Class 11 Biology MCQ – Body Fluids and Circulation

1. Which component of blood helps in clotting?

a) Red blood cells
b) White blood cells
c) Platelets
d) Plasma

Answer:

c) Platelets

Explanation:

Platelets are responsible for blood clotting, preventing excessive bleeding during injuries.

2. Which chamber of the heart receives oxygenated blood from the lungs?

a) Right atrium
b) Right ventricle
c) Left atrium
d) Left ventricle

Answer:

c) Left atrium

Explanation:

The left atrium receives oxygen-rich blood from the lungs via the pulmonary veins.

3. What is the largest artery in the human body?

a) Pulmonary artery
b) Carotid artery
c) Aorta
d) Femoral artery

Answer:

c) Aorta

Explanation:

The aorta is the main and largest artery in the human body, originating from the left ventricle of the heart.

4. Which protein in blood carries oxygen to different parts of the body?

a) Albumin
b) Hemoglobin
c) Fibrin
d) Globulin

Answer:

b) Hemoglobin

Explanation:

Hemoglobin, present in red blood cells, binds to oxygen and transports it to various body tissues.

5. Which part of the human body is called the 'blood bank'?

a) Heart
b) Kidneys
c) Liver
d) Spleen

Answer:

d) Spleen

Explanation:

The spleen stores blood and releases it during emergencies, earning it the nickname 'blood bank'.

6. Which type of blood vessel carries blood away from the heart?

a) Veins
b) Capillaries
c) Arteries
d) Venules

Answer:

c) Arteries

Explanation:

Arteries carry blood away from the heart to various parts of the body.

7. What percentage of plasma is water?

a) 55%
b) 70%
c) 90%
d) 95%

Answer:

c) 90%

Explanation:

Plasma, the liquid component of blood, is about 90% water.

8. Which blood component is responsible for immune responses?

a) Red blood cells
b) White blood cells
c) Platelets
d) Plasma

Answer:

b) White blood cells

Explanation:

White blood cells play a vital role in the body's immune response, defending against pathogens.

9. Which chamber of the heart pumps oxygenated blood to the body?

a) Right atrium
b) Right ventricle
c) Left atrium
d) Left ventricle

Answer:

d) Left ventricle

Explanation:

The left ventricle pumps oxygen-rich blood to the body via the aorta.

10. The 'double circulation' in mammals refers to the separate circulation of blood through:

a) Heart and lungs
b) Arteries and veins
c) Lungs and body tissues
d) Upper and lower body

Answer:

c) Lungs and body tissues

Explanation:

Double circulation means that blood passes through the heart twice: once through the pulmonary circuit (lungs) and once through the systemic circuit (body tissues).

11. The heartbeat is initiated by:

a) SA node
b) AV node
c) Bundle of His
d) Purkinje fibers

Answer:

a) SA node

Explanation:

The sinoatrial (SA) node, located in the right atrium, initiates the heartbeat and is known as the natural pacemaker.

12. Which blood vessels have the thinnest walls?

a) Arteries
b) Veins
c) Capillaries
d) Venules

Answer:

c) Capillaries

Explanation:

Capillaries have the thinnest walls, facilitating the exchange of substances with tissues.

13. Which blood protein helps maintain osmotic balance?

a) Hemoglobin
b) Globulin
c) Fibrinogen
d) Albumin

Answer:

d) Albumin

Explanation:

Albumin helps maintain the osmotic balance of blood by regulating the amount of water in the blood.

14. Which part of the heart prevents the backflow of blood from the ventricles to the atria?

a) Aortic valve
b) Pulmonary valve
c) Bicuspid valve
d) Tricuspid valve

Answer:

d) Tricuspid valve

Explanation:

The tricuspid valve prevents backflow from the right ventricle to the right atrium.

15. Which type of blood vessel connects arteries and veins?

a) Sinusoids
b) Arterioles
c) Capillaries
d) Venules

Answer:

c) Capillaries

Explanation:

Capillaries connect arterioles (small arteries) and venules (small veins), facilitating the exchange of substances.

16. The ‘universal donor’ blood type is:

a) A+
b) B+
c) AB+
d) O-

Answer:

d) O-

Explanation:

O- blood type lacks antigens on its red blood cells, making it a universal donor.

17. The heart's sound "lub-dub" is created by the closing of:

a) Atrioventricular and semilunar valves
b) Tricuspid and bicuspid valves
c) Aortic and pulmonary valves
d) Vena cava and pulmonary vein

Answer:

a) Atrioventricular and semilunar valves

Explanation:

The "lub" sound is due to the closing of atrioventricular valves, and the "dub" sound is due to the closing of semilunar valves.

18. Blood pressure is highest in:

a) Capillaries
b) Veins
c) Arteries
d) Venules

Answer:

c) Arteries

Explanation:

Blood pressure is highest in arteries as they carry blood pumped directly from the heart.

19. Which hormone increases the heartbeat rate?

a) Insulin
b) Glucagon
c) Adrenaline
d) Thyroxine

Answer:

c) Adrenaline

Explanation:

Adrenaline, the "fight or flight" hormone, increases the heartbeat rate in response to stress or danger.

20. Lymph primarily differs from blood in that it lacks:

a) White blood cells
b) Plasma
c) Platelets
d) Red blood cells

Answer:

d) Red blood cells

Explanation:

Lymph is similar to blood plasma but lacks red blood cells.

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