NCERT Exemplar Class 11 Biology Solutions Body Fluids and Circulation

Multiple Choice Questions
1.Which of the following cells does not exhibit phagocytic activity?
(a) Monocytes (b) Neutrophil
(c) Basophil (d) Macrophage
Solution. (c) : Basophils have less number of coarse granules. They release heparin, serotonin and histamine. They are probably like mast cells of connective tissue and are not phagocytic in nature. Macrophages are cells produced by the differentiation of monocytes in the tissues and are phagocytic in nature. Monocytes are the largest of all types of leucocytes. They are motile and phagocytic in nature and engulf bacteria and cellular debris. Neutrophils have fine granules, they are the most numerous of all leucocytes. They eat harmful germs and are, therefore, phagocytic in nature.

2.One of the common symptoms observed in people infected with dengue fever is
(a) significant decrease in RBC count
(b) significant decrease in WBC count
(c) significant decrease in platelets count
(d) significant increase in platelets count.
Solution.(c): Thrombocytopenia i.e., decrease in platelet count is one of the common symptoms observed in people infected with dengue fever.

3.Which among the followings is correct during each cardiac cycle?
(a) The volume of blood pumped out by the right and left ventricles is same.
(b) The volume of blood pumped out by the right and left ventricles is different.
(c) The volume of blood received by each atrium is different.
(d) The volume of blood received by the aorta and pulmonary artery is different.
Solution.(a):During a cardiac cycle, each ventricle pumps out approximately 70 mL . of blood, thus, both the ventricles pump out same volume of blood in each cardiac cycle.

4.Cardiac activity could be moderated by the autonomous neural system. Tick the correct answer.
(a) The parasympathetic system stimulates heart rate and stroke volume.
(b) The sympathetic system stimulates heart rate and stroke volume.
(c) The parasympathetic system decreases the heart rate but increase stroke volume.
(d) The sympathetic system decreases the heart rate but increase stroke volume.
Solution.(b) : A specialised neural centre in the medulla oblongata can moderate the cardiac function through autonomic nervous system (AN S). Neural signals through the sympathetic nerves (part of ANS) can increase the rate of heart beat, the strength of ventricular contraction and thereby the cardiac output. On the other hand, parasympathetic neural signals (another component of ANS) decrease the rate of heart beat, speed of conduction of action potential and thereby the cardiac output.

5.Mark the pair of substances among the following which is essential for coagulation of blood.
(a) Heparin and calcium ions
(b) Calcium ions and platelet factors
(c) Oxalates and citrates
(d) Platelet factors and heparin
Solution.(b) : Certain factors called clotting factors released by ‘the tissues at the site of injury initiate coagulation. Calcium ions play a very important role in clotting. Blood clotting can also be prevented in a test tube by adding a little oxalate or citrate. Oxalate or Citrate reacts with calcium to form an insoluble compound, so free calcium ions necessary for clotting are not available.

6.ECG depicts the depolarisation and repolarisation processes during the cardiac cycle, lathe ECG of a normal healthy individual one of the following
(a) Depolarisation of atria
(b) Repolarisation of atria
(c) Depolarisation of ventricles
(d) Repolarisation of ventricles
Solution.(b) : A normal ECG is composed of a P wave, QRS wave and a T Wave. P wave represents atrial depolarisation, QRS wave shows ventricular depolarisation and T wave represents ventricular repolarisation.

7.Which one of the following types of cells lack nucleus in humans?
(a) RBC (b) Neutrophils
(c) Eosinophils (d) Erythrocytes
Solution. (a, d) : Mature mammalian RBCs (or erythrocytes) do not have nucleus and some cell organelles. This increases the surface area of RBCs and enables them to contain more haemoglobin which is required for transport of gases.

8.Which one of the following blood cells is involved in antibody production?
(a) B-Lymphocytes (b) T-Lymphocytes
(c) RBCs (d) Neutrophils
Solution. (a) : Formation and maturation of B-lymphocytes take place in a bone marrow, primary lymphoid organs. B-cells transform into plasma cells. Mature plasma cells produce antibodies against invading antigens.

9.The cardiac impulse is initiated and conducted further upto ventricle. The correct sequence of conduction of impulse is
(a)
SA                   AV Node                      Purkinje                  AV
Node                                                      fibre                          Bundle
(b)
SA                   Purkinje                      AV Node                   AV
Node              fibre                                                                 Bundle
(c)
SA                   AV Node                      AV                              Purkinje
Node                                                     Bundle                      fibre
(d)
SA                  Purkinje                       AV                               AV Node
Node             fibre                              Bundle
Solution.(c)

10. Agranulocytes responsible for immune healthy individual one of the following waves is not represented. response of the body are
(a) basophils    (b) neutrophils
(c) eosinophils (d) lymphocytes.
Solution.(d): Lymphocytes are the agranulocytes involved in immune response of the body. Two types of lymphocytes are B- and T-lymphocytes. They produce antibodies to destroy microbes and their toxins reject grafts and kill tumour cells.

11 .The second heart sound (dubb) is associated with the closure of
(a) tricuspid valve
(b) semilunar valves
(c) bicuspid valve
(d) tricuspid and bicuspid valves.
Solution.(b) : During beginning of ventricular diastole the ventricles relax and the semilunar valves are closed. The second heart sound “dubb” is caused by the closure of semilunar valves and marks the end of ventricular systole. It lasts for 0.1 seconds.

12 .Which of the following correctly explains a  phase/ event in cardiac cycle in a standard electrocardiogram?
(a) QRS complex indicates atrial contraction.
(b) QRS complex indicates ventricular contraction.
(c) Time between S and T represents atrial systole.
(d) P-wave indicates beginning of ventricular contraction.
Solution.(b) : A normal electrocardiogram (ECG) is composed of a P wave, a QRS wave (complex) and T wave. The P wave represents electrical excitation or the atrial depolarisation which leads to contraction of both the atria (atrial contraction). The QRS wave (complex) begins after a fraction of second of the P wave. It represents ventricular depolarisation (ventricular contraction). This wave is due to spread of electrical impulse through ventricles. The T wave represents ventricular repolarisation (ventricular relaxation). The S – T interval represents the time between the end of the spread of impulse through ventricles and its repolarisation. Thus, the S-T segment begins at the end of the S wave and terminates at the beginning of the T wave.

13. Which of the following statements is incorrect?
(a) A person of’O’ blood group has anti ‘A’ and anti ‘B’ antibodies in his blood plasma
(b) A person of’B’ blood group cannot donate blood to a person of’A’ blood group.
(c) Blood group is designated on the basis of the presence of antibodies in the blood plasma.
(d) A person of AB blood group is universal recipient.
Solution. (c) : Blood groups are designated on the basis of antigen present on the surface of their RBCs. e.g., Person with blood group A have antigen A on surface of their RBCs and antibody B in plasma. Incompatibility during blood transfusion leads to reaction between antigens on the cells and antibodies in plasma, which produces clots that clog Human ABO blood groups and their compat ¬ibility is shown as:
ncert-exemplar-class-11-biology-solutions-body-fluids-and-circulation-1

14.What would be the cardiac output of a person having 72 heart beats per minute and a stroke volume of 50 mL?
(a) 360 mL (b) 3600 mL
(c) 7200 mL (d) 5000 mL
Solution.(b) : Cardiac output = Heart beats/min  x Stroke volume  = 72 beats/min x 50 ml/beat = 3600 ml.

15.Match the terms given under Column ‘A’ with their functions given under Column ‘B’ and select the answer from the options given below:
Column A                                       Column B
A.LymphaticSystem                     i. Carries oxygenated blood
B.Pulmonary vein                        ii. Immune Response
C.Thrombocytes                         iii. To drain back the tissue fluid to the circulatory system
D.Lymphocytes                           iv. Coagulation of blood
Options:
(a) A-ii,   B-i, C-iii, D-iv
(b) A-iii, B-i, C-iv, D-ii
(c) A-iii, B-i, C-iii, D-iv
(d) A-ii, B-i, C-iii, D-iv
Solution. (b)

16. Read the following statements and choose the correct option.
Statement 1 : Atria receive blood from all parts of the body which subsequently flows to ventricles.
Statement 2 : Action potential generated at sino-atrial node passes from atria to ventricles.
(a) Action mentioned in Statement 1 is  dependent on action mentioned in Statement 2.
(b) Action mentioned in Statement 2 is  dependent on action mentioned in Statement 1.
(c) Actions mentioned in Statements 1 and 2 are independent of each other.
(d) Actions mentioned in Statements 1 and 2 are synchronous.
Solution.(d)

Very Short Answer Type Questions
1.Name the blood component which is viscous and straw coloured fluid.
Solution. Plasma is straw coloured, viscous fluid, slightly alkaline and aqueous solution which constitutes about 55% of the blood.

2.Complete the missing word in the statement given below:
(a) Plasma without_______factors is called  serum.
(b) _______and monocytes are  phagocytic cells.
(c) Eosinophils are associated with  reactions.
(d)_______ions play a significant role in  clotting.
(e) One can determine the heart beat rate by  counting the number of_______in an ECG.
Solution.
(a) Plasma without blood clotting factors is called serum.
(b) Neutrophils and monocytes are phagocytic cells.
(c) Eosinophils are associated with allergic reactions,
(d) Calcium ions play a significant role in clotting.
(e) One can determine the heart beat rate by counting the number of ORS complex in an ECG.

3.Given below is the diagrammatic represen-tation of a standard ECG. Label its different peaks.
Solution.
ncert-exemplar-class-11-biology-solutions-body-fluids-and-circulation-2
Fig.: Diagrammatic representation of standard ECG.

4.Name the vascular connection that exists between the digestive tract and liver.
Solution.Hepatic portal system is the vascular connection between the digestive tract and liver. The flow of deoxygenated blood from the digestive organs to the liver before returning to the heart is called hepatic portal circulation.

5.Given below are the abnormal conditions related to blood circulation. Name the disorders.
(a) Acute chest pain due to failure of 02 supply to heart muscles
(b) Increased systolic pressure
Solution. (a) Acute chest pain due to failure of 02 supply to heart muscles causes angina, also/called angina pectoris. In this disorder enough oxygen does not reach the heart muscles, resulting in acute chest pain.
(b) Increased systolic pressure results in hypertension (high blood pressure). The normal blood pressure is 120/80 mmHg (120- systolic and 80-diastolic pressure). Blood pressure persistently higher than normal, e.g., 140/90 mmHg (140-systolic pressure) or higher causes hypertension.

6. Which coronary artery disease is caused due to narrowing of the lumen of arteries?
Solution. Atherosclerosis is coronary artery disease (CAD) which results in narrowing of lumen of arteries. It occurs due to deposition of fatty substances specially chloesterol and triglycerides in wall of arteries, which grow to form plaques and reduces the blood flow.

7. Define the following terms and give their location.
(a) Purkinje fibre
(b) Bundle of His
Solution. (a) Purkinje fibre is an impulse conducting fibre present in myocardium of the ventricles, formed by branching of Bundle of His.
(b) Bundle of His is a mass of specialised fibres originating from AV node, present in the wall of right atrium.
Both Purkinje fibres and Bundle of His conduct impulse of contraction from the AV node to myocardium of the ventricles.

8. State the functions of the following in blood
(a) Fibrinogen
(b) Globulin
(c) Neutrophils
(d) Lymphocytes
Solution.(a) Fibrinogen – It is present in blood plasma and” helps in clotting.
(b) Globulin – It is a plasma protein which helps in defence mechanism.
(c) Neutrophils – These are the most abundant WBCs and are granulocytes. They destroy foreign organisms entering the body and thus are phagocytic cells.
(d) Lymphocytes – The leucocytes are agranulocytes and are non motile and non phagocytic. The are responsible for immune responses in the body (B-and T-lymphocytes).

9.What physiological circumstances lead to erythroblastosis foetalis?
Solution. Erythroblastosis foetalis is destruction of the erythrocytes of foetus. It occurs when the father’s blood group is Rh+ and mother’s blood group is Rh and results in the Rh+foetus (Rh+ is dominant). During first pregnancy, Rh” blood of mother comes in contact with Rh+  blood of foetus, resulting in formation of anti Rh antibodies in mother’s blood, It does not affect the first child but in subsequent Rh+ foetuses, anti Rh factors of the mother’s blood destroy the foetal red blood corpuscles.

10. Explain the consequences of a situation in which blood does not coagulate.
Solution. Inability of blood to coagulate due to absence of clotting factors can prolong the bleeding time and thus leads to loss of large amount of blood, which might led to death of the person.

11 .What is the significance of time gap in the  passage of action potential from sino-atrial node to the ventricle?
Solution. The time gap in the passage of action potential from sinoatrial node to the ventricles allows ventricles to relax. Thus, ventricular pressure falls, causing the closing of semilunar valves, and prevents the back flow of blood into ventricles.

12 .How will you interpret an electrocardiogram (ECG) in which time taken in QRS complex is higher?
Solution. The QRS complex in an electro-cardiogram (ECG) represents ventricular depolarisation, i.e., spread of impulse of contraction from atrio-ventricular node (AVN) to ventricles through Purkinje fibres and Bundle of His. Duration of normal QRS complex is less than 0.10 sec and the enlarged Q and R waves indicate myocardial infarction.

Short Answer Type Questions
1. The walls of ventricles are much thicker than atria. Explain.
Solution.The walls of ventricles are much thicker than atrial walls because ventricles exert more pressure to pump the blood to all the body parts. Right ventricle pumps oxygenated blood received from lungs to the left ventricle – and left ventricle pumps oxygenated blood to different body tissues. Wall of left ventricle is the thickest portion of human heart.

2. Differentiate between
(a) Blood and lymph
(b) Basophils and Eosinophils
(c) Tricuspid and bicuspid valve
Solution. (a) Differences between blood and lymph are:
ncert-exemplar-class-11-biology-solutions-body-fluids-and-circulation-3
(b)Differences between basophils and eosinophils are:
ncert-exemplar-class-11-biology-solutions-body-fluids-and-circulation-4
(c) Differences between tricuspid valve and bicuspid valve are:
ncert-exemplar-class-11-biology-solutions-body-fluids-and-circulation-5
(b) Angina pectoris – It is also called angina. It causes chest pain. In this disease enough oxygen does not reach the heart muscles and the patient experiences heart pain usually in front of the chest. It is more common among the middle aged and elderly people.
(c) Atherosclerosis or Coronary Artery Disease (CAD) – It refers to the deposition of fatty substances specially cholesterol and triglycerides in the tunica interna and smooth muscles of medium sized and large arteries which results in plaque formation, which deform the arterial wall. Gradually these plaques grow and as a result, the lumen of the artery decreases and the flow of the blood is reduced. In extreme cases these plaques may block the artery completely. This may result in heart attack or stroke.
(d) Hypertension (High blood pressure)- It is the common disease affecting heart and blood vessels. A blood pressure of 120/80 is considered normal, but the increase in blood pressure beyond 140 mm Hg (systolic) and 90 mm Hg (diastolic) is called high blood pressure (hypertension). High blood pressure can harm heart, brain, kidneys and eyes.

3.Briefly describe the following:
(a) Anaemia
(b) Angina pectoris
(c) Atherosclerosis
(d) Hypertension
(e) Heart failure
(f) Erythroblastosis foetalis
Solution.(a) Anaemia – It is due to the less amount, of haemoglobin. It may be caused by loss of blood (haemorrhage), destruction of RBCs (haemolysis or faulty formation of blood).
(b) Angina pectoris – It is also called angina. It causes chest pain. In this disease enough oxygen does not reach the heart muscles and the patient experiences heart pain usually in front of the chest. It is more common among the middle aged and elderly people.
(c) Atherosclerosis or Coronary Artery Disease (CAD) – It refers to the deposition of fatty substances specially cholesterol and triglycerides in the tunica interna and smooth muscles of medium sized and large arteries which results in plaque formation, which deform the arterial wall. Gradually these plaques grow and as a result, the lumen of the artery decreases and the flow of the blood is reduced. In extreme cases these plaques may block the artery completely. This may result in heart attack or stroke.
(d) Hypertension (High blood pressure)- It is the common disease affecting heart and blood vessels. A blood pressure of 120/80 is considered normal, but the increase in blood pressure beyond 140 mm Hg (systolic) and 90 mm Hg (diastolic) is called high blood pressure (hypertension). High blood pressure can harm heart, brain, kidneys and eyes.  Hypertension can be due to mental stress, tobacco smoking, intake of diet having high cholesterol.
(e) Heart failure – It is the state of heart when it does not pump blood effectively enough to meet the need of the body. Congestion of lungs is one of the main symptoms of this disease. Heart failure is not the same as cardiac arrest (when the heart stops beating) or a heart attack (when the heart muscle is suddenly damaged by inadequate blood supply).
(f) Erythroblastosis foetalis – It is the destruction of foetal erythrocytes in pregnancy resulting from Rh+ male and Rh” female where foetus blood is Rh+, resulting in formation of anti Rh antibodies in maternal blood.

4.Explain the advantage of the complete partition of ventricle among birds and mammals and hence leading to double circulation.
Solution. Birds and mammals have four chambered heart, with two atria and two ventricles. The inter-atrial septum separates left and right atria and left and right ventricles are separated by inter-ventricular septum. In four chambered heart, oxygenated and deoxygenated blood received by left and right atria respectively passes into left and right ventricles without getting mixed. Thus, birds and mammals have two separate circulatory pathways; systemic circulation and pulmonary circulation, therefore, known as double circulation.

5.What is the significance of hepatic portal system in the circulatory system?
Solution.Hepatic portal circulation is flow of deoxygenated blood from the digestive organs to’the liver before returning to the heart. In hepatic portal system, the blood enters the liver from two sources; the hepatic artery supplies oxygenated blood from the abdominal aorta and the hepatic portal vein carries deoxygenated blood from the digestive organs. Hepatic portal system is a characteristic feature of all vertebrates. Significance of hepatic portal circulation :
(i) The blood which comes from the alimentary canal contains absorbed food like glucose and amino acids. The excess of glucose in converted into glycogen which is stored in the liver for later use. When an individual feels deficiency of food, the glycogen is converted into glucose and is transferred to the blood stream via hepatic veins.
(ii)Harmful nitrogenous waste like ammo ¬
nia is converted into urea which is later removed by kidneys. Thus the blood is detoxified (purified) of harmful nitrogenous waste.
(iii)Liver produces blood proteins which are put into blood circulation.

6.Explain the functional significance of lymphatic system.
Solution. Lymphatic system is an elaborate network of vessels, which collects the interstitial fluid (tissue fluid), along with some protein molecules and drains it back into the major veins. The lymphatic vessels are present in all tissues (except the central nervous system and cornea). It comprises of lymph, lymphatic capillaries, lymphatic vessels, lymphatic ducts and lymphatic nodes.
Lymph performs the following important functions:
(i) It acts as an important carrier of nutrients, hormones, etc.
(ii)Absorption of fat also occurs through lymph in the lacteals present in the intestinal villi.
(iii)It helps in the renewal of extra cellular fluid (ECF).
(iv)Maturation of lymphocytes, i.e., B-cells and T-cells occur with the help of lymph nodes, releasing them into the lymph.
(v) It helps in keeping tissue cells moist.

7.Write the features that distinguish between the two
(a) Plasma and Serum
(b) Open and closed circulatory system
(c) Sino-atrial node and Atrio-ventricular
Solution.(a) Differences between plasma and serum are:
ncert-exemplar-class-11-biology-solutions-body-fluids-and-circulation-6
ncert-exemplar-class-11-biology-solutions-body-fluids-and-circulation-7
(b)Differences between open and closed circulatory system:
ncert-exemplar-class-11-biology-solutions-body-fluids-and-circulation-8
(c) Differences between sinoatrial node and atrio-ventricular node are:
ncert-exemplar-class-11-biology-solutions-body-fluids-and-circulation-9

8. Thrombocytes are essential for coagulation of blood. Comment.
Solution. Thrombocytes are also called blood platelets. When an injury is caused, the blood platelets release certain chemicals which ‘are called the platelet factors (e.g., thromboplastin). The platelet factors help in the clotting of blood.
ncert-exemplar-class-11-biology-solutions-body-fluids-and-circulation-10

9.Answer the following:
(a) Name the major formed.  Which part of heart is responsible for initiating and maintaining its rhythmic activity?  What is specific in the heart of crocodiles among reptilians?
Solution.(a) In the early few weeks of embryonic life, primitive nucleated RBCs are produced in the yolk sac. In later embryonic stage, RBCs are mainly produced by the liver and spleen. But from birth onwards, RBCs are produced by bone marrow.
(b) The heart beat originates from the sinoatrial node (SA node) known as the pace maker of the heart. The SA node is a mass of neuromuscular tissue, which lies in the wrall of the right atrium near the opening of the superior vena cava.
(c) Reptiles have 3-chambered heart (2 atria and 1 ventricle) with exception of crocodiles, which have four chambered heart (2 atria and 2 ventricles) like birds and mammals which does not allow mixing of oxygenated and deoxygenated blood due to the presence of inter atrial and inter ventricular septum between atria and ventricles respectively.

Long Answer Type Questions
1.Explain Rh-incompatibility in humans.
Solution.In Rh blood group, a person with Rh antigen on surface of red blood corpuscles is  Rh+ and the other who do not have this antigen areRh  Both  Rh+ and Rh individuals are phenotypically normal. The problem arises during blood transfusion and pregnancy.
(i) Incompatibility during blood transfusion: The first blood transfusion of  Rh+ blood to the person with Rh blood does not cause any harm. The Rh person develops anti Rh factors or antibodies in his/her blood and in second blood transfusion of  Rh+ blood to the Rh person, the latter’s anti Rh factors attack and destroy the red blood corpuscles of the donor.
(ii)Incompatibility during pregnancy – In marriage between Rh- woman and  Rh+  man, the foetus’ blood is  Rh+ (  Rh+ is dominant). The Rh+ blood of the foetus stimulates the formation of anti-Rh factors or antibodies in the mother’s blood yet enough anti Rh factors are not produced in the mother’s blood to harm the foetus. But in the subsequent  Rh+ foetuses, the anti Rh factors (antibodies) of the mother’s blood destroy the foetal red blood corpuscles. This results in haemolytic disease of the newborn (HDN). It is called erythroblastosis foetalis (destruction of the erythrocytes of foetus). New born may survive but it is often anaemic. In order to prevent HDN,  Rh mothers are injected with a defective anti  Rhantibody during all pregnancies carrying  Rh+ foetus. Marriage between  Rh woman and  Rh+ man is not recommended.

2.Describe the events in cardiac cycle. Explain “double circulation”.
Solution.The cardiac cycle consists of one heart beat or one cycle of contraction and relaxation of the cardiac muscle. During a heart beat there is contraction and relaxation of atria and ventricles. The contraction phase is called the systole while the relaxation phase  is called the diastole. When both the atria and ventricles are in diastole or relaxed phase, this is referred to as a joint diastole. During this phase, the blood flows from the superior and inferior venae cavae into the atria and from the atria to the respective ventricles through auriculo-ventricular valves. But there is no flow of blood from the ventricles to the aorta and pulmonary trunk as the semilunar valves remain closed.
The successive stages of the cardiac cycle are briefly described below:
(a) Atrial systole : The atria contract due to a wave of contraction, stimulated by the SA node. The blood is forced into the ventricles as the bicuspid and tricuspid valves are open.
(b) Beginning of ventricular systole: The ventricles begin to contract due to a wave of contraction, stimulated by the AV node. The bicuspid and tricuspid valves close immediately producing part of the first heart sound.
(c) Complete ventricular systole: When the ventricles complete their contraction, the blood flows into the pulmonary trunk and aorta as the semilunar valves open.
(d) Beginning of ventricular diastole : The ventricles relax and the semilunar valves are closed. This causes the second heart sound.
(e) Complete ventricular diastole : The tricuspid and bicuspid valves open when the pressure in the ventricles falls and blood flows from the atria into the ventricles. Contraction of the heart does not cause this blood flow, it is due to the fact that the pressure within the relaxed ventricles is less than that in the atria and veins.
The duration of a cardiac cycle is 0.8 sec. Double circulation: The heart of birds and mammals is four chambered, it comprises of 2 atria and 2 ventricles. Right and left atria are separated by inter-atrial septum and right and left ventricles are separated by inter-ventricular septum, thus, preventing the mixing of oxygenated and deoxygenated blood. It results in double  circulation which includes systemic and pulmonary circulation.  Systemic circulation is the flow of oxygenated blood from the left ventricle to all parts of the body and deoxygenated blood from various body parts to the right atrium. All systemic arteries arise from the aorta. All the veins of the systemic circulation bring deoxygenated blood into the superior vena cava, the inferior vena cava or the coronary sinus, which open into the right atrium. The purpose of systemic circulation is to carry oxygen and nutrients to body tissues and to remove carbon dioxide and other wastes from the tissues.
Pulmonary circulation is flow of deoxygenated blood from the right ventricle to the lungs and the return of oxygenated blood from the lungs to the left atrium. The pulmonary trunk arises from the right ventricle and then divides into the right pulmonary artery and left pulmonary artery which supply deoxygenated blood to the right and left lungs respectively. Exchange of gases takes place in the lungs.

3. Explain different types of blood groups and donor compatibility by making a table.
Solution. ABO blood groups in human beings were reported for first time by Karl Landsteiner. ABO blood groups are determined by the gene / (isoagglutinin). There are three alleles, IA, IB and 7 ° of this gene. Proteins produced by the /A and /ll alleles are called A antigen and B antigen respectively. People with blood group A have the A antigen on the surface of their RBCs, and antibodies to antigen B in their plasma. Persons with blood group B have B antigen on their RBCs, and antibodies against A antigen in their plasma. Individuals with AB blood group have both antigen A and antigen B on their RBCs, and no antibodies for either of the antigens in their plasma. Type O individuals are without A and B antigens on their RBCs, but have antibodies for both these antigens in their plasma. Individuals with blood group AB can receive blood of A, B or O group, while those with blood group O can donate blood to anyone. This is the most important blood group for transfusion. Thus person with blood group AB is called universal recipient and person with blood group O is called universal donor. If a blood transfusion is made between an incompatible donor and recipient, reaction of antigens on the cells and antibodies in the plasma produces clots and clog capillaries,
Table : Human ABO blood groups and their compatibility.
ncert-exemplar-class-11-biology-solutions-body-fluids-and-circulation-11

4.Write short note on the following:
(a) Hypertension
(b) Coronary Artery Disease
Solution.(a) Hypertension (High blood pressure)- It is the most common disease affecting the heart and blood vessels. A blood pressure of 120/80mmHg is considered normal. But the increase in blood pressure beyond 140mmHg (systolic) and 90mmHg (diastolic) is called high blood pressure (hypertension). It can harm heart, brain, kidneys and eyes.
Causative factors of hypertension: Generally, a diet full of extremely oily and greasy products, is known to increase cholesterol level, causing thickening of the arteries which results in high blood pressure. Tobacco smoking speeds up the heart rate, contracts blood vessels and raises blood pressure. Mental tension also causes hypertension. Kidney disorder may be a caus(e of high BR
(b) Coronary Artery Disease (CAD) : It is known as atheroscleorosis. It refers to
the deposition of fatty substances specially cholesterol and triglycerides in the tunica interna and smooth muscles of medium sized and large arteries resulting in forming the plaques which deform the arterial wall. Gradually these plaques grow and as a result, the lumen of the artery decreases and the flow of the blood is reduced. In extreme cases these plaques may block the artery completely. Formation of atheromatous plaque in coronary arteries reduces the bipod supply to the heart or may stop the blood supply due to complete blockage of the coronary arteries. This may result in heart attack or stroke.

5.In the diagrammatic presentation of heart given below, mark and label, SAN, AVN, bundle of His and Purkinje fibres.
ncert-exemplar-class-11-biology-solutions-body-fluids-and-circulation-12
Solution.
ncert-exemplar-class-11-biology-solutions-body-fluids-and-circulation-13