Life Processes - Cbse Class 10 Biology

GURUKUL24X7 – WE TEACH YOU TO EXCEL Points to keep in mind 1. Non living things cannot move by themselves so movement is used as criteria to decide whether something is living/alive or not. Plants show movement in various ways like they respond to stimulus like sunlight such as they bend towards sunlight (please remember sunlight is not same as any other source of light), they grow with their shoot growing upward and root growing downward, etc. 2. Metabolic Activities- The chemical processes occurring in the human body in order to maintain life. These chemical processes either use or liberate energy which is required for various life processes common to all living organisms. These life processes are Nutrition and Respiration, Transport and Excretion, Control and Coordination, Growth, Movement and Reproduction. 3. The chemical energy is obtained from food by breaking of food or organic matter through various chemical reactions like respiration (respiration is a process that releases energy from food absorbed by the body).Carbohydrates and fats are most common food for providing energy. Example of carbohydrates – Glucose (simple sugar), spinach Example of fats – Oil Life processes also require energy for building for biosynthesis of body constituents like cells,tissues and organs. These processes consume the energy liberated by other chemical reactions. Proteins and minerals are nutrients used for biosynthesis. Examples of proteins: milk, eggs etc Modes of nutrition 1. Autotrophic mode: Organism synthesizes its own food from simple inorganic materials like CO 2 and H 2 O in presence of sunlight (solar energy) (absorb blue and red light and reflect green light) and green color pigment called chlorophyll. Examples of autotrophs:green plants (not all plants are green), autotrophic bacteria (not all bacteria are autotrophs) 2. Heterotrophs: They cannot prepare their own food from simple inorganic materials like CO 2 and H 2 O and depend on other heterotrophs or autotrophs for nutrition. What are three ways in which heterotrophs obtain their food from other orvganisms? (Modes of nutrition)

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GURUKUL24X7 – WE TEACH YOU TO EXCEL 1. Saprotrophic nutrition- Sapro means rotten, trophe means nutrition So food is obtained from dead plants and decaying animal bodies.As saprophytes secrete digestive enzymes on dead plants and animals to decompose them into simple molecules or absorbable nutrients for themselves and others. They help in recycling dead waste. Examples saprophytes – fungi like mushrooms, yeast and bread moulds. *Scavangers like crow,vultures also feed on dead animals So the word saprophytes is generally used for microbes 2. Parasitic nutrition: Obtain nutrition from the body of other living organisms (without killing them).Since parasytes consume food and nutrition meant for maintaining life processes in host, parasites harm the host. 3. Holozoic- Intake of food by ingestion, ingested food is then digested and absorbed by the body cells of organism.Example :human beings,cat,dogs and most of the animals have holozoic mode of nutrion. NUTRITION IN PLANTS Common points for experiments involving photosynthesis a) Before Testing for starch:To test for the formation of starch in these experiments, starch first needs to be removed.This is done by keeping the plant in dark room for 3 days atleast.It won't make any more food due to absence of sunlight and the plant will consume all the stored food i.e.starch during respiration.This process is called destarching. b) Test for starch: Starch gives blue black color with Iodine.Chlorophyll being green in color interferes with the test for starch.So it needs to be removed from leaf by putting the leaf in a beaker containing alcohol and heating over water bath.Alcohol is inflammable I.e. catches fire easily so alcohol beaker is placed in a beaker containing water which is then heated.Boiling alcohol will extract chlorophyll making the leaf colorless or pale yellow. Leaf is then washed with water to remove any remaining chlorophyll sticking to the it.Place the decolorised leaf in a petri dish and drop Iodine solution and observe the color change. Note *I am writing the common point above so that it is easy to remember these experiment.If asked in exams, write the experiment explaining the details about destarching and test for starch. *Support your answers with diagrams wherever possible depending on marks.Diagrams are good 3/5 marks questions Experiment to show sunlight is needed for photosynthesis

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GURUKUL24X7 – WE TEACH YOU TO EXCEL 1. Destarch the leaves of the plant. (write what is explained above in a) 2. Cover a part of leaf from both sides with aluminium foil tightly so that no sunlight can enter that portion. 3. Place the potted plant in bright sunlight for 3 to 4 days.Test for starch for the whole leaf. (write what is explained above in b) Observation: Covered portion remains white/decolourised while remaining uncovered portion that was exposed to sunlight shows blue black color indicating formation of starch in presence of sunlight. Conclusion: Sunlight is needed for photosynthesis. Experiment to show Chlorophyll is needed for photosynthesis 1. Destarch a plant having variegated leaves (partly green and partly white) like croton.(green part contains chlorophyll while white part does not) 2. After destarching, place the plant (croton) in bright sunlight for 3-4 days. 3. Test the veriegated leaf for starch (explained above in b).Alcohol will remove the chlorophyll from green part of veriegated leaf. Observation: White portion of veriegated leaf remains white while remaining uncovered portion that was intially greeen shows blue black color indicating formation of starch in presence of chlorophyll Conclusion:chlorophyll is needed for photosynthesis. Experiment to show CO 2 is needed for photosynthesis 1. Destarch the potted plant with green leaves (write what is explained in part a above) 2. Take a glass bottle with wide mouth and covered with a lid , put some KOH (potassium hydroxide) in it.It will consume all the CO 2 present in the bottle. 3. Take a rubber cork and cut it into 2 halves.Put a destarched leaf attached to the potted plant in between the 2 halves of the cork and fit the cork on the mouth of the bottle such that upper half of the leaf is outside the bottle.Place the arrangement in sunlight for 3-4 days.The upper half of leaf in air will get CO 2 and sunligh botht while part of leaf in glass bottle will only get sunlight (entering through glass). 4. Remove the cock, pluck the leaf from the plant and take it out of the glass bottle. Test the leaf for starch ( write what is explained in part b above) Observation: The part of leaf that was outside the glass bottle showed blue black color with iodine indicating presence of starch while other part that was in the bottle remained colorless with iodine not showing presence of starch. Conclusion:carbon dioxide is needed for photosynthesis. Contact Number:

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GURUKUL24X7 – WE TEACH YOU TO EXCEL Diffusion Vs Osmosis Movement of molecules from high concentration or high density (crowded region) to low concentration or low density (uncrowded region) down its concentration gradient. It basically means even spreading of molecules till whole region has a uniform average density. The membrabe is not necessary.

Movement of solvent (water) from low [solute] concentrated (more water) solution to high [solute]concentrated (less water) solution through a semi permeable membrane.Semi permeablemembrane allows only molecules of certain size to pass through it, for example

Basically occurs when we mix two (same It occurs when low concentrated solution is or different type) of gases or liquids separated from high concentrated solution together .Molecules will spread out evenly via semi permeablemembrane. throughout the mixture. Examples: Perfume spray -particles diffuse or spread out in air, ink molucles spread out in water, air diffuses in stomata of leaves. Dissolved gases in blood transported to different parts of body by process of diffusion.

Examples: water moves from one cell to another through semi-permeable cell membrane.Water also carries with it dissolved minerals.

Physical process I.e. no energy is expended.

Physical process.

*higher concentration of solution means more solute particles. for eg: strong coffee has less milk (or water) than a light coffee,So strong coffeee is more concentrated than a light coffee.

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GURUKUL24X7 – WE TEACH YOU TO EXCEL PHOTOSYNTHESIS IN DETAIL Equation of photosynthesis: 6CO2 6H2 O+ Light Energy

chlorophyl

> C 6 H 12 O 6 6O 2

C 6 H 12 O6 is Glucose 1. CO 2 enters by diffusion into the leaves through tiny pores called stomata present on the leaf surface. 2. Guard cells surrounding the stomata control the opening and closing of the pore thus controling the amount of CO 2 entering or O 2 leaving the leaf.Stomata have a pair of guard cells around them. 3. Guard cells swell and become curve as water flows into them and open up the pore to allow the exchange of gases.Gaurd cells become straight and close the pore when they lose water. 4. Water is absorbed by roots from the soil by process of osmosis. 5. Sunlight or solar energy is trapped/absorbed by chlorophyll present green color bodies called chloroplast.Chloroplast are disc shaped organelles present in large amount in photosynthetic cells (also called mesoohyll cells) 6. Some of the light energy gathered by chlorophylls is stored in the form of adenosine triphosphate (ATP). The rest of the energy is used to remove electrons from a substance such as water. These electrons are then used in the reactions that turn carbon dioxide into organic compounds. 7. Water is transported to leaves through xylem vessels. 8. Apart from CO 2 and water, plants need other nutrients like nitrogen, potassium, phosphorus for their growth.Nitrogen is absorbed in form of nitrate ion  NO−3  present in inorganic salts or ammonium ion  NH 4  or organic compounds produced by bacteria from atmospheric nitrogen.Nitrogen is also available in nitrogenous fertilizers. 9. Photosthesis occurs in chloroplast present in green plants.So chlorplast is the site for photosynthesis. Steps in process of Nutrtiion in animals –common for all the animals like amoeba (found in water), paramecium (in water), humans etc. 1. Ingestion – Intake of food or process of taking food into the body.  In amoeba occurs through pseudopodia (pseudo-false, pod- legs so false legs) which is finger like projection formed by ameoba temporarily to engulf its food into food vacuole.  In paramecium through cilia.Cilia are hair like projections found all over the body of paramecium.Can move back and forth rapidly in water. Contact Number:

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GURUKUL24X7 – WE TEACH YOU TO EXCEL In humans---mouth. 2. Digestion: Breaking down of food containing large insoluble molecules into smaller water soluble molecules by chemical or physical processes.  In amoeba: By action of digestive enzymes secreted into the food vacuole by surrounding cytoplasm.Same process in paramecium.  In humans: Humans are large multicellular animals.They have a digestive system comprising of Mouth,Oesophagus(food pipe), stomach, small intestine and large intestine.Glands that secrete digestive enzymes /juices are – Salivary glands (For salivary amylase), Liver (secretes bile juice) and Pancreas (secrete pancreatic juice) 3. Absorption:The digested food is absorbed by the blood to be transported to the body cells.In humans small intestine contains large number of finger like projections called villi that provide a very large area for absorption of digested food into the blood stream as shown below. 

In unicellular organims like amoeba and paramecium, digested food is absorbed into cytoplasm through diffusion (why not osmosis?) from the vacuole.No blood stream present. 4. Assimilation: Carrying the absorbed food to body cells by blood stream where the assimilated food is used for obtaining energy by respiration and for growth and repair of body cells.  Amoeba and paramecium being unicellular do not have any blood stream.The absorbed food already present in cytoplasm is used for releasing energy by respiration and for growth and reproduction. Contact Number:

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GURUKUL24X7 – WE TEACH YOU TO EXCEL In humans and other animals, blood carries absorbed food to body cells where it is utilized for releasing energy by respiration and for growth. 5. Egestion – Removal of undigested food.  In amoeba and paramecium by rupturing or breaking a part of cell membrane through which undigested food is thrown out.  In humans, the undigested food from small intestine moves to large intestine which absorbs most of the water to excrete out waste called feces from anus. 

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