Blood and Circulatory System – NDA Biology PYQs

Question [NDA 2007-II]
In human body, which one of the following stores extra blood for release when shortages occur?
(a) Liver
(b) Pancreas
(c) Spleen
(d) Lymph nodes

Answer: (c)
The spleen stores extra blood. When the body suddenly needs more blood — during blood loss or heavy exercise — the spleen contracts and releases this stored blood. The liver processes toxins and makes bile. The pancreas makes digestive enzymes and insulin. Lymph nodes are part of the immune system.

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Question [NDA 2009-I]
Which of the following are the possible blood groups of the offspring of parents with blood group O and AB?
(a) O, A, B and AB
(b) A and B
(c) A, B and AB
(d) O and AB

Answer: (b)
Group O has genotype ii. Group AB has genotype IAIB. The offspring gets one allele from each parent. From the O parent, the offspring always gets i. From the AB parent, the offspring gets either IA or IB. So offspring can be IAi (blood group A) or IBi (blood group B). They cannot be O or AB.

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Question [NDA 2009-I]
The wounds of face bleed profusely because —
(a) of its rich vascularity
(b) it is close to the heart
(c) its skin is soft
(d) of fast contraction of facial muscle

Answer: (a)
The face has a very dense network of blood vessels — rich vascularity. More vessels in a small area means more bleeding when any of them are cut. Being close to the heart does not cause more bleeding. Skin softness or muscle contraction do not affect blood loss this way.

Question [NDA 2009-II]
Jaundice in human beings is the result of —
(a) incomplete metabolism of biliverdin
(b) complete metabolism of biliverdin
(c) incomplete metabolism of bilirubin
(d) complete metabolism of bilirubin

Answer: (c)
When RBCs break down, haemoglobin is converted to bilirubin. The liver normally processes bilirubin and excretes it. In jaundice, this processing is incomplete — bilirubin accumulates in blood and tissues, causing yellow colouration. Biliverdin is a different green pigment; it is not the substance involved in jaundice.

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Question [NDA 2011-I]
An individual whose blood type is B may in an emergency donate blood to a person whose blood type is —
(a) B or A
(b) AB or A
(c) A or O
(d) AB or B

Answer: (d)
Blood group B can donate to B and AB only. It cannot donate to A or O. The correct answer is AB or B.

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Question [NDA 2011-II]
Which one among the following statements regarding heart sound is correct?
(a) Heart sounds are caused by the internal blood flow inside the heart
(b) Heart sounds are caused by the external blood flow outside the heart
(c) Heart sounds are caused by opening and closing of heart valves
(d) Normal sounds are called ‘murmurs’

Answer: (c)
Heart sounds (lub-dub) are caused by the opening and closing of heart valves, not by blood flow. The first sound (lub) is when the mitral and tricuspid valves close. The second sound (dub) is when the aortic and pulmonary valves close. Abnormal heart sounds are called murmurs — not normal sounds.

Question [NDA 2012-I]
Which one among the following statements is correct?
(a) All arteries carry oxygenated blood
(b) All veins carry oxygenated blood
(c) Except the pulmonary artery, all other arteries carry oxygenated blood
(d) Except the pulmonary vein, all other veins carry oxygenated blood

Answer: (c)
The pulmonary artery is the exception. It carries deoxygenated blood from the right ventricle to the lungs. All other arteries carry oxygenated blood. The pulmonary vein carries oxygenated blood — it is not the exception. So option (d) is also wrong.

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Question [NDA 2012-II]
Statement I: Red blood cells burst when placed in water.
Statement II: Due to the phenomenon of osmosis, water enters into red blood cells.
(a) Both statements are individually true and Statement II is the correct explanation of Statement I
(b) Both are true but II does not explain I
(c) I is true but II is false
(d) I is false but II is true

Answer: (a)
Water is hypotonic — it has a higher water concentration than the inside of RBCs. Water enters the RBCs by osmosis. This makes them swell. If enough water enters, they burst. Statement II correctly explains why Statement I happens.

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Question [NDA 2015-I]
‘Lub-dub’ sound is produced due to action of —
(a) Large intestine
(b) Lungs
(c) Heart
(d) Oesophagus

Answer: (c)
The lub-dub sound is produced by the heart — specifically by its valves opening and closing during each heartbeat.

Question [NDA 2017-II]
Red blood cells (RBCs) have —
(a) no nucleus, no mitochondria and no endoplasmic reticulum
(b) nucleus, mitochondria and endoplasmic reticulum
(c) nucleus, mitochondria but no endoplasmic reticulum
(d) no mitochondria but endoplasmic reticulum is present

Answer: (a)
Mature RBCs have no nucleus, no mitochondria, and no endoplasmic reticulum. This makes them very simple cells. The absence of these structures leaves more space for haemoglobin. But it also means RBCs cannot repair themselves and have a limited lifespan.

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Question [NDA 2018-II]
The oxygenated blood from the lungs is received by the —
(a) left auricle
(b) left ventricle
(c) right auricle
(d) right ventricle

Answer: (a)
Oxygenated blood travels from the lungs through the pulmonary vein and enters the left atrium (left auricle) first. From there it goes to the left ventricle, which pumps it to the body. The right side receives deoxygenated blood from the body.

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Question [NDA 2021-I]
If human blood is placed in a 2% detergent solution, what will happen to the RBC?
(a) The RBC will shrink
(b) The RBC will swell and become turgid
(c) The RBC will swell and burst
(d) The RBC will lyse

Answer: (d)
Detergent disrupts the cell membrane directly — it breaks down the phospholipid bilayer. When the membrane breaks down, the cell contents spill out. This is called lysis. It is different from osmotic bursting (option c) — in detergent, the membrane is chemically dissolved, not physically burst by pressure.

Question [NDA 2025-I]
Clotting of blood involves which one among the following clotting proteins?
(a) Pathogen
(b) Fibrinogen
(c) Macrophage
(d) Phagocytes

Answer: (b)
Fibrinogen is the plasma protein that is converted into fibrin during blood clotting. Fibrin threads form a mesh that seals the wound. Pathogens are disease-causing organisms. Macrophages and phagocytes are types of white blood cells — they engulf foreign particles, they do not form clots.

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Question [NDA 2025-I]
Which one among the following statements about arteries and veins in humans is NOT correct?
(a) Arteries carry blood away from heart while veins bring blood towards the heart
(b) Pulmonary arteries always carry oxygenated blood while Pulmonary veins always carry deoxygenated blood
(c) Arteries have thicker and more elastic walls compared to veins
(d) Arteries do not have valves but veins do have valves

Answer: (b)
Option (b) is the incorrect statement. Pulmonary arteries carry deoxygenated blood (from heart to lungs). Pulmonary veins carry oxygenated blood (from lungs to heart). The statement has it reversed. All other options are correct facts about arteries and veins.