle respiration, and skin is the body's protective barrier.

Iodine deficiency causes goiter (enlarged thyroid gland) because iodine is essential for thyroid hormone production. Rickets is from vitamin D deficiency, diabetes involves insulin, and beriberi is from vitamin B1 (thiamine) deficiency.