NCERT NEET Biology English Medium Part-1 | Chapter 15 : Body Fluids and Circulation.

NCERT NEET Biology English Medium Part-1 | Chapter 15 : Body Fluids and Circulation.

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Question 1: Which of the following plasma proteins is primarily responsible for maintaining the osmotic balance of the blood?

1. a) Fibrinogen.
2. b) Globulin.
3. c) Albumin.
4. d) Prothrombin.

Answer: c.

Question 2: In a healthy adult human, what is the average percentage of plasma in the blood and the water content in that plasma, respectively?

1. a) 45 percent and 90-92 percent.
2. b) 55 percent and 90-92 percent.
3. c) 55 percent and 6-8 percent.
4. d) 45 percent and 6-8 percent.

Answer: b.

Question 3: Identify the agranulocyte that acts as a highly active phagocytic cell in the blood.

1. a) Neutrophil.
2. b) Eosinophil.
3. c) Monocyte.
4. d) Basophil.

Answer: c.

Question 4: Which of the following leucocytes secretes histamine, serotonin, and heparin and is involved in inflammatory reactions?

1. a) Basophils.
2. b) Eosinophils.
3. c) Neutrophils.
4. d) Lymphocytes.

Answer: a.

Question 5: What is the average lifespan of a human erythrocyte, and where is it destroyed after this period?

1. a) 120 days, Liver.
2. b) 120 days, Spleen.
3. c) 100 days, Bone marrow.
4. d) 100 days, Spleen.

Answer: b.

Question 6: Serum can be defined as plasma minus which of the following components?

1. a) Calcium ions.
2. b) Formed elements.
3. c) Clotting factors.
4. d) Globulins.

Answer: c.

Question 7: A healthy adult has an average of how many grams of haemoglobin in every 100 ml of blood?

1. a) 10-12 gms.
2. b) 12-16 gms.
3. c) 16-20 gms.
4. d) 8-10 gms.

Answer: b.

Question 8: Megakaryocytes, which produce blood platelets, are specialized cells found in the:

1. a) Spleen.
2. b) Lymph nodes.
3. c) Bone marrow.
4. d) Liver.

Answer: c.

Question 9: Which of the following types of WBCs is most abundant in human blood?

1. a) Lymphocytes.
2. b) Monocytes.
3. c) Eosinophils.
4. d) Neutrophils.

Answer: d.

Question 10: Erythroblastosis foetalis can occur when:

1. a) Mother is Rh positive and foetus is Rh negative.
2. b) Mother is Rh negative and foetus is Rh positive.
3. c) Both mother and foetus are Rh negative.
4. d) Both mother and foetus are Rh positive.

Answer: b.

Question 11: A person with blood group AB is considered a universal recipient because their plasma contains:

1. a) Both anti-A and anti-B antibodies.
2. b) No natural antibodies against A and B antigens.
3. c) Neither A nor B antigens on RBCs.
4. d) Only anti-A antibodies.

Answer: b.

Question 12: The ABO blood grouping is primarily based on the presence or absence of two surface antigens on the:

1. a) Leucocytes.
2. b) Plasma.
3. c) Platelets.
4. d) Erythrocytes.

Answer: d.

Question 13: In the blood coagulation cascade, which enzyme catalyzes the conversion of inactive fibrinogen into fibrin?

1. a) Thrombokinase.
2. b) Prothrombin.
3. c) Thrombin.
4. d) Heparin.

Answer: c.

Question 14: Which specific metal ion plays an indispensable role in the blood clotting process?

1. a) Sodium ion.
2. b) Potassium ion.
3. c) Calcium ion.
4. d) Magnesium ion.

Answer: c.

Question 15: Thrombokinase, required to convert prothrombin to thrombin, is an enzyme complex formed by a series of linked enzymic reactions called a:

1. a) Glycolytic pathway.
2. b) Cascade process.
3. c) Feedback loop.
4. d) Bohr effect.

Answer: b.

Question 16: Interstitial fluid or tissue fluid has the same mineral distribution as that of:

1. a) Cytoplasm.
2. b) Plasma.
3. c) Pure water.
4. d) Whole blood.

Answer: b.

Question 17: Fats are absorbed through the lymph in specialized lymphatic vessels present in the intestinal villi known as:

1. a) Lacteals.
2. b) Capillaries.
3. c) Venules.
4. d) Sinuses.

Answer: a.

Question 18: Annelids and chordates share which of the following circulatory characteristics?

1. a) Open circulatory system.
2. b) Closed circulatory system.
3. c) Incomplete double circulation.
4. d) Haemocoel circulation.

Answer: b.

Question 19: Which of the following groups of animals possesses a three-chambered heart with two atria and a single ventricle?

1. a) Fishes and amphibians.
2. b) Amphibians and reptiles (except crocodiles).
3. c) Birds and mammals.
4. d) Crocodiles and birds.

Answer: b.

Question 20: In incomplete double circulation seen in amphibians, mixing of oxygenated and deoxygenated blood occurs in the:

1. a) Left atrium.
2. b) Right atrium.
3. c) Single ventricle.
4. d) Conus arteriosus.

Answer: c.

Question 21: The human heart is situated in the thoracic cavity, in between the two lungs, and is slightly tilted towards the:

1. a) Right side.
2. b) Left side.
3. c) Posterior side.
4. d) Anterior side.

Answer: b.

Question 22: The protective double-walled membranous bag enclosing the human heart is called the:

1. a) Pleura.
2. b) Pericardium.
3. c) Peritoneum.
4. d) Meninges.

Answer: b.

Question 23: The opening between the right atrium and the right ventricle is guarded by a valve formed of three muscular flaps called the:

1. a) Bicuspid valve.
2. b) Mitral valve.
3. c) Tricuspid valve.
4. d) Semilunar valve.

Answer: c.

Question 24: The bicuspid valve, also known as the mitral valve, regulates the flow of blood from the:

1. a) Right atrium to right ventricle.
2. b) Left atrium to left ventricle.
3. c) Right ventricle to pulmonary artery.
4. d) Left ventricle to aorta.

Answer: b.

Question 25: A specialized cardiac musculature distributed in the heart that possesses the highest auto-excitability and acts as the pacemaker is the:

1. a) Atrio-ventricular node (AVN).
2. b) Bundle of His.
3. c) Purkinje fibres.
4. d) Sino-atrial node (SAN).

Answer: d.

Question 26: The SAN generates an action potential that spreads to both atria, causing them to undergo simultaneous contraction known as:

1. a) Ventricular systole.
2. b) Atrial diastole.
3. c) Atrial systole.
4. d) Joint diastole.

Answer: c.

Question 27: What is the approximate duration of one complete cardiac cycle in a healthy resting human?

1. a) 0.1 seconds.
2. b) 0.3 seconds.
3. c) 0.4 seconds.
4. d) 0.8 seconds.

Answer: d.

Question 28: During a cardiac cycle, the volume of blood pumped out by each ventricle is approximately 70 mL, which is termed the:

1. a) Cardiac output.
2. b) End-diastolic volume.
3. c) Stroke volume.
4. d) Tidal volume.

Answer: c.

Question 29: Cardiac output can be defined and calculated as the product of:

1. a) Stroke volume and heart rate.
2. b) Blood pressure and heart rate.
3. c) Stroke volume and respiratory rate.
4. d) End-systolic volume and stroke volume.

Answer: a.

Question 30: The first heart sound (lub) is associated with the closure of the:

1. a) Semilunar valves.
2. b) Tricuspid and bicuspid valves.
3. c) Foramen ovale.
4. d) Eustachian valves.

Answer: b.

Question 31: The second heart sound (dub) is primarily associated with the closure of the:

1. a) Tricuspid valve.
2. b) Bicuspid valve.
3. c) Semilunar valves.
4. d) Thebesian valve.

Answer: c.

Question 32: In a standard ECG, the P-wave represents the electrical excitation or depolarisation of the:

1. a) Ventricles.
2. b) Atria.
3. c) Bundle of His.
4. d) Purkinje fibres.

Answer: b.

Question 33: In an electrocardiogram (ECG), the QRS complex specifically represents the:

1. a) Repolarisation of ventricles.
2. b) Depolarisation of atria.
3. c) Depolarisation of ventricles.
4. d) Repolarisation of atria.

Answer: c.

Question 34: The T-wave in a standard ECG signifies the return of the ventricles from excited to normal state, a process known as:

1. a) Repolarisation.
2. b) Depolarisation.
3. c) Hyperpolarisation.
4. d) Action potential generation.

Answer: a.

Question 35: The end of the T-wave in an ECG visually marks the end of:

1. a) Atrial systole.
2. b) Ventricular diastole.
3. c) Ventricular systole.
4. d) Joint diastole.

Answer: c.

Question 36: Double circulation implies that the blood passes through the heart twice during one complete cycle. It includes:

1. a) Renal circulation and portal circulation.
2. b) Pulmonary circulation and systemic circulation.
3. c) Open circulation and closed circulation.
4. d) Coronary circulation and lymphatic circulation.

Answer: b.

Question 37: Pulmonary circulation begins with the pumping of deoxygenated blood by the:

1. a) Left atrium.
2. b) Left ventricle.
3. c) Right atrium.
4. d) Right ventricle.

Answer: d.

Question 38: The systemic circulation provides nutrients, oxygen, and other essential substances to tissues and takes away carbon dioxide via the:

1. a) Pulmonary vein.
2. b) Pulmonary artery.
3. c) Aorta.
4. d) Vena cava.

Answer: c.

Question 39: A unique vascular connection exists between the digestive tract and liver, which carries blood from the intestine to the liver before it is delivered to the systemic circulation. It is called:

1. a) Renal portal system.
2. b) Hepatic portal system.
3. c) Hypophyseal portal system.
4. d) Coronary system.

Answer: b.

Question 40: Normal activities of the human heart are regulated intrinsically, meaning it is:

1. a) Neurogenic.
2. b) Myogenic.
3. c) Regulated entirely by the medulla oblongata.
4. d) Regulated by the cerebral cortex.

Answer: b.

Question 41: A special neural centre that can moderate the cardiac function through the autonomic nervous system (ANS) is located in the:

1. a) Cerebrum.
2. b) Hypothalamus.
3. c) Medulla oblongata.
4. d) Cerebellum.

Answer: c.

Question 42: Parasympathetic neural signals affect the heart by:

1. a) Increasing the rate of heartbeat and cardiac output.
2. b) Decreasing the rate of heartbeat and speed of conduction of action potential.
3. c) Increasing the strength of ventricular contraction.
4. d) Having no significant effect on cardiac output.

Answer: b.

Question 43: Adrenal medullary hormones can profoundly influence cardiac activity by:

1. a) Decreasing heart rate.
2. b) Increasing cardiac output.
3. c) Inhibiting the SA node.
4. d) Promoting vasodilation in the digestive system.

Answer: b.

Question 44: High blood pressure (Hypertension) is a clinical term for blood pressure that is consistently higher than:

1. a) 120/80 mm Hg.
2. b) 140/90 mm Hg.
3. c) 100/60 mm Hg.
4. d) 110/70 mm Hg.

Answer: b.

Question 45: In the measurement 120/80 mm Hg, the number 120 represents:

1. a) Diastolic pressure.
2. b) Venous pressure.
3. c) Systolic or pumping pressure.
4. d) Pulse pressure.

Answer: c.

Question 46: Coronary Artery Disease (CAD), characterized by deposits of calcium, fat, cholesterol, and fibrous tissue that make the lumen of arteries narrower, is also referred to as:

1. a) Atherosclerosis.
2. b) Arteriosclerosis.
3. c) Angina pectoris.
4. d) Heart failure.

Answer: a.

Question 47: A symptom of acute chest pain appears when no enough oxygen is reaching the heart muscle. This condition is termed as:

1. a) Myocardial infarction.
2. b) Heart block.
3. c) Angina pectoris.
4. d) Cardiac arrest.

Answer: c.

Question 48: The state of heart when it is not pumping blood effectively enough to meet the needs of the body is called:

1. a) Heart failure.
2. b) Heart attack.
3. c) Cardiac arrest.
4. d) Angina.

Answer: a.

Question 49: Heart failure is sometimes also called congestive heart failure because a major symptom of this disease is congestion of the:

1. a) Liver.
2. b) Kidneys.
3. c) Lungs.
4. d) Brain.

Answer: c.

Question 50: Cardiac arrest refers specifically to the condition where:

1. a) The heart muscle is suddenly damaged.
2. b) The heart stops beating completely.
3. c) The arteries are blocked by plaques.
4. d) Blood pressure remains consistently high.

Answer: b.

Question 51: The fluid that leaves the capillaries to form tissue fluid is nearly identical to plasma, EXCEPT that it lacks:

1. a) Glucose and amino acids.
2. b) Water and electrolytes.
3. c) Larger proteins and most formed elements.
4. d) Carbon dioxide and urea.

Answer: c.

Question 52: Which formed elements lack a nucleus in most mammals and possess a biconcave shape?

1. a) Eosinophils.
2. b) Lymphocytes.
3. c) Erythrocytes.
4. d) Monocytes.

Answer: c.

Question 53: If the stroke volume of an individual is 70 mL and their heart rate is 72 beats per minute, the cardiac output is approximately:

1. a) 4000 mL.
2. b) 5000 mL.
3. c) 6000 mL.
4. d) 7000 mL.

Answer: b.

Question 54: The bundle of His is a network of specialized muscle fibres found in the:

1. a) Wall of the atria.
2. b) Wall of the right ventricle only.
3. c) Inter-ventricular septum extending to ventricular walls.
4. d) Inter-atrial septum.

Answer: c.

Question 55: Which node is responsible for generating the maximum number of action potentials (70-75 per minute) in the heart?

1. a) Sino-atrial node (SAN).
2. b) Atrio-ventricular node (AVN).
3. c) Bundle of His.
4. d) Purkinje fibres.

Answer: a.

Question 56: The sequence of cyclical events taking place in the heart from the beginning of one heartbeat to the beginning of the next is called:

1. a) Systemic circulation.
2. b) Cardiac cycle.
3. c) Double circulation.
4. d) Stroke volume cycle.

Answer: b.

Question 57: During the initial stage of the cardiac cycle (joint diastole), the tricuspid and bicuspid valves are:

1. a) Completely closed.
2. b) Partially closed.
3. c) Open.
4. d) Fibrillating.

Answer: c.

Question 58: Atrial systole accounts for an increase in the flow of blood into the ventricles by approximately:

1. a) 10 percent.
2. b) 20 percent.
3. c) 30 percent.
4. d) 50 percent.

Answer: c.

Question 59: When ventricular pressure increases during ventricular systole, it first causes the closure of the:

1. a) Semilunar valves.
2. b) Tricuspid and bicuspid valves.
3. c) Sino-atrial node.
4. d) Pulmonary trunk.

Answer: b.

Question 60: The normal healthy resting heart rate in adult humans is around:

1. a) 60 - 65 beats per minute.
2. b) 70 - 75 beats per minute.
3. c) 80 - 85 beats per minute.
4. d) 90 - 100 beats per minute.

Answer: b.

Question 61: What clinical technique is routinely used to record the electrical activity of the heart over a complete cardiac cycle?

1. a) Electroencephalography (EEG).
2. b) Echocardiography (ECHO).
3. c) Electrocardiography (ECG).
4. d) Magnetic Resonance Imaging (MRI).

Answer: c.

Question 62: To obtain a standard ECG, a patient is typically connected to the machine using how many electrical leads?

1. a) Two (one to each wrist).
2. b) Three (one to each wrist and to the left ankle).
3. c) Four (one to each limb).
4. d) Six (on the chest only).

Answer: b.

Question 63: By counting the number of QRS complexes that occur in a given time period on an ECG, one can determine the:

1. a) Stroke volume of the patient.
2. b) Heart beat rate of an individual.
3. c) Cardiac output of the patient.
4. d) Blood pressure of the patient.

Answer: b.

Question 64: Annelids possess a closed circulatory system. This implies that their blood is:

1. a) Pumped into open sinuses.
2. b) Circulated through a closed network of blood vessels.
3. c) Directed primarily towards the gills for oxygenation.
4. d) Identical in composition to interstitial fluid.

Answer: b.

Question 65: Single circulation, where the heart pumps out only deoxygenated blood that is oxygenated by gills, is characteristic of:

1. a) Fishes.
2. b) Amphibians.
3. c) Reptiles.
4. d) Birds.

Answer: a.

Question 66: Crocodiles, unlike most other reptiles, possess a heart with:

1. a) Two chambers.
2. b) Three chambers.
3. c) Four chambers.
4. d) Five chambers.

Answer: c.

Question 67: In humans, the pulmonary artery carries deoxygenated blood from the right ventricle to the:

1. a) Left atrium.
2. b) Body tissues.
3. c) Lungs.
4. d) Liver.

Answer: c.

Question 68: The thick fibrous tissue separating the atrium and the ventricle of the same side is called the:

1. a) Inter-atrial septum.
2. b) Inter-ventricular septum.
3. c) Atrio-ventricular septum.
4. d) Chordae tendineae.

Answer: c.

Question 69: The walls of the ventricles are much thicker than those of the atria because:

1. a) They have to generate greater pressure to pump blood to distant organs.
2. b) They receive blood at a very low pressure.
3. c) They hold a much larger volume of blood permanently.
4. d) They are heavily innervated by parasympathetic nerves.

Answer: a.

Question 70: Chordae tendineae are special fibrous cords found within the heart that connect the:

1. a) Atria to the ventricles directly.
2. b) Semilunar valves to the aorta.
3. c) Ventricular walls to the SAN.
4. d) Tricuspid and bicuspid valve flaps to papillary muscles.

Answer: d.

Question 71: The systemic vein that returns deoxygenated blood from the upper body parts to the right atrium is the:

1. a) Pulmonary vein.
2. b) Superior vena cava.
3. c) Inferior vena cava.
4. d) Hepatic vein.

Answer: b.

Question 72: A small mass of specialized nodal tissue located in the lower left corner of the right atrium close to the atrio-ventricular septum is called:

1. a) Sino-atrial node (SAN).
2. b) Atrio-ventricular node (AVN).
3. c) Purkinje fibres.
4. d) Papillary muscle.

Answer: b.

Question 73: The right and left bundles derived from the AV bundle give rise to minute fibres distributed throughout the ventricular musculature called:

1. a) Nerve fibres.
2. b) Muscle spindles.
3. c) Purkinje fibres.
4. d) Collagen fibres.

Answer: c.

Question 74: During joint diastole, blood from the pulmonary veins and vena cava flows into the left and right ventricles respectively through the open:

1. a) Semilunar valves.
2. b) Eustachian valves.
3. c) Atrio-ventricular valves.
4. d) Thebesian valves.

Answer: c.

Question 75: Oxygenated blood from the lungs is carried to the left atrium by the:

1. a) Pulmonary artery.
2. b) Pulmonary veins.
3. c) Vena cava.
4. d) Aorta.

Answer: b.

Question 76: Which node sets the pace of the activities of the human heart?

1. a) AV node.
2. b) SA node.
3. c) Bundle of His.
4. d) Purkinje fibres.

Answer: b.

Question 77: The number of formed elements per cubic millimeter of blood normally is highest for:

1. a) Platelets.
2. b) Erythrocytes.
3. c) Neutrophils.
4. d) Lymphocytes.

Answer: b.

Question 78: A reduction in the number of blood platelets can lead to:

1. a) Anaemia.
2. b) Clotting disorders and excessive blood loss.
3. c) Immune deficiency.
4. d) Increased phagocytosis.

Answer: b.

Question 79: Which type of white blood cells resists infections and is associated with allergic reactions?

1. a) Basophils.
2. b) Monocytes.
3. c) Eosinophils.
4. d) Neutrophils.

Answer: c.

Question 80: 'B' and 'T' forms are the two major types of which of the following agranulocytes responsible for immune responses?

1. a) Monocytes.
2. b) Lymphocytes.
3. c) Neutrophils.
4. d) Basophils.

Answer: b.

Question 81: An Rh-ve individual receiving Rh+ve blood for the first time will:

1. a) Exhibit immediate severe agglutination.
2. b) Form specific antibodies against the Rh antigens.
3. c) Accept the blood without any future immune consequences.
4. d) Convert their own blood type to Rh+ve.

Answer: b.

Question 82: To prevent erythroblastosis foetalis in a subsequent pregnancy, an Rh-negative mother is administered:

1. a) Anti-Rh antibodies immediately after the delivery of her first Rh+ve child.
2. b) Rh antigens during the pregnancy.
3. c) Anti-A and anti-B antibodies before conception.
4. d) Immunosuppressants throughout the pregnancy.

Answer: a.

Question 83: Which mineral represents the major cation in extracellular fluids like plasma and interstitial fluid?

1. a) Potassium (K+).
2. b) Magnesium (Mg++).
3. c) Sodium (Na+).
4. d) Calcium (Ca++).

Answer: c.

Question 84: Lymphatic system ultimately drains the collected tissue fluid back into the:

1. a) Major arteries.
2. b) Interstitial spaces.
3. c) Major veins.
4. d) Kidneys.

Answer: c.

Question 85: The opening of the left ventricle into the aorta is provided with:

1. a) Bicuspid valves.
2. b) Tricuspid valves.
3. c) Semilunar valves.
4. d) Mitral valves.

Answer: c.

Question 86: The second heart sound 'dub' occurs when the ventricular pressure falls causing the closure of semilunar valves to prevent:

1. a) Forward flow of blood into the aorta.
2. b) Backflow of blood into the ventricles.
3. c) Backflow of blood into the atria.
4. d) Forward flow of blood into the pulmonary artery.

Answer: b.

Question 87: The T-wave represents the repolarisation of the ventricles. A flat T-wave on an ECG might clinically indicate:

1. a) Atrial hypertrophy.
2. b) Sufficient oxygen supply to the heart muscle.
3. c) Insufficient oxygen supply to the heart muscle (ischaemia).
4. d) Increased stroke volume.

Answer: c.

Question 88: Systemic circulation is highly significant because it ensures that:

1. a) Deoxygenated blood is converted to oxygenated blood.
2. b) Tissues receive oxygen and nutrients while wastes are carried away.
3. c) The liver receives direct oxygenated blood from the gut.
4. d) The lungs are supplied with nutrients.

Answer: b.

Question 89: Which component of the autonomic nervous system increases the heart rate and the strength of ventricular contraction?

1. a) Parasympathetic neural signals.
2. b) Sympathetic neural signals.
3. c) Vagus nerve.
4. d) Somatic motor nerves.

Answer: b.

Question 90: Sustained hypertension can lead to complications and primarily affects vital organs such as:

1. a) Skin and bones.
2. b) Brain and kidneys.
3. c) Lungs and liver.
4. d) Stomach and intestines.

Answer: b.

Question 91: Angina pectoris can occur in men and women of any age but it is most common among the:

1. a) Infants and teenagers.
2. b) Young adults.
3. c) Middle-aged and elderly.
4. d) Neonates.

Answer: c.

Question 92: The normal physiological function of the coronary circulation is to:

1. a) Supply oxygenated blood to the liver.
2. b) Supply oxygenated blood exclusively to the heart musculature.
3. c) Drain deoxygenated blood from the lungs.
4. d) Facilitate absorption of fats in the intestine.

Answer: b.

Question 93: Match the blood cells with their relative abundance in human blood: Neutrophils.

1. a) 60-65 percent.
2. b) 20-25 percent.
3. c) 6-8 percent.
4. d) 0.5-1 percent.

Answer: a.

Question 94: Lymph lacks which of the following crucial blood components?

1. a) Water.
2. b) Lymphocytes.
3. c) Erythrocytes and larger proteins.
4. d) Minerals like Na+ and Cl-.

Answer: c.

Question 95: Complete separation of oxygenated and deoxygenated blood occurs strictly in:

1. a) Fishes and amphibians.
2. b) Reptiles and amphibians.
3. c) Birds and mammals.
4. d) Fishes and reptiles.

Answer: c.

Question 96: In a normal electrocardiogram, which electrical event is invisible because it is masked by the QRS complex?

1. a) Atrial depolarisation.
2. b) Ventricular depolarisation.
3. c) Atrial repolarisation.
4. d) Ventricular repolarisation.

Answer: c.

Question 97: Myocardial infarction (heart attack) refers to the condition where:

1. a) Heart rhythm becomes irregular.
2. b) Heart muscle is suddenly damaged by an inadequate blood supply.
3. c) The heart valves fail to close properly.
4. d) The SA node stops generating action potentials completely.

Answer: b.

Question 98: A person has a blood type with no antigens on the RBC surface but both anti-A and anti-B antibodies in the plasma. The blood type is:

1. a) Group A.
2. b) Group B.
3. c) Group AB.
4. d) Group O.

Answer: d.

Question 99: If the parasympathetic nerve supplying the heart is severed, what will be the immediate physiological effect?

1. a) The heart will stop beating completely.
2. b) The heart rate will decrease.
3. c) The heart rate will increase.
4. d) Cardiac output will fall to zero.

Answer: c.

Question 100: Which of the following pathways correctly describes the flow of oxygenated blood in double circulation?

1. a) Lungs -> Pulmonary vein -> Left atrium -> Left ventricle -> Aorta -> Body tissues.
2. b) Body tissues -> Vena cava -> Right atrium -> Right ventricle -> Pulmonary artery -> Lungs.
3. c) Lungs -> Pulmonary artery -> Left atrium -> Left ventricle -> Aorta -> Body tissues.
4. d) Body tissues -> Vena cava -> Left atrium -> Left ventricle -> Aorta -> Lungs.

Answer: a.

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