hello friends welcome again we'll start with the ncert class seventh the very first chapter that talks about the nutrition in animals now in the class six we have talked about what are various nutrients so we can say carbohydrates fats proteins vitamins all these are basic nutrients that are required by our body for our normal functioning so all living organisms consume food the vein which they consume food all the mode of nutrition differs so primarily we can say there are two modes of nutrition the first mode is known as Auto drop e Auto means automatic so it's by oneself so organism produces food itself and those are known as Auto drops the next is hetero drops heterotrophs are those organisms that cannot produce their own food and rely on someone else for the food for example we human beings now when we talk about Auto drops those Auto drops are also known as the producers are the first producers or who produce their food themselves these can further be classified into two those are the chemoautotrophs and the photoautotrophs photoautotrophs are those which perform photosynthesis in presence of sunlight to manufacture food however chemo auto drops are those which performed chemo synthesis that's basically a synthesis by chemical reaction and it's mainly seen in the deep waters now the basic understanding here lies is that sun we can say is the ultimate source of energy what would happen if there is no sunlight if there is no sunlight there would be no production of food by the plants and if there is no production of food by the plants all the hydro drops directly or indirectly depend on Auto drops for their survival so if there would be no production of food from the autotrophs there could be no survival for the heterotrophs as well and the auto drops as well so we can say son is the ultimate source of all energy that we have now all the living organisms as we said consume food we'll first start with the plants in this section so plants do a process of process known as photosynthesis in the next chapter we'll talk about nutrition and animals where we'll focus on heterotrophs are those organisms which depend on other for the production of food now here when we see plants the process by which the plants manufacture their food is known as photosynthesis photo means light and synthesis means production that means production of food in presence of light now this food when it is manufactured it requires certain process so let's see I have a tree here these are the roots now from the roots you have water and mineral so various water and various minerals and water transport up to the leaves so all of that goes to the leaf leaf as we can see has a green color prick pigment and this is known as chloro fill so green colored leaves or the green color of the leaf is due to a pigment which is known as chlorophyll now when the water is transporting up till the leaves here are the leaves you have the process of photosynthesis time that takes place so what nice does is it takes water and mineral from the roots it takes carbon dioxide from the air and how is this carbon dioxide taken this carbon dioxide is taken through the stomata now these straw meters are covered by the outer layer which is known as guard cell so we have the two diagrams for the stomata here so one is for the open stomata the other is for the clothes to store meta so we have a open straw meter here and a closed system written here so what happens in the leaf is you have carbon dioxide that is taken from the air now this stomata the outermost layer we can see is surrounded by guard cells now leaf has taken carbon dioxide from the atmosphere water and minerals from the roots and in presence of sunlight it starts to manufacture the food so that is how you have the manufacturing of the food that takes place now we perform certain tests first test is this - test of the leaf so what do we do under a stache test of a leaf so another starch test of a leaf we will show that leaf becomes blue-black so what we do is we take the leaf we put it in a iodine solution now this green leaf which was in presence of sunlight will put into an iodine solution turns blue-black this shows that there is presence of carbohydrate or we can say starch we have also done the same experiment on a piece of potato in class 6 so if you have been following there this becomes much more easy now what I do is I put the same leaf in a solution of potassium hydroxide so when I put it in the solution of potassium hydroxide this potassium hydroxide absorbs carbon dioxide so you have Koh that would react with co2 to form potassium carbonate so what would happen is this potassium hydroxide will absorb carbon dioxide and as a result this leaf would now no more will be able to give a blue-black color and therefore the test of IOT the district iodine for starch would fail because there is lack of presence of carbon dioxide in that leaf so carbon dioxide we can say is very essential similarly if I take this leaf I put it in dark and then I do a iodine test it would fail because this requires a leaf requires sunlight for the manufacturing of food or for the process of photosynthesis now when we say water and mineral goes up these goes up by the whistles and once the leaf has prepared the food it would transport all this prepared food to the various parts of the trees again and this process of transportation is again taking place through vessels now we have both these vessels what is the difference between the two vessels the vessel that takes the water and the minerals up to the leaves is known as a xylem the vessel that takes the prepared food back to the different parts of the plant is known as phloem so we have xylem and phloem that are present there now the process of photosynthesis as we said you have Sun which is the ultimate source of energy and without Sun you cannot have the process of photosynthesis that could be completed however there are modifications that are seen so where can we find such modifications we can see those modifications in case of desert areas as we have already talked about in class sixth where we have talked about the life-form adaptations we have talked about how in desert areas leaves are modified into spines now what is the purpose of modification into a so this is a cactus and you have leaves which are modified as spines what is the benefit of modification as a spine so spine reduces the surface area rather than this whole leaf surface area now you have just a spine that is present so surface area becomes very less as a result the water that is lost by means of transpiration is greatly reduced so water loss by the transpiration can be greatly reduced by reducing the surface area as in the case of desert so a simple equation to understand the process of photosynthesis is water and carbon dioxide in presence of sunlight and chlorophyll would give you a finished product that is food or starch and oxygen so that's the key idea here now in this diagram as you can see this is the leaf you have this tomato you and this diagram shows the open and the close the stomata so when the stomata is taking in carbon dioxide its open the center part of the open stomata which you can see here is known as the stoma and then you have a close to stomata where you do not have any intake of carbon dioxide that is taking place now when does the systematic close so it's during the night when there is no process of photosynthesis that takes place you would have the stomata that would close and straw meter we can say it closes during the night time so that's again important thing that we need to remember however as we talked about in class sex it's important to remember this process is for manufacturing of food this is not related to the process of respiration so as a respiration is a normal process that the plants take or this is in this process the plants take in oxygen and give it give out carbon dioxide unlike the process of photosynthesis where they consume carbon dioxide so that's why it's recommended during the night time do not sleep under the trees because during the night trees release carbon dioxide however during the day time since they are manufacturing food I oxygen is a byproduct of the manufacturing of food so when plants manufacture food you get starch does the food of the plant as well as oxygen and this food becomes the source for the various heterotrophs and therefore we have life that is possible again oxygen that is reserved that comes out as a byproduct of the process of photosynthesis is used by the organisms to survive the next important thing here is we have already talked about the test of carbohydrate the next is the various forms in which you can see the green plants so you have slimy green patches that is seen mostly in the stagnant water or the ponds and these are known as el guy and they can be of various colors usually we say commonly found alga is green color and this green alga is again capable of manufacturing its own food I during the process it takes in the sunlight manufactures the food now this food can be stored both as carbohydrate and fat carbohydrate we can say is a composition of carbon oxygen and hydrogen molecules however in the atmosphere we say we have abundant of nitrogen this nitrogen in natural form that is presented to the atmosphere cannot be utilized by the plants so this nitrogen is not useful for the plants so what it requires is a kind of conversion of nitrogen into nitrite and nitrate which we would study further in higher classes so what would happen with this converse conversion or fixation of nitrogen this nitrogen in the form of nitrates or nitrites can be utilized by plants so Rhizobium is one such bacterium that does the process of nitrogen fixation Rhizobium lives in the root nodules of the plants it does the fixation for the nitrogen provide the plant with the necessary nutrients on the other hand since its present in the root area or in the shaded area it it is protected and basically it lies in the shaded it's protected so Rhizobium and the plant we can say have a mutual coexistence or we can say mutualism or a kind of symbiotic relationship is present symbiotic relationship is a relationship where both the organisms either have a positive relationship or one organisms benefit and other remains neutral there is no harm to any of the organism so we say it's a kind of symbiotic relationship so under symbiotic relationship or we have a mutualism where you have both the organisms that benefit so Rhizobium is benefiting because it's getting shelter and the plant is benefiting because it's getting the consumable form of nitrogen where you have the nitrogen fixation that takes place so this is again a kind of symbiotic relationships that are important we'll understand that in a while again now each of the living organisms bead plant or animal is made up of unique cells within the body and these cells are enclosed by cell membranes you have a nucleus that is present within the nucleus you have genes which carry your DNA and this is responsible for the harriday tree that we see which we would again study in detail in the higher classes for now you must remember the cell is surrounded by a cell membrane again the open space that could be seen here is the cytoplasm then you have the plant cell which would have the cell wall that would be present which is again absent in the animal cell so those are some of the basic characteristics of the cell and besides this you have other bodies like Golgi bodies and O plasmic reticulum you have lysosomes which digest the nutrients so digestion of nutrients takes place by the help of light so lysosome so those are the major Organa major parts are organized within the org within the cell that we talk about now so far we have talked about the production of food all the plants are not capable of producing their own food so that's again something very important usually students get confused considering that we have been taught that plants manufacture food so all the plants are capable of manufacturing their own food it's absolutely incorrect to say that all plants can manufacture their own food now what are the different versions of the plants we can say these plants which cannot manufacture their own food or are heterotrophs are broadly given as parasitic plants insectivorous plants and sepra fights so those are the major category of plants that could be seen now coming on to the first which is parasitic plant if you go out into a garden or a dense forest area you would see a plant with a yellow colored growth over the plant like this and this yellow colored growth over the plant is cuscuta on which is also known as a marble now this a marble is a parasite on this plant because it takes out all the beneficial nutrients and deplete the plant of the useful nutrients and ultimately the plant dies so that is a kind of parasitic plant so under parasitic plant what we see the parasitic plant basically is acts as a parasite on the body of the host so the plant on which it is growing is the host and this cuscuta automobile acts as a parasite and takes away or draws all the impurity nutrients other important examples of this parasitic plants are rafflesia draught mistletoe then you have Australian Christmas tree so these names are again important all the parasitic plants how do they act they have modified roots and these modified rules are known as hosteria historia and this historia extracts the important nutrients from the host plant by attacking either the xylem or the phloem or both so xylem as we said conducts water and minerals through the plan phloem takes the processed food or it takes both it attacks both the vessels the next year's insectivorous plant insectivorous plant a good example is a pitcher plant now we have a demonstration for a pitcher plant so this is a kind of pitcher plant now what happens is you have an insect that's flying close to it finally this insect finds a way and moves into this pitcher plant now as the insect goes into this pitcher plant what would happen this the body of this pitcher plant would start to secrete a kind of material that would start to dissolve the chemicals or the start to dissolve this insect and this this pitcher plant acts as a kind of host which would absorb the major nutrients from this insect and as soon as the insect moves in the lid gets closed so that there is no chance for the insect to escape and it traps the animal or the insect so that is how a pitcher plant works now pitcher plant is just one type of the insectivorous plants there are numerous other insectivorous plants which are commonly seen which are drosera article area and you have aldo venda so those are some of the important insectivorous plants these plants are mainly associated with the region where you have acidic soil a poor or a very thin soil why they are associated with places like those because in those places they do not have ample amount of water and minerals that could move in and manufacturing of food becomes difficult so for survival in those areas the only mechanism that remains is as hetero crops are consuming the existing food that is there so that's why you have insectivorous plants here so some of the examples the other examples we have talked about and an example of a pitcher plant is seen here the next rests a profiles under sacrifice a very good example as mushroom you might have seen mushrooms growing up in the rainy season so those are fluffy umbrella type structures that those are commonly seen and they are found in either moist soil or a kind of rotting wood they take the nutrients from the dead and the decaying material they have small pores that are present and these pores they are commonly seen and when they find a area which is moist or rotten or humid they start to germinate so you have growth of mushroom that suddenly is seen during the rainy season and these mushrooms disappear off in the dry seasons now some of the other examples of sepra fight include sly supers that is seen as bread mold so sometimes you might have seen a piece of bread keep it outside for 5 or 10 days you would see small growth of green color mold on the bread and that is basically saprophyte or rhizopus which is known as bread mold it is the dead end the decaying material that basically acts like a fungi and consumes all the important nutrients from the plant and bread itself similarly you have a Greek us witches mushroom and mukha which is pin mold and then you have yeast so these are some of the major sacrifice that we commonly come across so this is an example of a mushroom now the next is the types of relations that could be seen within the organism so as we said there could be various types of relationship that could be seen the one most common is mutualism like we discussed in the case of Rhizobium and the plant so you have both the species that are benefitted so when we say plus and plus that means both the species are benefitted under commensalism we have one species that is benefited the other remains unaffected under parasitism you have one species that is benefitted like a malaria parasite female and hapless you have the mosquito that is benefitted but the human beings is harmed then you are neutralism both the organisms live together but they are neither benefit nor harm they just live together amensalism is one species is harmed the other remains neutral under competition both are adversely affected so those are the various kind of relations that could be seen parasitism oh sorry mutualism is most common among these a good example is Rhizobium and the plant the other good example is lichens so these are the association between fungus and algae that I see so a good semantic association between fungus and a guy where LJ prepares the food and provides his to the fungus and the fungus basically provides the mineral and other nutrients to the L guy so that's the kind of mutually beneficial relationship then you have commensalism as we said one benefits the other is unaffected our example is orchids on the tree so when the orchids grow on a tree orchids are benefited however tree remains unaffected so that is what is commensalism now a very important thing that you have commonly heard of is the term man your unfertilized and what is the difference between the two man your is the dead and the decaying material of the various plants and animals that is found in a very thin top layer of the soil so this is waters manner however fertilizers can be organic can be inorganic they could be produced naturally or produced in the factory but they affect the fertility of the soil it's not the just the our player of the soil which is known as humors so man here affects only the top layer of the soil that is the humors fertilizers affect the layer beyond the humors and increases the productivity of the soil now this man here is comparatively less rich and is slowly absorbed by the plant it's more economical to manufacture but because it's simply the decay of the plants and the animals however fertilizers are absorbed more rapidly they make the soil better for or in terms of fertility increases the richness of the soil and these fertilizers are expensive as compared to the manuals so those are some of the important things that we have discussed the commonly used fertilizers we say are the NPK type and means nitrogen P means phosphorus and K means potassium so these three are the major nutrients that are required for the plant growth nowadays we do have organic fertilizers that have been talked about and under the recent scheme of the government we have parampara growth Tricia Vikas Eugenia that talks about exclusive organic farming without the use of synthetic fertilizers so those are the things that we are moving towards for for replace replenishing the quality of soil now when do we need to replenish a swine let's say you have a mountain and a soil here what would happen when the water runoffs here when the water runoffs here you would have all the top layer that would go away with the water now this top layer or the humours as we said is a most fertile layer when it washes away with the flow of water the fertility in this area is greatly reduced in order to check that fertility we need to replenish that soil and for replenishment of the soil we requires we require manuals and fertilizers the process in which the soil is moved away is known as soil erosion so these are some of the common important terms that we have come in this chapter in the next chapter we would focus on nutrition in animals so all these topics are very very important and very very fundamental to understand stay tuned for further updates with us have a very good day ahead