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    by: Kislay

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    1 : LIFE PROCESSES By :- Kislay Raj 9th C 22
    2 : CONTENTS Introduction Nutrition Respiration Transportation Excretion Control & Coordination
    3 : Introduction The maintenance functions of living organisms must go on even when they are not doing anything particular . Even when we are just sitting in class, even if we are just asleep at our desks this has to go on. The processes which together perform this maintenance job are life processes. Energy is needed for these processes which comes from the outside body of the organism. So there must be a process to transfer a source of energy from outside to inside, a process which we call nutrition. These sources need to be broken down or built up in the body and must be converted to the kind of molecules the body needs to grow. The processes of breakdown of food sources for cellular needs is what we call respiration. In case of single celled organism no specific organs for taking in food, exchange of gases or removal of waste is needed. But in multicellular organism various body parts have specialized in these functions without which the organism cannot sustain. So a transportation system is needed . When chemical reactions take place inside the body, some harmful by-products are formed. They need to be removed from the body frequently. So an excretion system is required. Let us discuss these various processes, so essential to maintain life one-by-one.
    4 : NUTRITION The general requirement for energy and materials is common in all organisms, but it is fulfilled in different ways. Some organisms use simple food materials obtained from inorganic substances in the form of CO2 and H2O. These organisms are called autotrophs and include green plants and some bacteria. Other organisms utilise complex substances. These complex substances have to be broken down into simpler substances. To achieve this, organisms use bio-catalysts called enzymes. These organisms are called heterotrophs.
    5 : Autotrophic Nutrition Carbon and energy requirements of the autotrophic organisms are fulfilled photosynthesis. Quite simply it is the process by which autotrophs take in substances from the outside and convert them into stored form of energy. This material is taken in the form of CO2 and H2O which is converted into Carbohydrates in the presence of sunlight and chlorophyll too. Carbohydrates are utilised for providing energy to the plant. The Carbohydrates which are not used immediately are stored in the form of starch which serves as the international energy reserved to be used as and when required by the plant.
    6 : Heterotrophic Nutrition Each organism is adapted to its environment. The form of nutrition differs depending on the type and availability of food material as well as how it is obtained by the organism. There is a range of strategies by which the food is taken in and used by the organism. Some organisms break down the food material outside the body and then absorb it. Others take in whole material and break it down outside their bodies. Some other organisms derive nutrition from plants or animals without killing them.
    7 : Nutrition in human beings Human digestion begins in the mouth. The tongue tastes the food and moves it into the pharynx. The presence of food in the mouth stimulates the salivary glands to secrete saliva which has salivary amylase that breaks down starch and glycogen to maltose. The food is then passed into a tube called oesophagus. Here also salivary amylase acts on chewed food. The stomach is located below the diaphragm. It is a saclike muscular structure. Partial digestion takes place here. Its inner lining has sunken pits. Each pit constitute a gastric gland. The cell lining the gastric pits are of three kinds (1) mucous cells (2) parietal cells (3) zymogen cells. In the stomach digestion of protein occurs in acidic medium. In the duodenum, the food is turned alkaline by the bile juice and digestion occurs with the help of enzymes from the pancreas. In the ileum, digestion occurs with the help of intestinal juice produced by the intestinal glands. Absorption of digested food occurs in the small intestine with the help of villi.The large intestine helps in water absorption.
    8 : The Human Digestive System
    9 : RESPIRATION All living organisms require energy to carry out life processes. This energy comes from food. Cellular processes get usable energy from a process called respiration. Respiration commonly involves the use of O2 to break down carbohydrates and other organic molecules, giving usable energy, CO2 and H2O in the process.
    10 : Anaerobic Respiration Partial oxidation of food in the absence of oxygen, resulting in the release of some amount of energy, is called anaerobic respiration. Anaerobic means without oxygen or in the absence of oxygen, while aerobic means with oxygen. Glucose has six carbon atoms joined to each other by covalent bonds. Hydrogen and oxygen atoms are also attached to these carbon atoms. In anaerobic respiration of glucose, some hydrogen atoms are removed from it, resulting in oxidation. At the end of a series of reactions, glucose gets converted into two molecules of pyruvate. This process is called glycolysis. After glycolysis, pyruvate gets converted into different compounds depending on whether the further reaction takes place in the presence of oxygen or not. Less energy is generated from anaerobic respiration
    11 : Aerobic Respiration The complete oxidation of food yielding carbon dioxide, water and energy in the presence of oxygen is called aerobic respiration. Aerobic respiration takes place inside the mitochondria. After glycolysis, pyruvate enters the mitochondria and is oxidized in a series of reactions. The products of these reactions include ATP, CO2 and H2O. The no. of molecules of ATP formed in aerobic respiration is 38. Hence the energy made available is much greater than in the case of anaerobic respiration. Inside the mitochondria, when an inorganic phosphate group (Pi) gets attached to a compound called ADP, a molecule of ATP is formed. ADP + Pi ? ATP
    12 : Human Respiratory System The human respiratory system consists of a pair of lungs and a series of air passages leading to the lungs. The entire passage consists of the nose, pharynx, larynx ,trachea, bronchi and bronchioles. Air enters the nose through the nostrils. The air is moistened by the mucus present in the nose. Behind the nose lies the pharynx. The air passes from the pharynx to the larynx. The opening leading to the larynx is called glottis. It is protected by a lid called epiglottis, which prevents food from entering the passage to the lungs. From the larynx the air goes to the trachea or the windpipe. The trachea divides into two tubes called bronchi. Each bronchus divides and branches out in the form of thinner tubes called bronchioles. The bronchioles enter the lungs and divide further into finer branches called alveolar ducts. These open into extremely thin-walled, grape-shaped air sacs called alveoli. The lungs are a pair of spongy organs lying in the chest cavity. The actual exchange of gases between the air and the body takes place in the alveoli. Here oxygen from the air in the alveoli goes into the blood and the carbon dioxide in the blood goes out.
    13 : The Human Respiratory System
    14 : TRANSPORTATION In order to carry out various life processes like nutrition and respiration, organisms require food and oxygen. It is also necessary for the organism to get rid of the waste products of cellular processes. Food, oxygen and waste products need to be carried from one part of the body to another. In unicellular organisms and many simple multicellular organisms, materials are transported by osmosis and diffusion. In higher organisms this is done by a specialized transport system called the vascular system.
    15 : Transportation in Plants Transport of Water and Minerals : The xylem tissue transports water and minerals. It consists of interconnected vessels and tracheids. Plants absorb water from the soil through the root and transports it to the stem, leaves and flowers. Roots have root hairs that are unicellular, thin-walled outgrowths of the epiblema. Water is absorbed by osmosis while the minerals are absorbed as ions by active transport. The ions then move upward through the xylem, to the leaves and other aerial parts of the plant.
    16 : Transport of Food and Other Substances : The food manufactured in the leaves is translocated upwards, downwards and laterally to parts of the plant through the phloem. The phloem conducts some other substances such as amino acids. The conducting cells of the phloem are cylindrical cells called sieve tubes, which have sievelike partitions at both ends. These partitions are called sieve plates. Besides sieve tubes, the phloem also has companion cells and phloem parenchyma. Sucrose is the main form of carbohydrate that is translocated in plants. Its translocation into the phloem tissue occurs with the expenditure of energy.
    17 : Human Circulatory System The human heart is a muscular, conical and dark red organ that plays a role of a pump in the circulatory system. Blood from different parts of the body comes to the right atrium when it expands. This impure blood is brought from the upper part of the body through the superior vena cava and from the lower part of the body through the inferior vena cava. As the right atrium contracts, the blood goes to the right. The atrioventricular aperture is closed by a valve after the blood transfer. When the right ventricle contracts, the blood is forced out to the lungs for oxygenation through the pulmonary artery. In the lungs there is an exchange of CO2 and O2 . Then the pulmonary vein brings this oxygenated blood to the left atrium,as it relaxes. Then this blood is transported to all parts of the body through arteries. The pure blood is used by cells for oxygen and after use the veins bring the de-oxygenated blood to the heart. Then again this blood is sent to lungs for oxygenation. This process continues till death.
    18 : The Human Circulatory System
    19 : EXCRETION Chemical reactions occur in the cells of living organisms all the time to carry out the life processes. The sum of these reactions is called metabolism. Metabolism produces useful products as well as toxic by-products. These toxic substances have to be removed as they are harmful if allowed to accumulate. The removal of metabolic waste products from the body is called excretion.
    20 : Excretion in Plants Compared to animals, plants do not have a well-developed excretory system to throw out nitrogenous waste materials. This is because of the differences in their physiology. The gaseous waste materials produced during respiration (CO2) and photosynthesis (O2) diffuse out through stomata in leaves. Many plants store organic waste products in their permanent tissues that have dead cells. Plants also store waste within their leaves or barks. These wastes are periodically removed as the leaves and barks fall off. S0me plant wastes are stored as a thick, white fluid. This white fluid is called latex. Aquatic plants lose most of their metabolic wastes by direct diffusion into the water surrounding them. Terrestrial plants excrete some waste into the soil around them.
    21 : Human Excretory System Our excretory system consists of kidneys, blood vessels that join them, ureters, urinary bladder and urethra. They help produce and excrete urine. There are two bean-shaped kidneys that lie in the abdominal cavity. The kidneys are reddish-brown. They receive a lot of blood for filtration. A volume of blood nearly equivalent to that in the whole body passes through the kidneys every four or five minutes! The kidneys produce urine to filter out the waste products, like urea and uric acid, from the blood. Urine leaves each kidney through a tube called ureters. The ureters from both the kidneys are connected to the urinary bladder that collects and stores urine. Ureters carry urine from the kidneys into the urinary bladder. The urethra is a canal that carries urine from the bladder and expels it outside the body.
    22 : The Human Excretory System
    23 : CONTROL & COORDINATION Our body is made up of billion cells that get organized into different tissues. Tissues constitutes organs, and organs constitute systems. In the absence of such working in harmony an organism can’t do many things that it normally does. For eg. when we run, our muscles require greater energy, which can be produced when there is greater supply of oxygen. To increase the oxygen supply, the rate of breathing increases. When we stop running, our muscles do not need so much energy. Consequently, there is no need for extra energy and the rate of breathing comes down to the normal level. All these activities are coordinated. The working together of various systems in the body is called coordination.
    24 : Response & Coordination in Plants Continuous movements of plants : As a plant grows, the stem tip does not grow upward in a straight line but follows a curved path. This movement is known as nutation. This type of movement is more pronounced in climbing plants such as pea etc. Quick movements of plants : In Mimosa pudica, the leaflets fold up quickly if any leaflet is touched. It happens because touch triggers a sudden and rapid loss of water from cells
    25 : at the base of the leaflets. These movements of sensitive plants in response to touch are very sensitive. All these movements are directed neither towards nor away from the stimulus. Such movements are called nastic movements. Stomatal movements : The opening and closing of stomata is controlled by changes in the turgor pressure of guard cells and is not coordinated with light and darkness.
    26 : Tropic movements : The movement of an organism in the direction of a stimulus or away from it is called tropic movement, or tropism. There are many types of tropic movements such as :- Phototropism
    27 : Geotropism Hydrotropism
    28 : Chemotropism Thigmotropism
    29 : The Human Nervous System The nervous system performs the following three functions:- Sensory input i.e. the detection of stimuli by the receptors, or sense organs. Transmission of this input by nerve impulses to the brain and spinal cord, which generate an appropriate response. Motor input i.e. carrying out of the response by muscles or glands, which are called effectors. In humans, the nervous system is divided into the (1) central, (2) peripheral, and (3) autonomic nervous system. The central nervous system consists of the brain and the spinal cord. Brain : it is the most important coordinating centre in the body. The brain may be divided into three parts – forebrain, midbrain and hindbrain. Spinal cord : it is a long cord which arises from the medulla oblongata and runs through the backbone.
    30 : The Human Nervous System

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