SSC CGL Human Body Questions and Answers

Do not confuse an organ that produces a substance with an organ on which that substance acts, or a vector with the organism that causes a disease. Therefore option C, Neurotransmitter, is factually consistent with the stem, the marked correct index, and the explanation.✅ Correct Answer: C — Neurotransmitter They bind to receptors on the next neuron and transmit the nerve impulse forward. Haemoglobin — It is a protein in RBCs that carries oxygen, not involved in nerve signal transmission. Insulin — A hormone secreted by the pancreas to regulate blood glucose levels; has no role at synapses. Enzyme — Enzymes catalyze biochemical reactions but do not transmit nerve impulses between neurons. Neurotransmitters are the only molecules responsible for chemical transmission across synapses.

Therefore option C, 10 million, is factually consistent with the stem, the marked correct index, and the explanation.✅ Correct Answer: C — 10 million The human eye can distinguish approximately 10 million (1 crore) different colors. The combination of signals from these three types of cones allows the brain to perceive the vast range of colors. 1000 — 1000 colors is a massive underestimate; the human eye is far more sensitive than that. 10000 — 10,000 colors is still far too low; the true number is 10 million. 1 billion — 1 billion (100 crore) is an overestimate; the scientifically established figure is 10 million. The eye can distinguish ~10 million colors but only about 200 pure hues.

Therefore option C, Hypothalamus, is factually consistent with the stem, the marked correct index, and the explanation.✅ Correct Answer: C — Hypothalamus The Hypothalamus is a small but vital region of the brain (part of the diencephalon) that acts as the body's 'thermostat'. It monitors blood temperature and regulates body temperature by: initiating sweating (for cooling), causing shivering (for warming), regulating blood vessel dilation/constriction, and controlling metabolic heat production. Normal body temperature is 37°C (98.6°F). Cerebrum — Cerebrum is the largest part of the brain responsible for conscious thought, memory, language, and voluntary movement; not body temperature regulation. Cerebellum — Cerebellum controls balance, coordination, and fine motor movements; not temperature regulation. Medulla oblongata — Medulla oblongata controls involuntary functions like breathing, heart rate, and blood pressure; not body temperature. 📝 Important Note: Hypothalamus = thermostat of the body. Fever occurs when hypothalamus resets to a higher set point. Key brain function fact for SSC CGL.

Therefore option C, Lungs (bronchi), is factually consistent with the stem, the marked correct index, and the explanation.✅ Correct Answer: C — Lungs (bronchi) The Trachea (windpipe) is a tube that carries air from the larynx (voice box) down to the lungs. It divides at the lower end into two primary bronchi — right bronchus and left bronchus — each leading into the respective lung. The epiglottis prevents food from entering the trachea during swallowing. Stomach — The stomach is connected to the oesophagus (food pipe), not the trachea. The trachea carries only air. Oesophagus — Oesophagus (esophagus) is the food pipe that connects the throat to the stomach; it runs parallel to the trachea but carries food. Heart — The heart is not directly connected to the trachea; blood vessels (arteries and veins) connect to the heart, not the trachea. 📝 Important Note: Trachea = windpipe; Oesophagus = food pipe. Epiglottis closes the trachea during swallowing to prevent choking. Trachea is about 10-12 cm long, has C-shaped cartilage rings. Bronchi lead to bronchioles then alveoli in lungs.

Therefore option C, Vitamin D, is factually consistent with the stem, the marked correct index, and the explanation.✅ Correct Answer: C — Vitamin D Vitamin D (specifically its active form Calcitriol) is essential for calcium absorption from the intestine into the bloodstream. Without adequate Vitamin D, the intestine cannot absorb sufficient calcium, leading to low blood calcium levels, which causes Rickets in children (soft bones) and Osteomalacia/Osteoporosis in adults. Vitamin D is synthesized in skin when exposed to sunlight (UV rays). Vitamin A — Vitamin A is essential for vision (rhodopsin production), skin health, and immune function; not for calcium absorption. Vitamin B12 — Vitamin B12 is important for red blood cell formation and nervous system function; not for calcium absorption. Vitamin E — Vitamin E is an antioxidant that protects cell membranes; not for calcium absorption. 📝 Important Note: Vitamin D = 'Sunshine Vitamin' synthesized by skin from sunlight. Vitamin D deficiency = Rickets (children), Osteomalacia (adults). Calcium absorption requires Vitamin D. SSC CGL frequently tests vitamin-deficiency diseases.

Therefore option C, Oxytocin, is factually consistent with the stem, the marked correct index, and the explanation.✅ Correct Answer: C — Oxytocin Oxytocin is released by the Posterior Pituitary Gland during childbirth. It stimulates uterine contractions (labour pains) to facilitate delivery of the baby. After birth, oxytocin also stimulates milk ejection (let-down reflex) during breastfeeding. It is also called the 'love hormone' or 'bonding hormone' as it promotes social bonding and maternal behavior. Oestrogen — Oestrogen is the female sex hormone (produced by ovaries); prepares uterus for pregnancy but doesn't directly stimulate uterine contractions during labor. Progesterone — Progesterone maintains pregnancy and inhibits uterine contractions (opposite effect!); levels drop before labor begins. Prolactin — Prolactin (from anterior pituitary) stimulates milk production (not ejection); it doesn't stimulate uterine contractions. 📝 Important Note: Oxytocin = uterine contractions + milk ejection. Prolactin = milk production. Oxytocin is also called 'love hormone' / 'cuddle hormone'. Synthetic oxytocin (Pitocin) used medically to induce or augment labor.

Therefore option C, Duodenum, is factually consistent with the stem, the marked correct index, and the explanation.✅ Correct Answer: C — Duodenum The Duodenum is the first and shortest part of the small intestine that directly connects to the stomach. It receives partially digested food (chyme) from the stomach. In the duodenum, bile from the liver (via gallbladder) and pancreatic juice (from pancreas) are added to complete digestion of fats, proteins, and carbohydrates. Jejunum — Jejunum is the second part of the small intestine (middle segment), not connected to the stomach; it is where most nutrient absorption occurs. Ileum — Ileum is the third and longest part of small intestine; it connects to the large intestine at the ileocecal valve, not to stomach. Caecum — Caecum is the first part of the large intestine; not connected to the stomach at all. 📝 Important Note: Small intestine has 3 parts: Duodenum (1st, 25 cm), Jejunum (2nd, 2.5 m), Ileum (3rd, 3.5 m). Duodenum = 'twelve' in Latin (12 finger-breadths long = 25cm). Most digestion happens in duodenum; most absorption in jejunum and ileum.

Blood plasma is approximately 90-92% water. Plasma makes up about 55% of total blood volume. 55% — 55% is actually the percentage of plasma in total blood volume (not water content in plasma). 70% — 70% is approximately the water content of the entire human body, not specifically plasma. 99% — 99% is close to the water content of some body fluids like saliva/urine, but not plasma. 📝 Important Note: Blood = Plasma (55%) + Formed elements (45% RBCs, WBCs, platelets). Plasma = 90-92% water + 8-10% proteins and other substances. Serum = Plasma without clotting factors. Fibrinogen in plasma helps in blood clotting.

Therefore option C, Inferior vena cava, is factually consistent with the stem, the marked correct index, and the explanation.✅ Correct Answer: C — Inferior vena cava The Inferior Vena Cava (IVC) is the largest vein in the human body. It collects deoxygenated blood from all body parts below the diaphragm (lower limbs, abdomen, pelvis) and carries it to the right atrium of the heart. Its large diameter accommodates the massive blood flow from the lower body. Pulmonary vein — Pulmonary veins carry oxygenated blood from the lungs to the left atrium; they are not the largest veins. Superior vena cava — Superior vena cava (SVC) carries blood from upper body (head, arms, chest) to the heart; smaller than IVC. Portal vein — Portal vein carries nutrient-rich blood from digestive organs to the liver; not the largest vein. 📝 Important Note: Largest vein = Inferior Vena Cava (IVC). Largest artery = Aorta. Veins carry deoxygenated blood (except pulmonary veins). Arteries carry oxygenated blood (except pulmonary arteries).

Do not confuse an organ that produces a substance with an organ on which that substance acts, or a vector with the organism that causes a disease. Therefore option C, Pineal gland, is factually consistent with the stem, the marked correct index, and the explanation.✅ Correct Answer: C — Pineal gland Melatonin is produced by the Pineal Gland, a small endocrine gland located in the brain. Melatonin regulates the sleep-wake cycle (circadian rhythm). The pineal gland is also called the 'third eye' and is sensitive to light. Thyroid gland — Thyroid gland produces Thyroxine (T3 and T4), not melatonin; regulates metabolism. Pituitary gland — Pituitary gland produces growth hormone, TSH, FSH, LH, prolactin, oxytocin; not melatonin. Adrenal gland — Adrenal gland produces cortisol, adrenaline (epinephrine), aldosterone; not melatonin. 📝 Important Note: Pineal gland = Melatonin (sleep hormone). Pituitary gland = 'Master gland' of the body. Adrenal = Adrenaline (fight or flight). Melatonin supplements are used to treat jet lag and sleep disorders. Key SSC CGL endocrine gland question.