PSEB 10th Class Science Notes Chapter 6 Life Processes

This PSEB 10th Class Science Notes Chapter 6 Life Processes will help you in revision during exams.

PSEB 10th Class Science Notes Chapter 6 Life Processes

→ Visible movement is not the only defining characteristic of life.

→ Plants do not show locomotory movements, but movements occur at the molecular level.

→ Viruses are living only inside living organisms.

→ Every living organism takes food, derives energy, passes out waste material, and responds to changes within the body and environment. All these activities are collectively termed life processes.

→ These life processes are required for the maintenance of life.

→ The body needs energy which is obtained from the food that the organism eats.

PSEB 10th Class Science Notes Chapter 6 Life Processes

→ The source of energy is called food. So there must be a process to transfer a source of energy (food) from outside to inside the body of an organism. This process is commonly called nutrition.

→ Since life on earth depends on carbon-based molecules, most of these food sources are also carbon-based.

→ Oxidizing-reducing reactions are some of the most common chemical means to break-down large molecules.

→ The process of acquiring oxygen from outside the body and using it in the process of breakdown of food sources for cellular needs is called respiration.

→ In the case of a single-celled organism, there are no specific organs for taking in food, exchange of gases, or removal of wastes because the entire surface of the organism is in contact with the environment.

→ In multicellular organisms, various body parts are specialized for the functions they perform.

→ The uptake of food and of oxygen will also be the function of specialized tissues.

→ We need energy every time for our life activities.

PSEB 10th Class Science Notes Chapter 6 Life Processes

→ The general requirement for energy and materials is common in all organisms, but it is fulfilled in different ways.

→ The heterotrophs’ survival depends directly or indirectly on autotrophs. Heterotrophic organisms include animals and fungi.

→ The carbon and energy requirements of the autotrophic organism are fulfilled by photosynthesis.

→ Photosynthesis is the process by which autotrophs take in substances from the outside and convert them into stored forms of energy.

→ This material is taken in the form of carbon dioxide and water which is converted into carbohydrates in the presence of sunlight and chlorophyll.

→ Some of the energy derived from the food we eat is stored in our bodies in the form of glycogen.

→ The green dots are cell organelles called chloroplasts which contain chlorophyll.

→ Stomata are tiny pores present on the surface of the leaves.

→ Massive amounts of gaseous exchange take place in the leaves through these pores for the purpose of photosynthesis.

→ Since large amounts of water can also be lost through these stomata, the plant closes these pores when it does not need carbon dioxide for photosynthesis.

PSEB 10th Class Science Notes Chapter 6 Life Processes

→ Plants take up materials like nitrogen, phosphorus, iron, and magnesium from the soil.

→ Nitrogen is an essential element used in the synthesis of proteins and other compounds.

→ The form of nutrition differs depending on the type and availability of food material as well as how it is obtained by the organism.

→ Fungi like bread moulds, yeast, and mushrooms break down the food material outside the body and then absorb it.

→ In single-celled organisms, the food may be taken in by the entire surface.

→ Amoeba takes in food using temporary finger-like extensions of the cell surface which fuse over the food particle forming a food vacuole.

→ In Paramecium, which is also a unicellular organism, the cell has a definite shape, and food is taken in at a specific spot.

→ The alimentary canal is basically a long tube extending from the mouth to the anus.

→ When we eat something we like, our mouth ‘waters’. This is actually a fluid called saliva secreted by the salivary glands.

→ The saliva contains an enzyme called salivary amylase that breaks down starch which is a complex molecule to give sugar.

→ The stomach is a large organ that expands when food enters it.

PSEB 10th Class Science Notes Chapter 6 Life Processes

→ The gastric glands present in the wall of the stomach release hydrochloric acid, a protein-digesting enzyme called pepsin and mucus.

→ The small intestine is the longest part of the alimentary canal.

→ Meat is easier to digest, hence carnivores like tigers have a shorter small intestine. It is the site of the complete digestion of carbohydrates, proteins, and fats.

→ The pancreas secretes pancreatic juice which contains enzymes like trypsin for digesting proteins and lipase for breaking down emulsified fats.

→ The undigested food is sent into the large intestine where a large number of villi absorb water from this material.

→ The food material taken in during the process of nutrition is used in cells to provide energy for various life processes.

→ The respiration takes place in the presence of air (oxygen), it is called aerobic respiration.

→ The release of energy in this aerobic process is much greater than in the anaerobic process.

→ The synthesis of lactic acid in our muscles during strenuous activity causes cramps.

→ The energy released during cellular respiration is immediately used to synthesize a molecule called ATP which is the fuel for all other activities in the cell.

→ ATP is broken down to release a fixed amount of energy which can drive the endothermic reactions taking place in the cell.

PSEB 10th Class Science Notes Chapter 6 Life Processes

→ At night, when there is no photosynthesis occurring, CO2 elimination is the major exchange activity going on.

→ Aquatic animals that live in water need to use the oxygen dissolved in water.

→ Since the amount of dissolved oxygen is fairly low as compared to the amount of oxygen in the air, the rate of breathing in aquatic organisms is much faster than that of terrestrial organisms.

→ The air passing through the nostrils is filtered by fine hairs that line the nasal passage.

→ Within the lungs, the passage divides into smaller and smaller tubes which finally terminate in balloon-like structures called alveoli.

→ The blood brings carbon dioxide from the rest of the body for release into the alveoli, and the oxygen in the alveolar air is taken up by the blood in the alveolar blood vessels to be transported to all the cells in the body.

→ In human beings, the respiratory pigment is hemoglobin which has a very high affinity for oxygen.

→ If the alveolar surface were spread out, it would cover about 80 square meters.

→ The blood is a fluid connective tissue.

→ Blood consists of a fluid medium called plasma.

→ Plasma transports food, carbon dioxide, and nitrogenous wastes in dissolved form.

PSEB 10th Class Science Notes Chapter 6 Life Processes

→ The heart is a muscular organ that is as big as our fist.

→ The heart has two regions; the atrium and ventricle. Ventricle has a thicker muscular wall than the atrium because the ventricle has to pump blood through the whole body.

→ Valves ensure that blood does not flow backward when the atria or ventricles contract.

→ The separation of the right side and the left side of the heart is to prevent oxygenated and deoxygenated blood from mixing. Such separation allows a highly efficient supply of oxygen to the body.

→ Amphibians or many reptiles have three-chambered hearts while Fishes have only two-chambered hearts.

→ Blood goes through the heart twice during each cycle in amphibians and other vertebrates. This is known as double circulation.

→ The force that blood exerts against the wall of a vessel is called blood pressure. This pressure is much greater in arteries than in veins.

→ The normal systolic pressure is about 120 mm of Hg and diastolic pressure is 80 mm of Hg.

→ Blood pressure is measured with an instrument called a sphygmomanometer.

→ High blood pressure is also called hypertension. It can lead to the rupture of an artery and internal bleeding.

→ Arteries are the vessels that carry blood away from the heart to various organs of the body. Veins collect the blood from different organs and bring it back to the heart.

→ The blood has platelet cells that circulate around the body and they plug the leaks by helping to clot the blood at these points of injury.

PSEB 10th Class Science Notes Chapter 6 Life Processes

→ There is another type of fluid also involved in transportation. This is called lymph or tissue fluid.

→ The xylem tissue (vessels and tracheids) of the roots, stems, and leaves are interconnected to form a continuous system of water-conducting channels reaching all parts of the plant.

→ The loss of water in the form of vapours from the aerial parts of the plant is known as transpiration.

→ The transport of soluble products of photosynthesis is called translocation and it occurs in the part of the vascular tissue known as phloem.

→ Unlike transport in the xylem which can be largely explained by simple physical forces, the translocation in the phloem is achieved by utilizing energy.

→ Excretronr-All plants and animals produce harmful substances due to a number of metabolic activities occurring in their body tissues. These harmful substances are to be eliminated from the body, otherwise, they act as toxic substances.

→ In human beings, excretory products in the form of soluble nitrogen compounds are removed by the nephrons in the kidneys.

→ Plants use a variety of techniques to get rid of waste materials that are stored in the cell vacuoles, like removing them in the falling leaves or excreted into the surrounding soil.

→ The excretory system of human beings includes a pair of kidneys, a pair of ureters, a urinary bladder, and a urethra.

→ The purpose of making urine is to filter out waste products from the blood.

PSEB 10th Class Science Notes Chapter 6 Life Processes

→ Nitrogenous wastes such as urea or uric acid are removed from blood in the kidneys.

→ Enzymes: The bio-catalysts initiate or enhance the rate of reaction in a living system without undergoing any change in themselves. They are proteinic in nature.

→ Nutrition: It is the process by which living organisms take up nutrients from the environment and use them for the development of cells and tissues and also for energy.

→ Autotrophs: The organisms which make their food from simple substances like CO2, water, and minerals with their own chlorophyll in the presence of sunlight are called autotrophs.

→ Heterotrophs: The organisms which cannot synthesize their own food. They depend on autotrophs for their food supply directly or indirectly. Saprophytes. The organisms which depend on dead, decaying organic matter for their nutritional requirements are called saprophytes.

→ Parasites: Those organisms which depend upon other living organisms (host) for their food and shelter are called parasites. There are two types of parasites i.e. ectoparasites (outside the body) and endoparasites (inside).

→ Holozoan: Holozoans are heterotrophs that involve the intake of solid pieces of food. Since solid food is taken in, holozoic nutrition is also called ingestive nutrition. It is found in animals and Protozoa.

→ Herbivorous: The organisms which take their food in the form of plants and plant products are called herbivorous.

→ Carnivorous: Those organisms which rely on the flesh of other organisms are called carnivorous.

→ Omnivorous: Those organisms which can feed upon plants, as well as other organisms, are called omnivorous.

PSEB 10th Class Science Notes Chapter 6 Life Processes

→ Ingestion: The process of intake of food in the mouth is called ingestion. Digestion. The process of breakdown of complex food material into -simpler substances is called digestion.

→ Photosynthesis: The autotrophs take in CO2 and H2O and convert these into carbohydrates in the presence of chlorophyll and sunlight is called Photosynthesis.

→ Compensation point: In the shadow (morning and evening) when photosynthesis is very low, the CO2 produced in respiration is equal to the CO2 consumed in photosynthesis. This situation when the CO2 absorption from the environment is about nil is called a compensation point.

→ Respiration: It is the process of oxidation of carbohydrates in the cells to release energy that is used by the cells for different purposes.

→ Aerobic respiration: The respiration taking place in the presence of air – (oxygen) is called aerobic respiration.

→ Anaerobic respiration: The respiration taking place in the absence of air is (oxygen) called anaerobic respiration.

→ Respiratory substrate: The substance which is oxidized during respiration is called the respiratory substrate.

→ Glycolysis: It is the metabolic pathway in the cytoplasm that converts glucose into pyruvate.

→ Anabolism: It refers to chemical reactions in which simpler substances are combined to form more complex molecules. Anabolic reactions usually require energy.

→ Catabolism: It refers to chemical reactions that result in the breakdown of more complex organic molecules into simpler substances.

→ Fermentation: Fermentation is a metabolic process that converts sugar/glucose to CO2 and other simple carbon compounds like alcohol, lactic acid, malic acid, acetic acid, etc.

PSEB 10th Class Science Notes Chapter 6 Life Processes

→ ATP: Adenosine triphosphate is a nucleoside triphosphate used in cells as a coenzyme often called the “molecular unit of currency” of intracellular energy transfer.

→ Stomata: These are tiny pores present on the surface of the leaves. Massive amounts of gaseous exchange take place in the leaves through these pores for the purpose of photosynthesis.

→ Breathing: The process of taking air into and expelling it from the lungs is called breathing.

→ Inspiration: The intake of oxygen from the environment into the lungs is called inspiration.

→ Expiration: The process of throwing out CO2 from the lungs is called expiration.

→ Transpiration: The loss of water in the form of vapours from the aerial parts of the plant is known as transpiration.

→ Xylem: A continuous system of water-conducting channels reaching all parts of the plant is called the xylem.

→ Phloem: The system transporting products of photosynthesis from the leaves where they are synthesized to other parts of the plant is called phloem.

→ Translocation: The transport of soluble products of photosynthesis is called translocation and it occurs through the phloem.

→ Artery: The blood vessels which carry the oxygenated blood from the heart to various parts of the body are called arteries.

→ Veins: The blood vessels which bring the deoxygenated blood from various parts of the body to the heart are called veins.

PSEB 10th Class Science Notes Chapter 6 Life Processes

→ Capillaries: Very thin blood vessels within the tissues which connect arteries with veins.

→ Lymph: It is a clear-to-white fluid containing white blood cells that attack bacteria in the blood.

→ Hemoglobin: The iron-containing red pigment present in red blood cells to transport oxygen is called hemoglobin.

→ Clotting: The process of blood clot formation in the body is called clotting.

→ Dialysis: It is a process of removing waste and excess water from the blood and is used as an artificial replacement for kidney failure.

→ Osmoregulation: The process of maintaining a balance of water and ions inside the body is called osmoregulation.

→ Excretion: Excretion is the process by which waste products of metabolism are eliminated from the body.

→ Nephron: The basic functional unit of the kidney is called a nephron.

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