MCQs on Body Fluids and Circulation – NCERT Class 11 Biology

MCQs on Body Fluids and Circulation – CBSE Class 11 Biology (Unit V | NCERT-Based)

CBSE Class 11 Biology – MCQs with Answers and Explanations

Unit V: Human Physiology

Topic: Body Fluids and Circulation

Section A: Body Fluids – Blood, Plasma & Lymph (Q1–Q10)

Q1. The fluid connective tissue that transports substances in the body is:

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

Answer: C
Explanation: Blood is a fluid connective tissue that transports gases, nutrients, hormones, and wastes.

Q2. The liquid part of blood without clotting factors is called:

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

Answer: B
Explanation: Serum is plasma without fibrinogen and clotting factors.

Q3. Which component constitutes about 55% of blood volume?

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

Answer: D
Explanation: Plasma forms the liquid matrix of blood (~55%).

Q4. The most abundant protein in plasma is:

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

Answer: C
Explanation: Albumin maintains osmotic balance and transports substances.

Q5. Which plasma protein helps in blood clotting?

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

Answer: C
Explanation: Fibrinogen is converted to fibrin during clotting.

Q6. Red blood cells are also called:

A. Leukocytes
B. Thrombocytes
C. Erythrocytes
D. Lymphocytes

Answer: C
Explanation: RBCs are known as erythrocytes.

Q7. Normal RBC count in human blood is about:

A. 1–2 million/mm³
B. 3–4 million/mm³
C. 5–5.5 million/mm³
D. 7–8 million/mm³

Answer: C
Explanation: Normal adult RBC count is ~5 million/mm³.

Q8. Which pigment is present in RBCs?

A. Myoglobin
B. Chlorophyll
C. Hemoglobin
D. Melanin

Answer: C
Explanation: Hemoglobin binds and transports oxygen and carbon dioxide.

Q9. Mature mammalian RBCs lack:

A. Cell membrane
B. Hemoglobin
C. Nucleus
D. Cytoplasm

Answer: C
Explanation: Absence of nucleus allows more space for hemoglobin.

Q10. Lymph differs from blood because it:

A. Contains RBCs
B. Has high protein content
C. Lacks RBCs and platelets
D. Is red in colour

Answer: C
Explanation: Lymph lacks RBCs and platelets and has fewer proteins.

Section B: Blood Groups & Coagulation (Q11–Q20)

Q11. Blood grouping is based on presence of:

A. Enzymes
B. Hormones
C. Antigens on RBCs
D. Proteins in plasma

Answer: C
Explanation: Antigens on RBC membranes determine blood groups.

Q12. Which blood group is known as universal donor?

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

Answer: D
Explanation: Group O lacks A and B antigens.

Q13. Which blood group is universal recipient?

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

Answer: D
Explanation: AB group has no antibodies against A or B.

Q14. Rh factor is a type of:

A. Antibody
B. Enzyme
C. Antigen
D. Hormone

Answer: C
Explanation: Rh factor is an antigen present on RBCs.

Q15. Rh incompatibility is dangerous during:

A. First pregnancy
B. Second pregnancy
C. Childhood
D. Puberty

Answer: B
Explanation: Maternal antibodies affect subsequent Rh⁺ foetus.

Q16. Blood clotting involves conversion of:

A. Fibrinogen to fibrin
B. Prothrombin to thrombin
C. Thrombin to fibrinogen
D. Fibrin to fibrinogen

Answer: A
Explanation: Fibrin forms a mesh to stop bleeding.

Q17. Vitamin required for blood clotting is:

A. Vitamin A
B. Vitamin B
C. Vitamin C
D. Vitamin K

Answer: D
Explanation: Vitamin K is essential for prothrombin synthesis.

Q18. Platelets are also called:

A. Leukocytes
B. Erythrocytes
C. Thrombocytes
D. Lymphocytes

Answer: C
Explanation: Platelets help in blood clotting.

Q19. Decrease in platelet count leads to:

A. Anemia
B. Leukemia
C. Thrombocytopenia
D. Hemophilia

Answer: C
Explanation: Low platelets cause excessive bleeding.

Q20. Hemophilia is a disorder related to:

A. RBCs
B. WBCs
C. Platelets
D. Clotting factors

Answer: D
Explanation: Hemophilia results from deficiency of clotting factors.

Section C: Heart – Structure & Cardiac Cycle (Q21–Q35)

Q21. Human heart is located between:

A. Two lungs
B. Two kidneys
C. Liver and stomach
D. Brain and lungs

Answer: A
Explanation: Heart lies in thoracic cavity between lungs.

Q22. Human heart has how many chambers?

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

Answer: C
Explanation: Two atria and two ventricles form four chambers.

Q23. The chamber with thickest wall is:

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

Answer: D
Explanation: Left ventricle pumps blood to entire body.

Q24. Which valve prevents backflow from left ventricle to left atrium?

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

Answer: B
Explanation: Bicuspid (mitral) valve prevents backflow.

Q25. The valve present between right atrium and right ventricle is:

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

Answer: C
Explanation: Tricuspid valve ensures unidirectional flow.

Q26. The pacemaker of the heart is:

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

Answer: B
Explanation: SA node initiates cardiac impulse.

Q27. One complete heartbeat is called:

A. Pulse
B. Cardiac output
C. Cardiac cycle
D. Heart rate

Answer: C
Explanation: Cardiac cycle includes systole and diastole.

Q28. Duration of one cardiac cycle is approximately:

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

Answer: C
Explanation: One cardiac cycle lasts 0.8 seconds.

Q29. Lub sound of heart is produced due to:

A. Opening of valves
B. Closing of semilunar valves
C. Closing of atrioventricular valves
D. Blood flow in arteries

Answer: C
Explanation: “Lub” is due to closure of AV valves.

Q30. Dub sound is caused by:

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

Answer: C
Explanation: “Dub” occurs due to closure of semilunar valves.

Q31. Cardiac output is defined as:

A. Blood pumped per beat
B. Blood pumped per minute
C. Heart rate
D. Stroke volume

Answer: B
Explanation: Cardiac output = stroke volume × heart rate.

Q32. Normal heart rate in adults is about:

A. 40–50/min
B. 60–70/min
C. 72/min
D. 100/min

Answer: C
Explanation: Average resting heart rate is ~72 beats/min.

Q33. Stroke volume refers to:

A. Blood pumped per minute
B. Blood pumped per beat
C. Total blood volume
D. Plasma volume

Answer: B
Explanation: Stroke volume is ~70 mL per beat.

Q34. The heart muscle is called:

A. Smooth muscle
B. Skeletal muscle
C. Cardiac muscle
D. Voluntary muscle

Answer: C
Explanation: Cardiac muscle is involuntary and striated.

Q35. The right side of heart receives blood from:

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

Answer: C
Explanation: Vena cava brings deoxygenated blood to right atrium.

Section D: Blood Vessels, Circulation & Disorders (Q36–Q50)

Q36. Arteries carry blood:

A. Towards heart
B. Away from heart
C. Only oxygenated
D. Only deoxygenated

Answer: B
Explanation: Arteries carry blood away from heart.

Q37. Veins differ from arteries because veins:

A. Have thick walls
B. Lack valves
C. Carry blood under low pressure
D. Carry only oxygenated blood

Answer: C
Explanation: Veins have thin walls and valves.

Q38. Capillaries connect:

A. Arteries to arteries
B. Veins to veins
C. Arteries to veins
D. Heart to arteries

Answer: C
Explanation: Capillaries allow exchange of materials.

Q39. Double circulation means blood passes through heart:

A. Once
B. Twice
C. Thrice
D. Continuously

Answer: B
Explanation: Blood passes heart twice in one cycle.

Q40. Pulmonary circulation carries blood between:

A. Heart and body
B. Heart and lungs
C. Body and kidneys
D. Heart and brain

Answer: B
Explanation: Pulmonary circulation oxygenates blood in lungs.

Q41. Systemic circulation carries blood between:

A. Heart and lungs
B. Lungs and kidneys
C. Heart and body tissues
D. Heart and liver

Answer: C
Explanation: Systemic circulation supplies body tissues.

Q42. Blood pressure is measured using:

A. Spirometer
B. Hemocytometer
C. Sphygmomanometer
D. Electrocardiograph

Answer: C
Explanation: BP is measured with sphygmomanometer.

Q43. Normal blood pressure is:

A. 90/60 mm Hg
B. 110/70 mm Hg
C. 120/80 mm Hg
D. 140/90 mm Hg

Answer: C
Explanation: Normal BP is 120/80 mm Hg.

Q44. Hypertension refers to BP:

A. Below normal
B. Slightly low
C. Persistently high
D. Fluctuating

Answer: C
Explanation: Hypertension increases risk of heart diseases.

Q45. Which condition involves blockage of coronary arteries?

A. Angina pectoris
B. Atherosclerosis
C. Hypertension
D. Heart failure

Answer: B
Explanation: Fatty deposits narrow coronary arteries.

Q46. ECG records:

A. Blood pressure
B. Heart sounds
C. Electrical activity of heart
D. Blood flow

Answer: C
Explanation: ECG reflects electrical events of cardiac cycle.

Q47. Angina pectoris is caused due to:

A. Low blood sugar
B. Reduced oxygen supply to heart
C. Valve failure
D. Infection

Answer: B
Explanation: Inadequate oxygen to cardiac muscle causes chest pain.

Q48. Heart failure refers to:

A. Sudden cardiac arrest
B. Inability of heart to pump sufficient blood
C. Blocked arteries
D. Valve damage

Answer: B
Explanation: Heart cannot meet body’s circulatory demands.

Q49. Which blood vessel carries oxygenated blood from lungs to heart?

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

Answer: C
Explanation: Pulmonary veins carry oxygen-rich blood.

Q50. Body fluids and circulation are essential because they:

A. Digest food
B. Provide structural support
C. Transport materials and maintain homeostasis
D. Produce hormones

Answer: C
Explanation: Circulatory system ensures transport, regulation, and balance.