NEET Biology Body Fluids and Circulation MCQs Set 12

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Chapter-wise Objective Questions: Body Fluids and Circulation

View or download the dedicated Body Fluids and Circulation MCQ resource below. Practicing these 50 objective questions regularly builds familiarity with standard exam patterns and helps secure higher marks in final Biology evaluations.

Multiple Choice Questions

Question 1: Match the animal group with the type of heart:
(a) Fishes (b) Amphibians (c) Crocodile (d) Mammals
(i) 4 chambered heart (ii) 3 chambered heart (iii) 2 chambered heart
(a) (a)-(i), (b)-(ii), (c)-(ii), (d)-(iii)
(b) (a)-(iii), (b)-(ii), (c)-(ii), (d)-(i)
(c) (a)-(iii), (b)-(ii), (c)-(i), (d)-(i)
(d) (a)-(iii), (b)-(i), (c)-(i), (d)-(ii)
Show Answer & Explanation

Answer: (c) (a)-(iii), (b)-(ii), (c)-(i), (d)-(i)

Explanation:
1. Fishes have a 2-chambered heart, amphibians a 3-chambered heart, and crocodiles and mammals a 4-chambered heart.

Teacher's Note:
1. Fishes have a 2-chambered heart, amphibians and most reptiles a 3-chambered heart, and crocodiles, birds and mammals a 4-chambered heart.
2. The SA node is the pacemaker; the cardiac cycle lasts 0.8 s and cardiac output is stroke volume multiplied by heart rate.

Question 2: In amphibians and reptiles, the left atrium receives oxygenated blood from the gills/lungs/skin and the right atrium gets the deoxygenated blood from other body parts. However, they get mixed up in the single ventricle which pumps out mixed blood called:-
(a) Incomplete single circulation
(b) Complete single circulation
(c) Incomplete double circulation
(d) Complete double circulation
Show Answer & Explanation

Answer: (c) Incomplete double circulation

Explanation:
1. Mixing of oxygenated and deoxygenated blood in the single ventricle gives incomplete double circulation.

Teacher's Note:
1. The first heart sound (lub) is due to closure of the AV valves and the second (dub) is due to closure of the semilunar valves.
2. Normal blood pressure is 120/80 mm Hg; hypertension is 140/90 mm Hg or above.

Question 3: The heart is __a__ derived organ, situated in the __b__ cavity between the two __c__, slightly tilted to the __d__.
(a) a - endodermally, b - thoracic, c - lungs, d - left
(b) a - mesodermally, b - thoracic, c - lungs, d - left
(c) a - mesodermally, b - thoracic, c - lungs, d - right
(d) a - endodermally, b - thoracic, c - lungs, d - left
Show Answer & Explanation

Answer: (b) a - mesodermally, b - thoracic, c - lungs, d - left

Explanation:
1. The heart is mesodermal in origin, lies in the thoracic cavity between the two lungs and is tilted slightly to the left.

Teacher's Note:
1. Among leucocytes neutrophils are the most abundant and basophils the least; serum is plasma without clotting factors.
2. Learn the sequence of pulmonary and systemic circulation and the hepatic portal system.

Question 4: Choose the wrong statement:
(a) The heart has the size of a clenched fist
(b) The heart is protected by a double walled membranous bag, the pericardium
(c) The human heart has four chambers, two relatively large upper chambers called atria and two smaller lower chambers called ventricles
(d) The atrium and ventricle of the same side are separated by a thick fibrous tissue called the atrio-ventricular septum
Show Answer & Explanation

Answer: (c) The human heart has four chambers, two relatively large upper chambers called atria and two smaller lower chambers called ventricles

Explanation:
1. The atria are the relatively small upper chambers and the ventricles are the larger lower chambers, so statement 3 is wrong.

Teacher's Note:
1. Fishes have a 2-chambered heart, amphibians and most reptiles a 3-chambered heart, and crocodiles, birds and mammals a 4-chambered heart.
2. The SA node is the pacemaker; the cardiac cycle lasts 0.8 s and cardiac output is stroke volume multiplied by heart rate.

Question 5: The opening between the right atrium and the right ventricle is guarded by a valve called __x__, whereas __y__ guards the opening between the left atrium and the left ventricle :-
(a) x is bicuspid valve, y is tricuspid valve
(b) x is semilunar valve, y is tricuspid valve
(c) x is bicuspid valve, y is semilunar valve
(d) x is tricuspid valve, y is bicuspid
Show Answer & Explanation

Answer: (d) x is tricuspid valve, y is bicuspid

Explanation:
1. The right atrium opens into the right ventricle through the tricuspid valve and the left atrium into the left ventricle through the bicuspid (mitral) valve.

Teacher's Note:
1. The first heart sound (lub) is due to closure of the AV valves and the second (dub) is due to closure of the semilunar valves.
2. Normal blood pressure is 120/80 mm Hg; hypertension is 140/90 mm Hg or above.

Question 6: Which of the following is considered as pacemaker of human heart?
(a) SA node
(b) AV node
(c) Purkinje fibres
(d) Bundle of His
Show Answer & Explanation

Answer: (a) SA node

Explanation:
1. The SA node generates the highest number of action potentials and is the pacemaker.

Teacher's Note:
1. Among leucocytes neutrophils are the most abundant and basophils the least; serum is plasma without clotting factors.
2. Learn the sequence of pulmonary and systemic circulation and the hepatic portal system.

Question 7: Which of the these has a double closed type of circulatory system ?
(a) Cockroach, Fish
(b) Fish, Frog
(c) Earthworm, Human
(d) Birds, Human
Show Answer & Explanation

Answer: (d) Birds, Human

Explanation:
1. Birds and humans have a closed, double circulation; fishes have single circulation and a cockroach has an open system.

Teacher's Note:
1. Fishes have a 2-chambered heart, amphibians and most reptiles a 3-chambered heart, and crocodiles, birds and mammals a 4-chambered heart.
2. The SA node is the pacemaker; the cardiac cycle lasts 0.8 s and cardiac output is stroke volume multiplied by heart rate.

Question 8: Role of pacemaker is :-
(a) To initiate and maintain the rhythmic contractile activity of the heart
(b) To initiate and maintain the arhythmic contractile activity of the heart
(c) To initiate and maintain the rhythmic contractile activity of blood vessels
(d) To generate minimum action potentials for initiating and maintaining the rhythmic contractile activity of the heart
Show Answer & Explanation

Answer: (a) To initiate and maintain the rhythmic contractile activity of the heart

Explanation:
1. The pacemaker initiates and maintains the rhythmic contractile activity of the heart; it generates the maximum number of action potentials.

Teacher's Note:
1. The first heart sound (lub) is due to closure of the AV valves and the second (dub) is due to closure of the semilunar valves.
2. Normal blood pressure is 120/80 mm Hg; hypertension is 140/90 mm Hg or above.

Question 9: Duration of a cardiac cycle:-
(a) 0.8 seconds
(b) 1.2 seconds
(c) 1.8 seconds
(d) 2.0 seconds
Show Answer & Explanation

Answer: (a) 0.8 seconds

Explanation:
1. One cardiac cycle lasts about 0.8 seconds at 72 beats per minute.

Teacher's Note:
1. Among leucocytes neutrophils are the most abundant and basophils the least; serum is plasma without clotting factors.
2. Learn the sequence of pulmonary and systemic circulation and the hepatic portal system.

Question 10: The second heart sound "dub" is associated with :-
(a) Opening of semilunar valves
(b) Opening of AV valves
(c) Closure of AV valves
(d) Closure of the semilunar valves
Show Answer & Explanation

Answer: (d) Closure of the semilunar valves

Explanation:
1. The second sound, dub, is produced by closure of the semilunar valves at the end of ventricular systole.

Teacher's Note:
1. Fishes have a 2-chambered heart, amphibians and most reptiles a 3-chambered heart, and crocodiles, birds and mammals a 4-chambered heart.
2. The SA node is the pacemaker; the cardiac cycle lasts 0.8 s and cardiac output is stroke volume multiplied by heart rate.

Question 11: A unique vascular connection exists between the digestive tract and liver called :-
(a) Renal portal system
(b) Hypophyseal portal system
(c) Gastric portal system
(d) Hepatic portal system
Show Answer & Explanation

Answer: (d) Hepatic portal system

Explanation:
1. The hepatic portal vein carries blood from the intestine to the liver, forming the hepatic portal system.

Teacher's Note:
1. The first heart sound (lub) is due to closure of the AV valves and the second (dub) is due to closure of the semilunar valves.
2. Normal blood pressure is 120/80 mm Hg; hypertension is 140/90 mm Hg or above.

Question 12: All arteries carry oxygenated blood except :-
(a) Hepatic
(b) Systemic
(c) Coronary
(d) Pulmonary
Show Answer & Explanation

Answer: (d) Pulmonary

Explanation:
1. The pulmonary artery carries deoxygenated blood to the lungs; the other arteries listed carry oxygenated blood.

Teacher's Note:
1. Among leucocytes neutrophils are the most abundant and basophils the least; serum is plasma without clotting factors.
2. Learn the sequence of pulmonary and systemic circulation and the hepatic portal system.

Question 13: The volume of blood pumped out by each ventricle per minute and average 5l in a healthy individual is called :-
(a) Stroke volume
(b) Joint diastole
(c) Cardiac output
(d) Ventricular diastole
Show Answer & Explanation

Answer: (c) Cardiac output

Explanation:
1. The volume of blood pumped by each ventricle per minute, about 5 litres, is the cardiac output.

Teacher's Note:
1. Fishes have a 2-chambered heart, amphibians and most reptiles a 3-chambered heart, and crocodiles, birds and mammals a 4-chambered heart.
2. The SA node is the pacemaker; the cardiac cycle lasts 0.8 s and cardiac output is stroke volume multiplied by heart rate.

Question 14: Cardiac output is :-
(a) Stroke volume x heart beat
(b) Stroke volume - heart beat
(c) Stroke volume + heart beat
(d) Stroke volume ÷ heart beat
Show Answer & Explanation

Answer: (a) Stroke volume x heart beat

Explanation:
1. Cardiac output equals stroke volume multiplied by heart rate.

Teacher's Note:
1. The first heart sound (lub) is due to closure of the AV valves and the second (dub) is due to closure of the semilunar valves.
2. Normal blood pressure is 120/80 mm Hg; hypertension is 140/90 mm Hg or above.

Question 15: Match the terms in Column I with Column II and Column III:
a1. Blood pressure, a2. Hypertension, a3. Hypotension
b1. Blood pressure higher than normal, b2. Blood pressure lower than normal, b3. Pressure applied by flowing blood on the walls of arteries
c1. 120/80 mm Hg, c2. 140/90 mm Hg, c3. 100/70 mm Hg
(a) a1-b3-c1, a2-b2-c2, a3-b1-c3
(b) a1-b3-c1, a2-b1-c2, a3-b2-c3
(c) a1-b2-c2, a2-b3-c3, a3-b1-c1
(d) a1-b1-c1, a2-b2-c2, a3-b3-c3
Show Answer & Explanation

Answer: (b) a1-b3-c1, a2-b1-c2, a3-b2-c3

Explanation:
1. Blood pressure is the pressure of flowing blood on artery walls (normal 120/80); hypertension is higher than normal (140/90) and hypotension lower than normal (100/70).

Teacher's Note:
1. Among leucocytes neutrophils are the most abundant and basophils the least; serum is plasma without clotting factors.
2. Learn the sequence of pulmonary and systemic circulation and the hepatic portal system.

Question 16: In humans, blood passes from the ventricles to the pulmonary artery and aorta due to :-
(a) Increase in atrial pressure
(b) Increase in ventricular pressure
(c) Decrease in ventricular pressure
(d) Suction pull
Show Answer & Explanation

Answer: (b) Increase in ventricular pressure

Explanation:
1. Blood leaves the ventricles for the pulmonary artery and aorta because ventricular pressure rises above the pressure in these vessels during systole.

Teacher's Note:
1. Fishes have a 2-chambered heart, amphibians and most reptiles a 3-chambered heart, and crocodiles, birds and mammals a 4-chambered heart.
2. The SA node is the pacemaker; the cardiac cycle lasts 0.8 s and cardiac output is stroke volume multiplied by heart rate.

Question 17: Cause of closure of semilunar valves in human heart is :-
(a) Ventricular diastole and increase in ventricular pressure
(b) Ventricular systole and increase in ventricular pressure
(c) Ventricular diastole and decrease in ventricular pressure
(d) Atrial diastole and decrease in atrial pressure
Show Answer & Explanation

Answer: (c) Ventricular diastole and decrease in ventricular pressure

Explanation:
1. The semilunar valves close when the ventricles relax (diastole) and ventricular pressure falls below that in the arteries.

Teacher's Note:
1. The first heart sound (lub) is due to closure of the AV valves and the second (dub) is due to closure of the semilunar valves.
2. Normal blood pressure is 120/80 mm Hg; hypertension is 140/90 mm Hg or above.

Question 18: During each cardiac cycle two prominent sounds are produced which can be easily heard through a :-
(a) Electro cardiograph
(b) Stethoscope
(c) Sphygmomanometer
(d) Galvanometer
Show Answer & Explanation

Answer: (b) Stethoscope

Explanation:
1. The two heart sounds are heard with a stethoscope.

Teacher's Note:
1. Among leucocytes neutrophils are the most abundant and basophils the least; serum is plasma without clotting factors.
2. Learn the sequence of pulmonary and systemic circulation and the hepatic portal system.

Question 19: Acute chest pain when no enough oxygen is reaching the heart muscle is called :-
(a) Heart failure
(b) Heart attack
(c) Cardiac arrest
(d) Angina pectoris
Show Answer & Explanation

Answer: (d) Angina pectoris

Explanation:
1. Angina pectoris is acute chest pain caused by insufficient oxygen supply to the heart muscle.

Teacher's Note:
1. Fishes have a 2-chambered heart, amphibians and most reptiles a 3-chambered heart, and crocodiles, birds and mammals a 4-chambered heart.
2. The SA node is the pacemaker; the cardiac cycle lasts 0.8 s and cardiac output is stroke volume multiplied by heart rate.

Question 20: Which of the following is not a function of sympathetic nervous system ?
(a) Increase the rate of heart beat
(b) Decrease the rate of heart beat
(c) Increase the cardiac output
(d) Increase the strength of ventricular contraction
Show Answer & Explanation

Answer: (b) Decrease the rate of heart beat

Explanation:
1. The sympathetic system increases heart rate and contraction strength and cardiac output; the parasympathetic system decreases the rate.

Teacher's Note:
1. The first heart sound (lub) is due to closure of the AV valves and the second (dub) is due to closure of the semilunar valves.
2. Normal blood pressure is 120/80 mm Hg; hypertension is 140/90 mm Hg or above.

Question 21: Which one of the statements is incorrect ?
(a) Factors for blood clotting present in blood plasma found in an inactive form
(b) Plasma without clotting factor is called serum
(c) Basophils are involved in inflammatory reactions
(d) Neutrophil are the most and eosinophils are the least among leucocytes
Show Answer & Explanation

Answer: (d) Neutrophil are the most and eosinophils are the least among leucocytes

Explanation:
1. Neutrophils are the most abundant leucocytes but basophils, not eosinophils, are the least.

Teacher's Note:
1. Among leucocytes neutrophils are the most abundant and basophils the least; serum is plasma without clotting factors.
2. Learn the sequence of pulmonary and systemic circulation and the hepatic portal system.

Question 22: Which of the following statements are true ?
(a) Albumin helps in osmotic balance.
(b) Plasma without the clotting factors is called serum.
(c) Globulins are involved in defence mechanism.
(d) All of these
Show Answer & Explanation

Answer: (d) All of these

Explanation:
1. Albumin maintains osmotic balance, globulins help in defence and serum is plasma without clotting factors, so all are true.

Teacher's Note:
1. Fishes have a 2-chambered heart, amphibians and most reptiles a 3-chambered heart, and crocodiles, birds and mammals a 4-chambered heart.
2. The SA node is the pacemaker; the cardiac cycle lasts 0.8 s and cardiac output is stroke volume multiplied by heart rate.

Question 23: A healthy individual has ...... gms of haemoglobin in every 100 ml of blood.
(a) 12-16 gm
(b) 16-20 gm
(c) 10-12 gm
(d) 9-12 gm
Show Answer & Explanation

Answer: (a) 12-16 gm

Explanation:
1. A healthy person has 12-16 g of haemoglobin per 100 mL of blood.

Teacher's Note:
1. The first heart sound (lub) is due to closure of the AV valves and the second (dub) is due to closure of the semilunar valves.
2. Normal blood pressure is 120/80 mm Hg; hypertension is 140/90 mm Hg or above.

Question 24: ............ are the most abundant cells of the total WBCs and ............. are the least among them.
(a) Acidophils, Basophils
(b) Basophils, Neutrophils
(c) Neutrophils, Monocyte
(d) Neutrophils, Basophils
Show Answer & Explanation

Answer: (d) Neutrophils, Basophils

Explanation:
1. Neutrophils (60-65 per cent) are the most abundant and basophils (0.5-1 per cent) the least abundant WBCs.

Teacher's Note:
1. Among leucocytes neutrophils are the most abundant and basophils the least; serum is plasma without clotting factors.
2. Learn the sequence of pulmonary and systemic circulation and the hepatic portal system.

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