Chapter 18: Body Fluids and Circulation – MCQs with Answers & Explanations

CBSE Class 11 Biology MCQs – Body Fluids and Circulation (NCERT-Based)

Course & Examination Details

• Course: CBSE Class 11 Biology
• Prescribed By: Central Board of Secondary Education
• Based On: NCERT
• Unit: Unit V – Human Physiology
• Chapter: Chapter 18 – Body Fluids and Circulation
• Question Type: Multiple Choice Questions (MCQs)
• Exam Relevance: CBSE Class 11 Annual Exam, Unit Tests, School Assessments

Section A: Blood (MCQ 1–20)

1. Blood is classified as a

A. Nervous tissue
B. Muscular tissue
C. Fluid connective tissue
D. Epithelial tissue

Correct Answer: C
Explanation:
Blood connects different body parts by transporting substances and is therefore classified as a connective tissue.

2. Which component forms about 55% of blood volume?

A. RBCs
B. WBCs
C. Plasma
D. Platelets

Correct Answer: C
Explanation:
Plasma constitutes approximately 55% of blood and acts as the transport medium.

3. The most abundant plasma protein is

A. Globulin
B. Fibrinogen
C. Albumin
D. Prothrombin

Correct Answer: C
Explanation:
Albumins maintain osmotic pressure and constitute the largest fraction of plasma proteins.

4. Which plasma protein is directly involved in blood clotting?

A. Albumin
B. Globulin
C. Fibrinogen
D. Haemoglobin

Correct Answer: C
Explanation:
Fibrinogen is converted into fibrin during blood clotting.

5. Red blood cells are enucleated in humans to

A. Increase immunity
B. Reduce size
C. Increase haemoglobin content
D. Increase lifespan

Correct Answer: C
Explanation:
Absence of nucleus provides more space for haemoglobin, enhancing oxygen transport.

6. Average lifespan of human RBCs is

A. 30 days
B. 60 days
C. 90 days
D. 120 days

Correct Answer: D
Explanation:
Human RBCs circulate for about 120 days before destruction.

7. Which blood cells are mainly responsible for immunity?

A. RBCs
B. Platelets
C. WBCs
D. Plasma

Correct Answer: C
Explanation:
White blood cells defend the body against pathogens.

8. Neutrophils primarily function in

A. Antibody production
B. Blood clotting
C. Phagocytosis
D. Allergic reactions

Correct Answer: C
Explanation:
Neutrophils engulf and destroy microbes by phagocytosis.

9. Platelets are formed from

A. Lymphocytes
B. Monocytes
C. Megakaryocytes
D. Erythrocytes

Correct Answer: C
Explanation:
Platelets are cell fragments derived from megakaryocytes in bone marrow.

10. Calcium ions are essential for

A. Oxygen transport
B. Immunity
C. Blood clotting
D. RBC formation

Correct Answer: C
Explanation:
Calcium ions act as cofactors in several steps of blood clotting.

11. Tissue fluid is formed from

A. Lymph
B. Blood plasma
C. RBC cytoplasm
D. Platelets

Correct Answer: B
Explanation:
Plasma filters out of capillaries to form tissue fluid.

12. Which fluid transports absorbed fats from intestine?

A. Plasma
B. Blood
C. Tissue fluid
D. Lymph

Correct Answer: D
Explanation:
Lymph carries absorbed fats from intestinal lacteals.

13. Erythropoiesis is regulated by the hormone

A. Insulin
B. Thyroxine
C. Erythropoietin
D. Adrenaline

Correct Answer: C
Explanation:
Erythropoietin stimulates RBC production in bone marrow.

14. Anaemia is caused by deficiency of

A. WBCs
B. Platelets
C. Haemoglobin
D. Plasma proteins

Correct Answer: C
Explanation:
Anaemia results from reduced haemoglobin concentration.

15. Which WBC type is involved in allergic reactions?

A. Neutrophils
B. Basophils
C. Monocytes
D. Lymphocytes

Correct Answer: B
Explanation:
Basophils release histamine during allergic responses.

16. Lymphocytes are important because they

A. Carry oxygen
B. Initiate clotting
C. Produce antibodies
D. Digest bacteria

Correct Answer: C
Explanation:
Lymphocytes play a central role in immune responses.

17. Blood clotting prevents

A. Oxygen loss
B. Water loss
C. Excessive blood loss
D. Infection

Correct Answer: C
Explanation:
Clotting seals damaged vessels to prevent blood loss.

18. The yellowish liquid portion of blood is

A. Serum
B. Plasma
C. Lymph
D. Tissue fluid

Correct Answer: B
Explanation:
Plasma is the liquid component containing proteins and solutes.

19. Which component is absent in lymph?

A. Proteins
B. WBCs
C. RBCs
D. Lipids

Correct Answer: C
Explanation:
Lymph lacks red blood cells.

20. Blood helps in regulation of body temperature by

A. Evaporation
B. Insulation
C. Distribution of heat
D. Metabolism

Correct Answer: C
Explanation:
Blood distributes heat uniformly throughout the body.

Section B: Heart & Blood Vessels (MCQ 21–35)

21. The human heart is located in the

A. Abdominal cavity
B. Thoracic cavity
C. Cranial cavity
D. Pelvic cavity

Correct Answer: B
Explanation:
The heart lies between the lungs in the thoracic cavity.

22. The protective covering of the heart is

A. Pleura
B. Peritoneum
C. Pericardium
D. Endocardium

Correct Answer: C
Explanation:
Pericardium encloses and protects the heart.

23. Human heart has how many chambers?

A. Two
B. Three
C. Four
D. Five

Correct Answer: C
Explanation:
Two atria and two ventricles form a four-chambered heart.

24. Valve between left atrium and left ventricle is

A. Tricuspid
B. Semilunar
C. Mitral
D. Pulmonary

Correct Answer: C
Explanation:
The bicuspid or mitral valve separates left atrium and ventricle.

25. The thickest wall is present in

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

Correct Answer: D
Explanation:
Left ventricle pumps blood to the whole body at high pressure.

26. The natural pacemaker of the heart is

A. AV node
B. SA node
C. Bundle of His
D. Purkinje fibres

Correct Answer: B
Explanation:
SA node initiates rhythmic impulses for heartbeat.

27. Human heart is myogenic because

A. Nerves control heartbeat
B. Muscles generate impulses
C. Hormones initiate heartbeat
D. Blood pressure controls beat

Correct Answer: B
Explanation:
Heartbeat originates from cardiac muscle itself.

28. Coronary arteries supply blood to

A. Brain
B. Lungs
C. Heart muscles
D. Kidneys

Correct Answer: C
Explanation:
Coronary circulation nourishes the heart muscle.

29. Arteries are characterized by

A. Thin walls and valves
B. Thick elastic walls
C. One-cell thick walls
D. Low pressure

Correct Answer: B
Explanation:
Arteries withstand high pressure due to thick elastic walls.

30. Valves are absent in

A. Veins
B. Arteries
C. Capillaries
D. Venules

Correct Answer: C
Explanation:
Capillaries are microscopic vessels without valves.

31. Capillaries are best suited for exchange because they have

A. Thick walls
B. Valves
C. One-cell thick walls
D. Elastic walls

Correct Answer: C
Explanation:
Thin walls facilitate diffusion of substances.

32. Double circulation ensures

A. Faster heartbeat
B. Mixing of blood
C. Efficient oxygen supply
D. Reduced blood pressure

Correct Answer: C
Explanation:
Oxygenated and deoxygenated blood remain separate.

33. Which vessel carries oxygenated blood from lungs to heart?

A. Pulmonary artery
B. Aorta
C. Pulmonary vein
D. Vena cava

Correct Answer: C
Explanation:
Pulmonary veins carry oxygenated blood to left atrium.

34. Hypertension refers to

A. Low blood pressure
B. High blood pressure
C. Normal blood pressure
D. Irregular heartbeat

Correct Answer: B
Explanation:
Hypertension is persistently elevated blood pressure.

35. Heart failure occurs when

A. Valves malfunction
B. Heart stops beating
C. Heart cannot pump enough blood
D. Blood pressure drops suddenly

Correct Answer: C
Explanation:
Heart failure is inadequate pumping ability.

Section C: Cardiac Cycle & Blood Groups (MCQ 36–50)

36. One complete cardiac cycle lasts about

A. 0.4 s
B. 0.6 s
C. 0.8 s
D. 1.2 s

Correct Answer: C
Explanation:
A normal heartbeat cycle takes about 0.8 seconds.

37. Atrial systole involves

A. Ventricular contraction
B. Atrial contraction
C. Relaxation of all chambers
D. Closure of semilunar valves

Correct Answer: B
Explanation:
Atria contract to fill ventricles.

38. ‘Lub’ sound of heart is due to

A. Opening of valves
B. Closure of semilunar valves
C. Closure of AV valves
D. Blood flow

Correct Answer: C
Explanation:
AV valve closure produces the first sound.

39. ‘Dub’ sound is produced by

A. AV valves
B. Semilunar valves
C. Atrial contraction
D. Ventricular relaxation

Correct Answer: B
Explanation:
Semilunar valve closure produces the second sound.

40. During joint diastole

A. Only atria relax
B. Only ventricles relax
C. All chambers relax
D. Ventricles contract

Correct Answer: C
Explanation:
All chambers are relaxed in joint diastole.

41. Blood group O has

A. Antigen A
B. Antigen B
C. Both antigens
D. No antigens

Correct Answer: D
Explanation:
O group lacks both A and B antigens.

42. Universal donor blood group is

A. A
B. B
C. AB
D. O

Correct Answer: D
Explanation:
Absence of antigens makes O group safe donor.

43. Universal recipient blood group is

A. A
B. B
C. AB
D. O

Correct Answer: C
Explanation:
AB group lacks antibodies.

44. Rh factor is

A. An antibody
B. A hormone
C. An antigen
D. An enzyme

Correct Answer: C
Explanation:
Rh is an antigen on RBC surface.

45. Rh incompatibility may cause

A. Anaemia
B. Leukemia
C. Erythroblastosis fetalis
D. Thrombosis

Correct Answer: C
Explanation:
Occurs in Rh- mother carrying Rh+ fetus.

46. Agglutination is due to

A. RBC rupture
B. Antigen-antibody reaction
C. Plasma protein loss
D. Platelet deficiency

Correct Answer: B
Explanation:
Mismatch causes clumping of RBCs.

47. Blood grouping is important before transfusion to

A. Increase immunity
B. Prevent clotting
C. Prevent agglutination
D. Improve circulation

Correct Answer: C
Explanation:
Incorrect transfusion can be fatal.

48. Sympathetic nerves

A. Decrease heart rate
B. Increase heart rate
C. Stop heartbeat
D. Do not affect heart

Correct Answer: B
Explanation:
Sympathetic stimulation raises heart rate.

49. Parasympathetic nerves

A. Increase heart rate
B. Decrease heart rate
C. Stop circulation
D. Increase blood pressure

Correct Answer: B
Explanation:
Parasympathetic action slows heartbeat.

50. Circulation is essential for homeostasis because it

A. Produces energy
B. Digests food
C. Maintains internal balance
D. Forms hormones

Correct Answer: C
Explanation:
Circulation distributes substances and regulates internal conditions.

NCERT & CBSE Compliance Note

✔ Strictly based on NCERT Class 11 Biology
✔ Concept-clearing explanations included
✔ Fully aligned with CBSE exam pattern
✔ Ideal for revision, practice, and assessments

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🎯 Targeting Exams

This MCQ practice set is useful for the following examinations:

• CBSE Class 11 Biology Annual Examination

• CBSE Unit Tests & Periodic Assessments

• NEET (UG) – Human Physiology Basics

• CUET (UG) – Biology Section

• State Board Class 11 Biology Exams

• Medical & Paramedical Entrance Foundation Courses

🔑 Related & Semantic Keyphrases

• Body Fluids and Circulation MCQs Class 11

• CBSE Class 11 Biology Chapter 18 MCQs

• NCERT Body Fluids and Circulation Objective Questions

• Human Physiology MCQs Class 11 Biology

• Blood and Circulation MCQs Class 11

• Cardiac Cycle and Blood Groups MCQs

• NCERT Class 11 Biology Online MCQ Practice

• Body Fluids and Circulation Exam Questions