Body Fluids and Circulation Class 11 Biology Exam Questions

Please refer to Body Fluids and Circulation Class 11 Biology Exam Questions provided below. These questions and answers for Class 11 Biology have been designed based on the past trend of questions and important topics in your class 11 Biology books. You should go through all Class 11 Biology Important Questions provided by our teachers which will help you to get more marks in upcoming exams.

Class 11 Biology Exam Questions Body Fluids and Circulation

Class 11 Biology students should read and understand the important questions and answers provided below for Body Fluids and Circulation which will help them to understand all important and difficult topics.

Objective Type Questions

Question. The chordae tendinae
(a) Close the AV valves
(b) prevent the AV valves flaps from reversing
(c) Open semilunar valve
(d) Are present in auricles

Question. How many double circulation are normally completed by human heart in one min?
(a) 8
(b) 16
(c) 36
(d) 72

Question. During systole of heart
(a) Only atria contract
(b) Only ventricles contract
(c) Auricles and ventricles contract separately
(d) Auricles and ventricles contract simultaneously

Question. When ventricular systole occurs?
(a) Auricular diastole coincides
(b) Tricuspid and bicuspid valve close
(c) Semilunar valves guarding pulmonary artery and aorta are forced to open
(d) All

Question. Which of the following events Do not occur during joint diastole?
A. All 4 chambers of heart are in relaxed state
B. Tricuspid and bicuspid valves open
C. Action potential is conducted from SAN to AVN
D. Blood from pulmonary veins and vena cava flows into left and right ventricle repesctively through the left and right atria
E. The semilunar valves are closed
Options :
(a) Only E
(b) Only C
(c) Only D
(d) Only A and B

Question. P-wave represents
(a) Depolarisation of ventricles
(b) Repolarisation of ventricle
(c) Repolarisation of atria
(d) Depolarisation of atria

Question. Which of the following is false statements?
(a) ECG is of great clinical significance
(b) Electrocardiogram is the recording of electrical changes during cardiac cyclye
(c) To obtain a standard ECG, a patient is connected to machine with 3 electrical leads
(d) Normal activity of heart are regulated intrinsically

Question. Which one of the following is not true?
(a) Cardiac output of an athlete is much higher than that of an ordinary man
(b) In each minute a single cardiac cycle is performed
(c) Cardiac sounds are of clinical diagnostics significance
(d) Cardiac cycle includes auricular systole ventricular systole joint diastole

Question. Which of the following is wrong for second cardiac sound
(a) It is heard as dub
(b) It is produced due to closer of semilunar valves
(c) It is clinically significant
(d) It is clinically non-significant

Question. Incomplete blood circulation is found in which of the following animals?
(a) Birds
(b) Mammals
(c) Birds and Mammals
(d) Amphibians and reptiles

Question. Which of the following is correct about human heart?
(a) The volume of both atria > the volume of both ventricles
(b) The volume of both ventricles > the volume of both atria
(c) The volume of both atria = the volume of both ventricles
(d) Ventricles are upper chambers and atria are lower chambers in our heart

Question. Tricuspid valve is present between
(a) Two atria
(b) Two ventricles
(c) Left atrium and left ventricles
(d) Right atrium and right ventricle

Question. Ventricles are thick Walled as compared to atrium because
(a) It is to receive blood from atria
(b) It is present on posterior side
(c) It is to pump blood
(d) None

Question. Match the column.

Column – I	Column – II
A. Superior vena cava	I. Carries deoxygenated blood to lungs
B. Inferior vena cava	II. Carries oxygenated blood from lungs
C. Pulmonary artery	III. Brings deoxygenated from lower part of body to right atrium
D. Pulmonary vein	IV. Brings deoxygenated blood from upper part of body to right atrium

Options :
(a) A – II, B – IV, C – III, D – I
(b) A – IV, B – I, C – II, D – III
(c) A – IV, B – III, C – I, D – II
(d) A – IV, B – I, C – III, D – II

Question. Heart of heart is
(a) SA – node
(b) AV – node
(c) Bundle of his
(d) Purkinje fibres

Question. SA node is pacemaker of heart, why?
(a) It can change contractile activity generated by AV node
(b) It delays the transmission of impulse between the atria and ventricles
(c) It gets stimulated when it receive neural signal
(d) It initiates and maintains the rhythmic contractile activity of heart

Question. The impulse of heart beat originates from
(a) SAN
(b) AVN
(c) Vagus nerve
(d) Cardiac nerve

Question. Bundle of his is a group of
(a) Ganglia
(b) Nerve fibres
(c) Muscular fibres
(d) Connective tissue

Question. Atrio ventricular node is situated in
(a) Lower left corner of left auricle, close to AV septum
(b) Lower left corner in right auricle, close to AV septum
(c) Upper left corner of right auricle, close to AV Septum
(d) Upper left corner of left auricle, close to AV septum

Very Short Answer Type Questions:

Question. Given below is the diagrammatic representation of a standard ECG. Label its different peaks.

Ans. The representation of a standard ECG diagram

Question. Given below are the abnormal conditions related to blood circulation.
Name the disorders
(a) Acute chest pain due to failure of O₂ supply to heart muscles
(b) Increased systolic pressure
Ans. (a) Angina also called as ‘angina pectoris’. It a symptom of acute chest pain that appears when there is no enough oxygen is reaching to the heart muscle. Angina can occur in men and women of any age but it is more common among the middle aged and elder people. It occurs due to condition that affect the blood flow (hypertension etc.)
(b) High Blood Pressure (hypertension) is the term for blood pressure that is higher than normal (120/80). In this measurement 120 mm Hg is the systolic, or pumping pressure and 80 mm Hg is the diastolic or resting pressure.
Increased systolic pressure, i.e., 140/80 or 150/80, shows hypertension. High blood pressure leads to heart diseases and also affects vital body organs like brain and kidney.

Question. What is the significance of time gap in the passage of action potential from sino-atrial node to the ventricle?
Ans. The time gap in the passage of action potential from sino-atrial 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.

Question.Which coronary artery diseases is caused due to narrowing of the lumen of arteries?
Ans. Atherosclerosis is the coronary artery disease caused due to the narrowing of the lumen of arteries. The narrowing of arteries occurs due to deposition of calcium, fat, cholesterol and fibrous tissue affecting vessels that supply blood to the heart muscles.

Question. Name the blood component which is viscous and straw coloured fluid.
Ans. Blood is a special connective tissue consisting of a fluid matrix, plasma and cells.
Plasma is a straw coloured, viscous fluid constituting of nearly 55 % of the blood, 90-92% of plasma is water and proteins contributes approx 6-8% . The plasma proteins contains fibrinogen, globulins and albumins.

Question. State the functions of the following in blood
(a) fibrinogen (b) globulin
(c) neutrophils (d) lymphocytes
Ans. (a) Fibrinogens are inactive components of blood plasma. Under the action of enzyme thrombin they form a clot or coagulum of a network of threads called fibrin in which dead and damaged elements of blood are trapped.
(b) Globulins are primarily involved in immunity, i.e., defence mechanisms of the body.
(c) Neutrophils are phagocytic cells which destroy foreign organisms entering the body.
(d) Lymphocytes are specialised cells which are responsible for the immune responses in the body. Two major types of lymphocytes, that are involved in this process are B and T-lymphocytes.

Question. Define the following terms and give their location?
(a) Purkinje fibre (b) Bundle of His
Ans. (a) Purkinje fibres are the impulse conducting fibres which relay the contraction impulses from AV node into the walls of ventricles.
(b) Bundle of His are mass of specialised fibres that originates from the AV node.

Question. How will you interpret an electrocardiogram (ECG) in which time taken in QRS complex is higher?
Ans. Electrocardiograph (ECG) is a graphical representation of the electrical activity of the heart during a cardiac cycle. A patient is connected to the machine with three electrical leads (one to each wrist and one to the left ankle) that continuously monitor the heart activity. For a detailed evaluation of the heart functions multiple leads are attached to the chest region.
The QRS complex represents the depolarisation of the ventricles, which initiates the ventricular contraction. The contraction starts shortly after Q and marks the beginning of the systole. The time taken in QRS complex is 0.12 second in normal ECG.

The larger Q and R wave indicate a myocardial infarction (heart attack). The S-T segment is elevated in acute myocardial infarction and depressed when the heart muscle receives insufficient oxygen.

Question. Name the vascular connection that exists between the digestive tract and liver.
Ans. The unique vascular connection that, exists between the digestive tract and liver is called hepatic portal system.

Question. What physiological circumstances lead to erythroblastosis foetalis?
Ans. A protein named as rhesus antigen, is present on the surface of red blood corpuscles.
The population having this protein are called Rh positive (Rh⁺) while others who do not have this protein are known as Rh negative (Rh⁻) (dominant).
Erythroblastosis Foetalis occurs due to Rh incompatibility between the foetus and mother during pregnancy. Rh antigen of the foetus do not get exposed to the Rh− blood of the mother in the first pregnancy. However, during the delivery of the first child, there is a possibility of exposure of the maternal blood to small amounts of the Rh+ blood from the foetus.
In such cases, the mother starts preparing antibodies against Rh antigen in her blood and during her subsequent pregnancies the Rh antibodies from the mother (Rh − ve) leak into the blood of the foetus (Rh + ve) resulting in the destruction of foetal RBCs. This could be fatal to the foetus or could cause severe anaemia and jaundice , even may lead to the death of the foetus.

Question. Explain the consequences of a situation in which blood does not coagulate.
Ans. Blood exhibits coagulation or clotting in response to an injury or trauma.
Coagulation prevents excessive loss of blood from the body. In its absence their could be huge loss of blood, which can be fatal.

Question. 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.
Ans. (a) Plasma without 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 QRS complex in an ECG.

Short Answer Type Questions:

Question. Briefly describe the followings
(a) anaemia (b) angina pectoris
(c) atherosclerosis (d) hypertension
(e) heart failure (f) erythroblastosis foetalis
Ans. (a) Anaemia is the decrease in the number of RBC than the normal amount and also due to less quantity of haemoglobin than the normal value in blood This is the most common
disorder of the blood.
(b) Angina Pectoris Ocurs when there is blockage in coronary artery, thus in sufficient supply of blood reaches to heart muscles. This results in chest pain, fear, anxiety, pale skin, profuse sweating and vomitting. The anginal pain usually starts in the centre of the chest spreads down to the left arm which last for only few second.
(c) Atherosclerosis is the deposition of cholesterol in the inner lining of arteries called atherosclerotic plaque. Sometimes arteries are completely blocked, this result in stroke or heart attack.
(d) Hypertension Ps sometimes also called as arterial hypertension. The blood pressure in the arteries getselevated. It could be primary hypertension which has no obvious medical reason but secondary hypertension are caused by various conditions which affect kidneys, arteries heart or endocrine system.
(e) Heart Failure is the state of heart when it does not pump blood effectively enough to meet the needs of the body.
(f) Erythroblastosis foetalis is a haemolytic disease of new borns which is an allo-immune condition that develops in foetus when IgG molecules produced by mother pass through placenta and attack RBC causing reticulocytosis and anaemia. It develops due to Rh incompatibility between the couples.
In a man with RH+ blood and women with Rh⁻, blood the second pregnancy foetus may have this problem due to IgG accumulation in women during first child development and delivery. 

Question. The walls of ventricles are much thicker than atria. Explain.
Ans. The structure of heart of fishes, reptiles, birds and mammals show many structures of evolutionary significance. Thicker walls of ventricles is one of them.
Ventricles have thick walls because these are mainly involved in pumping the blood to the body parts with certain pressure.
The walls of the left ventricle is about 3 times thicker from the right ventricle, while the atria acts as a collecting chambers for the blood which is starting to the heart thus have thin walled. Also they have to force the blood into the ventricles that lies just below there thus atria have thin walls.

Question. What is the significance of hepatic portal system in the circulatory system?
Ans. Hepatic Portal System
There is special vascular connection that exists between the digestive tract and liver in all chordates and is called as hepatic portal system. This system carries blood from intestine to the liver before it is delivered to the systemic circulation.
Significance of hepatic portal system in circulatory system
(i) Blood that comes from alimentary canal contain glucose, amino acids and other nutrients. The liver absorbs excess of fats and glucose to be used at the time of starvation when blood passess through given.
(ii) Harmful nitrogenous wastes like ammonia is converted into urea which is later removed by kidney.
(iii) Liver produces proteins which are transported through blood circulation (e.g., fibrinogen for blood clotting).

Question. Answer the following
(a) name the major site where RBCs are formed.
(b) which part of heart is responsible for initating and maintaining its rhythmic activity?
(c) what is specific in the heart of crocodiles among reptilians?
Ans. (a) Bone marrow (b) SA Node (Sino Atrial Node)
(c) Reptile have 3 chambered heart with an exception of crocodile which possess 4 chambered heart, due to the partial division of ventricle through a septum.

Question. Explain the functional significance of lymphatic system?
Ans. Human Lymphatic System comprises of lymph, lymphatic capillaries, lymphatic vessels, lymphatic ducts and lymphatic nodes.
Functional significance of lymphatic system
(i) It removes CO₂ and other metabolic waste from the tissue where blood vessels can not reach.
(ii) Lymphatic blood capillaries of intestine are called lacteals, which help in absorption of fats.
(iii) Lymph filters through out lymph nodes where phagocytotic WBC and macrophages are present in a good number which eats harmful microorganisms and remove foreign particles from the body fluid.

Question. 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 node
Ans. (a) Difference between plasma and serum are as follows

(b) Difference between open and closed circulatory system are as follows

(c) Difference between sino atriol node and artrio-ventricular node are as follow

Question. Differentiate between
(a) blood and lymph (b) basophils and eosinophils
(c) tricuspid and bicuspid valve
Ans. (a) Difference between blood and lymph are as follows

Question. Explain the advantage of the complete partition of ventricle among birds and mammals and hence leading to double circulation.
Ans. The birds and mammals have evolutionary advancement as far as structure of heart is concerned. They need more oxygen to live in terrestrial habitat.
In these animals, the blood received by left and right auricles is oxygenated and deoxygenated respectively. It passes towards the left and right ventricles and thus no oxygenated and deoxygenated blood is mixed. The ventricles pump oxygenated deoxygenated blood without mixing.
Thus, two separate circulatory pathways are found thus this type of blood circulation is called as double circulation, which include systemic and pulmonary circulation.

Question. Thrombocytes are essential for coagulation of blood. Comment.
Ans. Blood is a connective tissue. It has many cellular components. Thrombocytes or platelets are one of them.
Thrombocytes or platelets are found in blood. There number in the blood is 250,000/cubic mL of blood. They are formed in bone marrow and their life span is one week.
When an injury is caused in the blood vessel, bleeding starts, and the platelets are disintegrated to release the clotting factor 3 called thromboplastin. This in presence of Ca²⁺ ions activate prothrombokinase. A series of reactions ultimately occurs which causes blood to clot and plugg the injured blood vessel thus preventing further loss of blood.

Long Answer Type Questions:

Question. Describe the events in cardiac cycle. Explain ‘double circulation’.
Ans. The cardiac cycle consist of one heart beat or one cycle of contraction and relaxation i.e., takes place in the cardiac muscles. During the heart beat there is a contraction and relaxation of atria and ventricles. The contraction phase is referred as systole while the relaxation phase is called as diastole.
The successive events of the cardiac cycle are briefly described as below
(i) Atrial Systole The atria contract due to the wave of contraction, stimulated by the SA node. The blood is forced into the ventricles as the bicuspid and tricuspid valves are open.
(ii) Beginning of Ventricular Systole The contraction of ventricles begin due to the wave of contraction stimulated by AV node. This led to the closing of bicuspid and tricuspid valve producing part of first heart sound, i.e., lub.
(iii) Complete Ventricular Systole After ventricular contraction, the blood flows into the pulmonary trunk and aorta as the semilunar valves open.

(d) Beginning of the Ventricular Diastole The ventricles relax and the semilunar valves are closed. This cause the second heart sound, i.e., dub.
(e) Complete Ventricular Diastole The opening of tricuspid and bicuspid valves due to fall in pressure of ventricles and blood flows from the atria into the ventricles. Contraction of the heart does not cause this blood to flow, backward direction, due to the fact that the pressure within the relaxed ventricles is less than that of the atria and veins.
The duration of cardiac cycle last for 0.8 sec.
In double circulation, the blood passes twice through the heart during one complete cycle.
Double circulation is carried out by two ways
(i) Pulmonary circulation
(ii) Systemic circulation
Significance of Double Circulation In birds and mammals, two separate circulatory pathways are present. Oxygenated and deoxygenated blood received by the left and right atria respectively passes on to the ventricles of the same sides. The ventricles pump it out without mixing the oxygenated and deoxygenated blood in the heart.

Question. Explain different types of blood groups and donor compatibility by making a table.
Ans. There are more than 30 antigens on the surface of blood cells that give rise to different blood groups.
ABO Grouping ABO grouping is based on the presence or absence of two surface antigens on the RBCs namely. A and B. The plasma of different individuals contain two natural antibodies. The distribution of antigen and antibody in the four groups of blood, A, AB, B and O are explained above in the table.

From the above table it is evident that group ‘O’ blood can be donated to persons with any other blood group and hence ‘O’ group individuals are called ‘Universal donors’. Person with ‘AB’ blood can accept blood from persons with AB, as well as the other groups of blood. Therefore, such persons are called ‘Universal recipients’.

Question. Explain Rh^– incompatibility in humans.
Ans. Rh antigen is observed on the surface of RBCs of majority (nearly 80%) of humans. Such individuals are called Rh positive (Rh⁺ ) and those individuals where this antigen is absent are called Rh negative (Rh⁻).
Both Rh⁺ and Rh⁻ individuals are phenotypically normal. The problem in them arises during blood transfusion and pregnancy.
(i) Incompatibility During Blood Transfusion The first blood transfusion of Rh+ blood to the person with Rh⁻ blood causes no harm because the Rh⁻ person develops anti Rh factors or antibodies in his/her blood.
In second blood transfusion of Rh⁺ blood to the Rh⁻ person, the already formed anti Rh factors attack and destroy the red blood corpuscles of the donor.
(ii) Incompatibility During Pregnancy If father’s blood is Rh+ , mother blood is Rh− and the foetus blood is Rh⁺ . it will lead to a serious problem. Rh antigens of the foetus do not get exposed to the Rh− ve blood of the mother in the first pregnancy as the two bloods are well separated by the placenta.
But in the subsequent Rh+ foetus, the anti Rh factors (antibodies) of the mother destroy the foetal red blood corpuscles due to mixing of blood.
This result in the Haemolytic Disease of the New Born (HDN), called as erythroblastosis foetalis. In some cases new born may survive but will be anaemic and may also suffer with jaundice.

This condition can be avoided by administering anit-Rh antibodies to the mother immediately after the delivery of the first child.

Question. In the diagrammatic presentation of heart given below, mark and label.
SAN, AVN, AV bundles, bundle of his and Purkinje fibres.
Ans. The diagrammatic presentation of heart with labelled SAN, AVN, AV bundles bundle of His and purkinje fibres in heart is show as follows

Question. Write short note on the following.
(a) Hypertension (b) Coronary Artery Disease
Ans. (a) Hypertension The high blood pressure can harm heart, brain kidneys and eyes. High blood pressure is most common disease affecting the heart and blood vessels, Blood pressure is considered normal at 120/80. When it goes beyond 140 mm Hg and 90 mm Hg it is called hypertension or high blood pressure.
Causes of Hypertension
(i) Blockage in the coronary heart vessels.
(ii) Tobacco smoking speeds up heart rate. It constrict blood vessels and raises blood pressure.
(b) Coronary Artery Disease (CAD) It is caused due to the deposition of fatty substances on the arterial wall causing atherosclerotic plaques. The lumen of artery decreases, thus obstructing the blood flow and sometimes completely blocks the artery resulting into thus, heart attack.