30. Which of these animals has a four-chambered heart?
[RRB NTPC CBT-II, Level 6 — 9 May 2022, Shift 1]
- (A) Peacock
- (B) Seahorse
- (C) Frog
- (D) Fish
Answer: (A) Peacock
Explanation: Peacocks are birds, and birds possess two atria and two ventricles that keep oxygenated and deoxygenated blood separate. Frogs have a three-chambered heart, whereas most fish and seahorses have two principal chambers. Four-chambered hearts support efficient systemic oxygen delivery.
29. Rh incompatibility between mother and foetus can arise when the mother is ______ and the foetus is ______.
[RPSC RAS Prelims — 27 October 2021]
- (A) Rh-positive; Rh-negative
- (B) Rh-negative; Rh-positive
- (C) Rh-negative; Rh-negative
- (D) Rh-positive; Rh-positive
Answer: (B) Rh-negative; Rh-positive
Explanation: An Rh-negative pregnant person can develop anti-D antibodies after exposure to Rh-positive foetal red cells. In a subsequent sensitised pregnancy, these antibodies may cross the placenta and destroy foetal erythrocytes. Antenatal anti-D immunoglobulin markedly reduces this preventable risk.
28. How many chambers does the heart of a crocodile have?
[RRB NTPC CBT-I — 23 July 2021, Shift 2]
- (A) Six
- (B) Four
- (C) One
- (D) Two
Answer: (B) Four
Explanation: Crocodilians are unusual among reptiles because their hearts have four chambers, structurally separating right and left atria and ventricles. They also possess specialised connections that can shunt blood in particular conditions. Most non-crocodilian reptiles have incompletely divided ventricles.
27. On which date is World Blood Donor Day observed?
[RRB NTPC CBT-I — 23 July 2021, Shift 1]
- (A) 10 June
- (B) 14 June
- (C) 12 June
- (D) 16 June
Answer: (B) 14 June
Explanation: World Blood Donor Day is observed on 14 June, the birth anniversary of Karl Landsteiner. It promotes safe blood donation and recognises voluntary donors. Donated blood and its separated components are vital in treating severe blood loss and several haematological disorders.
26. For which discovery is Karl Landsteiner especially remembered?
[RRB NTPC CBT-I — 7 April 2021, Shift 1]
- (A) Research on the nervous system
- (B) Isolation of DNA
- (C) Identification of Zika virus
- (D) Classification of blood groups
Answer: (D) Classification of blood groups
Explanation: Karl Landsteiner established the basis of the ABO blood group system by identifying differences in red-cell antigens and corresponding serum reactions. His work made blood transfusions much safer and earned him the Nobel Prize in Physiology or Medicine in 1930.
25. Which statement about mammals is incorrect?
[RRB NTPC CBT-I — 6 April 2021, Shift 2]
- (A) Most have hair
- (B) Some mammals lay eggs
- (C) Their heart is three-chambered
- (D) Mammary glands nourish young
Answer: (C) Their heart is three-chambered
Explanation: Mammals generally have a four-chambered heart with fully separated pulmonary and systemic circulation. They characteristically possess hair and mammary glands. Although most give birth to live young, monotremes such as platypuses and echidnas lay eggs, making that statement accurate.
24. The commonly cited normal systolic blood pressure in adults is approximately ______.
[RRB NTPC CBT-I — 5 April 2021, Shift 1]
- (A) 110 mmHg
- (B) 120 mmHg
- (C) 80 mmHg
- (D) 130 mmHg
Answer: (B) 120 mmHg
Explanation: Systolic pressure is the maximum pressure recorded in arteries during ventricular contraction. A familiar illustrative blood-pressure reading is 120/80 mmHg, where 120 is systolic and 80 is diastolic. Clinical interpretation depends on repeat readings, patient circumstances and applicable guidelines.
23. Which glands help regulate blood pressure in the human body?
[RRB NTPC CBT-I — 19 March 2021, Shift 2]
- (A) Adrenal glands
- (B) Pituitary glands
- (C) Pancreas
- (D) Pineal gland
Answer: (A) Adrenal glands
Explanation: The adrenal glands secrete hormones involved in circulatory regulation. Aldosterone supports sodium and water retention, influencing blood volume, while adrenaline affects heart rate and vascular responses. Both mechanisms can alter arterial pressure as part of the body’s broader homeostatic systems.
22. Which of these cell types is NOT normally a constituent of human blood?
[RRB NTPC CBT-I — 14 March 2021, Shift 1]
- (A) Leucocyte
- (B) Lymphocyte
- (C) Monocyte
- (D) Chondrocyte
Answer: (D) Chondrocyte
Explanation: Leucocytes circulate in the blood, and lymphocytes and monocytes are particular leucocyte types. Chondrocytes are mature cells embedded in cartilage, where they maintain the cartilaginous matrix. They are not normal circulating components of human blood under healthy conditions.
21. Which vessel supplies blood from the main arterial circulation to the kidneys?
[RRB NTPC CBT-I — 22 February 2021, Shift 2]
- (A) Vena cava
- (B) Renal vein
- (C) Renal artery
- (D) Coronary artery
Answer: (C) Renal artery
Explanation: Each renal artery branches from the abdominal aorta to deliver blood to a kidney for filtration and tissue nourishment. Blood returns through the renal veins. Coronary arteries instead supply the heart muscle, while the venae cavae return systemic venous blood to the heart.
