Blood & Circulatory System – NDA Biology PYQs

NDA 2026-I

Q. 1. Which one of the following valves guards the opening between the right ventricle and the pulmonary artery?

(a) Bicuspid valve

(b) Semilunar valve

(c) Mitral valve

(d) Tricuspid valve

Answer: (b) Semilunar valve

Explanation: The semilunar valve guards the opening between the right ventricle and the pulmonary artery. When the right ventricle contracts, blood is pushed into the pulmonary artery. The semilunar valve prevents backflow of blood into the ventricle. There are two semilunar valves: the pulmonary semilunar valve and the aortic semilunar valve. Concept Tested: Pulmonary semilunar valve: guards the right ventricle–pulmonary artery opening

NDA 2025-II

Q. 2. 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 in general

(d) Arteries do not have valves but veins do have valves

Answer: (b) Pulmonary arteries always carry oxygenated blood while Pulmonary veins always carry deoxygenated blood

Explanation: Option (b) is incorrect. The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs. The pulmonary vein carries oxygenated blood from the lungs to the left atrium. These are exceptions to the general rule that arteries carry oxygenated and veins carry deoxygenated blood. Options (a), (c), and (d) are all correct. Concept Tested: Pulmonary artery carries deoxygenated blood; pulmonary vein carries oxygenated blood: exceptions to the general rule

★ JOVIK Exam Insight The pulmonary vessels are a high-frequency NDA trap. The general rule is: arteries carry oxygenated blood, veins carry deoxygenated blood. The exception is the pulmonary circuit: the pulmonary artery carries deoxygenated blood and the pulmonary vein carries oxygenated blood.

NDA 2025-I

Q. 3. Clotting of blood involves which one among the following clotting proteins?

(a) Pathogen

(b) Fibrinogen

(c) Macrophage

(d) Phagocytes

Answer: (b) Fibrinogen

Explanation: Blood clotting (coagulation) involves a cascade of reactions. Fibrinogen is a soluble plasma protein. When a blood vessel is damaged, fibrinogen is converted to insoluble fibrin threads by the enzyme thrombin. These fibrin threads form a meshwork that traps blood cells and forms a clot. Pathogens, macrophages, and phagocytes are not clotting proteins. Concept Tested: Fibrinogen: the clotting protein converted to fibrin during blood coagulation

NDA 2022-II

Q. 4. Lymph is a tissue fluid present in intercellular spaces. It resembles to

(a) digestive juice

(b) cytoplasmic fluid

(c) urine

(d) plasma

Answer: (d) plasma

Explanation: Lymph is derived from blood plasma. When blood passes through capillaries, some plasma filters out into the tissue spaces. This filtered fluid, called lymph or tissue fluid, closely resembles blood plasma in composition but lacks most red blood cells and contains fewer proteins. Lymph is collected by the lymphatic system and returned to the bloodstream. Concept Tested: Lymph resembles blood plasma in composition

NDA 2019-I

Q. 5. Which one of the following statements regarding Electrocardiogram is correct?

(a) Electrocardiogram is graphical representation of electrical activity of cornea

(b) Electrocardiogram is graphical representation of activity of kidney

(c) Electrocardiogram is graphical representation of activity of brain

(d) Electrocardiogram is graphical representation of electrical activity of heart

Answer: (d) Electrocardiogram is graphical representation of electrical activity of heart

Explanation: An Electrocardiogram (ECG or EKG) records the electrical activity of the heart over a period of time. Each heartbeat is triggered by an electrical impulse. The ECG captures these impulses as waves on a graph. It is used to diagnose heart rhythm disorders, heart attacks, and other cardiac conditions. Concept Tested: ECG: graphical representation of the electrical activity of the heart

NDA 2018-II

Q. 6. The oxygenated blood from the lungs is received by the

(a) left auricle

(b) left ventricle

(c) right auricle

(d) right ventricle

Answer: (a) left auricle

Explanation: Oxygenated blood from the lungs is carried by the pulmonary veins into the left atrium (left auricle). From there, it flows into the left ventricle, which pumps it out to the body through the aorta. The right side of the heart receives deoxygenated blood from the body and sends it to the lungs. Concept Tested: Left atrium receives oxygenated blood from the lungs via pulmonary veins

★ JOVIK Exam Insight The path of oxygenated blood is tested repeatedly by NDA: Lungs → Pulmonary veins → Left atrium (auricle) → Left ventricle → Aorta → Body. Deoxygenated blood travels the reverse path on the right side.

NDA 2018-I

Q. 7. The Poisonous nature of Carbon monoxide (CO) is due to its

(a) insolubility in water

(b) ability to form a complex with haemoglobin

(c) ability to reduce some metal oxides

(d) property of having one sigma bond

Answer: (b) ability to form a complex with haemoglobin

Explanation: Carbon monoxide (CO) binds to haemoglobin with an affinity about 200–250 times greater than oxygen. It forms carboxyhaemoglobin (COHb), which cannot carry oxygen. This prevents oxygen transport to body tissues, leading to cellular hypoxia and death. CO poisoning is particularly dangerous because the gas is colourless and odourless. Concept Tested: CO poisoning: CO binds haemoglobin 200× more strongly than O₂, forming carboxyhaemoglobin

NDA 2017-I

Q. 8. 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) no nucleus, no mitochondria and no endoplasmic reticulum

Explanation: Mature mammalian red blood cells (erythrocytes) lack a nucleus, mitochondria, and endoplasmic reticulum. These organelles are expelled during RBC maturation. This maximises the space available for haemoglobin, increasing the oxygen-carrying capacity. RBCs obtain energy through anaerobic glycolysis since they have no mitochondria. Concept Tested: Mature mammalian RBCs: no nucleus, no mitochondria, no endoplasmic reticulum

NDA 2016-I

Q. 9. To prevent heart problems, blood of a normal healthy person should have

1. low cholesterol level.

2. high HDL level.

3. high VLDL level.

4. high LDL level.

Select the correct answer using the code given below:

(a) 1 and 2 only

(b) 1, 2 and 4 only

(c) 3 and 4 only

(d) 1, 2 and 3 only

Answer: (a) 1 and 2 only

Explanation: To prevent heart disease, total cholesterol should be low. HDL (high-density lipoprotein) is “good cholesterol”: it transports cholesterol from arteries to the liver for removal. High HDL is protective. LDL (low-density lipoprotein) is “bad cholesterol”: it deposits cholesterol in arteries, causing blockages. High LDL is harmful. VLDL (very low-density lipoprotein) is also harmful. Therefore, a healthy person should have low total cholesterol, high HDL, and low LDL and VLDL. Concept Tested: Heart health: high HDL is protective; low LDL, VLDL, and total cholesterol are desirable

★ JOVIK Exam Insight NDA tests the HDL vs LDL distinction. HDL = good (higher is better). LDL = bad (lower is better). VLDL = bad. This is a direct applied-biology trap question.

NDA 2015-II

Q. 10. In blood, platelets are required for:

(a) transporting oxygen

(b) transporting carbon dioxide

(c) initiating blood clotting

(d) initiating degradation of urea

Answer: (c) initiating blood clotting

Explanation: Platelets (thrombocytes) are small, disc-shaped cell fragments in the blood. They play a central role in blood clotting (haemostasis). When a vessel is damaged, platelets adhere to the site and release chemicals that initiate the clotting cascade. This leads to fibrin formation and clot sealing. Oxygen and CO₂ transport are functions of RBCs and haemoglobin. Concept Tested: Platelets (thrombocytes): initiate blood clotting at sites of vessel damage

NDA 2015-I

Q. 11. ‘Lub-dup’ sound is produced due to action of

(a) Large intestine

(b) Lungs

(c) Heart

(d) Oesophagus

Answer: (c) Heart

Explanation: The “lub-dup” sound is produced by the heart valves closing. “Lub” (S1) is produced by the closure of the mitral and tricuspid valves at the beginning of ventricular contraction. “Dup” (S2) is produced by the closure of the aortic and pulmonary semilunar valves at the end of ventricular contraction. These sounds are heard using a stethoscope. Concept Tested: “Lub-dup” heart sounds produced by closure of heart valves

NDA 2012-II

Q. 12. Which one among the following parts of blood carries out the function of body defence?

(a) Platelets

(b) White Blood Cells

(c) Haemoglobin

(d) Red Blood Cells

Answer: (b) White Blood Cells

Explanation: White blood cells (WBCs or leucocytes) are the primary defenders of the body against infections. They include neutrophils, lymphocytes, monocytes, eosinophils, and basophils. WBCs identify and destroy pathogens, produce antibodies, and carry out immune responses. RBCs carry oxygen; platelets help in clotting; haemoglobin is a protein in RBCs. Concept Tested: White blood cells (leucocytes): primary agents of body defence and immunity

NDA 2012-I

Q. 13. 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) Except the pulmonary artery, all other arteries carry oxygenated blood

Explanation: The general rule is that arteries carry oxygenated blood and veins carry deoxygenated blood. The exception is the pulmonary circuit. The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs. Therefore, option (c) is correct: except the pulmonary artery, all other arteries carry oxygenated blood. The pulmonary vein carries oxygenated blood from the lungs to the left atrium. Concept Tested: Pulmonary artery exception: carries deoxygenated blood; all other arteries carry oxygenated blood

Q. 14. Sickle-cell anaemia is a disease caused due to the abnormality in

(a) white blood cells

(b) red blood cells

(c) thrombocytes

(d) blood plasma composition

Answer: (b) red blood cells

Explanation: Sickle-cell anaemia is a genetic disorder affecting red blood cells. A point mutation in the beta-globin gene causes an abnormal form of haemoglobin (HbS). Under low-oxygen conditions, HbS polymerises, causing the RBC to deform into a sickle (crescent) shape. Sickle-shaped RBCs are fragile, block small blood vessels, and have a shorter lifespan: causing anaemia. Concept Tested: Sickle-cell anaemia: genetic abnormality causing sickle-shaped red blood cells

NDA 2011-II

Q. 15. 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 are caused by opening and closing of heart valves

Explanation: Heart sounds are produced by the closing of heart valves, not by blood flow or valve opening. The first sound (S1, “lub”) occurs when the mitral and tricuspid valves close. The second sound (S2, “dup”) occurs when the aortic and pulmonary valves close. Murmurs are abnormal heart sounds caused by turbulent blood flow, not normal sounds. Concept Tested: Heart sounds caused by closing of heart valves; murmurs are abnormal

NDA 2011-I

Q. 16. 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) AB or B

Explanation: Blood group B individuals have B antigens on their RBCs and anti-A antibodies in their plasma. They can donate blood to people with blood group B (same group) or blood group AB (AB individuals have no anti-A or anti-B antibodies: they are universal recipients). Donating to group A would cause an immune reaction because group A individuals have anti-B antibodies. Concept Tested: Blood group B donors can give to B or AB recipients; AB is the universal recipient

NDA 2009-I

Q. 21. 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) of its rich vascularity

Explanation: The face has an exceptionally rich network of blood vessels (high vascularity). Both the external carotid artery and its many branches supply the face. When facial tissue is cut, multiple small vessels are severed, causing profuse bleeding. Proximity to the heart does not determine bleeding volume; vascularity does. Concept Tested: Profuse facial bleeding due to rich vascularity of the face

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