CBSE Class 11 Biology VBQs Body Fluids and Circulation

Question. Arteriosclerosis is mainly due to
(a) intake of protein rich diet
(b) inelasticity of arteries
(c) malfunctioning of heart
(d) deposition of potassium salts.

Answer. B

Question. Blood capillaries are made of
(a) endothelium and thin coat of connective tissue
(b) endothelium and thin coat of muscle fibres
(c) endothelium and thin coat of connective tissue and muscle fibres
(d) only endothelium.

Answer. D

Question. The important function of lymph is to
(a) transport oxygen to the brain
(b) transport carbon dioxide to the lungs
(c) return RBCs to the lymph nodes
(d) return interstitial fluid to the blood.

Answer. D

Question. Select an incorrect statement for arteries.
(a) They are thick walled.
(b) They are elastic and muscular.
(c) They have valves.
(d) None of these

Answer. C

Question. Ventricular systole lasts for
(a) 0.1 second
(b) 0.3 seconds
(c) 0.4 seconds
(d) 0.6 seconds.

Answer. B

Question. Characteristics of cardiac muscles are that they
(a) contract quickly and get fatigued
(b) contract quickly and do not get fatigued
(c) contract slowly and get fatigued
(d) contract slowly and do not get fatigued.

Answer. B

Question. Vasoconstriction causes
(a) increase in heart beat
(b) decrease in heart beat
(c) increase in blood pressure
(d) decrease in blood pressure.

Answer. C

Question. Heart beats are decelerated by
(a) cranial nerve
(b) sympathetic nerve
(c) parasympathetic nerve
(d) sympathetic ganglion.

Answer. C

Question. 

In the above given diagram which blood vessel represents vena cava?
(a) C
(b) D
(c) A
(d) B

Answer. B

Question. Anticoagulants like streptokinase is useful in treatment of
(a) hypertension
(b) angina pectoris
(c) coronary thrombosis
(d) fibrillation.

Answer. C 

Question. Globulins contained in human blood plasma are primarily involved in
(a) osmotic balance of body fluids
(b) oxygen transport in the blood
(c) clotting of blood
(d) defence mechanisms of body.

Answer. D

Question. Polymorphism is exhibited by _______ and they can squeeze out of the blood capillaries into the tissues by the process of ________ .
(a) WBCs, diapedesis
(b) RBCs, phagocytosis
(c) blood platelets, phagocytosis
(d) RBCs, diapedesis

Answer. A

Assertion & Reasoning Based MCQs

For question numbers 48-57, two statements are given-one labelled Assertion and the other labelled Reason.
Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Assertion is false but reason is true.

Question. Assertion : The normal heart rate is 75 beats/min and cardiac cycle is 0.8 sec.
Reason : Cardiac cycle is inversely proportional to the heart rate.

Answer. B

Question. Assertion : Cardiac output rises during exercise.
Reason : Cardiac output helps in less oxygen consumption.

Answer. C

Question. Assertion : Cardiac output is the volume of blood pumped by left or right ventricle in one minute.
Reason : Cardiac output is calculated by multiplying the heart rate by the stroke volume.

Answer. B

Question. Assertion : Walls of ventricles are thicker than the auricles.
Reason : This helps in preventing the back flow of the blood.

Answer. C

Question. Assertion : Pulmonary circulation consists of flow of deoxygenated blood from right ventricle to the lungs and flow of oxygenated blood from lungs to the left atrium.
Reason : Systemic circulation consists of flow of oxygenated blood from the left ventricle to all parts of the body and deoxygenated blood from different parts of body to right atrium.

Answer. B

Read the following passage and answer questions from 38 to 42 given below:
The schematic plan of complete double circulation in humans is shown in the figure. The blood flows through arteries and veins which consist of three layers-tunica intima, tunica media and tunica externa. Left and right atrium passes oxygenated and deoxygenated blood into the left and right ventricles. Ventricles then pump it out without mixing into aorta and pulmonary artery. The volume of blood pumped out by each ventricle of heart per minute is called cardiac output.  

Question. Which of the following carries oxygenated blood during circulation ?
(a) F
(b) E
(c) D
(d) Both (b) and (c)

Answer. D

Question. Select the correct sequence of pulmonary circulation.
(a) G → H → A → I
(b) A → E → D → F
(c) G → H → B → E
(d) F → A → G → B

Answer. A

Question. Following are the significance of double circulation.
A. It checks the mixing of oxygenated and deoxygenated blood.
B. Oxygenated blood carries more oxygen.
C. Deoxygenated blood carries less carbondioxide for removal.
(a) A and B are correct.
(b) A is correct.
(c) B is correct.
(d) B and C are correct.

Answer. A

Question. Calculate the cardiac output of athlete having a beats 75 times/minutes and pumps out about 75 mL of blood per beat.
(a) 5040 mL
(b) 5625 mL
(c) 4000 mL
(d) 6000 mL

Answer. B

Very Short Answer Type Questions

Question. A person with blood group O can be transferred blood of only O group. Why?

Answer.  Since blood group O has both anti-a and anti-b antibodies, no other blood group with any antigen can be accepted by it. Only blood group O which lacks any antigen can be transferred.

Question. What is the life span of
(a) Granulocytes
(b) Thrombocytes?

Answer. (a) Granulocytes - 4 to 8 hours in blood, 4 to 5 days in tissue. (b) Thrombocytes - around 7 days.

Question. Why is blood group identification not needed for serum transfusion?

Answer. Blood group identification is not needed for serum transfusion because serum does not have the coagulation/ clotting factors.

Question. Name the blood component which is viscous and straw coloured fluid.

Answer. Plasma is straw coloured, viscous fluid, slightly alkaline and aqueous solution which constitutes about 55% of the blood.

Question. Name the embryonic/germ layer from where human heart develops.

Answer.  Mesoderm develops human heart.

Short Answer Type Questions

Question. Differentiate between heart failure and cardiac arrest.

Answer. Differences between heart failure and cardiac arrest are as follows: 

Question. What is the importance of body fluids?

Answer. Significance of body fluids are as follows : (i) Homeostasis : The maintenance of internal environment is called homeostasis. Water forms not only the essential constituent of internal environment but also plays important role in homeostasis. (ii) Transport mechanism : Body water forms the transport medium by which nutrients and other essential substances enter the cells and unwanted substances come out of the cells. (iii) Metabolic reactions : Water inside the cells is necessary for the growth and functional activities of the cells. (iv) Texture of tissues : Water inside the cells is necessary for the characteristic form and texture of various tissues. (v) Temperature regulation : Water plays an essential role in the maintenance of normal body temperature.

Question. Draw a well labelled diagram of:
(a) Basophil
(b) Eosinophil
(c) Neutrophil.

Answer. Labelled diagrams are as follows:

Question. (a) State the functions of the following: (i) Fibrinogen (ii) Globulin
(b) Which factors are activated by thrombin during the clotting mechanism?
(c) What is a haemocytometer?

Answer. (a) (i) Fibrinogen - It is present in blood plasma and helps in blood clotting. (ii) Globulin - It is a plasma protein which helps in defence mechanism. (b) Thrombin converts fibrinogen to an active form that assembles into fibrin. Thrombin also activates factor XI, factor V and factor VIII. This positive feedback accelerates the production of thrombin. (c) Haemocytometer is a device used to estimate the concentration of cells in blood samples.

Question. Give differences between erythrocytes and leucocytes.

Answer. Differences between erythrocytes and leucocytes of man are as follows:

Question. Explain the functional significance of lymphatic system.

Answer. 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 fats also occurs through lymph in the lacteals present in the intestinal villi.
(iii) It helps in the renewal of extracellular 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.

Question. Enlist the important functions of the circulatory system.

Answer.  The important functions of the circulatory system are as follows:
(i) The circulatory system supplies food, oxygen, enzymes, hormones and other substances to the different cells of the body.
(ii) It carries the end products of metabolism to the excretory organs.
(iii) It provides a strong defence to the body in prevention against invasion of infectious microorganisms.
(iv) It maintains body temperature, homeostasis of the tissue fluids and acid base balance.

Question. Explain the advantage of the complete partition of ventricle among birds and mammals and hence leading to double circulation.

Answer. 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.

Long Answer Type Questions

Question. (a) Draw a neatly labelled diagram of human heart.
(b) Explain the structure of right and left ventricles of heart.

Answer. (a) The structure of human heart is as follows: 
(b) The right ventricle of the heart receives blood from the right atrium. When the heart contracts the blood is forced out through the pulmonary semilunar valve into the pulmonary artery. The pulmonary semilunar valve is a three flap valve that stops the backflow of blood. The pulmonary arteries carry the blood from the right ventricle to both of the lungs. There the blood is oxygenated and sent to the left atrium in the heart. The wall of the right ventricle is a little thicker than the right atrium. The chamber of the left ventricle has walls that are three times the thickness of the right ventricle and this is the thickest portion of the human heart. This is so because the oxygenated blood that it receives from the left atrium has to be pumped throughout the body. When the heart muscle contracts the blood is forced through the aortic semilunar valve which has the same features as the pulmonary valve. The blood then passes through the aortic semilunar valve into the aorta. Fine tendinous cords called chordae tendinae are attached to the ventricular surface of the valves. On the other end, the chordae tendinae are attached with the special muscles of the ventricular wall known as papillary muscles. During atrial systole, the blood flows from the atria to the ventricles. When the ventricles contract the valves close and the chordae tendinae support the valves preventing reflux of blood into the atria. The chordae tendineae can be seen extending from the valves to the columnae carneae, which are the muscular ridges or projections on the walls of the ventricles. The columnae carneae divide the cavity of the ventricles into smaller spaces, known as fissures.

Question. (a) Briefly describe the three types of blood vessels found in the circulatory system.
(b) Give a brief description of the layers found in blood vessels.

Answer. (a) The blood vessels form a complex network of tubes throughout the body. The blood vessels carry blood between the heart, different tissues, and organs of the body. The three types of blood vessels are arteries, veins and capillaries. The arteries are elastic, muscular tubes that carry the blood from the left ventricle of the heart to the tissues. The walls of the arteries are thicker than the other vessels because of the high pressure. The wall thickness of the arteries prevent them from collapsing. The veins carry blood from the tissues to the heart. The veins are more in number than arteries due to the draining of large areas when needed. Located within the veins are valves that allow blood to flow toward the heart but does not allow blood to flow backwards. The veins that are in the lower part of the body tend to have more valves to counteract the force of gravity. The capillaries are the smallest working unit in the blood vessels that connect the arterioles to the venules. The walls of the capillaries are only 1 cell thick, this allows for the exchange of nutrients and other substances like oxygen and carbon dioxide. The number of capillaries vary depending on the need for oxygen and other nutrients. The blood flow through the capillaries is regulated by a sphincter. This is important because there would not be enough blood to fill all the blood vessels at one time. (b) Blood vessels consists of three layers. They are as follows: (i) Tunica adventitia or tunica externa is the outer layer of blood vessels. It is composed largely of collagen, but smooth muscle cells may be present, particularly in veins. The tunica adventitia is often the most prominent layer in the walls of veins. (ii) Tunica media is the middle layer in a blood vessel wall and is composed predominantly of smooth muscle reinforced by organised layers of elastic tissue which form elastic laminae. Tunica media is particularly prominent in arteries, being relatively indistinct in veins and virtually non-existent in very small vessels. (iii) Tunica intima or tunica interna is composed of a lining layer of highly specialised multifunctional flattened epithelial cells termed endothelium. This sits on a basal lamina; beneath this is a very thin layer of fibrocollagenous supporting tissue. It is continuous with the endocardial lining of the heart and is the only layer that is present in all blood vessels.