LIFE PROCESSES Life is all around us. We have life, so does other animals,birds, plants etc. But there are some things which do not have life. Howexactly do you differentiate between these living and non-living things?                           FUN TO DO!!! Mark the correct box. First one is done for you.

    ITEM   LIVING   ONCE LIVING   NON-LIVING   Eraser       x     Microbes           Copper Jug         Woollen sweater         Plucked Apple         Spider web         Rust on Iron         Paper Bag           Coral            CHARACTERISTICS OFLIVING THINGS·        Movement·        Cellular structure·        Growth and Development·        Nutrition·        Reproduction·        Respiration·        Excretion·        Response to stimulus LIFE PROCESSESAll living organisms performcertain processes to continue their existence. These functions and processesthat are carried out by the organisms to maintain their life are called life processes. The above processes require energy in form of nutrients andother substances. The process of providing or obtaining the food necessary forhealth and growth is called Nutrition.The sources of energy (food) are quite varied and complex,hence are needed to be broken down in the body and converted into simplerforms.

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For this, most organisms use oxygen. The process ofgetting oxygen from outside of the body, and to use it for the break-down offood is called respiration.When energy is generated bychemical reactions, certain by-products are also released which are of no useto the body and could be harmful.

  These metabolic wastes are neededto be removed and discarded. This process of elimination of waste is called excretion. FUN TO DO!!!Unscramble the answer Life process which:·        Combining oxygen and glucose to obtain energy (OAESIIPNTRR)·        Filters toxins and waste out of blood (CNOXEEIRT)·        Maintains your growth and development (UTTINNORI)     NUTRITIONWe are using up energy in everyactivity that we perform. Even in a state of rest like sleeping and sitting, energyis needed to maintain our state of life. We gain this energy from the food weeat.

Food offers several key nutrients like carbohydrate, protein, fat,vitamins and minerals, which help us to grow, develop, maintain proper bodyfunction etc. A good nutrition is very important to promote overall health andreduce the risk of acquiring diseases. When we eat, our body breaks down thenutrients into smaller components and absorbs them to use as fuel to carry outbody activities.

 ROLES OF NUTRITION IN ORGANISMS·        It enables the organism to get necessary energyto carry out all life activities ·        Helps the cells to grow and divide whichultimately helps in the growth of organisms·        Provides raw materials that are vital for thesynthesis of hormones, enzymes and other components needed for the building ofcells·        Helps in the repair of damaged cells, tissuesand to replace worn out cells of the organisms·        Protect out body from diseases and infections HOW DO LIVINGORGANISMS OBTAIN FOOD?It is true that all organisms consume food, consisting thesame nutrients and minerals, to gain energy but their need is fulfilled bydifferent means. Based on this, nutrition is divided into 2 main categories;AUTOTROPHICNUTRITIONGreen plants and some bacteria belong to this category as theyhave the ability to use simple inorganic substances such as carbon dioxide andwater and synthesize organic molecules i.e. carbohydrate (Glucose).Energy, required to carry out this process, is obtained fromsunlight (solar energy) and Chlorophyll is the vital component, present in theleaves, which allows plants to absorb the light energy. The entire process is called Photosynthesis.

Photosynthesis is a process used by plants and certain otherorganisms to convert inorganic molecules like carbon dioxide and water intoorganic molecules like glucose (food), with the help of sunlight and chlorophyll.  The process of photosynthesis occurs in 3 steps:(i) Chlorophyll absorbs light energy (sunlight)(ii) Conversion of light energy to chemical energy andsplitting of water molecules(iii) Hydrogen, released by the splitting of water molecule,is utilized for reduction of CO2 to produce carbohydrates WHAT ARE THE COMPONENTS NECESSARY FOR PHOTOSYNTHESIS?Photosynthesis requires chlorophyll, CO2, waterand sunlight. Let’s learn about some interesting experiments that show us therequirement of these components in photosynthesis.A.

Role ofsunlight in photosynthesis1.     Takea potted plant and keep it in a dark place for 2-3 days so that the leavesloose starch.2.     Coveran area of leaf with a strip of black paper.3.

     Placethis plant under sunlight for 4-5 hours.4.     Pluckthe selected leaf and remove the black paper.5.     Testfor starch by adding a few drops of iodine solution to it.Observation: After the addition of iodine solution the leaf turns blue-blackexcept in the covered region. Inference:The covered region did not receive any light. Therefore,photosynthesis did not occur and start was not formed.

Whereas the uncoveredregion received sunlight and carried out photosynthesis forming starch.B. Role ofchlorophyll in photosynthesisTake a variegated leaf plant for this experiment (variegatedleaf is a leaf in which different patches of colors, mainly green and yellow).

Test the leaf for starch with iodine solutionObservation:Areas with green patches test positive and turn blue-black,areas with pale yellow patches don’t change color.Inference:Photosynthesis takes place only in the green parts of leafbecause of the presence of chlorophyll. C.

Role of CO2in photosynthesis1.     Taketo destarched potted plants.2.     Placeboth the plants in Bell jars.3.     InBell jar A, keep sodium bicarbonate (NaHCO3) which produces CO2.4.     InBell jar B, keep sodium hydroxide (NaOH) which absorbs CO2.

5.     Placeboth the plants in the sunlight for at least 6 hours.6.     Takea leaf from both the plants and perform starch test. Observation:Leaf from Bell jar A turns blue- black. Leave from Bell jarbe do not change colour.Inference:Plant of Bell jar A had access to carbon dioxide and hencecarried out photosynthesis. Whereas in Bell jar B carbon dioxide was absent.

 STOMATAStomata are tiny openings or pores used for gas exchange. Theseare mostly found on the under-surface of plant leaves. Stomata open and closeto allow the intake of carbon dioxide and the release of oxygen. The opening and closing of stomata is controlled by guardcells. During daytime, guard cells take up water by osmosis and become turgid.

They are pulled apart and thus open the pore. At night, water is lost and thepores close.The gaseous exchange occurs across the surface of stems androots as well.     HETEROTROPHICNUTRITIONIt is the nutrition obtained by digesting organic compoundsprepared by other plants or animals.

Organisms that are unable to synthesizeorganic compounds to use as food are called heterotrophs.Some organisms obtain food from dead matter. These organismsare called saprophytes. They secreteextracellular enzymes that break down the complex organic compounds and thenabsorb the simpler molecules. Ex. FungiSome organisms live on or inside other living organisms andderive nutrition from their body, these are called parasites. Ex. TapewormHolozoic nutrition: Others take in food as wholeand break it down or digest it inside the body.

The food to be taken in and howit has to be broken down depends on the body design and functioning. Thishappens in 5 steps:Ingestion: The process of taking in thefood.Digestion: The process of breakingcomplex food substances into simpler molecules.Absorption: The process of absorption ofdigested food particles.Assimilation: The process of utilization ofdigested food particles.Egestion: The process of removingundigested food from the body.

 Nutrition inHuman Beings – Digestive system Human digestive system includes alimentary canal anddigestive glands. The alimentary canal is a long tube extending from the mouthto the anus. Various parts of the tube are specialized to perform differentfunctions.The alimentary canal consists of mouth, esophagus,stomach, small intestine, large intestine rectum and anus.

The glands which are associated with human digestive systemare salivary glands, liver and pancreas.    ALIMENTARYCANALMouth·        Itis the entry point for food.·        Itsfunction is to masticate (chew) complexfood to give it a certain size andtexture, so it’s able to pass through the esophagus to the stomach. ·        Thelining of the alimentary canal is soft; therefore the food has to be moistenedto make its passage smooth.

·        Ourteeth perform the cutting andgrinding function of food.·        Saliva is released by salivary glands into our mouth when wesmell and taste food. ·        Thetongue assists in mixing the foodwith the saliva·        Chewingbreaks the food into small pieces and saliva mixes with the food to begin theprocess of digestion. ·        Salivacontains the enzyme salivary amylase (also called ptyalin) that begins the breakdown ofstarch (in food) to simpler sugars.·        About30% starch digestion takes place in oral cavity (mouth)·        Theball-like mixture of food and saliva is called Bolus·        Theprocess of swallowing is called deglutination Esophagus (Foodpipe)Esophagus runs behind the windpipe (trachea)It is a muscular tube that contracts and relaxes in asynchronized fashion (called peristalsis)to move the food down towards the stomachThe food moves forward when the muscles behind the foodcontract and the muscle ahead of food relaxPeristaltic movement occurs all along the gut Stomach·        Itis a large hollow organ that holds the food. It expands when food enters it.

·        Thecells in the wall of the stomach secrete a strong acid and several powerfulenzymes that continue the process of digestion·        Gastric glands in present in the wall of thestomach contains –         Zymogenic cells: secrete protein digestingenzyme called pepsinogen which islater activated into pepsin by HCl-         Parietal cells: secrete Hydrochloric acid (HCl). It creates an acidic medium which facilitatesthe action of enzyme pepsin-         Mucus-producing cells: secrete mucus which protects thedelicate stomach walls from own acid and enzyme actions ·        Stomachmuscles further mix and churn the food·        Thismixture of food and digestive juices is called chyme·        Thefood exits the stomach in small amounts into the small intestine; this movementis regulated by a sphincter muscle Small Intestine·        Itis 22-25 feet long muscular tube (longest part of alimentary canal)·        Itis highly convoluted (coiled) and acquire a compact space·        Siteof complete digestion of Carbohydrates, Proteins and Fats·        Intestinal glands secrete intestinal juicecontaining enzymes that convert proteins to amino acids, complex carbohydratesinto glucose and fats into fatty acids and glycerol·        Ithas three segments –         Duodenum: receive bile (liver) andpancreatic juice (pancreas), further breakdown of food takes place-         Jejunum: middle segment of smallintestine, absorbs most of the nutrients present in food-         Ileum: absorb vitamin B12, bile acidsand other remaining nutrients ·        Jejunumand ileum contains small finger-like projections called villi which increasesthe surface area for better absorption·        Thevilli are connected to blood vesselswhich takes the absorbed nutrients to each and every cell of the body·        Theunabsorbed left-over residue is thenpassed on to the large intestine·        Showsperistaltic movement Large Intestine(Colon)·        6-feetlong muscular tube·        Thewaste product passes through the colon, water is observed and stool is formed·        Villi are present for water absorption·        Movementof stool is by peristalsis·        Largeintestine consists of: –         Caecum is a pouch connected to the junctionof the small and large intestine (considered the beginning of the largeintestine).Appendix is a tube-shaped sac connected to caecum.-         Ascending (right) colon –         Transverse (across) colon –         Descending (left) colon –         Sigmoid colon ·        Stoolis stored in sigmoid colon until it enters into the rectum.·        Itusually takes about 36 hours for the waste / stool to pass through the colon Rectum·        Connectthe colon to the anus ·        Receivestool from colon and stores it until evacuation or egestion Anus·        Lastpart of alimentary canal·        Theexit of stool is regulated by the analsphincter·        Voluntarycontrol over the sphincter lets us hold the stool and it relaxes to release thecontents ACCESSORYGLANDS (helping on digestion) Liver·        Producesbile for fat digestion and elimination·        Bilejuice contain salts which breaks down the fat into smaller globules thusincreasing the efficiency of the enzymes working on them·        Alsodetoxifies harmful chemicals and toxins Pancreas·        Secretepancreatic juice into the duodenum·        Thisdigestive juice has enzymes thatbreakdown protein, fats and carbohydrates. Some of them are:-         Trypsin: digests protein-         Lipase: breaks down emulsified fat-         Pancreaticamylase:digests starch ·        Alsosecretes insulin directly into the bloodstream, helps to maintainthe blood sugar level in body Gall Bladder·        Storesand concentrates bile·        Itis released into the duodenum to help absorb and digest fats                   RESPIRATIONYou must understand that ‘respiration’ does not have thesame meaning as ‘breathing’.

Breathingis just a physical process where we inhale and exhale air in and out of ourlungs, whereas, respiration is achemical reaction where oxygen (taken in by inhalation) is used to break downfood (glucose) to generate energy.


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