60. Which blood cells protect the body against infections?
[SSC Selection Post, Matriculation Level — 2 August 2025, Shift 1]
- (A) Red blood cells
- (B) White blood cells
- (C) Platelets
- (D) Plasma
Answer: (B) White blood cells
Explanation: White blood cells form a crucial cellular component of innate and adaptive immunity. Some engulf pathogens, while lymphocytes mediate targeted defence and antibody responses. Red blood cells transport oxygen; platelets support clot formation, and plasma is the liquid transport medium.
59. Blood pressure is measured with which apparatus?
[BSSC Group D — 11 May 2025]
- (A) Thermometer
- (B) Barometer
- (C) Crescograph
- (D) Sphygmomanometer
Answer: (D) Sphygmomanometer
Explanation: A sphygmomanometer records arterial pressure through an inflatable cuff and pressure measuring system. The device yields systolic and diastolic values, commonly expressed in mmHg. A barometer measures atmospheric pressure, a thermometer measures temperature, and a crescograph measures plant growth.
58. Which instrument is used for manually measuring a person’s blood pressure?
[UPSC CDS-I, General Knowledge — 13 April 2025]
- (A) Sphygmomanometer
- (B) Centrifuge
- (C) Electrophoresis apparatus
- (D) Thermal cycler
Answer: (A) Sphygmomanometer
Explanation: Manual pressure assessment uses a sphygmomanometer cuff with a gauge, often alongside a stethoscope to detect arterial Korotkoff sounds. The pressure at sound appearance estimates systolic pressure; disappearance usually estimates diastolic pressure. The other instruments serve laboratory separation or amplification functions.
57. Which activity is NOT a function of circulating blood?
[RRB Technician Grade III — 30 December 2024, Shift 1]
- (A) Making starch
- (B) Transporting gases
- (C) Carrying hormones
- (D) Carrying wastes
Answer: (A) Making starch
Explanation: Blood transports oxygen, carbon dioxide, hormones, nutrients and metabolic waste throughout the body. Starch synthesis occurs chiefly in photosynthetic plant tissues and is not a function of human blood. Circulating blood additionally assists temperature regulation, immunity and internal fluid balance.
56. Which of the following is classified as a connective tissue?
[RRB Technician Grade III — 27 December 2024, Shift 3]
- (A) Cuboidal epithelium
- (B) Muscle
- (C) Blood
- (D) Columnar epithelium
Answer: (C) Blood
Explanation: Blood is specialised fluid connective tissue because living cellular elements are suspended within an extracellular matrix called plasma. Its transport role links different tissues throughout the body. Epithelial tissues mainly line surfaces, and muscle tissue specialises in contraction and movement.
55. Which human organ pumps blood around the body?
[RRB Technician Grade III — 27 December 2024, Shift 3]
- (A) Pancreas
- (B) Heart
- (C) Stomach
- (D) Liver
Answer: (B) Heart
Explanation: The muscular heart maintains blood circulation by alternating relaxation and contraction. Its right half pumps blood to the lungs, while the left half pumps oxygenated blood into systemic arteries. Four chambers and coordinated valves maintain efficient, largely one-way flow throughout the body.
54. Which substance is NOT normally present as a dissolved constituent of blood plasma?
[RRB Technician Grade III — 27 December 2024, Shift 3]
- (A) Salts
- (B) Proteins
- (C) Undigested food
- (D) Hormones
Answer: (C) Undigested food
Explanation: Plasma contains water, proteins, electrolytes, nutrients, hormones and metabolic wastes. Food is first digested into absorbable molecules before entering the circulation; undigested food remains within the digestive tract. Albumin, globulins and fibrinogen are major classes of plasma proteins.
53. Which statements about vessels are correct?
(i) Arteries carry blood away from the heart;
(ii) arteries have thin elastic walls;
(iii) venous valves prevent backflow.
[RRB Technician Grade III — 23 December 2024, Shift 2]
- (A) Only (i) and (iii)
- (B) Only (i) and (ii)
- (C) All three
- (D) Only (i)
Answer: (A) Only (i) and (iii)
Explanation: Arteries conduct blood outward from the heart and require thick muscular elastic walls to handle pulsatile pressure. Therefore the assertion that their walls are thin is false. Many veins contain valves which prevent reverse flow during low-pressure venous return.
52. Which pigment is present in human red blood corpuscles?
[RRB Technician Grade III — 23 December 2024, Shift 3]
- (A) Melanin
- (B) Xanthophyll
- (C) Haemoglobin
- (D) Chlorophyll
Answer: (C) Haemoglobin
Explanation: Haemoglobin is a protein containing iron-bearing haem groups, which gives red blood cells their characteristic colour. It reversibly binds oxygen in the lungs and releases it to body tissues. Melanin colours skin and hair; chlorophyll and xanthophyll are plant pigments.
51. Which blood component carries dissolved nutrients, carbon dioxide and nitrogenous wastes?
[RRB Technician Grade III — 23 December 2024, Shift 2]
- (A) Plasma
- (B) Blood platelets
- (C) Lymph
- (D) Red blood corpuscles
Answer: (A) Plasma
Explanation: Plasma carries dissolved materials, including glucose, mineral ions, hormones and urea. Some carbon dioxide is carried as dissolved gas, but most travels in the blood as bicarbonate. The fluid plasma matrix distributes these substances among organs responsible for nutrition and excretion.
