Past Entrance Papers

Hint

(d) Person with \(A B\) blood group are universal recipients because they do not have any antibodies to anti-A and anti-B in their blood hence they can receive blood from a donor of any blood type.

During the transfusion, plasma is matched to avoid \(\mathrm{A}\) and \(\mathrm{B}\) antibodies in the transfused plasma that will attack the recipient’s red blood cells. Person with \(A B\) blood type does not contain \(A\) and \(B\) antibodies in plasma. Therefore, they are also called universal plasma donors.

Hint

(a) Plasma contains prothrombin and fibrinogen. During clotting, inactive prothrombin converts to active thrombin. Thrombin acts as a proteolytic enzyme to convert soluble plasma protein fibrinogen molecules produced from the liver in the presence of vitamin-K to form insoluble fibrin monomer.

Hint

(d) It can be explained as follows Eosinophils are associated with allergic reactions and release histaminase, destructive enzymes. Basophils secrete histamine, serotonin, heparin, etc., and are involved in inflammatory reactions. Neutrophils are phagocytic cells. Both B and T lymphocytes are responsible for immune responses of the body.

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(b) is correct and can be explained as in an ECG there occurs five consecutive waves: \(P, Q, R, S\), and \(T\).
\(P\) wave represents depolarisation of atria and leads to contraction of both atria.

QRS complex represents depolarisation of ventricles which leads to initiation of ventricular contraction.

T wave represents the return of ventricles from excited to normal state.

Hint

(b) If the mother is Rh-ve and foetus is \(\mathrm{Rh}+\) ve then there can occur a condition called erythroblastosis foetalis. It is a special case of Rh incompatibility in which during the second pregnancy of \(\mathrm{Rh}-\mathrm{ve}\) mother carrying \(\mathrm{Rh}\) + ve foetus, the \(\mathrm{Rh}\) antibodies from the mother (Rh – ve) can leak into the blood of the foetus \((R h+v e)\) and destroy the foetal RBCs.

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(d) SA node acts as a pace-maker of the heart because its autoexcitable tissue have the ability to generate heart impulses at the highest rate (frequency).

This electrical impulse is then transmitted by perinodal cells, or transitional (T) cells, to the right atrium and then through the rest of the heart’s electrical conduction system, eventually resulting in myocardial contraction and blood distributed to the rest of the body. The sinus node continuously generates electrical impulses, thereby setting the normal rhythm and rate in a healthy heart. Hence, the SA node is referred to as the natural or normal pacemaker of the heart.

Hint

(a) The delay in transmission of impulse from SAN to the ventricles provided by AVN prevents simultaneous contraction of ventricles and auricles. This allows the atria to empty completely before ventricles start contraction.

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(b) As per the given data, the heart rate of the person would be 100 beats per minute. It can be calculated as follows Given, Cardiac output \(=5 \mathrm{~L}(5000 \mathrm{~mL})\) Blood volume in ventricles at the end of diastole \(=100 \mathrm{~mL}\)

Blood volume at the end of ventricular systole
\(=50 \mathrm{~mL}\)
So, Stroke volume \(=100-50=50 \mathrm{~mL}\)
Cardiac output \(=\) Stroke volume \(\times\) Heart rate, i.e.
\(5000 \mathrm{~mL}=50 \mathrm{~mL} \times\) Heart rate
Therefore, Heart rate \(=100\) beat \(/ \mathrm{min}\).

Hint

(a) In an Electrocardiograph (ECG), P-wave represents the depolarisation of the atria which is caused by the activation of the SA node. The QRS complex represents depolarisation of ventricles which is caused by the impulse of contraction from the AV node.
T-wave represents repolarisation of ventricles and reduction in its size signifies coronary ischemic, i.e. when the heart muscles receive insufficient oxygen as in arteriosclerotic heart disease.

Hint

(d) Fibrinogen forms fibrin strands during coagulation. These strands form a network and the meshes of which are occupied by blood cells, this structure finally forms a clot.

Antibodies are derived from the Gamma-Globulin fraction of plasma proteins which means globulins are involved in defence mechanisms. Albumin is a plasma protein mainly responsible for Blood Colloidal Osmotic Pressure (BCOP).

Fibrinogen is a soluble plasma protein that is stimulated by thrombin and gets converted into insoluble form fibrin. The latter helps in the formation of the blood clot to seal the wound and stop bleeding.

Globulins are simple proteins that form a large fraction of blood serum proteins involved in defence mechanisms. There are four main types of globulins that are manufactured in the liver, namely alpha-1, alpha-2, beta, and gamma.
Albumin is a plasma protein that is manufactured by the liver. It helps in maintaining osmotic pressure which prevents fluid leakage out into the tissues from the bloodstream.

Hint

(c) The atrioventricular opening between the left at rium and left ventricle is guarded by the bicuspid valve. It is also called as mitral valve. The right atrioventricular opening is guarded by the tricuspid valve. It has three flaps. The semilunar valve is found in the right ventricle and pulmonary artery. 

Hint

(d) The absence of nucleus in RBC is an adaptation that allows it to contain more haemoglobin and carry more oxygen by providing empty space. This adaptation also aids in effective diffusion of oxygen. Concept Enhancer RBC s are initially produced in bone marrow with a nucleus. They, then undergo enucleation at maturity, in which their nucleus is removed.

Hint

(c) Blood enters the liver from two sources. From the hepatic artery, it gets oxygenated blood and from the hepatic portal vein, it receives deoxygenated blood. Blood in the hepatic artery comes from the aorta. Blood in the hepatic portal vein comes directly
from the intestine containing newly absorbed nutrients.

Hint

(d) Thrombocytes are called blood platelets. They are minute disc-shaped cell fragments in mammalian blood. They are formed as fragments of larger cells found in the red bone marrow; they have no nucleus. They play an important role in blood clotting and release thromboxane \(A_{2}\), serotonin, and other chemicals, which cause a chain of events leading to the formation of a plug at the site of the damage, thus preventing further blood loss. A reduction in their number can lead to clotting factors which will lead to excessive loss of blood from the body.

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(c) Serum is the fluid that separates from blood plasma on centrifugation. Serum is essentially similar in composition to plasma but lacks fibrinogen and other substances that are used in the coagulation process.

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(a) Arteries have higher blood pressure than vein because blood is forced inside them from the heart and also their lumen is narrow.

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(a) Hepatic vein carries the largest amount of urea. Urea is produced in the liver. Hepatic vein transports the liver’s deoxygenated blood to the heart for oxygenation.

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(c) Reduction of \(\mathrm{pH}]\)of blood will decrease the affinity of haemoglobin with oxygen which in turn causes acidosis.

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(d) Second heart sound i.e., dup is caused by the closure of the semilunar values and marks the end of ventricular systole.

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(d) Erythropoiesis is the formation of red blood cells (erythrocytes) which occurs in the red bone marrow. Proerythroblast is the earliest precursor which gives rise successively to the early erythroblast, intermediate erythroblast, and late erythroblast. Then, the nucleus is forced out and a biconcave, enucleated cell called reticulocyte is formed, which is released into the blood. In blood, it develops into mature erythrocytes.

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(b) Lymph \(=\) Plasma \(+\mathrm{WBC}\) Plasma \(=\) Blood \(–\) Cellular components Serum \(=\) Plasma \(–\) Clotting factors

Hint

(a) The temporary rise in blood pressure during the contraction of the heart is called systolic pressure and the temporary fall in blood pressure during relaxation of the heart is called diastolic pressure. Blood pressure is expressed as the ratio of the systolic pressure over diastolic pressure. For a healthy resting adult person, the average systolic/diastolic pressures are \(120 / 80 \mathrm{mmHg}\). Aorta is directly supplied by the left ventricle thus, the blood pressure in the aorta is highest during systole of the left ventricle. During it, the left ventricle contracts and pushes blood into the aorta.

Hint

(a) Individuals with \(\mathrm{AB}\) blood group have both antigen \(\mathrm{A}\) and \(\mathrm{B}\) on their \(\mathrm{RBCs}\), and no antibodies for either of the antigen in their plasma. Type \(\mathrm{O}\) individuals are without \(\mathrm{A}\) and \(\mathrm{B}\) antigens on their RBCs, but have antibodies for both these antigens in their plasma. Individuals with blood group \(\mathrm{AB}\) can receive blood of \(\mathrm{A}, \mathrm{B}\) or \(\mathrm{O}\) group, while those with blood group \(\mathrm{O}\) can donate blood to anyone.

Hint

(a) A special neural centre in the medulla oblongata can moderate cardiac function through the autonomic nervous system (ANS). Neural signals through the sympathetic nerves (part of ANS) can increase the rate of heartbeat, the strength of ventricular contraction, and thereby the cardiac output. Parasympathetic neural signals (component of ANS) decrease the rate of heartbeat, speed of conduction of action potential, and thereby the cardiac output.

Hint

(c) In the given diagram the \(\mathrm{P}\)-wave represents the electrical excitation (or depolarisation) of the atria, which leads to the contraction of both the atria. The QRS complex represents the depolarisation of the ventricles, which initiates the ventricular contraction. The contraction starts shortly after \(\mathrm{Q}\) and marks the beginning of the systole. The T-wave represents the return of the ventricles from excited to normal state (repolarisation). The end of the T-wave marks the end of systole.

Hint

(c) A-Artery: Carries blood from the heart to different body parts. It is thick-walled and elastic. The flow of blood in it is intermittent.

B – Capillary: Nutrients, hormones, gases, etc. can diffuse into tissue cells through capillaries and vice versa. It is thin-walled, and only one layer thick resting on the basement membrane.
\(\mathrm{C}\) – Vein: Brings blood from different body parts to the heart. It is thin-walled and acts as low-resistance conduct for blood flow.

D – Pulmonary vein: Two pulmonary veins from each lung transport the oxygenated blood to the left atrium.

Hint

(a) Basophils have nucleus which is three-lobed and have less number of coarse granules. Their granules take basic stain and release heparin, histamine, and serotonin.

Hint

(c) The blood group was \(\mathrm{O}\). The person having \(\mathrm{O}\) blood group is the universal donor. It lacks both antigens ‘ \(A\) ‘ and ‘ \(B\) ‘ and thus does not cause agglutination or clumping of blood cells when transfused into a person with any of the four blood groups.

Hint

(c) Spleen is a vertebrate organ, lying behind the stomach, that is basically a collection of lymphoid tissue. Its functions include producing lymphocytes and destroying foreign particles. It acts as a reservoir for \(\mathrm{RBC}\) s and can regulate the number in circulation. It is also the site for the breakdown of worn out \(\mathrm{RBCs}\) and thus is known as the graveyard of RBCs.

Hint

(b) ‘Bundle of His’ is a part of heart. A bundle of nodal fibres, atrioventricular bundle (AV bundle), continues from the atrioventricular node (AVN) and passes through the atrioventricular septa. It emerges on the top of the interventricular septum and immediately divides into a right and left bundle, which give rise to minute fibres throughout the ventricular musculature of the respective sides called Purkinje fibres. These fibres along with right and left bundles are known as Bundle of His.

Hint

(d) Blood plasma is a faint yellow, slightly alkaline, and somewhat viscous fluid. The plasma contains a number of proteins: serum albumin, serum globulins, properdin, prothrombin, and fibrinogen. Prothrombin and fibrinogen play a role in blood clotting.

Hint

(b) Arteries and veins are the main blood vessels. Arteries carry blood from the heart to different body parts. Veins bring blood from different body parts to the heart.

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(d) If repeated checks of blood pressure of an individual is 140/90 or higher, it shows hypertension or high blood pressure. It leads to heart diseases and also affects vital organs like the brain and kidneys.

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(c) The person who donated blood very soon will have “O” blood group. It is easily guessed because \(\mathrm{O}\) blood group is the universal donor blood group.

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(a) By counting the number of QRS complexes that occur in a given time period, one can determine the heartbeat rate (pulse) of an individual. The QRS complex represents the depolarisation of the ventricles, which initiates the ventricular contraction.

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(d) Tricuspid valve is the valve in the heart between the right atrium and right ventricle. It consists of three cusps that channel the flow of blood from the atrium to the ventricle. When the right ventricle contracts, forcing blood into the pulmonary artery, the tricuspid valve closes the aperture to the atrium, thereby preventing any backflow of blood. The valve reopens to allow blood to flow from the atrium into the ventricle. Thus, if the tricuspid valve is partially nonfunctional the flow of blood into the pulmonary artery will be reduced.

Hint

(a) The body undergoes numerous changes at higher elevation in order to increase oxygen delivery to cells and improve the efficiency of oxygen use. The early changes include increased breathing rate, increased heart rate, and fluid shifts. The later changes include increased red blood cell production, increased 2, 3 DPG production, and increased number of capillaries.

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(c) Intravenous injection is given for rapid distribution of drugs/substance. Intramuscular injection is given for producing the local effect.

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(a) The term angina means chest pain. In this disease, enough oxygen does not reach the heart muscles. The patient experiences heart pain usually in front of the chest.
\(\mathrm{AB}\) blood group person have both antigens \(\mathrm{A}\) and \(\mathrm{B}\), but do not have antibodies in the plasma. Due to the presence of both the antigens, AB blood group person cannot donate blood to anyone. However, the person can receive blood from any blood group as it has no antibodies. Thus, AB blood group is a universal recipient.

Hint

(d) Haemoglobin binds with oxygen and transports it to various tissues of our body through RBC’s present in our blood. There is minimum concentration or amount of haemoglobin rquired to meet the oxygen demand of the cell in tissues. the minimum amount required is 12-16 g per decilitre \((100 \mathrm{~mL})\).

Hint

(c) The three alleles in ABO blood groups in humans can produce six different genotypes and four different phenotypes.
\(
\begin{array}{|l|l|}
\hline \text { Genotypes } & \text { Phenotypes } \\
\hline \mathrm{I}^{\mathrm{A}}, \mathrm{I}^{\mathrm{A}}, \mathrm{I}^{\mathrm{A}} i & \text { Blood group } \mathrm{A} \\
\hline \mathrm{I}^{\mathrm{B}} \mathrm{I}^{\mathrm{B}}, \mathrm{I}^{\mathrm{B}} i & \text { Blood group } \mathrm{B} \\
\hline \mathrm{I}^{\mathrm{A}} \mathrm{I}^{\mathrm{B}} & \text { Blood group } \mathrm{AB} \\
\hline i i & \text { Blood group } \mathrm{O} \\
\hline
\end{array}
\)

Hint

(a) Hair root or hair follicle is the living part of the hair that produces the shaft, follicle contains a group of cells that are nucleated. An enucleated ovum contains DNA in the mitochondria A mature spermatozoan contains DNA in the head region A mature RBC in all mammals except Camel does not contain nucleus at maturity. Hence they do not contain DNA. So, the correct answer is ‘Mature RBCs’

Hint

(c) A normal electrogram (ECG) is composed of a P wave, a QRS wave (complex), and a T wave. The P-wave represents the electrical excitation or depolarisation of the atria. 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 T-wave represents the repolarisation of ventricles. The end of the T-wave marks the end of systole.

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(d) Globulins in human blood plasma are primarily involved in defence mechanisms of the body. Globulins like immunoglobulins act as antibodies that destroy bacteria, viruses, and toxic substances that may enter into the blood from outside.

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(b) Lymph is a mobile connective tissue comprising lymph plasma and lymph corpuscles (type of WBCs). Its composition is just like plasma except that it lacks RBCs and large plasma proteins.

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(d) Landsteiner divided the human population into four groups based on the presence
of antigens found in their RBCs. Each group represented a blood group. Thus,
there are four types of blood groups \(A, B\), \(A B\), and 0. Blood group ‘ \(O\) ‘ does not contain any antigen on \(\mathrm{RBC}\), hence can be given to any person, that’s why this blood group is called a universal donor.

Hint

(b) Due to the pressure difference between the post caval and atrium, the blood passes from the post caval to the diastolic right atrium. Diastolic right atrium has less pressure and post caval has high pressure, thus blood moves from post caval to right atrium.

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(b) Phagocytes are cells that are able to engulf and breakdown foreign particles, cell debris, and disease producing microorganisms. Neutrophils and monocytes (types of white blood cells) are the most active phagocytic cells.

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(d) The type of white blood cells is concerned with the release of histamine and the natural anticoagulant heparin are Basophils. They contain granules filled with histamine, When basophils encounter allergens they release histamine. Histamine increases blood flow to damaged tissues, resulting in swelling and inflammation. Basophils also contain anticoagulant heparin, which prevents blood from clotting too quickly. So, the correct answer is ‘Basophils’.

Hint

(a) Blood serum is blood plasma from which the fibrin and clotting factors have been removed by centrifugation or vigorous stirring, so that it cannot clot. Serum containing a specific antibody or antitoxin may be used in the treatment or prevention of certain infections. Such serum is generally derived from a nonhuman mammal (e.g., a horse).

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(b) Deficiency of antibodies can be confirmed by serum globulins as antibodies are also called immunoglobulins and constitute the gamma globulin part of blood proteins. These are secreted by activated B-cells or plasma cells.

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(c) Since RBCs do not have mitochondria so they can respire only anaerobically.

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(c) Periplaneta ( \(P\). americana, the Indian Cockroach) is an insect & insects do not have closed blood circulation. Their blood (called haemolymph) even does not serve for respiration. They do not possess blood vessels in this circulatory system and hence it is an open system.

Hint

(c) Clotting of collected blood can be prevented by –
(i) coating test tubes with silicon (which produce non-wettable surface similar in its smoothness to the endothelial lining of blood vessels).
(ii) adding chelating agents (includes trisodium citrate, sodium oxalate, and sodium EDTA) which remove calcium which is important for blood coagulation, and prevent blood clotting.
(iii) adding heparin, the most powerful anticoagulant which acts indirectly by activating plasma antithrombin III. Heparin is effective both in vivo and in vitro whereas the option \(\mathrm{a}, \mathrm{b}\) and \(\mathrm{d}\) are effective in vitro.

Heparinized blood is not suitable for blood counts (as it alters the shape of RBCs and WBCs which affects blood testing), Fragility testing, and complement fixation tests.

Hint

(d) Anaemia refers to any condition in which there is an abnormally low haemoglobin concentration and/or blood cell count. The most common cause is deficiency of iron which is an essential element of haemoglobin molecule. Thus, the iron compounds in the diet will help to alleviate the symptoms of anaemia.

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(d) Antibodies are the proteins (glycoproteins) called immunoglobulins. These are produced by B-lymphocytes in response to the entry of a foreign substance or antigen into the body. Lipoproteins are the micellar complex of protein and lipids.

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(b) In insects circulating body fluid called haemolymph does not help in the circulation of respiratory gases for the body. It only circulates the food and nutrients to the different body parts. Distribution of oxygen (respiration) takes place through small air chambers called spiracles.

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(d) Lipoproteinaceous, thromboplastin is released by the injured tissue which causes blood clotting. In blood vessels, thromboplastin does not release due to which blood does not clot.
But external thromboplast into blood will cause blood clotting at the site of its introduction due to the formation of prothrombinase.

Hint

(c) Human blood groups are special characteristics of blood in human and related primates due to presence of genetically controlled antigens and antibodies. ABO blood groups were the first to be discovered and are the most important in assuring safe blood transfusion. This system reflect the presence or absence of \(A\) and \(B\) agglutinogens (antigen) which are carried on the surface of plasma membrane of red blood cells. The \(\mathrm{ABO}\) blood groups are determined by the gene \(\mathrm{I}\) having three alleles – \(\mathrm{I}^{\mathrm{A}}, \mathrm{I}^{\mathrm{B}}\), \(\mathrm{I}^{0}\). In human being, there are present two antigens \(A\) and \(B\) produced by \(\mathrm{I}^{\mathrm{A}}\) and \(\mathrm{I}^{\mathrm{B}}\) alleles respectively. These antigens are always present on the surface of \(\mathrm{RBCs}\). Also are present two antibodies in the plasma-anti \(A\) and anti \(B\). Blood group \(A B\) has both antigens \(A\) and \(B\) but no antibodies.

Hint

(c) SA node is the natural pacemaker located in the right atrium. SA node initiates the cardiac impulse. So, the artificial pacemaker will be grafted at the site of SA node.

SA is located at the junction of the crista terminalis in the upper wall of the right atrium and the opening of the superior vena cava. These cells have the ability to spontaneous generate an electrical impulse. It is the integrated activity of these so-called pacemaker \((\mathrm{P})\) cells that form the SA node.

Hint

(b) The bundle of his is a network of muscle fibers found in the wall of ventricles.
Which transmits the electrical impulses from \(\mathrm{AV}\) node to the point of the apex of the heart via bundle branches of bundle of his.

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(a) Systemic heart refers to the enteric heart in lower vertebrates. It pumps the blood to different body parts and not to the lungs.

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(a) SA node is a specialised bundle of neurons located in the upper part of the right atrium of the heart. SA node is the natural cardiac pacemaker from which the heartbeat originates. If this system is damaged, it may send non-coordinated impulses to the heart chambers resulting in symptoms like irregular heart rate, tiredness, dizziness, and loss of consciousness. As the pacemaker cells create these rhythmical impulses therefore an artificial pacemaker is implanted at the site of the SA node to mimic the actions of the node and conducting system and helps to regulate the heartbeat.

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(b) Lymph is known as blood minus RBCs and some proteins. The main site of lymph formation is the interstitial space and normally the rate of lymph formation is equal to the rate of its return to the bloodstream.

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(c) SA node lies in the right wall of the right auricle below the opening of the superior vena cava. It is also called a pacemaker as it is the first to originate the cardiac impulses and determines the rate of heartbeat.

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(c) Vitamin- \(K\) is required for the clotting process, it is required for the formation of prothrombin in the liver, the deficiency of which leads to severe bleeding
disorders. Deficiency of vitamin-A causes night blindness, xerophthalmia, keratomalacia, retarded growth. Deficiency of vitamin-B causes beri-beri
disease. Deficiency of vitamin-E causes sterility.

Hint

(a) In blood of the O group, no antigens are present on red blood cells, but both anti-a and anti-b antibodies are present in plasma. Blood group \(A\) has antigen ‘ \(A\) ‘ and antibody ‘b’.
Blood group \(B\) has antigen ‘ \(B\) ‘ and antibody ‘a’. Blood group \(A B\) has antigens ‘ \(A\) ‘ and ‘ \(\mathrm{B}\) ‘ but no antibody in plasma.

Hint

(c) An artery has thick and more elastic wall but its lumen is narrow as compared to the vein. Pulmonary artery carries deoxygenated blood from the right ventricle to the lungs for oxygenation. Pulmonary vein carries oxygenated blood from the lungs to the left auricle.

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(b) The pulmonary artery carries deoxygenated blood from the heart to the lungs while the pulmonary vein carries oxygenated blood from the lungs to the heart. A pulmonary artery has a smaller lumen and thicker walls as compared to a pulmonary vein.
So, the correct answer is ‘It has a thick wall.’

Hint

(d) WBCs are the colourless nucleated amoeboid cells that can squeeze through blood capillaries by a process known as diapedsis. The increase in their number causes leukaemia a type of cancer. WBCs are of two types, granulocytes (formed in bone marrow) and agranulocytes (formed in bone marrow and thymus).

Hint

(a) Most of the \(T\) and B-lymphocytes(types of leukocytes) continuously circulate between the blood and lymph. These leave the bloodstream, squeezing out
between specialised endothelial cuts found in certain small vessels and enter various tissues including all the lymph nodes. After percolating through a tissue, these accumulate in small lymphatic vessels which connect to a series of lymph nodes, from where they ultimately enter the main lymphatic vessel(thoracic duct) which carries them back into the blood.

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(b) Rhesus antibodies are formed in the plasma of \(\mathrm{Rh}^{-}\)woman who have been pregnant with \(\mathrm{Rh}^{+}\)babies if the foetal blood leaks across the placenta during the birth the mother body starts preparing antibodies against the Rh-antigen. Later \(\mathrm{Rh}^{+}\)foetus would be at risk and may suffer from haemolysis.

Hint

(d) SA node is a specialised bundle of neurons located in the upper part of the right atrium of the heart. SA node is the natural cardiac pacemaker from which the heartbeat originates. If this system is damaged, it may send non-coordinated impulses to the heart chambers resulting in symptoms like irregular heart rate, tiredness, dizziness, and loss of consciousness. As the pacemaker cells create these rhythmical impulses therefore an artificial pacemaker is implanted at the site of the SA node to mimic the actions of the node and conducting system and helps to regulate the heartbeat.

Hint

(a) The antibodies are present in human blood without prior exposure to the antigen, which means that people with a particular \(\mathrm{ABO}\) antigen carry the antibody against the other antigen in their serum. A person with ‘ \(\mathrm{B}[latex] ‘ blood group carries ‘ [latex]\mathrm{B}\) ‘ antigen on their RBCs and only anti- \(\mathrm{A}\) antibodies in their serum. A person with ‘A’ blood group carries ‘ \(A\) ‘ antigen on their RBCs and only anti-B antibodies in their serum. Since the ‘AB’ blood group has both ‘A’ and ‘B’ antigen on their RBC, both of antibodies are absent in the serum. Since type O persons do not have either antigen on their RBCs, so it carries both anti-A and anti- \(\mathrm{B}\) antibodies in the serum.

Hint

(a) Arteriosclerosis is the hardening of arteries and arterioles due to the thickening of the fibrous tissue, and the consequent loss of elasticity. In this disease, calcium salts precipitate with the cholesterol. This calcification ultimately makes the wall of arteries stiff and rigid.

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(d) Haemoglobin \((\mathrm{Hb})\) is a proteinaceous respiratory pigment made up of a protein called globin with iron \(\left[\mathrm{Fe}^{2+}\right]\) containing porphyrin as prosthetic group. It binds to oxygen reversibly.

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(b) Mast cells contain granules of heparin and histamine. Heparin prevents blood clotting. Histamine produces inflammation.

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(b) SA is the site of the generation of the rhythmic cardiac impulse. AV node is a compact mass of myogenic fibres which receives impulse from the SA node and transmits it to ventricles. Purkinje fibres are in contact with the contractile muscles of the ventricular walls. Chordae tendinae are the muscles which keep the AV valves in position.

Purkinje fibers are part of the specialized conduction network of the heart that ensures that the wave of excitation spreads rapidly and almost synchronously to the ventricular muscle mass.

Hint

(a) The temporary rise in blood pressure during the contraction of the heart is called systolic pressure and the temporary fall in blood pressure during relaxation of the heart is called diastolic pressure. Blood pressure is expressed as the ratio of the systolic pressure over the diastolic pressure. For a healthy resting adult person, the average systolic/diastolic pressures are \(120 / 80 \mathrm{~mm} \mathrm{Hg}\).

Hint

(a) Formation of WBCs, antibodies, and destruction of bacteria occur in lymph glands while the formation of RBCs occurs in the bone marrow. Lymph gland is a rounded mass of lymphatic tissue that is surrounded by a capsule of connective tissue. Lymph glands filter lymph (lymphatic fluid), and they store lymphocytes (white blood cells). They are located along lymphatic vessels. They are also called a lymph node.

Hint

(c) Vitamin- \(\mathrm{B}_{12}\) (cobalamin) promotes DNA
synthesis, maturation of erythrocytes and myelin formation. Vitamin-D
(calciferol), It is necessary for the formation of healthy bones and teeth.
Vitamin-A (retinol), It is necessary for proper body growth and night vision.
Vitamin-C (ascorbic acid), It helps in wound healing, blood formation, and
absorption of iron.

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(d) Histamine is a potent vasodilator formed by decarboxylation of the amino acid histidine and released by mast cells in response to appropriate antigens.

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(c) Blood group is determined by three alleles \(-\mathrm{I}^{\mathrm{A}}, \mathrm{I}^{\mathrm{B}}\), and \(\mathrm{I}^{\mathrm{O}}\). Alleles \(\mathrm{I}^{\mathrm{A}}\) and \(\mathrm{I}^{\mathrm{B}}\) are codominant. Blood group \(A\) is determined by \(\mathrm{I}^{\mathrm{A}} \mathrm{I}^{\mathrm{A}}\) or \(\mathrm{I}^{\mathrm{A}} \mathrm{I}^{\mathrm{O}}\). Blood group \(\mathrm{B}\) is \(\mathrm{I}^{\mathrm{B}} \mathrm{I}^{\mathrm{B}}\) or \(\mathrm{I}^{\mathrm{B}} \mathrm{I}^{\mathrm{O}}\). Blood group \(O\) is \(I^{0} I^{0}\). Blood group \(A B\) is \(I^{A}\) \(\mathrm{I}^{\mathrm{B}}\).

Hint

(c) Agranulocytes are leucocytes that lack granules in the cytoplasm. They are formed in the spleen and lymph nodes and bone marrow. Since lymphocyte does not have granules in their cytoplasm so it is called agranulocyte. Lymphocytes are important in the body’s defence and are responsible for immune reactions as the presence of antigens stimulates them to produce antibodies. Another type of agranulocyte is monocyte. The other three are granulocytes which are produced in the red bone marrow.

Hint

(c) WBCs (also called leucocytes) are rounded or irregular colourless cells with a nucleus. They can change their shape and are capable of amoeboid movement. Leucocytes, formed in lymph nodes and red bone marrow, can produce antibodies and move through the walls of vessels to migrate to the sites of injuries, where they surround and isolate dead tissue, foreign bodies, and bacteria. They survive for a few days generally 3-4 days after which they die and get phagocytized in blood, liver, and lymph nodes.

Hint

(d) Only the spleen and brain always receive oxygenated blood. The gills and lungs are the blood purifying organs, i.e. here blood becomes oxygenated and these two organs always receive deoxygenated blood. The liver is a part of the hepatic portal system, in which the hepatic portal vein carries food laiden blood from the alimentary canal and associated glands before finally returning to the heart.

Hint

(b) Impulse for contraction starts in the SA node. From there it travels to the AV node. It is then conducted to the Purkinje fibres through the Bundle of His fibres. The Purkinje fibre situated in the lateral walls of the ventricles spread the impulse to the ventricles. Thus the ventricular contraction is initiated. The pressure exerted by the blood pushed into the aortic arteries is recorded as pulse.
So, the correct answer is ‘SA node \(\rightarrow \mathrm{AV}\) node \(\rightarrow\) Bundle of \(\mathrm{His} \rightarrow\)
\(\rightarrow\) Purkinje fibres \(\rightarrow\) Heart muscles. \(\rightarrow\)

Hint

(a) Lymph (also called tissue fluid in the intercellular spaces) is the colourless liquid found within the lymphatic system. An important function of lymph is to return interstitial fluid back to the blood. The interstitial fluid is the filtered form of the blood without the cellular components and plasma proteins. It consists of water containing dissolved materials. It receives \(\mathrm{CO}_{2}\), nitrogenous waste products, hormones, and other synthetic substances from the tissue cells and enters the lymph capillaries to discharge them into the blood.

Hint

(c) Veins carry blood at low pressure as compared to blood carried by arteries. Arteries carry blood from the heart whose function is to pump blood at high pressure so that blood can reach each and every part of the body. Veins carry blood from tissues to the heart, so they carry blood at low pressure. Valves are present in the veins to prevent the backflow of blood due to the force of gravity.

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(b) The neurogenic heart is a characteristic feature of most arthropods and some annelids. In this, the heartbeat is initiated by a nerve impulse coming from a nerve ganglion situated near the heart. The myogenic heart is a characteristic feature of molluscs and vertebrates. In this, heartbeat is initiated by a patch of the modified heart muscle itself. So, humans, rabbits, and rats have myogenic heart.

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(b) Antigens \((\mathrm{Ag})\) are foreign particles present on the surface of the cell and when introduced into the blood they initiate a specific immune response against themselves.

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(d) The haemorrhagic disease of newborn is caused due to the deficiency of vitamin-K, characterised by delayed blood clotting and haemorrhage (blood loss).

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(a) Blood cancer is known as leukemia which is characterised by uncontrolled division of leukocytes.

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(b) Whale is a mammal. It has four chambered heart having two atria and two ventricles. Oxygenated and deoxygenated blood flow in separate circulatory pathways.

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(b) The wall of the left ventricle is the thickest of all the chambers. It supplies oxygenated blood throughout the body. Aorta arises from the left ventricle and the musculature is best developed.

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(b) The second sound heard by doctors using stethoscope occurs when semilunar valves close down after the blood flows into vessels from ventricles.

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(b) The kdup sound is produced by the closure of the semilunar valves at the start of ventricular relaxation. It lasts for \(0.1\) seconds and its principle frequency is 50 cycles/sec. It is higher pitched, louder, sharper and of short duration as compared to ‘lub’. The semilunar valves close to prevent any backflow of blood from the aorta to the ventricles.

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(b) AV (atrioventricular) node is a mass of modified heart muscle situated in the lower middle part of the right atrium. It receives the impulse to contract from the SA node via the atria and transmits it through the atrioventricular bundles to the ventricles. AV node is called the pacesetter. Here, the impulses are delayed for 0.1 seconds to ensure that the auricles will contract first and empty fully before the ventricles contract.

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(b) Closed circulatory system means blood flows in some definite vessels in a specific direction in a more organised manner than that of an open system in which blood does not flow in vessels.

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(a) The inheritance of blood group is determined by some allelic genes which are \(\mathrm{I}^{\mathrm{A}}, \mathrm{I}^{\mathrm{B}} \& \mathrm{I}^{\circ}\). In one individual two allelic genes are present. \(\mathrm{I}^{\mathrm{A}} \& \mathrm{I}^{\mathrm{B}}\) are dominant while \(\mathrm{I}^{\mathrm{O}}\) is recessive in heterozygous condition. So if a child has a blood group \(\mathrm{O}\) he/she must have \(I^{0} I^{0} \&\) he/she cannot have the parents of blood group \(\mathrm{AB} \& \mathrm{AB} / \mathrm{O}\).

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(d) The wall of capillaries is very thin (usually less than one micron) and has numerous minute pores and is made up of only endothelium. Exchange of material takes place between blood and tissue fluid across the endothelial membrane of capillaries through active diffusion.

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(b) In the developing foetus, the haemopoietic tissues are the liver and spleen, while after birth RBCs are mainly produced in the bone marrow of the long bones. The formation of leucocytes occurs in the bone marrow, Peyer’s patches, lymph nodes, thymus, spleen, etc. and it is called as leucopoiesis.

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(d) Vitamin-K (phylloquinone) is required for the synthesis of prothrombin necessary for blood clotting. It is synthesised by bacteria in the colon. Vitamin- \(\mathrm{K}\) is commonly called anti-haemorrhagic vitamin. Its deficiency leads to bleeding, i.e. no coagulation or clotting.

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(c) Each capillary is lined by a single layer of flat cells, called endothelium. The
endothelium allows the exchange of materials like the nutrients, respiratory gases, waste products, hormones, etc between the blood and surrounding tissue cells through the tissue fluid.

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(d) The genotype child of having \(O\) blood group is \(\mathrm{I}^{\circ} \mathrm{I}^{\circ}\)

If father has \(B\) blood group it is either \(-\mathrm{I}^{\mathrm{B}} \mathrm{I}^{\mathrm{B}}\) or \(\mathrm{I}^{\mathrm{B}} \mathrm{I}^{\mathrm{o}}\) But if father has \(\mathrm{I}^{\mathrm{B}} \mathrm{I}^{\mathrm{B}}\) then child cannot have \(\mathrm{I}^{\circ} \mathrm{I}^{\circ}\), so father must have \(\mathrm{I}^{\mathrm{B}} \mathrm{I}^{\mathrm{O}}\).

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(d) Lymphocyte is a type of white blood cells in the vertebrate immune system. Lymphocytes are responsible for making antibodies.

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(b) Blood group A has Antigen-A & antibody ‘b’ or anti A or a,

Blood group B has antigen-B & antibody a or anti \(\mathrm{B}\) or \(\mathrm{b}\).

Blood group \(\mathrm{AB}\) has antigen- \(\mathrm{A}\) & \(\mathrm{B}\) and no antibody.
Blood group \(\mathrm{O}\) has no antigen & antibodies a & b both.

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(c) During transport of \(\mathrm{CO}_{2}\) in the blood, about \(70 \%\) of \(\mathrm{CO}_{2}\) released by respiring tissue cells is transported as bicarbonate ions. It diffuses into the plasma and then into the RBCs. Here, \(\mathrm{CO}_{2}\) combines with water to form carbonic acid. This reaction is catalyzed by a zinc-containing enzyme carbonic anhydrase. Carbonic acid dissociates into bicarbonate and hydrogen ions. A small amount of bicarbonate ions is transported in the RBCs, whereas most of them diffuse into the plasma to be carried by it.

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(d) Wall of a vein consists of tunic externa, tunica media, and tunica interna. All these layers are also present in the wall of the artery. However, in the wall of a vein, the elastic membrane of tunica interna is relatively thin, and muscle fibres and elastic fibres in tunica media are fewer. Therefore, a vein has a thinner and less elastic wall but a wider cavity than an artery of the same diameter.

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(a) Pulmonary artery carries the blood from the right ventricle of the heart to the lungs for oxygenation so it carries deoxygenated blood.

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(b) Thromboplastin, a lipoprotein, helps in clot formation. Thromboplastin helps in the formation of an enzyme prothrombinase. This enzyme inactivates heparin and it also converts the inactive plasma protein prothrombin into its active form, thrombin. Both the changes require calcium ions. Thrombin converts fibrinogen molecule to insoluble fibrin. The fibrin monomers polymerize to form long, sticky fibres. The fibrin threads form a fine network over the wound and trap blood corpuscles (RBCs, WBCs, platelets) to form a crust, the clot. Thus, if calcium is removed from the blood, clotting process will not occur.

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(c) Blood group A has A antigen and \(b\) antibody and blood group \(O\) has no antigens and both a and \(b\) antibodies so, if a patient with blood group \(A\) needs blood, both \(A\) and O blood group can be given to him.

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(b) The right auricle opens into the right ventricle through a wide passage, the right auriculoventricular or A-V aperture. This aperture is muscles of the right ventricle by a number of tough, white cords, the chordae tendineae.

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(a) Lymph (called tissue fluid in the intercellular spaces) is a vascular tissue consisting of two parts-a clear, colourless fluid matrix, the plasma and floating amoeboid cells, the white blood cells, mostly lymphocytes. It differs from the blood in lacking red blood cells and some blood proteins. The lymph eventually enters the blood near the heart.

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(d) Neutrophils are granulocytes, i.e., cytoplasm is filled with fine granules. These granules are actually lysosome and Golgi bodies. These are the chief phagocytic cells of the body and engulf the microbes by phagocytosis, so neutrophils are also called soldiers of the body.

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(b) Mineral found in the red pigment of vertebrate blood is iron.

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(c) Haemophilia is a sex linked disease (linked with \(\mathrm{X}\) chromosomes). In this disease, blood lacks the thromboplastin protein which causes blood clotting during injury. In normal human, blood clots in 2-6 min. While in haemophilic human, it may take from 3 hrs to 24 hrs due to which death may occur.

Hemophilia disease was Ist discovered by Jon Catto in 1803. The most famous families in which the inheritance of this disease was found were the Royal families of Britain & Russia, so it is also called Royal disease.

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(c) Presence of RBCs in the blood is known as hematuria. Alkaptonuria is the excretion of large amount of alkapton in urine which when comes in contact with light turns black. Proteinuria is the presence of proteins in the blood.

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(a) The haemoglobin is broken down into haem i.e. iron and globin protein which is then converted into the yellowish substance bilirubin which is extracted by the liver cells from the blood and stored in the form of bile in the gall bladder.

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(d) In sickle cell anaemia, normal haemoglobin \((\mathrm{HbA})\) gets changed in denatured form of haemoglobin (HbS) in which the haemoglobin molecule’s configuration changes and it changes its shape, in low \(\mathrm{O}_{2}\) concentration unable to transport \(\mathrm{O}_{2}\) and \(\mathrm{RBCs}\) become sickle-shaped. It is a genetic disease caused by the denaturation of haemoglobin, that is why it is known as hemolytic anaemia.