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BIOLOGY Standard Mar Theophilus Training College Nalanchira, Thiruvananthapuram

GREESHMA GIREESAN MSc Zoology Kerala University BSc Zoology Kerala University





CONSTITUTION OF INDIA Part IV A FUNDAMENTAL DUTIES OF CITIZENS ARTICLE 51A Fundamental Duties-It shall be the duty of every citizen of India: (a) to abide by the Constitution and respect its ideals and institutions, the National Flag and the National Anthem; (b) to cherish and follow the noble ideals which inspired our national struggle for freedom; (c) to uphold and protect the sovereignty, unity and integrity of India (d) to defend the country and render national service when called upon to do so; (e) to promote harmony and the spirit of common brotherhood amongst all the p.eople of India transcending religious, linguistic and regional or sectional diversities; to renounce practices derogatory to the dignity of women (f) to value and preserve the rich heritage of our composite culture; (g) to protect and improve the natural environment including forests, lakes, rivers, wild life and to have compassion for living creatures; (h) to develop the scientific temper, humanism and the spirit of inquiry and reform; (i) to safeguard public property and to abjure violence; (J) to strive towards excellence in all spheres of individual and collective activity so that the nation constantly rises to higher levels of endeavour and achievements; (k) who is a parent or guardian to provide opportunities for education to his child or, as the case may be, ward between age of six and fourteen years.

Dear Students, Science is activity based. Its method is the unprejudiced investigation of truth, based on scientific evidence. If what is generally considered right today is scientifically proved wrong tomorrow, it would be accepted. This is how Science works. This rational method has to be employed in learning Science. Continuous observations, experimentations and analyses lead the scientific perspectives to new dimensions. Hence, you have to make use of every possible opportunity to observe and experiment. The student's role is pivotal in the process of construction of knowledge. This Science textbook is only a resource in the learning process. Your teachers and supplementary materials will help you in the creation of knowledge. 'Samagra', the education portal and technology enabled Q R Code printed textbooks would definitely make your learning activity in classrooms easy and joyful. The National Skills Qualifications Framework, the current relevance of Disaster Management and the possibilities of 1.C.T have also been considered in the textbook. This book includes lessons which spread light on circulation and body fluids. Structure and function of human heart,types of circulation in plants and animals. The method of presentation adopted is centred in the life processes that would be conducive to the learner to achieve Life skills and Health habits. Learning experiences which provide knowledge and delight have been included here. We expect the textbook to be helpful in the further learning of Science. Love and Regards, GREESHMA GIREESAN

HUMAN CIRCULATorY System

Contents 1 BLOOD 2 THE HUMAN HEART 3 DOUBLE CIRCULATION 4 SIMPLE NUTRIENTS TO THE HEART 5 LYMPHATIC SYSTEM 6 HUMAN CIRCULATORY SYSTEM 7 TRANSPORTATION IN PLANTS

CERTAIN ICONS USED IN THE TEXTBOOK FOR CONVENIENCE EXTENDED READING LET US ASSESS EXTENDED ACTIVITIES

You have learnt that all living cells have to be provided with nutrients, 02 and other essential substances. Also, the waste or harmful substances produced, have to be removed continuously for healthy functioning of tissues. It is therefore, essential to have efficient mechanisms for the movement of these substances to the cells. Different groups of animals have evolved different methods for this transport. Simple organisms like sponges and coelenterates circulate water from their surroundings through their body cavities to facilitate the cells to exchange these substances. More complex organisms use special fluids within their bodies to transport such materials. Blood is the most commonly used body fluid by most of the higher organisms including humans for this purpose. Another body fluid, lymph, also helps in the transport of certain substances. In this chapter, you will learn about the composition and properties of blood and lymph (tissue fluid) and the mechanism of circulation of blood is also explained herein.

BLOOD It is the fluid connective tissue that consist of plasma, formed elements and fluid matrix. COMPONENTS OF BLOOD If you add chemicals like EDTA (Ethylene Diamine Tetra Acetic acid) an anticoagulant of blood, to a test tube containing blood, and wait for sometime, we can observe blood cells and the liquid part of the blood distinctly as shown in figure 1.1. Figure1.1 Components of blood PLASMA Plasma is the pale yellow coloured fluid that constitutes 55% of blood. Blood cells are found in the plasma. The simpler molecules formed as a result of digestion, namely glucose, amino acids, fatty acids, glycerol etc., reach cells through the plasma. The different constituents of plasma are given in the below illustration 1.2. Figure 1.2 Plasma 2

FORMED ELEMENTS figure 1.3 Erythrocytes Erythrocytes, leucocytes and platelets are collectively called formed elements and they constitute nearly 45 per cent of the blood. Erythrocytes or red blood cells (RBC) Erythrocytes are the most abundant of all the cells in blood. RBCs are formed in the red bone marrow in the adults. RBCs are devoid of nucleus in most of the mammals and are biconcave in shape. These molecules play a significant role in transport of respiratory gases. They contain the pigment haemoglobin RBCs have an average life span of 120 days after which they are destroyed in the spleen (graveyard of RBCs). Leucocytes or white blood cells (WBC) Leucocytes are also known as white blood cells (WBC) as they are colourless due to the lack of haemoglobin. They are nucleated and are relatively lesser in number which averages 6000-8000 mm-3 of blood. Leucocytes are generally short lived. We have two main categories of WBCS granulocytes and agranulocytes. - Neutrophils, eosinophils and basophils are different types of granulocytes, while lymphocytes and monocytes are the agranulocytes figure 1.4 Leucocytes 3

PLATELETS Figure 1.5 platelets Platelets also called thrombocytes, are cell fragments produced from megakaryocytes (special cells in the bone marrow). Platelets can release a variety of substances most of which are involved in the coagulation or clotting of blood. LET US ASSESS 1. List the various types of blood cells. ° ° ° ° 2. Which are the types of WBC? EXTENDED ACTIVITIES Prepare a chart showing types of blood cells along with its function 4

THE HUMAN HEART The circulatory patterns are of two types open or closed. Open circulatory system is present in arthropods and molluscs in which blood pumped by the heart passes through large vessels into open spaces or body cavities called sinuses. Annelids and chordates have a closed circulatory system in which the blood. pumped by the heart is always circulated through a closed network of blood vessels. This pattern is considered to be more advantageous as the flow of fluid can be more precisely regulated. All vertebrates possess a muscular chambered heart. Fishes have a 2-chambered heart with an atrium and a ventricle. Amphibians and the reptiles (except crocodiles) have a 3- chambered heart with two atria and a single ventricle, whereas crocodiles, birds and mammals possess a 4-chambered heart with two atria and two ventricles. Now let us study in detail about human heart.

STRUCTURE AND POSITION OF HEART As the human heart works relentlessly like a pump, blood flows through blood vessels continuously in all directions. The heart is a muscular organ situated slightly tilted towards the left in between the two lungs, behind the sternum in the thoracic cavity). The size of the human heart is equal to the size of one's fist. Pericardium is a double layered membrane that covers the heart. Pericardial fluid is filled in between the pericardial membranes. This fluid helps to reduce friction between the membranes when the heart beats. CHAMBERS OF HEART Our heart has four chambers, two relatively small upper chambers called atria and two larger lower chambers called ventricles. A thin, muscular wall called the interatrial septum separates the right and the left atria, whereas a thick-walled, the inter- ventricular septum, separates the left and the right ventricles. The atrium and the ventricle of the same side are also separated by a thick fibrous tissue called the atrio- ventricular septum. However, each of these septa are provided with an opening through which the two chambers of the same side are connected. Figure3.1 Section of human heart 6

VALVES OF THE HEART The opening between the right atrium and the Figure3.2 valves of the heart right ventricle is guarded by a valve formed of three muscular flaps or cusps, the tricuspid valve, whereas a bicuspid or mitral valve guards the opening between the left atrium and the left ventricle. The openings of the right and the left ventricles into the Pulmonary artery and the aorta respectively are provided with the semilunar valves. The valves in the heart allows the flow of blood only in one direction, i.e., from the atria to the ventricles and from the ventricles to the pulmonary artery or aorta. These valves prevent any backward flow of blood. (Figure 3.2). BLOOD VESSELS Figure3.3 capillaries Blood is carried through blood vessels. These are arteries and veins. Blood going to the heart is carried in veins. Blood going away from the heart is carried in arteries. The main artery going out of the right ventricle is the pulmonary artery. The main artery going out of the left ventricle is the aorta. The veins going into the right atrium are the superior vena cava and inferior vena cava. These bring blood from the body to the right heart. The veins going into the left atrium are the pulmonary veins. These bring blood from the lungs to the left heart. Capillaries connect arteries to veins. Arteries divide into branches to form arterioles. This will form smaller blood vessels called capillaries which again join and widen to form venules and again converge to form veins 7

Vein carries blood to the heart. thin wall. valves are seen inside. blood flows with low speed and low pressure Artery carries blood from the heart. thick and elastic walls. blood flows with high speed and high pressure. Capillaries thin vessels that connect veins and arteries together. wall is formed of a single layer of cells. minute pores on the walls. valves are absent. blood flows with low speed and low pressure. WORKING OF HEART The heart beat continuously with a rhythm. Initiation of contraction and relaxation of the heart and regulation of the rate of heartbeat are controlled by Sino Atrial Node. It is located on the right atrial wall. As it functions like an electric cell, it is known as pacemaker. The right side of the heart receives deoxygenated blood and sends it to the lungs. The right atrium receives deoxygenated blood from the body through veins called the superior and inferior vena cava. These are the largest veins in the body. The right atrium contracts, and blood passes to the right ventricle. Once the right ventricle is full, it contracts and pumps the blood to the lungs via the pulmonary artery. In the lungs, the blood picks up oxygen and offloads carbon dioxide. The left side of the heart receives blood from the lungs and pumps it to the rest of the body. Newly oxygenated blood returns to the left atrium via the pulmonary veins. The left atrium contracts, pushing the blood into the left ventricle. Once the left ventricle is full, it contracts and pushes the blood back out to the body via the aorta. 8

CARDIAC CYCLE Illustration 3.1 The cardiac cycle is the performance of the human heart from the beginning of one heartbeat to the beginning of the next. It consists of two periods: one ARTIFICIAL during which the heart muscle relaxes and refills with PACEMAKER blood, called diastole, following a period of robust The pacemaker has to function properly for the heart to beat contraction and pumping of blood, called systole. After rhythmically, otherwise the heart beat will become non rhythmic. This emptying, the heart immediately relaxes and expands to can be life threatening if not resolved. However, nowadays it is receive another influx of blood returning from the not a problem. Medical science has made possible to implant the lungs and other systems of the body, before again artificial pacemaker beneath the skin through surgery. The artificial contracting to pump blood to the lungs and those pacemaker has two parts. The first part is the pulse generator. The systems. A normally performing heart must be fully second part is the mechanism which transmits electric signals from the expanded before it can efficiently pump again. first part to the heart. Wilson Greatbatch, an American electrical Assuming a healthy heart and a typical rate of 70 to 75 engineer was the one behind the invention of this equipment. beats per minute, each cardiac cycle, or heartbeat, takes Artificial pacemaker surgeries have been conducted since 1960, about 0.8 seconds to complete the cycle. DID YOU KNOW? Heart beats 100000 times a day. The LUB DUB sound of the heart is the opening and closing of valves. A women's heart beats faster than man's heart. 9

LET US ASSESS 1. Complete the table given below. 2. Label the parts of heart. EXTENDED ACTIVITIES 1. Prepare a chart showing the direction of flow of blood in the heart 2. Create a 3 model of heart using eco-friendly materials. 10

DOUBLEBCIRCULATION pCurainfyytohuehbellopodm?e to ofcoYuersse! Heart is the key organ for blood circulation and the double circulation is an efficient way of circulation as it provides an effective way of circulation. The main difference is that the blood follows two routes - one for oxygenated blood and the other for deoxygenated blood. Hence, the name \"Double circulation.\" The majority of mammals, including humans utilize a double circulatory system. The heart is connected to the lungs through the pulmonary artery and vein. In double circulation, there are two pathways in which the blood flows. They are, Systemic Circulation Pulmonary Circulation

Systemic Circulation The flow of oxygenated blood from the left ventricle of the heart to various parts of the body and deoxygenated blood from various parts of the body to the right atrium is called systemic circulation. The systemic arteries arising from the aorta carry oxygenated blood from the left of the ventricle to various parts of the body. The systemic veins carry deoxygenated blood from various parts of the body to the right atrium of the heart (Figure 4.1). Pulmonary Circulation The flow of deoxygenated blood from the right ventricle to the lungs and the return of oxygenated blood from the lungs to the left atrium is called the pulmonary circulation. The pulmonary trunk (right and left pulmonary artery) carries blood from the right ventricle to the lungs where the exchange of gases takes place. The oxygenated blood from the lungs returns to the left atrium of the heart through two pulmonary veins, one from each lung. Figure 4.1 Double Circulation 12

Double circulation supports a strict separation of both oxygenated and deoxygenated blood. Therefore, this circulation ensures that the body always has a dedicated supply of oxygen and also, it improves body efficiency. This is also one of the reasons why mammals can maintain their body temperatures. Apart from the double circulation, a third portal system also exists to improve circulation efficiency. Systemic Circulation Right atrium Superior venacava Different parts Aorta Left ventricle of the body Right ventricle Pulmonary artery Lungs Pulmonary vein Left atrium Pulmonary Circulation Illustration 4.1 LET US ASSESS 1. Which are the two pathways in which blood flows in double circulation? ° ° 2. Complete the illustration 13

EXTENDED ACTIVITIES 1. Contruct a working model of heart showing double circulation 2. Collect as much as information regarding the relation between tobacco and heart 14

SIMPLE NUTRIENTS TO THE HEART WHHEEFRYOE!OISDM? Y How do the simple nutrients, which are absorbed into the blood from the small intestine reach heart? Portal Circulation Certain veins do not reach the heart and they carry blood from organ to organ. Such veins are called portal veins. They begin from one organ as capillaries and end in another organ as capillaries. Portal system is the system of blood circulation in which portal veins are included. Eg: Hepatic portal system.

Capillaries in the Hepatic portal vein Capillaries in the intestine Hepatic vein liver Venacava illustration4.1 Have you ever thought why simple nutrients reach the liver? Liver is the centre of metabolism. Simple nutrients undergo several changes in the liver. Storage of glucose in the form of glycogen, releasing energy from fatty acids, producing cholesterol etc. are such changes. Have you understood the role of heart in the distribution of simple nutrients to all parts of the body? It is through rhythmic heart beats that the functioning of heart is made possible. HEART BEAT One systole and the subsequent diastole together constitute a heart beat. It takes about 0.8 seconds. Contraction of the chambers of the heart is termed as systole. During this phase, blood flows from the atria to the ventricles and from the ventricles to outside. Subsequently along with the atria, the ventricles also relax. This stage of relaxation is termed as diastole. In this phase, chambers of the heart get filled with blood. The heart beats at an average rate of 72 times/minute. PULSE The wave-like movement formed due to the contraction and relaxation of the heart is felt throughout the walls of the arteries. This is called pulse. Rate of pulse is equivalent to that of the heartbeat. 16

BLOOD PRESSURE About 70 ml of blood is pumped into the arteries everytime the heart contracts. The pressure exerted by this excess blood on the walls of the arteries is systolic pressure. This is 120 mm Hg. When the heart dilates fully the same quantity of blood enters the heart. A low pressure felt in the arteries during this time is known as diastolic pressure. This is 80 mm Hg. The blood pressure of an individual is stated in terms of these two pressures. VARIATION IN BLOOD PRESSURE The desired rate of blood pressure is 120/80 mmHg. The condition in which the blood pressure increases above the normal rate is a disease condition called hypertension. This happens due to many reasons. Unhealthy habits, such as excess use of salt and fat, smoking, lack of excercise etc. often lead to high blood pressure. The condition in which blood pressure rate goes below the prescribed rate is called hypotension. If not regulated, hypotension and hypertension may lead to stroke or heart attack. DID YOU KNOW? Sphygmomanometer is the instrument used to Only about 12% people with measure blood pressure. hypertension in India have their blood Digital B.P. apparatus is pressure under control. Uncontrolled also available nowadays. blood pressure is one of the main risk factors for cardiovascular diseases (CVDs) such as heart attacks and stroke, and are responsible for one-third of total deaths in India. 17

LET US ASSESS 1. Complete the illustration given below. 2. Find the difference between heartbeat and pulse 3. Find true or false °Hepatic portal system carries blood to the lungs . °Hepatic portal vein carries blood to the heart. . ° Liver purifies the blood. EXTENDED ACTIVITIES 1. Prepare a chart showing the direction of flow of blood in the hepatic portal system. 18

LYMPHATIC SYSTEM HAOBWFSOODORODBBEIEOSEDDTAYIHTNEMY As the blood passes through the capillaries in tissues, some water along with many small water soluble substances move out into the spaces between the cells of tissues leaving the larger proteins and most of the formed elements in the blood vessels. This fluid released out is called the interstitial fluid or tissue fluid. It has the same mineral distribution as that in plasma. Exchange of nutrients, gases, etc., between the blood and the cells always occur through this fluid. An elaborate network of vessels called the lymphatic system collects this fluid and drains it back to the major veins. The fluid present in the lymphatic system is called the lymph. Lymph is a colourless fluid containing specialised lymphocytes which are responsible for the immune responses of the body. Lymph is also an important carrier for nutrients, hormones, etc. Fats are absorbed through lymph in the lacteals present in the intestinal villi. Lymphatic system helps in the transport of materials along with blood.

How does lymph transport materials? Along with blood, lymph also participate in the transport of materials. Fatty acids and glycerol are transported from intestine mainly through lymphatic system. In centre of microvilli there are special lymph capillaries called lacteals that absorb fatty acids and glycerol. From the lacteals (lymph), it is transported to small and large lymph ducts and reach the heart via venacava along with blood (Illustration: 2.1). FATTY ACIDS AND GLYCEROL LACTEALS (LYMPH) LARGE LYMPH DUCTS SMALL LYMPH DUCTS VENACAVA(BLOOD) HEART figure2.2 illustration2.1 The lymph formed from blood passes through lymph ducts and return to blood near the heart. In addition to lymph, the lymphatic system consists of lymph capillaries, lymph ducts, lymph nodes and spleen (Figure2.2) Spleen and lymph nodes play a major role in defending disease causing germs. 20

DID YOU KNOW ? The human body has an average of between 500-700 lymph nodes mostly located near stomach,armpits,neck and groins LET US ASSES 1. Complete the illustration. 2. Which are the organs involved in lymphatic system? EXTENDED READING 1. Collect as much information on lymphatic system and prepare pare a note in your science diary. 21

HUMAN CIRCULATORY DISORDERS IanIc'yammn'oetxrteahkauesitted. A disorder is defined as a state of irregular functioning of the body. The disorders of the circulatory system could be defined as any ailment which affects the heart, blood vessels, and the blood cells. This disorder leads to the insufficient or reduced transportation of blood, oxygen, hormones, and nutrients to the tissue and cells.Let us look into detail some of the disorders of circulatory system.

CORONARY ARTERY DISEASE / ATHEROSCLEROSIS Coronary Artery Disease is the disease Figure 5.1 Atherosclerosis which is caused by the deposition of waxy substances in the blood vessels which supplies the blood to the heart muscle and this deposition leads to the blockage of the blood flow. (Figure 5.1). The examples of waxy substances are fat, cholesterol and fibrous tissues. As a result, it may also cause a heart attack. Coronary Artery Disease (CAD) could be caused by smoking, high blood pressure,cholesterol, diabetes or insulin resistance. ANGINA PECTORIS Angina is usually due to obstruction or spasm of the arteries that supply blood to the heart muscle. Other causes include anemia, abnormal heart rhythms, and heart failure. The main mechanism of coronary artery obstruction is atherosclerosis as part of coronary artery disease. The term derives from the Latin angere (\"to strangle\") and pectus (\"chest\"), and can therefore be translated as \"a strangling feeling in the chest\". Mainly caused due to smoking, diabetes, tension,etc. ARTERIOSCLEROSIS Figure 5.2 Arteriosclerosis Arteriosclerosis is the thickening, hardening, and loss of elasticity of the walls of arteries. This process gradually restricts the blood flow to one's organs and tissues and can lead to severe health risks brought on by atherosclerosis, which is a specific form of arteriosclerosis caused by the buildup of fatty plaques, cholesterol, and some other substances in and on the artery walls. It can be brought on by smoking, a bad diet, or many genetic factors. 23

CARDIAC ARREST Cardiac arrest is the sudden loss of blood flow throughout the body resulting from the heart not being able to pump blood efficiently. Cardiac arrest results in rapid loss of consciousness and breathing may be abnormal or absent. While cardiac arrest may be caused by heart attack or heart failure, these are not the same, and in 15 to 25% of cases there is a non-cardiac cause. Some individuals may experience chest pain, shortness of breath or nausea immediately before entering cardiac arrest. MYOCARDIAL INFARCTION Myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which may travel into the shoulder, arm, back, neck or jaw. Often it occurs in the center or left side of the chest and lasts for more than a few minutes HYPERTENSION High blood pressure or hypertension means the force or pressure of the blood flowing through the vessels is consistently too high. High blood pressure can lead to stroke, loss of vision, heart failure, heart attack, kidney disease, and reduced sexual function. STROKE A stroke can happen when one of the vessels that lead to the brain either becomes blocked by a blood clot or bursts. This stops blood flow and prevents oxygen from getting to the brain. 24

HEART TRANSPLANTATION AND ARTIFICIAL HEART Organ donation and transplantation is not a breaking news today. There are records of transplantation of skin parts done in India during BC 200. In 1946 the first heart transplantation surgery was initiated by transplanting a dog's heart by Demikov, a Russian doctor. In humans, this surgery was first performed successfully in 1967 under the leadership of Christian Bernard in South Africa. Eventhough the patient survived only for 18 days, it was a great beginning. In 1994, Dr. P.Venugopal and team repeated the success at All India Institute of Medical Sciences, New Delhi. WORLD HEART DAY LET US ASSESS September 29 1.Name some heart related diseases 2.Briefly explain the reasons for heart problems 3.How can we overcome heart problems. EXTENDED ACTIVITIES Prepare a note on heart diseases after analysing the changing lifestyle Figure 5.2 Arteriosclerosis 25

TRANSPORTATION IN PLANTS As in animals, substances are transported in plants too. The food has to be transported to all parts of the plant. This is done by the vascular tissue called the phloem. Thus, xylem and phloem transport substances in plants. In most animals the blood that circulates in the body distributes food and oxygen to different cells of the body.

CONDUCTION THROUGH XYLEM Figure 7.1 Vascular tissues in plants extend from the roots to leaves, in an interconnected manner. You know that the water and salts that roots absorb from the soil reach the leaves through xylem, the vascular tissue. Transportation of water takes place through tracheids and vessels, the dead cells of xylem. The diameter of vessels is greater than that of tracheids. Vessels are arranged one above the other. As the cell walls between the vessels disintegrate, they look like long pipes (figure 7.1) How does water reach the tree-top through the xylem naturally? This happens due to the combined action of many Figure 7.2 processes. Let us examine these processes. Transpiration, root pressure, cohesion and adhesion are important among them. Transpiration can be observed through a simple experiment. Take two potted plants, one with leaves and the other without leaves. Cover them using transparent polythene bags as shown in figure 7.2 Examine both the bags after sometime. It can be inferred that water came out from the leaves. Water is expelled from leaves due to evaporation. This process is called transpiration. Water is lost from the intercellular spaces of leaves through stomata by transpiration. It reduces the pressure in the cells of leaves. In order to compensate this pressure difference, water enters these cells from adjacent cells through osmosis. The transpiration pull developed due to transpiration helps to carry water to the top. Besides this, water molecules have the capacity to stick to themselves and with the walls of the vessels through which they move. These processes are known as cohesion and adhesion respectively. Along with these, the root pressure developed in the cells of root due to absorption of water also helps in raising water. 27

illustration 7.1 conduction of water in plants TRANSPORT THROUGH PHLOEM figure7.3 Food is transported in the form of sucrose through the sieve tube, the main part of the phloem. Like xylem vessels, sieve tubes are also seen as pipes arranged one above the other (figure 7.3). But differing from xylem vessels, pores are seen in their cross walls. Through these pores,the cytoplasm of sieve tubes are interconnected through which food molecules can travel. Companion cells are seen along with sieve tubes. They also help in the transportation of food. 28

LET US ASSESS 1. Identify the vascular tissues indicated by A and B 2. Name the processes that help water absorbed by the roots to reach the leaves. 3. In some plants, the rate of transpiration is very high. Does it affect the availability of water in that locality? Why? EXTENDED ACTIVITIES 1. Construct a model of transportation of water in plants. Show the direction of water flow. 2. Prepare a science edition by including information regarding forces helps in the transportation of materials. 29

LET US ASSESS 1. Choose the simple nutrients which are absorbed into blood from those given below. A) Fatty acid B) Amino acid C) Fructose D) Glycerol E) Glucose 2. Observe the illustration of the lungs, the heart and body parts. 30

Redraw the illustration and connect the lungs and body parts to the heart using lines. Also show the route of blood flow. 3. Observe the figure showing the transportation of materials in plants. a. Identify the vascular tissues indicated by A and B b. Name the processes that help water absorbed by the roots to reach the leaves. c. In some plants, the rate of transpiration is very high. Does it affect the availability of water in that locality? Why? EXTENDED READING 1. Construct a model of double circulation using coloured threads, thermocol etc. Show the direction of flow of blood also. Part where oxygenated blood is present - red colour Part where deoxygenated blood is present - blue colour) 2. Prepare a Science edition by including information regarding Cardiac Health care 31

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