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

MCQ 101:
What is the main component of plasma?

A) Red blood cells
B) White blood cells
C) Water
D) Platelets

Answer: C) Water

Explanation: Plasma is composed of about 90% water, which serves as a solvent for transporting nutrients, hormones, and waste products.

MCQ 102:
Which blood component is primarily responsible for oxygen transport?

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

Answer: C) Erythrocytes

Explanation: Erythrocytes, or red blood cells, contain hemoglobin, which binds to oxygen and transports it throughout the body.

MCQ 103:
What is the role of the sinoatrial (SA) node?

A) Pump blood
B) Generate electrical impulses to initiate heartbeats
C) Filter blood
D) Regulate blood pressure

Answer: B) Generate electrical impulses to initiate heartbeats

Explanation: The SA node, located in the right atrium, acts as the heart’s natural pacemaker, generating electrical impulses that initiate each heartbeat.

MCQ 104:
What condition is characterized by high blood pressure?

A) Hypotension
B) Hypertension
C) Anemia
D) Tachycardia

Answer: B) Hypertension

Explanation: Hypertension refers to abnormally high blood pressure, which can lead to various cardiovascular issues.

MCQ 105:
Which of the following is a function of the spleen?

A) Pump blood
B) Store oxygen
C) Filter blood and recycle iron
D) Produce hormones

Answer: C) Filter blood and recycle iron

Explanation: The spleen filters blood, removes old red blood cells, and recycles iron, playing a vital role in the immune system.

MCQ 106:
What does the term “bradycardia” refer to?

A) Rapid heart rate
B) Irregular heartbeat
C) Slow heart rate
D) High blood pressure

Answer: C) Slow heart rate

Explanation: Bradycardia is defined as a slower than normal heart rate, usually below 60 beats per minute.

MCQ 107:
Which type of immunity is provided by antibodies?

A) Innate immunity
B) Adaptive immunity
C) Passive immunity
D) Active immunity

Answer: B) Adaptive immunity

Explanation: Adaptive immunity involves the production of specific antibodies against pathogens, providing a targeted response to infections.

MCQ 108:
What is the primary function of capillaries?

A) Transport blood
B) Regulate blood pressure
C) Exchange substances between blood and tissues
D) Pump blood

Answer: C) Exchange substances between blood and tissues

Explanation: Capillaries are tiny blood vessels where the exchange of gases, nutrients, and waste products occurs between blood and surrounding tissues.

MCQ 109:
What is the role of the pericardium?

A) Pump blood
B) Provide structural support to the heart
C) Protect the heart and reduce friction
D) Generate electrical impulses

Answer: C) Protect the heart and reduce friction

Explanation: The pericardium is a fibrous sac that surrounds the heart, providing protection and reducing friction during heartbeats.

MCQ 110:
Which hormone is primarily responsible for increasing blood pressure?

A) Insulin
B) Adrenaline
C) Estrogen
D) Thyroxine

Answer: B) Adrenaline

Explanation: Adrenaline (epinephrine) increases heart rate and constricts blood vessels, leading to an increase in blood pressure.