NEET 2025 MCQ with Answer Explanation : “Body fluid and Circulation”.

MCQ 141:
Which type of leukocyte is primarily responsible for fighting bacterial infections?

A) Eosinophils
B) Basophils
C) Neutrophils
D) Lymphocytes

Answer: C) Neutrophils

Explanation: Neutrophils are the most abundant type of white blood cell and are primarily responsible for responding to bacterial infections.

MCQ 142:
What structure helps maintain blood pressure during diastole?

A) Atria
B) Arteries
C) Valves
D) Capillaries

Answer: B) Arteries

Explanation: Arteries maintain blood pressure through their muscular walls that can constrict and regulate blood flow even during diastole.

MCQ 143:
What condition is indicated by an abnormally high level of carbon dioxide in the blood?

A) Hypoxia
B) Hypercapnia
C) Hyperventilation
D) Hypoventilation

Answer: B) Hypercapnia

Explanation: Hypercapnia refers to elevated levels of carbon dioxide in the blood, often resulting from inadequate ventilation.

MCQ 144:
Which part of the heart receives oxygenated blood from the lungs?

A) Right atrium
B) Left atrium
C) Right ventricle
D) Left ventricle

Answer: B) Left atrium

Explanation: The left atrium receives oxygenated blood from the lungs via the pulmonary veins.

MCQ 145:
Which blood vessel is the largest in the body?

A) Pulmonary artery
B) Aorta
C) Vena cava
D) Femoral artery

Answer: B) Aorta

Explanation: The aorta is the largest artery in the body, distributing oxygenated blood from the heart to the rest of the body.

MCQ 146:
What is the role of the atrioventricular (AV) node?

A) Generate electrical impulses
B) Delay impulses between the atria and ventricles
C) Pump blood
D) Filter blood

Answer: B) Delay impulses between the atria and ventricles

Explanation: The AV node delays the electrical impulses from the atria to allow for complete filling of the ventricles before they contract.

MCQ 147:
Which of the following is a risk factor for cardiovascular disease?

A) Regular exercise
B) Healthy diet
C) Smoking
D) Low cholesterol

Answer: C) Smoking

Explanation: Smoking is a major risk factor for cardiovascular disease as it damages blood vessels and promotes the buildup of plaques.

MCQ 148:
What is the purpose of the pulmonary artery?

A) Carry oxygenated blood to the body
B) Carry deoxygenated blood to the lungs
C) Return deoxygenated blood to the heart
D) Supply blood to the brain

Answer: B) Carry deoxygenated blood to the lungs

Explanation: The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs for oxygenation.

MCQ 149:
What is the function of the myocardium?

A) Protect the heart
B) Contract to pump blood
C) Filter blood
D) Generate electrical impulses

Answer: B) Contract to pump blood

Explanation: The myocardium is the muscular layer of the heart responsible for the contraction and pumping of blood throughout the circulatory system.

MCQ 150:
Which blood component plays a key role in immune responses and inflammation?

A) Plasma
B) Erythrocytes
C) Platelets
D) Leukocytes

Answer: D) Leukocytes

Explanation: Leukocytes are crucial for immune responses, helping to identify and eliminate pathogens and participating in inflammation.