Transcript for:
Key Biology Topics for IAT Exam Review

Hello students, how are you? I hope that you will be all very fine and you will be busy in your studies. Now uh today we are here to give you a one short video or to give you an idea or overview of the most important topics with respect to IAT biology section. Okay. So today we'll be mainly focusing on covering the most important topics of biology with respect to biology with respect to IAT exam. Okay. So let's [Music] see. So your biology section or the syllabus the whole syllabus of biology it is basically divided into two parts. We know that biology is quite a factual uh subject as well as there are conceptual topics also but yes so we have actually divided biology into two parts. One is factual one is conceptual. Factual topics includes the first unit of your 11th standard uh that is classification unit microbes in human welfare, morphology and anatomy of plants and animals, plant growth and development, human physiology. All these chapters they have lots of facts in it and you know that facts they don't need a rigorous understanding but they need rigorous revision. Okay. So in order to cover these all chapters you have to just write down these chapter these chapters in your copy notebook or you can just simply tick mark on whatever book you follow and start revising them uh per day so that after these 8 n days or one week it actually starts to come in your subconscious memory. Okay. So we are not going to cover these all topics because these chapters requires only your hard work not our hard work but yes we'll be covering all the conceptual topics in this today's session because it requires your hard work as well as our hard work okay because these are conceptual topics. So we will start with cell biology followed by biomolelecules, photosynthesis, respiration, genetics, molecular basis of inheritance, evolution, biotechnology and then ecology. Okay. So let's see them one by one. Let's first start with cell biology. So cell biology it this unit includes two chapter. First chapter is the chapter which includes a basic information which gives you a basic information about the structure of a cell different cell organals and their functions and then the second chapter comes that is cellulence and division that chapter is even more important. Let's see the first chapter. Okay, let's see the first chapter. Now in this chapter we'll mainly we have to mainly get an idea of three things. What are the different cell organals in a cell? What are the functions of those cells of those cell organals? And third one is how many membranes are enclosing these cell organals. Okay, let's see. Like we know that there are different cell organoggonals. Starting from the most important which is nucleus. Nucleus it contains DNA. It is a central coordinating unit of the cell. H it is just like our brain of our body. It includes structure like nucleololis where our RNA synthesis happens. Okay. This is a double membrane system followed by mitochondria. We know that mitochondria is a structure which is known as powerhouse of the cell and respiration happens in this cell organal and it is also a double membrane system. Chloroplast is also a double membrane system and it is involved in photosynthesis. Ribosomes it do not have any cell wall and it is involved in protein synthesis. Golgi body is very essential because it is involved in different kinds of functions like packaging, secretion, sorting also it's a single membrane structure. It was it was discovered by count camo de gallology in 1800s some 1800s. Okay. Next is lizoome which is also a single membrane system and it in it it is involved in digesting the cell debris and digesting anything which is foreign in the cell and know and sometimes when the cell gets older it digest the whole cell also because it contains hydraytic enzymes which are active at acidic pH. It is involved in regulated cell death which is apoptosis which is apoptosis. Okay. Now let's move ahead. There is one structure which is known as endopplasmic reticulum. This endopplasmic reticulum. It is of two types. Smooth endopplasmic reticulum and rough endopplasmic reticulum. Smooth endoplasmic reticulum is involved in lipid metabolism, lipid breakdown, lipid formation or lipid or steroidal drug metabolism. Protein synthesis is a function of rough endopplasmic reticulum because it is rough and rough by rough how does how do this endopplasmic reticulum become rough because they have ribosomes attached on the endopplasmic reticulum and we know that ribosome has a function of protein synthesis and if ribosome is attached on this endoplasmic reticulum that means that it is also going to be involved in protein synthesis. Clear? Now vacule is one structure which is very important because it is involved in the storage of excess water, minerals and excess uh and some amount of those substance which are meant to be excreted later. Okay. Centrialsles and centrosomes are involved in formation of spindle fibers which ultimately helps in cell division. Okay. Out of all these celloggonals nucleus, mitochondria and chloroplast are double membrane system. Ribosome and centriol. Ribosome and centrialsles are no membrane system, non-membrane system and the remaining ones which are known as endommembrane system are single membrane system which includes GG body, lo, endopplasmic reticulum and vacule. It is also known as GL plus vacule. Okay. Now next chapter next chapter actually is cell cycle and cell division and we know that cell cycle and cell division is divided into two part. First one is known as interphase and the next phase is known as Mphase. Mphase is a phase where actual cell division happen where actual cell division happens and interphase is a phase in which cell division do not happen but the preparation of the cell division happens. Okay. It's just like a marriage h. So the preparation for the marriage it starts quite earlier but the marriage happens at one night only. Okay. So this is analogous to the day of marriage and this is analogous to the whole preparation that goes on before marriage. Okay. So in these stages or interface the cell is metabolically active but it is not dividing and it is divided into three phases G1 S G2. G stands for growth phase. S stands for synthesis phase. G2 stand for second growth phase. In G1 and G2 there is all lot of growth and all lot of protein sugar synthesis that happens and a for cell division. But this Sphase is very critical because in this phase what happens replication of DNA happens here. Okay. Replication of DNA happens in the Sphase of cell division and that's why after Sphase the amount of DNA is doubled. So if we compare a cell in G1 phase and in Sphase the amount of chromosome will be same but the amount of DNA in Sphase will be double as that of G1 phase. Okay? There is one more stage which is known as G0 phase. In this phase, the cell is confused that whether it should undergo cell division or not. That's why it is known as a cushioned stage because it's a confusing state. Okay. Now let's move ahead. The Mphase or the actual cell division phase is divided into two parts. First one is known as mitosis and the second one is known as meiosis. Mitosis is the phase is the phase of cell division or is the type of cell division which occurs in somatic cells while the miosis occurs in germ cells as written over here. Okay. Now mitosis occurs in order to replenish regenerate the lost cell or the growth of our body. But meiosis it happens only for one specific function that is the formation of gameamtes. We know that gamts are hloid and germ cells are deployed. So in meiosis the number of chromosome it is halfed. Okay. It becomes half of the parent cell. That's why it is known as reductional division. But in case of mitosis, the new cell has same number of chromosomes and same number of DNA, same amount of DNA as that of the parent cell. That's why it is known as equational division because the cell number or the chromosome number remains equal in them. Clear? Let's move ahead. Now mitosis it is divided into four different phases. Prophase, metaphase, anaphase and tilophase. By the way, these phases are known as karaocchinuses. Karao chinuses because here the nucleus divides not cytoplasm. This is a phase where nucleus divide not cytoplasm. So, so in prophase we know that the chromosome it is present in decondensed form earlier. That's why it starts to condensate in prophase. In metaphase those chromosomes they start to align at the equator just like this. The chromosome they start to align at the equator okay of the cell and spindle fibers they start to attach them on the kinetto course of the chromosomes on the kinetes of the chromosomes. Okay, clear. And in anaphase, these spindle fibers which were formed by these centrialsles, they actually split the chromosomes into two chromatids. So one chromosome is divided into two chromatids and these two chromatids they start to move on opposite pole. They start to move on opposite poles. Clear? And in the tilophase stage in the tilophase stage the nuclear membrane around these two sides are formed and that's how the karaocyuses or the nuclear division ends. Now nuclear division is not the end of cell division because one cell can't have two nucleus if they are normal cells. So that's why their cytoplasm needs to be divided and in order to divide a cytoplasm we have to do a stage or a process known as cytochinosis and cytochinus they are different in case of animals and plants because animals don't have cell wall while plants have a cell logic cell wall. So in animals the moment cell division cell has to undergo cytochinusis the cell membrane it starts to form a furrow. The cell membrane it starts to form a furrow which gradually comes inside. Okay, which gradually starts to come inside and move toward the center and hence it joins at the center and hence the one cell containing two nucleuses they divide into two cells containing one one nucleus. Clear? This is known as cell furrow method. Now the second one is known as plants and plants we know that there is cell wall that's why there is no furough formation here rather a cell plate is formed at the center of the cell which contains calcium and magnesium pectate and this and this cell plate it starts to move from center towards the end of the cell and hence at one point it joins the periphery of the cell and one cell is divided into two cells. Okay, clear this thing should be clear to you. Now let's move ahead. Now meiosis is the next thing or the next stage that we are going to discuss here. In meiosis we know that the deployed content has to get divided into hloid content. Okay, the deployed content has to get divided into the hloid content. That's why this meiosis it takes place in two phases. It takes place in two phases. In one phase the chromosome number is halfed or in meiosis one chromosome number is halfed chromosome number is halfed while in meiosis 2 DNA content is also half DNA content is also halfed clear that's why in meiosis there are two rounds of cell division that happens meiosis one and meiosis 2 now in meiosis One there are again four phases prophase, metaphase, anaphase and tilophase. In prophase there are separate five phases known as leptroine, zygotine, pectitine, deproin and diachinus. Leptoin is not that important phase but from zygotine it becomes very important. In zygotine there occurs a process or a phenomenon known as synapsis. In synapsis the homologous chromosomes they start to come together they start to align one after another or at the front of each other and this is known as synapsis which is mediated by a protein complex known as synaponal complex and hence these homologous chromosomes they start to align uh near each other or else we can say that they start to look like this. 1 2 3 four chromosomes they start to align just in front of them. Clear? They start to align just in front of them. So these are homologous chromosomes. These are homologous chromosomes. Okay. Now after homologous chromosome they come together there occurs a process known as crossing over which leads to recombination which leads to recombination and it is done with the help of an enzyme known as recombinase. It it is done with the help of an enzyme known as recombinase. known as recombinase. Here there is a mutual exchange of genetic material between the homologous chromosomes which is important for variations to happen in gamut at gamtic level. So when there is exchange of genetic material at that time the chromosomes the homologous chromosome they start to look like this. Okay, it seems that they are very close to each other and the mutual exchange of genetic material is also seen and this is known as kasmita. This is known as kasmmeta. And now at the end diainosis these kasmeta they start to move away from each other which is known as termininalization of kasmmeta. Okay, this was the prophase one of meiosis one which is very essential and which is very different from that of mitosis also. Now the cell enters metaphase one in which homologous chromosome they condense fully but they are still aligned in the front of each other like this. And in anaphase one, in anaphase one, what happens is that these chromosomes, they are attached to the spindle fibers and they start to move on opposite poles. They start to move on opposite poles. Now here there is a catch. In anaphase one of meiosis one, homologous chromosomes are moving on opposite poles. But in the anaphase one of miosis of mitosis chromatids were moving on opposite poles. This is very important difference between mossis and mitosis that in the anaphase of mitosis chromosome breakdown into chromatids and they move to opposite poles. But in anaphase one of miosis chromosomes do not break but rather homologous one of the homologous pair of chromosome they start to move on opposite poles. Okay. And then in tilophase one the chromosomes they had the one one chromosomes of each pair of homologous chromosomes they moved they have moved on the opposite poles and nuclear membrane forms on them. Okay. Nuclear membrane forms on them. Okay. Clear? Now chromosomes number has been hard from 46 chromosome. Let's say in humans 23 are present now in one cell. Okay. But we know that on each of the chromosome there is double the number of there's double the number of DNA. Okay. That's why in order to half the number of DNA miosis 2 happens which is same as that of mitosis. Okay. Which is same as that of mitosis. So it occurs as prophase 2, metaphase 2, anaphase 2 and tilophase 2. Clear? Now let's move on to next chapter that is biomolecule. Biomolelecule is a very important chapter because it has lots of concepts in it but at the same time it has lots of facts in it. Okay. Like in biomolelecules chapter there are lots of biomolelecules which are polymers but they are made up of monomers. We know that polymers are made up of monomers. But yes, we have to study these things that which polymers are made up of which monomers or which monomers combines to form a specific type of polymer. Okay. Then we have to see enzyme kinetics, nucleic acid structure and tables and diagrams. This you can take as homework because this chapter has lots of tables and diagrams in it. Diagrams you can skip also but tables are very important. specifically the table of secondary metabolites. Okay, let's move ahead and see this chapter. Let's see. So, we know that biomolelecules are divided into two parts. Biomacroolelecule and biomicroolelecule. Lipid is not placed in any of these categories because lipid it lipid is a different kind of molecule. Its weight is very less. That's why it is a microolelecule. biomicroolelecule but it do not it it forms aggregates and that's why it is not able to separate itself as a biomicroolelecule. It comes under the fraction of biomacroolelecule but except lipids other molecules can be grouped under biomicroolecules or macroolelecules. Monomers of all the biomolelecules will be placed under microolelecules and their polymers will be macroolelecules. Like if I tell you about sugars, sugars they are monomers are known as monosaccharide. They polymerize to form a polysaccharide. Okay. Now glucose glucose is a monomer. Fructose is a monomer. Glucose it polymerizes to form starch. It can also form glycogen. It can also form cellulose. Okay. Iodine test of starch, glycogen and cellulose it gives blue, red and no color respectively. Why cellulose gives no color? Because cellulose do not have a helical or a branch structure. Cellulose is a straight chain molecule. Okay. That's why it's do not give any color on starch test. Clear? Clear. Let's move ahead. Fructose polymer of fructose is known as inoline and polymer of nacetyl glucosamine is known as kitin which is present in the cell wall of fungi and it is also present on the exoskeleton of many insects. Okay. Now there is something known as disaccharide. There is something known as disaccharide. What do you mean by disaccharide? Daccharide means a sugar containing two monosaccharides. Okay. Like lactose is made up of glucose plus galactose. Sucrose is made up of glucose plus fructose. Maltos and trihalos are made up of glucose plus glucose. Two glucose molecule. Basically among all these disaccharides we know that most of the sugars are reducing in nature. But some sugars whose alihide or ketone group is not free those sugars are actually non-reducing sugars and among them sucrose and this trihalos is a nonreducing sugar. Okay, this is an important point to remember. Let's move ahead. Now amino acids, what do you mean by amino acid? Amino acids are those molecules which contains an amine group and a caroxile group. Okay. Along with it, it has one hydrogen ion, hydrogen atom, not ion. And there is an R group. So this R group is a variable group and we have different types of amino acids in nature based on the differences in this R group because other groups remains same always. Okay. In nature we have 20 types of R groupoups. That's why we have 20 types of amino acids. Clear? Out of these 20 amino acids you have to mainly remember the structure of three of them which are mentioned in your book also syllabus also. Those are glycine, alanine and serene. Glycine has R group as H. Elanine has R group as CS3. Serene has R groupoup as CH2O. Other things remains the same. Other things remains the same. clear because N2, H and CO they always remain the same just R group is different. R group is H here in glycine. R group is CH3 here in alanine and R group is serene here in this CH2 O. Clear? Now this if this RH is H then this amino acid will look like what? C H CO H and NH2 CO H and NH2 it has two H atoms that's why it is non-chyal in nature all the amino acids shows kyality and optical activity except glycine except glycine okay and these amino acids they polymerize to form proteins and proteins are of four types primary, secondary, tertiary and quadary. Primary, secondary, tertiary and quadary. Okay. Now, primary structure is a straight chain. Tertiary uh secondary structure is a little bit folding. And tertiary structure, it has 3D folding in it. But in quartary structure, there is more than one protein chain which combines to form quartary structures. If I try to give you an example of all these things like primary structure if you will heat any structure of protein be it secondary, tertiary or quartonary they will always come in its primary form and primary form we are able to get the positional information of amino acid very easily. Okay. Secondary structure it is of two types alpha helix and beta plated sheet. Alphah helix and beta plated sheets they are stabilized by hydrogen bonds. Alphah helix example will be what? The keratin of your hair. Beta plated sheet the example will be fibroid of silk. Clear? And tertiary structure all the enzymes are present in its tertiary structural form. Many enzymes are present in their secondary structural forms also. But yes, most of the enzymes are present in their tertiary structural forms. One very common example is myoglobin. Okay. The quadrinous structure of protein has a very great and a very common example that is hemoglobin. Hemoglobin is made up of four chains two alpha and two beta. And I have said that quarterin structure is what? Where more than one type of polyeptide chains combine. So hemoglobin is that structure. Okay. Clear? Let's move ahead. Now amino acid they have a very unique feature that they have two ionizable groups. Two ionizable groups. Okay. One is an acidic group and one is a basic group. We know that the basicity of base it increases at acidic pH and acidity of acid increases at basic pH because acid it it actually tends to release H+ ions and which is more facilitated in the basic pH. But but in the acidic if in the acidic pH we know that the base will show its basicity more often because base it tends to accept H+ ions and it will only accept H+ ion if there are plenty of H+ ions surrounding the amino acid or in the surrounding environment. Okay. But so we can say that at low pH the charge on this amino acid will be positive because it will be it will have it will accept H+ ions to become positively charged and it will be neutral at acidic pH at and at very high pH this will be neutral but this will be negatively charged. So at very high pH the amino acid as a whole will have negative charge. At very low pH the amino acid as a whole will have positive charge. But at a certain optimal pH there will be equal positive and negative charge. So the net charge will be equal to zero and that stage is known as zutter ionic stage of amino acid. And the pH at which zutter ionic stage is reached is actually known as pi or isoeleronic pH. So at isoeleronic pH amino acid will have no net charge that stage is known as zutanic stage. And yes zutanic and at zutanic stage we know that this amine and this co this amine and this caroxile group will be will will contain equal and opposite charges. Okay, clear. Let's move ahead. Now, enzyme activity. We know that enzymes are what? Enzymes are mostly protein. Not all enzymes are protein. Like there is an enzyme known as ribosyme known as ribosyme which is not a protein. It's an RNA molecule. But yes, most of the enzymes are protein in nature and enzymes are specific in nature. Okay. Enzymes are okay. Enzymes are very specific in nature which means that one enzyme binds with only one type of substrate and it binds with substrate to form enzyme substrate complex followed by enzyme product complex and then enzyme and products they gets separated. Clear? One property let's see some of the properties of enzymes. One properties of enzyme is that it is not degraded in this whole reaction. Second property is that enzyme do not change the equilibrium constant of any reaction but it increases the rate of the reaction. Clear? So this is the thing. Now enzymes we know that enzyme reacts with substrate to form enzyme substrate complex then product then product will get separated here. But we know that enzyme initially they will be present uh not enzyme substrate it will be present at some potential energy state and product will also have some potential energy. Okay. If this substrate has to form product then initially it has to activate itself and it will get activated if and only if it absorbs certain amount of energy known as activation energy otherwise it will not form product. It is not like that the substrate it has some potential energy and it releases some energy to form product. No this will never happen. Substrate even if it is at a higher energy level then also it has to absorb at a certain amount of energy which is known as activation energy to form a transition state and then from this transition stage forms a product. Okay, clear? So this is a thing and how enzyme increases the rate of reaction because enzyme decreases the activation energy. Enzymes. Enzymes. It decreases activation energy. Enzymes decreases activation energy. Enzymes decreases activation energy and hence it increases the rate of the reaction. Clear? Now let's see what's next enzyme. In this chapter uh or in this topic there's a concept of enzyme inhibition. Anything which decreases the rate of enzyme catalyzed reaction are known as inhibitors. And in your syllabus only one kind of inhibitor is mentioned that is competitive inhibitor. Okay. Competitive inhibitor is a type of inhibitor which looks similar to substrate and it competes with the substrate to bind on the active site of enzyme. Okay, clear. So it means that inhibitor or competitive inhibitor specifically they have same shape as that of substrate and they compete with substrate normal substrate to bind with the active site of enzyme. Clear? Clear. Now the examples of competitive inhibitor will be inhibition of suenic dehydrogenase by melanate and oxalloacetate. This is one very important example and there is also one example which is methanol poisoning. So ethanol and methanol are produced by alcohol dehydrogenase. Mainly ethanol is prod produced. But once the amount of ethanol it starts to increase at that time alcohol dehydrogenous enzyme it starts to produce methanol oils also which actually competitively inhibits the activity of this enzyme. Sulfa drug is also one example of competitive inhibitor but it is not there in your syllabus. So you don't need to remember it. You just need to remember this and this example specifically. This one is very important. Okay, let's move ahead. Enzyme, if we talk about the structure of enzyme, we know that enzyme it is known as the whole enzyme or the active enzyme is known as holo enzyme. Okay, whose 90% of part is comprised of epoenzyme which is a proteinious which is main proteinious part. It has the active site. But in order to activate this epoenzyme we have to add some co-actor in it. Okay. And that co-actor can be an organic compound or else it can be an inorganic compound. Okay. If it is organic and tightly bound to enzyme then it is known as prosthetic group. And the example of proetic group is hem which is present in peroxidase and catalase enzymes which is important to break down these hydrogen peroxides into water and oxygen because peroxides are not good for our health. Okay. If the organic compound is loosely bound to enzyme then it is known as co-enzyme and all the and many of the vitamins that you take from outside they come under this the category of co-enzyme. So now you will be able to understand that why vitamins are important because these vitamins they act as micronutrients and one of their function is to activate enzymes. Okay. If it is inorganic ion then it can be metal ions also. So there are many metal ions which activates many type of enzymes. Such enzymes which requires metal ions to get activated are known as metalloenzymes. Like one example is zinc. Zinc activates many enzymes like caroxyeptidesis, carbonic andhydraises, alcohol dehydrogenesis. Okay, clear. Now in enzymes only one topic is remaining that is classification of enzyme and you know that enzymes are divided into different groups or different classes based on their functions. Like those enzymes which are involved in oxidation reduction reaction or the transfer of electrons and protons they are grouped under oxidor reductases class. If it is involved in transfer of any functional group then it is grouped under the class transferis. If they are involved in hydrarolysis reaction or breakage of any molecule in the presence of water then it is known as hydrarolysis. If they are involved in breakage of any molecule in the absence of water in the absence of water then they are known as liases. If they are involved in isomerization reaction then they are known as isomeises. If they are involved in liation reaction or joining of two groups or joining of two groups then they are known as lies. Okay. Clear? Clear? Okay. So let's see other things now in this chapter which is nucleotide or the structure of DNA molecules. Take DNA is basically made up of nucleotide. What is a nucleotide? Nucleotide is made up of three structures. Nitrogenous base, pento sugar and a phosphate group and they are present like this. So phosphate group you know that it is P43 negative. Okay. This pento sugar it is of two types ribos and deoxyibbos. on the basis of whether the two prime position has H or O. If it has O then it is ribos. If it is H then it is deoxxyibbos. Let's see what is a nitrogenous base. A nitrogenous base is of two types purine and pyramidine. Purine has two ring structure like this. Pyramidine has one ring structure like this. Purine are of two types adinine and guanine. Pyramidine is of three types thymine, uracil and cytosine. Okay. In RNA we have uracil and in DNA we have thymine and these all three structure nitrogenous base phosphate and pento sugar it joins to form a typical nucleotide and this nucleotide in this nucleotide pento sugar adds with nitrogenous base to form gly adds with nucleotide add with nitrogenous base with the help of glycoidic bond and this Sugar its five prime position it adds with or it bonds with phosphate with the help of phosphoester bond to form a nucleotide. Now it can be a deoxybonucleotide or a ribboucleotide. Ribouleide has all these structures except o except urasil. Okay. And also it has O at the two prime position and deoxxybonucleide. It has thymine and it has H at two prime position. Okay. And these structures they polymerize to form DNA or RNA. Now RNA we'll see later but DNA its first structure or the double helical model was given by Crick and Watson which was a secondary structure and it was a BDNA structure. A DNA a typical DNA is a double helical structure which is antip parallel and its backbone is made up of sugar and phosphate. Sugar phosphate sugar phosphate sugar phosphate forms its backbone and these two backbones are joined by hydrogen bond where A forms two hydrogen bonds with D and G forms three hydrogen bonds with C. Okay. Now the sugar phosphate they are joined by they are joined by phosphodiester bonds. Okay. So each chain has phosphodiester bonds to join them and both chains are joined by hydrogen bonds. Take next. So these were some of the typical structure typical information about DNA but specific information about BDNA is present over here in this U diagram. So one 360° turn the length of the DNA covered by one the length of the DNA covered by 360° turn or covered after 360° turn of a DNA is known as pitch or one pitch. Okay. And one pitch contains a length of 34 ammstrong. And one pitch contains 10 base pair. And in one pitch there is a 360° rotation. there's a 360° rotation. Okay. So if there is a 360° rotation in one pitch then the rotation between two base pair will be 360 by 10 that is 36°. And if one pitch has 34 Armstrong and one pitch has 10 base pair then the length or the size between two base pair is 360 or is is 34x 10 that is 3.4 armstrong. Okay. The diameter of this helix is 20 armstrong. Okay. Now the next chapter is photosynthesis. In photosynthesis we know that plants they capture sunlight to produce C6206 which is glucose. This is a reaction and this reaction it actually can be broken down into two parts. First one is breakage of water to oxygen and second one is CO2 reduction of CO2 to 66 to C6 S12 O6. The CO2 to C6 H1206 is known as dark reaction. The H2O2 O2 is known as light reaction and light reaction occurs first which is followed by dark reaction because in light reaction there are some energy rich molecules which are produced which are used in dark reaction to produce glucose. Okay, let's see now plant they have green parts mainly leaf and in the misophil of leaf are present chloroplast and in these chloroplast we have stroma the cytoplasm of your chloroplast is stroma and these stack- like structure known as graina and these stack-like structure known as graina each coin-like structure of this graina is known as a thila coin And these philyloid they are divided into two part the central lumen and the membrane present over here. This membrane has different proteinicious structure known as photos systems. These photo systems are composed of light harvesting complexes. These light harvesting complexes there of two parts light harvesting proteins and light light harvesting pigments and light harvesting proteins. These pigment molecules can be of many types. chlorophyll A, B, C, D, xenophil, kerotin, all those things. But the main pigment is chlorophyll A which is a reaction center. Okay. Now these photo systems they are they are can be divided into two parts based on the light or the wavelength of light which they absorb. If they are absorbing 680 nanometer of light then they are P680 they're also known as PS2. If they absorb 700 nanometer of light then they are known as PS1. Okay, let's see. Let's see now light reaction. Light reaction occurs in the philyloid membrane. Okay. And they have photos system like these. This is PS2, photos system 2. This this is PS1, photos system 1. Now both of them has chlorophyll a molecule and these chlorophyll a molecules they have electrons in them which gets excited by absorbing light of 680 and 700 nanometer respectively and these electrons once they are excited they are transferred to different electron carriers. Okay, they are transferred to different electron carriers but at the end it is accepted by NADP+ which accepts one electron and one proton to form NADPH with the help of an enzyme known as FNR or paradoxin NADP reductase. Okay. So we are able to now produce what we are able to now produce one of the two energy rich molecules. Okay. And we know that it's looking like a zigzag. That's why it is a Z scheme. And it's a non-cyclic photophosphorilation. And this cycle also has one thing which is known as water splitting complex activated by manganesees ions which are involved in breakage of water into two H+ 2 electrons and oxygen. Why we need this system? Because once the chlorophyll a once the electron is of this chlorophyll a is excited then this chlorophyll a becomes electron deficient. So that's why it needs a constant supply of electrons which is supplied by this electron produced by the breakage of water molecules. Okay clear? Now let's begin the next topic which is cyclic photophosphilation. So let's say we don't have PS2 or we don't have light of 680 nanometer or else we don't have water splitting complex or we don't have FNR molecule then we know that only PS1 is remaining and at that time cyclic photophosphilation happens in which 700 nanometer of light excites electron from PS1 from the chlorophyll a of PS1 which is cycled back again and again in this system. Okay. So this is a way in which PS1 happens or cyclic photophosphilation happens. Okay. I mean to say this is the manner in which PS1 acts alone in cyclic photophosphorilation. Okay. Now you must be wondering that what are the products that we got here? We got nothing here. You showed us nothing. here at least you showed NADPH but here you showed nothing h so I will tell that that in both the cycles uh non-cyclic and cyclic photophosphorilations in both of them ATP is produced how ATP is produced let's see ATP is actually produced by by actually uh breaking the proton gradient which is created by the transfer of electron electrons. The electrons are transferred in different ecos in different photos systems and due to those transfers electrons are continuously transferred from stroma to the lumen of the okay due to which the H+ concentration rises in the lumen of thyloid which creates a a proton gradient. Here it has high amount of proton and outside in the stroma we have less amount of protons and this proton gradient actually create also creates a concentration gradient or an ionic gradient. H and it it actually wants to break this gradient and it is broken down by this complex known as f_0 f_sub_1 complex. This f_sub_1 is a channel protein and this f_sub_0 is a channel protein and this f_sub_1 is an ATP synthes. So H+ they start to move from this system from this F-Z F1 system and activate this ATP synthes activity of F_sub_1 which actually starts to produce ATP utilizing ADP and phosphates present in the stroma side of your philyloid. Clear? clear. Okay. So this is the way or this is a manner in which ATP are synthesized in both cyclic and non-cyclic photophosphorilation. Okay. Now if we compare non-cyclic and cyclic photophosphorilation we can say that non-cyclic photophosphorilation it happens in grain lamea while cyclic photophosphorilation it can occur in graina as well as stroma lamela non-cyclic photophosphorilation it it has PS2 PS1 but cyclic has PS1 only ATP and ATP both are produced in non-cyclic but there only ATP is produced here oxygen evolving complex is present there oxygen evolving complex is absent here we have light of 680 and 700 nanometer both but here only 700 nanometer light is required okay now let's move ahead now we have produced ATP as well as NADPH which are transferred to the stroma of the chloroplast because in the stroma of chloroplast is going to happen what dark reaction dark reaction dark reaction Dark reaction occurs in the stroma of chloroplast in which ATP and NADPH are used and glucose is produced. So this is a cycle known as C3 cycle because the first product is a threecarbon product known as phosphoglyceric acid. It is also known as a Kelvin cycle on the name of the discoverer of this cycle known as Melvin Kelvin. Here a substrate is present from right from the beginning beginning which is known as RUBP ribulos bisphosphate which accepts one CO2. So this is a fivecarbon molecule. This is a one carbon molecule which is CO2 5 + 1 is six. So this six carbon it actually breaks down into two three carbon molecules which is phosphoglyceric acid. This step is known as caroxilation. In the next step which is known as reduction trios phosphate is formed and one carbon is released from these two phosphoglyceric acid. Okay. So these two phosphoglyceric acid they are both 33 three carbon molecule. So total six but one carbon is removed. That's why now only five carbon remains. Okay. So here one carbon is released after every cycle and five carbons are again regenerated. Okay. So this cycle comprises of three steps caroxilation, reduction and regeneration. And in every cycle one carbon is fixed or released. Take we know that we know that glucose contains C6 H1206. Okay. Which contains six carbon. One cycle has one carbon fixed. So how many cycles do we need to produce one glucose molecule? We need six cycles. Okay. So we need six cycle to produce one glucose molecule in one cycle. In the reduction step we use 2 ATP and 200D in the reduction step. In regenation step we need 1 ATP. So total in one cycle we need 3 ATP and two NADPH. Okay. And two NADPH. Okay. But we actually have to do six cycle to produce one glucose molecule. Okay. So in six cycle 18 ATP 12 NADPH are used to produce one glucose molecule in case of C3 cycle. In case of C3 cycle. Okay. Now next thing this this step is the first step of your C3 cycle which is combination of five carbon molecule RUBP riblobs bisphosphate and CO2 to produce two threecarbon molecule that is phosphoglyceric acid. This is an enzyme catalyzeed reaction which needs an enzyme known as rubiscoco. Rubiscoco is an enzyme which is present which is the most abundant protein of this whole biosphere. This rubiscoco it has dual characteristic. This rubiscoco it has dual characteristic. It can combine this rub with CO2 and oxygen also or oxygen also. Okay. Based on the concentration of both of them based on the partial pressure of both of them. Okay. If CO2 is present in large amount then it will combine with CO2 and will produce phosphoglyceric acid. Two molecules of phosphog glyceric acid. If O2 is present in larger amount or very high amount then it will combine with O2 to produce one phosphoglyceric acid and one phosphoglycolate and this phosphoglycolate enters a cycle or a chain of reaction known as photorespiration known as known as photorespiration and it's a wasteful process which do not produces any glucose molecule rather it uses ATP and NAD PPH which were high energy molecules. Okay. So which is a bad thing of C3 cycle. So that's why there are some plants which have evolved a novel strategy to to inhibit this reaction from happening. Okay. And that thing is known as hatch and slack pathway. Some plants have evolved hatch and slack pathway or C4 pathway in which no photorespiration happens. Okay. But this C4 cycle it happens in two cells misophil cells and bundled seed cells both and such plants known as C4 plants they shows crans anatomy. CR anatomy means wreath. Okay. Cr means wreath which means that there is a similar pattern of arrangement of cells in them. Okay. How does this cycle look like? It looks like this. It has two cells. One is misophil cell. One is bundle sheet cell. In misophil cell the carbon dioxide from the outer environment it will come and it will get converted into bicarbonate ion which will be accepted by phosphonol pyrovate using enzyme pepkase to produce oxyloacic acid. So the first product of this H and slack pathway is a fourcarbon product because it is formed by three carbon phosphonol pyate plus one bicarbonate ion to 1 + 3 4 okay that's why it is known as C4 cycle now this oxylo acidic acid or aolacetate will enter the bundle sheet cell where it will release this CO2 and hence several cycles like this will ultimately increase the amount of CO2 present in the bundle sheet cells. Okay. And due to increased CO2 count, there will be no process known as photorespiration that will happen here. Okay? Because rubiscoco has both the properties but here CO2 is present in very large amount that's why there will be no photo respiration. Okay. And here C3 cycle will happen because here we have rubiscoco enzyme present. Okay. The remaining thing after it oxyloic acid decarboxilate here the remaining thing which is there is pyroate. This pyrovate will again regenerate into phosphor pyrovate and then this cycle will again be continued again and again. Okay. Now let's compare C3 cycle with C4 cycle. A C3 cycle. In C3 cycle the first product is phosphoglyceric acid but in C4 cycle it is oxyloastic acid. In C3 cycle the first in C3 cycle there is only one cell involved which is misophil. But in C4 cycle there are two cell involved which are misophil and bundle cells. Now in C3 cycle for one C3 cycle to happen we need three ATP and 2 NADPH. But for one C4 cycle to happen, we need 5 ATP and 2 NADPH. Okay. In C3 cycle, rubiscoco is present in misoil cells. But in C4 cycle, rubiscoco is present in bundle sheath cells. Okay. So with this, we are ending up the chapter known as photosynthesis. Now we'll move on to our next chapter that is respiration. Okay. Okay. So let's start our new chapter that is respiration because respiration is also the follow on chapter u as compared to this thing photosynthesis and in photosynthesis we have made glucose and in respiration we'll break down glucose in the presence of oxygen to release energy what to release energy okay so here CCO6 is broken down in the presence of oxygen to release CO2 and S2O to produce energy in the form form of ATP in the form of ATP okay let's see so glycolysis crab cycle and electron transport chain these are the main three steps which are involved in respiration okay let's see let's see so glucose breakdown it occurs in a sequential manner first it is convert first it is broken down to pyrovate via glycolysis in the cytoplasm of the cell Then this pyroate is uh transferred to the mitochondrial matrix where it under go scrap cycle and then electron transport chain happens in the inner mitochondrial membrane in the inner in the inner mitochondrial membrane in the inner mitochondrial membrane in the inner mitochondrial membrane in the inner mitochondrial membrane to produce ATP. Let's see. So glycolysis it's a it's a it's a reaction in which glucose is broken down one glucose is broken down into two molecules of pyrovic acid. So it occurs via 10 sequential steps. Glucose is broken down to glucose 6 phosphate in the presence of hexokinus followed by its conversion to fructose 6 phosphate fructose 16 bis phosphate then glyceraldihide 3 phosphate and dihydroxy acetone phosphate followed by formature of 13 bis phosphoglycerate three phosphoglycerate two phosphoglycerate phosphonol pyrovate and then pyrovic acid. This is typical glyotrotic cycle. But what is important is to note that that how many ATP and NADPH are produced in this reaction. So total four ATP are produced out of which two ATPs are used in glycolysis. So net production is 2 ATP and two NADH2 are also produced in this reaction. Okay, clear. So one one glucose is broken down to two pyroic acid producing 2 ATP and two NADH2. Now this pyroic acid if it do not get oxygen then it under go anorobic respiration which is known as fermentation. If it gets oxygen then it is then it under goes a cycle known as aerobic respiration. Okay. First let's study if it does not get oxygen. If it does not get oxygen then it can undergo lactic acid fermentation or alcoholic fermentation. In lactic acid fermentation, the pyrovate is converted into lactic acid with the help of an enzyme known as lactate dehydrogenase. Okay. And in alcoholic fermentation, the pyrovate is first converted to acetalihide with the release of one CO2 molecule. Then this acetal dihide is further reduced to produce ethanol. Okay. Which is used as a beverage in some countries in many countries not some countries. Okay. And this conversion is done with the help of an enzyme known as alcohol dehydrogenase whose activity is increased or who is activated by zinc dipositive ions. Okay, clear now. So this was a case when it do not get oxygen. But when it gets oxygen when oxygen is present then what happens is that this pyroate is transferred to mitochondrian matrix mitochondrian matrix where it first under goes oxidative decarboxilation in which pyroate is broken down into acetil coa. This is a three-carbon molecule. This is a twocarbon molecule which means that one carbon dioxide is released in this step with the help of an enzyme known as pyroate dehydrogenase which is a metallo enzyme activated by magnesium dipositive ions and the net ATP or NADH production is written over here which is 2 NADH2 other than that no ATP no FADH is produced in this reaction. So what is the fate of this oxidative decarbonation? It produces one acetyl co from one pyroate. But we are more concerned about one glucose. One glucose produce two pyates. So here two acetil co are produced and two NADH2 are produced here. Okay. With the release of two CO2. Okay. Now let's move ahead. This acetil coa it now under goes the cycle known as citric acid cycle or tririccaroxilic acid cycle or crab cycle which also occurs in mitochondrial matrix in which this oxalloacetic acid it accepts acetil coa to form six carbon molecule known as citric acid cycle which further under goes two rounds of decarboxilation to produce alpha gtoluteric acid and saxinic acid. Here it under goes decarboxation means release of CO2. And then this saxinic acid is converted to fumemericic acid, manic acid and oxalloastic acid which are all fourcarbon molecule which are all fourcarbon molecule. This is also four carbon molecule. This is a five carbon. This is a six carbon molecule. Okay. Now one very important thing that I must tell you here is that this suxenic acid to fumeic acid conversion it occurs with the help of an enzyme known as suinic dehydrogenase. This senic dehydrogen is it is the only enzyme of trap cycle which is not present in mitochondrial matrix. It is present in inner mitochondrial membrane where it is present in inner mitochondrial membrane and this senic dehydrogenase it is involved in both the reactions in KB cycle as well as electron transport system. Okay? So in these sequence of reactions the net release of ATP NADH and FADH by one acetil by breakdown of one estil KOA is that it produces three NADH to one FADH and 1 ATP by the breakdown of one estil co. But we know that from one glucose we produce two acetil co. So two acetil co will be produced and broken down. That's why we have to multiply it by two. Clear? Clear. So total six NADH 2 FADH2 and 2 ATP will be produced by this cycle. Okay, let's see the respiratory chart in glycolysis, oxidative decaroxilation, crab cycle. Let's see how many ATP, NADPH and NADH and FADH are produced. In glycolysis, 2 ATP are produced and two NADH are produced. Check oxidative decaroxation only two NADH are produced. In crab cycle 2 ATP, six NADH and two FADH are produced. Okay. Now one thing that I must tell you here is that one NADH is equal to 3 ATP and one FADH is equal to 2 ATP. So if we calculate all the reaction reaction substrates and we multiply with respective amount of ATP equivalents then it will come out to be 38 ATP. So in aerobic respiration total 38 ATP are produced by breakdown of f glucose. In anorobic respiration total only two ATP are produced by incomplete breakdown of one glucose molecule. Okay. The direct ATPs which are produced are known as substrate level phosphorilation. And the NADH which are produced which are ATP equivalents those are known as oxidative phosphorilation. Okay. NADH and FADH they do not they are not ATP but they are ATP equivalents. So one NADH is equal to 3 ATP and one FADH is equal to 2 ATP. that we know they are converted into ATP by the process no known as oxidative phosphorilation which is electron transport system which is electron transport system which occurs in the inner membrane of mitochondria where NADH and FADH are broken down into NAD FAD NAD and FAD plus NAD+ and FAD plus releasing protons and two electron electrons releasing protons and true electrons and these electrons again enter and move via different electron carriers to produce a proton gradient and breakage of this proton gradient produces ATP just as we saw in the light reaction of photosynthesis. Okay. Now there are five total complexes which are involved in respiration. These five complexes are named as NADS dehydrogenase. FADS dehydrogenase which is also known as succeeding dehydrogenase that was also involved in KB cycle. Cytochrome BC1 complex which is known as cytochrome reductase. Cytochrome A3 complex which is also known as cytochrome oxidase. F0 f1 complex. Okay, which is ATP synthes also. Now the electrons which are moving here in these system they are finally accepted by what? by oxygen to produce water molecules. So the final electron acceptor in case of respiration is what is oxygen which accept electron to produce water. But in case of photosynthesis it was it was NAD NADP which produces NADPH. Okay. So likewise the energy stored in NADH and FADH are converted into ATP equivalents. 2 ATP from FADH and one and 3 ATP from FADH. Okay, let's move ahead and see some other things like one topic in this chapter is respiratory quotient. What is respiratory quotient? Respiratory quotient is basically it's a ratio which actually tells us that on complete breakdown of any molecule how many CO2 is released and how many O2 are used. Okay, complete breakdown of any biomolelecule releases how many CO2 upon how many oxygen are used there. Okay, that is respiratory quotient. And knowing respiratory quotient, we can get an idea of how easily or how tough is the breakdown of that molecule. Like glucose, it has respiratory quotient of one, protein 0.9, fats 7. The lower is the respiratory quotient the more difficult is it to break down them or to break them. Okay, clear. Now your you know that we studied this cycle or this whole respiration with respect to breakdown of glucose. But in the absence of glucose, amino acids, fatty acid, glycerol, they also can enter into this respiratory pathways at the step of pyrobic acid synthesis, acetil coa synthesis and dihydroxy acetyl phosphate, acetone phosphate synthesis respectively. Okay, one more thing is that our respiration it seems that it's a it's a catabolic reaction but during the course of respiration there are many intermediates which are produced also. That's why it is not strictly a catabolic reaction. It's also an anabolic reaction. So it is anabolic plus catabolic reaction which is also known as amphibolic pathway. Okay, which is known as amphibolic reaction or amphibolic pathway. Now the next chapter which is very important chapter is genetics. Genetics is something um from which questions are asked every year. So that's why we have kept here this chapter and we'll study it. Okay. Now, genetics it it includes Mendel's laws which is Mendel's law of dominance, law of segregation, law of independent assortment. Law of dominance says that says that if we take a pure line of two character of two traits of one characteristic, one is dominant, one recessive, then in the F1 only one of the trait will be expressed and that trait will be dominant. Okay. Law of segregation what does it say? It says that during the gamt formation the the alals of the two traits they segregate from each other and they combine again during the formation of zygote or a new progeny. Okay. So even if one of the trait is not expressing but still the the alles of those traits are present in the genotype of those individuals. Okay. Law of independent assortment says that if you are studying two characters at the same time then inheritance of one of the characteristic will be independent to from that of the inheritance of the other characteristic. Okay. So that's that is the law of independent assortment. Law of dominance has an exception that is incomplete dominance and co-ominance. segregation generally do not have any exception but law of independent assortment it has exception which is known as linkage. So I have made here a typical Menel's cross for one characteristic. It's a monohybrid cross. Let's say a pure line of capital T capital T tall and a pure line of pure line of small T small T dwarf. It is it is mated to produce a hetererozygous capital T small T which is F1 generation where all the individuals are tall. Okay. Now if they are selfded to capital T small capital T small Ty if they are selfd on selfing there is a possibility of production of four offsprings out of which three will be tall and one will be dwarf. So 3 ratio 1 will be the ratio of the physical characteristics or phenotypes and genotypes will look like 1 ratio 2 ratio 1 where one will be capital T capital T two will be capital T small T and one will be small T small T. So the monohybrid cross in the F2 generation it shows a phenotypic ratio of 31 and a genotypic ratio of 1 to 2 r 1. Clear? Now let's move ahead. Law of independent assortment is actually meant to study more than one characteristic at a time. Like if if we take a dihybrid cross then uh then let's let's take two characteristics at the same time height and color height of the plant and the color of the the flower of the plant. Okay. Color of the flower of the plant and the height of the plant and take a pure line of both the dominant and both recessive characteristic like the both the dominant characteristics are tall and purple. Both recessive characteristics are dwarf and white. Okay, just made them. And in the F1 progeny, you will be able to see that for both the characteristic dominant traits are expressed. Like in the F1 generation, all the plants will be tall and all the colors of the flower will be purple. Both dominant both dominant. Tall is dominant, purple is dominant. But when you will self them or on self crossing the f_sub_2 hybrids that will be generated there will be total 16 possibilities of f_sub_2 hybrids which will phenotypically segregate in these manners 9 31 and zero typically they will be segregate in this manner 1 2 1 2 3 2 4 2 1 2 1 Okay. uh this 9 to 31 is very important because 9 will show both dominant rates. Three will show one dominant, one recessive. Three will show one recessive, one dominant and one will show both recessive. Okay, this is a thing like this we have mentioned it over here. Now if if if you are studying this dihybrid cross and in the F2 generation your ratio you were expecting that the ratio will come out to be 9 to 31 but it did not came it came some it came it deviated from this ratio. Then what can you predict? You can predict that the genes are linked. Genes are that genes for both the characters are not present on the different chromosome. they are present on the same chromosome. They are linked. So in for independent assortment to happen your both the characters the genes of both the characters should be present on different chromosomes. But if they are linked which means that the genes for the characters are present on the same chromosomes then then they are linked genes and in case of linkage your F2 ratio will always deviate from these two ratios. Okay. But one thing that I must tell you here is that if the genes are linked then the number of parental combination will be more as compared to the recombinant. So recominance will be less parentals will be more but the extent of the parental generations produced will vary. It will vary as per the distance of the genes on the chromosome. If the distance of both the characters of both the genes for both the characters are very far or if is very mo much then we know that amount of linkage will be less and the amount of recominance that will be produced will be higher in amount. And if both the if the genes for both the characters are present on the same chromosome and they are very close to each other then we'll show that the extent of linkage will be higher and the amount of recominance will be very less. Okay. So if genes are closed then linkage is more and recominant is very less. If genes are far away then linkage is less and recominant frequency is very high. Okay. Now next in this chapter there's a topic known as known as sex determination and in sex determination we mainly study what we mainly study that whether the progeny which is going to come is male or a female. In that case we have male hetrochemmetry and female hetrochemtry. Male hetrochemtry means the males which are produced contains two different aloomes or two different sex chromosomes. Like in humans we have X Y. Males are XY, females are XX. Females are homogamits, males are hetrogammits. Like there are insects which shows XX and X0 inheritance. Those are also the examples of male hetrogmatry. But there are cases like in chickens henna in some birds they show female hetrotry in which females have two different chromosomes not males. So females have ZW chromosome and males have Zed chromosomes. Okay. Now there is a very important case of sex determination which is known as hlo deployed sex determination in which males are hloid and females are deployed. In honeybee males have 16 chromosomes and females have 32 chromosomes. Males are developed by parthenogenesis of the egg and females are developed by by the trivial type of fertilization and then zygote development processes. The females are developed by fertilization and males are developed by partheno genesis and in this case the males males actually they don't have father and they can't have sons also but females they have father and son. Males can have father. Males can have grand grandfather and grandson but not father and son. Okay. But let me tell you one thing that though it is hloid but still it is fertile. Females in females only queen bee is fertile. This worker is not at all fertile. Okay. Now there is one more very important topic in this chapter. Actually all the topics are important in this chapter. uh one more important chapter uh one more important topic here is that is this one pedigree analysis. So in pedigree analysis pedigree analysis is basically the study of family chart or the study of inheritance of any character in the family. Okay. So let's say in a pedigree analysis we can't write names and whether each individual is male or female and that's why we that's why in pedigree analysis we have assigned a particular shape and condition for particular gender and all those things and we study it in the same pattern for different families. Okay. Like males are denoted as square. Female are denoted as circles. If they are mating or if they are getting married then they are joined by a line horizontal line. If they are having kids then kids are denoted below them like this. If they have one male and one female kid or one son and one daughter then it is written over here. It's it's mentioned like this. Okay. If any individual is affected by any disease that we are studying then they are shaded. Okay. If male is affected then male is shaded. If female is affected then female is shaded. Affected male and female. Okay. Clear? And let me try to give you one example here like this. If this is a pedigree chart and this male is affected, this female is affected, this male is affected. This is a simple case of X-link recessive inheritance because it is showing criss-cross inheritance. Male to female to male and male to female to male pattern of inheritance is seen in case of X-ling recessive inheritance. Okay. Like hemophilia. Hemophilia is a is a disorder which is inherited like this because that is an X-link recessive disorder. There are multiple cases of pedigree uh analysis but this is one very trivial case. Okay, clear? Now let's move on to the next topic which is disorders. Disorders, genetic disorders are of two types. Mandelian disorder and chromosomal disorders. Mandelian disorders are caused by the mutation in the gene in any gene. Check. And chromosomal disorders are chromosomal disorders are caused because of presence of extra chromosome or because of absence of any chromosome in the whole genomic set or or the whole deployed set of chromosomes. Okay. Now chromosomal disorders they are of three types not three types there are of many types but you have to study only three types of chromosomal disorder that is down syndrome clinophelter syndrome and turner syndrome. Down syndrome is caused due to tisomia of 21st chromosome. Kleinophelter syndrome is caused due to tomi of X chromosome. Turner syndrome is caused due to monomi of X chromosome. What do you mean by triom and monosom? Monosomi means one less chromosome. Like we have 46 chromosome. If one X is missing we have if we have only 45 chromosome due to absence of one X chromosome that is known as monomi of X chromosome. Triomi means one extra chromosome. Okay. Like if in a clinopelter syndrome there is triom of X chromosome. What does it mean? It means that one X is extra. That individual will have 47 chromosome 44 autoomes and X Y and 1 X more. 44 plus XXY is clifter syndrome. Okay. How one chromosome becomes more or one chromosome becomes less in these cases because here law of segregation is broken down. Here there is nondisjunction of chromosomes during anaphase one. Okay? Now let's move on to mandelian disorders. Let's see mandelian disorder. You have to study three mandelian disorder. First one is known as hemophilia. Second is cleetemia. And third word is phenile keonura. Hemophilia is an xlink recessive disorder. Clear anemia is autotosomal recessive disorder caused by a point mutation in the in the globin chain in the gene coding for globin chain of our RBC red blood cell. Okay. Actually the the point mutation it is actually in the gene at some position we have G A which codes for glutamic acid but it changes to GUG. So A changes to U. G A codes for glutamic acid but GG codes for valin. So there is a change of one amino acid from glutamic acid to valine which actually changes the shape of RBC drastically and the shape of RBC becomes sickle shaped instead of by concave discshaped. Okay. Now next is phenileia which is also an autoomal recessive disorder. It's a metabolic disorder in which phenile alanine is not able to get converted to tyrosine rather it gets converted to phenile pyroic acid which starts to precipitate in our major organs like brain, heart, kidneys and it causes damage in those organs. Okay, clear. So knowing all this information I hope that you will be able to solve questions from different from these different disorders. So they will not give you questions regarding this that I am uh teaching you over here. They will give you a an a question and then they will try to ask some numerical type of problem to you. Okay. These are the theoretical information that I have given you. You need to know these things to solve those questions. But you have to apply your brain to solve those questions. Knowing these facts. Okay, let's move ahead. Now the next chapter that we have to study is molecular basis of inheritance in which we'll mainly study about how characters are actually expressed in at a genetic or at an at a molecular level. Let's see. So a a human or any individual has a cell and in the cell we have a structure known as nucleus. Nucleus has chromosomes in them. Chromosomes are nothing but they are proteins and DNA. DNA wrapped in protein is known as chromosome. DNA if we try to study DNA, DNA has many base pairs in them. Okay, most of them are non-coding but some of them are coding and coding region of DNA they are able to express themselves into mRNA and then they are able to translate themselves into proteins and these proteins and these proteins they start to produce enzymes and those enzymes are involved in various reactions of our bodies and those reaction lead to expression of different types of traits in our body. Okay. So it is basically the expression of DNA to proteins which actually leads to what? Which actually leads to expression of different types of traits in our body. Okay. Clear? Clear. Let's move ahead. Let's move ahead and try to see the central dogma of molecular biology. So the first phase of molecular biology is replication. We know that in the Sphase of cell cycle our DNA it replicates and one DNA converts into two DNA because it has to divide into two cells. One cell divides into two cell it needs same amount of DNA. That's why we have to double the DNA to segregate properly to or to separate or to distribute same amount of DNA in both the cells which are going to be formed after cell division. Okay. So the DNA here it unwinds like this with the help of an enzyme known as helicase or unwinders and then primers are added over here with the help of an enzyme known as primise and then DNA polymerase comes and it polymerizes both the strands. Okay. So this is a main process how our DNA replicates. But DNA polymerase it is able to move towards the unwinding site or the side at where the things are getting unwinded. But this strand is formed opposite to the strand opposite to the uh direction of unwinding opposite to the unwinding strand. That's why this strand is a lagging strand. This is a leading strand. Why? Because here the DNA is synthesized continuously and here the DNA is synthesized discontinuously in the form of fragments. And these fragments are known as Okazaki fragments. These Okazaki fragments they are produced in fragments but they are joined by the help of an enzyme known as DNA liase. known as DNA liase. Okay. And that's how the whole DNA gets replicated from one DNA to two DNA we get. Okay. So this is DNA replication. Now up to DNA replication we are not trying to express DNA. But once it's time for the expression of DNA then we have to convert this DNA into mRNA and then this mRNA to protein because protein is the thing which which actually governs most of the processes of our body like the structural and functional roles of our body are mainly governed by proteins. So we have to produce proteins to express any characteristics that we have got from our parents let's say. Okay. So first of all DNA should be converted to mRNA. It will be done with the help of transcription. mRNA to protein is done with the help of translation. First let's study transcription. Okay? Because without transcription we can't do translation. Transl transcription will be done on which side of DNA? The coding site. Because the coding DNA is only the one which is going to produce protein not the non-coding part. So coding part of DNA is known as what is known as cyron. Coding part of DNA is known as cyron. Cyron also have coding and non-coding regions. Coding regions are known as exxon and non-coding regions are known as introns. Okay. Now this cyron a typical cyone it looks like this. It has three regions. The initial region known as known as promoter. The middle region known as structural gene and the last portion is known as a terminator. The strand which is three prime to five prime is known as template strand whose information is studied by RNA polymerase to synthesize an mRNA. The other strand, the next stand is known as five prime to three prime polarity strand is known as coding stand. Who whose temp who is not template but its sequence if you start to see or start to see see the sequence of this coding strand then you will get to know that it has the same sequence as that of the mRNA because because why? Because both of them coding stand and the mRNA are complimentary to template. So both of them are complimentary. It means that both of them are same in terms of their base sequences present in them. Okay, clear. So that's why we try to study all the things regarding mRNA or regarding the transcription with respect to coding stand not the template stand. though the main transcription happens by by reading the information on template strand. So RNA polymerase it attaches on the promoter site after binding to after binding to a factor known as sigma factor. Okay, known as sigma factor. Then it starts to move like this here and and start to synthesize RNA. And after synthesizing RNA it reaches the terminator region where it binds to the row factor. And after binding to the row factor the RNA polymerase complex it breaks down and it releases the nent RNA as well as as well as itself also RNA polymerase and the nent RNA it get detached from this cyron. Okay. So that's how mRNA is produced. Clear? Now let's move ahead. So in procariots we have only coding regions that's why procariots they don't need any post transcriptional event for the maturation of nent RNA. Okay but in ukarots we know that cyrons of ukarots they have a split gene arrangement they have a split gene arrangement which means that they have coding and non-coding sequences both. So we have synthesized the whole coding plus non-coding RNA but we have to remove this non-coding RNA from the nent RNA or the heterogenous nuclear RNA that we have produced. Okay. Now it is done with the help of a post transcriptional modification step which involves three steps known as capping, tailing and splicing. In capping a fivep prime cap is added. In capping a five prime a fivep prime cap is added and that five prime cap is known as seven methile guanosine triphosite in tailing 200 to 300 adenine containing nucleotides are added at the three prime end known as poly a tail and in splicing the non-coding sequences or the inrons are removed from the nent RNA known as heterogenous RNA heterogenous nuclear RNA with the help of a complex known as splyosomes. And hence after these three steps the RNA gets matured. This HNR RNA matures to form mRNA. Okay, clear. Now let's move ahead and see further processes. Now we have produced RNA. We have produced RNA. Okay. So yes uh so we have till now we have covered our transcription process how it is formed what how mRNA is formed or HNRNA is formed and how does it mature okay so that thing we have covered till now we have to cover what now we have to cover translation process and so if we have to study translation then we need to know what are the different types of RNA because translation of RNA leads to production of proteins. So RNA are of three types. mRNA which stores genetic information, RRNA which has a catalytic role in which shows a catalytic role in translation and tRNA which carries specific amino acid acid with respect to particular codon present in mRNA. Okay. So it forms a machinery like this. So this machinery is mainly comprised of rna in which there's a T-shaped or a plus-shaped tRNA which carries specific amino acid here and it reads the tRNA reads information present on this mRNA the the codon it reads codon because it has antic-codon and it adds specific amino acid with respect to that codon in the protein chain growing protein chain and that's how this machinery keeps on moving ahead and ahead. Okay. And hence it forms a long chain of amino acid. And at the end when they when they when this u when they get near the stop codon or they get on the stop codon which are UAA, UG and UAG then release factor binds on this machinery and this whole complex breaks down because stopcodon they don't have amino acid in nature. There are no tRNA which have amino acid specific to these three these three this is stopcodons okay that's why release vector bind and this whole machinery gets disintegrated so the tRNA the rRNA and the mRNA they gets disintegrated and the protein chain is released in the system which starts to modify itself with the help of different machinery like chaperons And after modification it becomes active for for its structural and functional role. And hence it it actually controls the what it actually controls the different traits of our body. Check. Now these genes are not always expressed in our body. These genes are expressed when it is needed. So it means that the gene expression is highly regulated and it is studied it was studied first by Jacob and Mon in case of E.coli and they basically studied a lac operon and operon system which is known as lac operon. It's a catabolic system which is involved in giving energy to the cell or E.coli. It actually breaks down lactose to produce glucose and galactose and hence these glucose are then further used in respiration to produce energy. Take so we know that the primary source of energy is glucose but lactose is also used as a as an energy source when glucose is less. So this operon so this operon which is known as lac operon it is involved in break breakdown of lactose when glucose is less and lactose is high. This operon this operon has certain set of genes like the promoter of inhibitor inhibitor gene and the z ya genes. This z gene codes for beta galactoidase. This Y gene codes for permease and this A gene codes for transacetilase. Out of which this beta galactoidase gene it is involved in the breakdown of lactose into glucose and galactose. Then this glucose will undergo respiratory process. Okay. But this gene is only activated once the level of glucose goes down because if glucose is present then why do we need to break down lactose? Hannah and how it is switched off. It is switched off in normal condition because this inhibitor gene it produces a protein known as inhibitor protein or repressor protein which binds to the operator site of this operon and it do not let the RNA polymerase to polymerize or to transcribe this Z Y and A gene. But if glucose is present in less amount and lactose is present in high amount then lactose binds with this repressor and this and changes the confirmation of this repressor and the change in the confirmation of repressor actually leads to to what to decrease in the affinity of this inhibitor towards the this operator region. That's why this inhibitor or repressor do not bind to the operator region once lactose is bound to it. Okay. And hence in the absence of glucose this thing is switched on and this beta galactoidase is produced which breaks down glucose which break downs lactose into glucose and galactose. Okay. So that's how gene regulation is done. This is a very simple case but it is also done in any kind of gene. Okay. But one thing which is very important is that is that this inhibitor is a constitutive protein. It is a constitutive protein because it is produced any time or every time in the cell of E.coli. Now one thing that is that is important for you which is remaining in this chapter is to know about DNA fingerprinting. Okay. Now our DNA it's 1% is coding region and 99% of our DNA is non-coding. Okay. But among this 99% DNA, there is some part of DNA which is polymorphic. What do you mean by polymorphic DNA? The the polymorphic DNA has same type of sequence repeating multiple times like ATGC, ATGC, ATGC repeating 100 times. That type of non-coding DNA is known as polymorphic DNA. Polymorphic DNA can be of many types like single nucleotide polymorphism or satellite DNA. Satellite DNA are of two type mini satellite and microatellite. Mini satellites are used in DNA fingerprinting process and this mini satellite it has V and TR regions or variable number of tandem repeats in them which are unique or which are universal for particular individual. So these VNTRs are different for different individuals except monozygotic twins and these VNTRs are compared in different individuals to compare their DNA fingerprints and that's how the universality or specific or specificity of particular individual is uh noted or is recognized using DNA fingerprinting. Like if I give you one example of a crime scene. Let's say from a crime scene we got a blood and we extracted the mini satellites whose banding pattern looks like this. The VNTR showed like this. Okay. And we suspected that A B C D among these ABCD one of them is the criminal. And the person who is criminal his bands his bands will concside with these all bands. And if you note down or if you see try to watch all the bands here which one among them which one among these whose bands among these are conciding with these bands it's C. So the person C has all the bands conciding with these whole bands. So that's why he is a convict or he is a criminal and that's how we study DNA fingerprints. Okay, clear. So this is a way how we study DNA fingerprints. Its process is there written in your book that you should do by yourself because it's not a very tough job but you you need to know how to read a DNA fingerprint. Okay, clear now. So, till now we were studying about molecular basis of inheritance which which actually uh actually told us or which actually led us to understand how traits are transferred from one generation to another generation. Yeah, next generation at a molecular level. Now we will study mainly those chapters which which are actually studied as a macrobiological chapters. Okay. So, evolution and ecology are two chapters which are done at a macro level. But yes, there are some other chapters also that we'll cover like biotechnology is also there. Okay, let's see. So, in evolution chapter we will mainly we will be mainly covering two three things. First one is Darwin's theory of natural selection. Second one is homology analogy adaptive radiation and third one is Hardy Binbuck principle. Let's study. So Darwin he gave his theory of natural selection based on his findings in the Galapagos islands and the world tour that he did on HMS Beagle ship h and he gave his five points which are OSBsn which is that whenever there is overpopulation then there is a scarcity of resource or resource limitation which leads to struggle for existence and this struggle leads to competition and due to competition there are various variants which are present in nature and some of the variants which are better able to survive that stress are selected naturally selected and other ones they themselves get deselected but deselected term is not so good to use but yes the better ones get selected so survival of the fittest whenever we say survival of the fittest the term fittest actually do not mean to say that it is physically strong it actually tries to say that the person is reproductively fit or reproductively active or is able to lay the progenies. Okay, this is men this is Darwin's theory of natural selection. Now there is one very important term which is known as adaptive radiation uh which was actually uh which is which which was seen by Darwin in his um tour to Galapagos Island in the Darwin finches and also it is seen in Australian marshups also. So if we talk about adaptive radiation what does it mean that if we have a common ancestor but this these ancestor they start to live in different ecological niches then due to different type of environment due to different type of ecological conditions they evolve different type of trait and they become different they they show they start to show variations and that divergence or that radiation is known as adaptive radiation and it is mainly seen or it is seen in many individuals but the two example that is important for you with respect to exam is adaptive radiation in Australian marupopials and Darwin finches. So Darwin finches showed variation in terms of their beak shape. Some had very pointed beaks, some had broad beak, some has average size beak. So such things. Okay. Now homology and analogy. What do you mean by homology and analogy? Analogy and homology they actually try to tell us whether the ancestry whether we actually try to compare two individuals or many individuals more than one individual and this comparison leads us to understand whether these two individuals has a common ancestry or they have a different ancestry. If they have a common ancestry then they are going to show similar body structure. Anatomical structures of their body will be same but the function performed by those structures body structures may be different. Okay. But more or less homology denotes common ancestry and divergent evolution. Adaptive radiation is also an example of homology. Okay. Now analogy analogy denotes different ancestry. Analogy denotes different ancestry and due to different ancestry they have different body anatomical structures. Okay. But due to living due to their living in ec same ecological niches they start to perform similar function. And this analogy is an example of convergent evolution like the wings of bats and wings of birds. They are both used for flight taking but but they looks very different. Their anatomical structure are very different because bird is a and bat is a mammal. Different ancestry but same function. Okay. Now Hardy Weinberg principle. Hardy vinber principle what is it? Hardy Vinberg principle says that if a population is not evolving then the alle frequencies capital T small T alle frequency P and Q their sum will be equal to one. If a population is not evolving or if the gene pool of a population is constant then their alle frequency then the sum of their al frequency will be equal to 1. P + Q = 1 and also their genotypic frequencies P ² + Q ² + 2 + 2 PQ will also sum up to be equal to 1. Okay, but the point here is that how does a population not evolve? H we know that populations they tend to evolve. Yes, this is a true fact that population they tend to evolve and they always evolve but the extent of their evolution is different. Okay. But this principle hardy vinb principle only applies if and only if population is not evolving. So generally uh whenever we do a research gentic research we do we do not get p + q is equal to 1 or p square + q ² + 2pq is equal to 1 it always come out to be 0.8 0.7 or 1.2 1.3 because never hardly principle is uh fully applied or fully correct. So the population they evolve due to these all characteristic migration, natural selection, genetic drift, recombination and mutation. These are the five characteristics which leads to evolution of a population or which leads to actually change in the gene pool. Change in the gene pool of a population. But if these all things are not happening in a population, then only the population will will not evolve at all. But we know that always in a in any population one among them will be happening. Okay, clear this is your hardy winber principle. Now next so next chapter is biotechnology which is actually dealing with recominant DNA technology. So in recommend DNA technology we are more concerned to produce a protein of our interest outside the body of any individual. Let's say insulin which is produced in our body if we are able to produce it in the outside media then it's very beneficial for us. We can we can sell that insulin in the market. H let's see. So recommend technology basically what does it tells? It tells that we can express a DNA a gene outside our body to produce a protein. Okay. How can we express it? We first have to uh extract our gene of interest from the whole DNA and that we can do do by by digesting this whole DNA with an enzyme known as restriction endonucleus. like Eco R1 which cuts at GA TTC. So the restriction endonucleus they cut at specific recognition sites known as recognition sites or known as pelindromic sequences. Okay. So once we'll cut the whole DNA we know that this whole process is happening in a test tube and know and once we cut our DNA of interest we know that multiple fragments of DNA will be produced and know but we need only our fragment of interest which is present here. How can we separate our DNA of interest from the other fragments? We can simply do a process known as gel electropherosis. we can simply do a process known as gel electrophorosis. Known as gel electrophoroses so that the DNA bands or the different fragments of DNA run uh in different uh so the DNA fragments they run as per their body weight and charge. Okay. So we tend to get different fragments of DNA on the basis of their body weight on the basis of their molecular weight. The lightest DNA moves the farthest and the smallest DNA it remains at the very initial side. So we just need to know the number of bases present in our DN of interest and we can cut it and se separate it out. Okay. by just illuminating a UV light on the gel that we have prepared because the gel that we prepare we add etheadium bromide to it which gives bright orange color to the DNA. Once UV light is illuminated on it and then after cutting the DNA of our interest we just purify that gel that DNA from the gel using a process known as elusion. Okay. Now, now once we are done extracting our gene of interest, we have to express it outside the outside the human's body. Let's say the but if we have to express it outside the human body, we have to express it some in some other organism. Okay? Like a bacteria. So we can express it in bacteria, express the gene coding for insulin in a bacteria. But we have to first transfer that gene of gene coding for insulin inside the bacteria and that is done by using a vector and vector most commonly in laboratory the vector is plasmid. Plasmid is an extra cellular independent and autonomously replicating DNA that is mainly present in bacteria only. Okay. So once we are we have extracted our gene of interest then we then we cut the plasmid of our interest by a restriction endonucleus and then we liate our gene of interest in this plasmid with the help of DNA liase enzyme. Okay. Now once we have got a plasmid containing our gene of interest then we simply transform it inside a host and the host in most of the cases is a bacteria or else it can be a plant cell or an animal cell. Okay. And it is inserted inside a cell by using different methods like heat shock treatment like retroviral vector using retroviral vector. We can use gene gun also in order to transform it into a plant cell. We can also use agroacterium tumifasian vectors in order to transform it into a plant and we can also use micro injections to transform it inside an animal body. Okay, clear. Clear. Now let's move ahead. Now let's move ahead and see and see what happens next. Once we have once we have uh inserted our plasmid of interest inside a host then what will happen is that then what will happen is that this plasmid which is autonomously replicating DNA it actually starts to express itself and once it will start to express itself it will also express our gene of interest. So it will produce a protein of our interest that we'll purify using downstream processing and hence we can market it as per our need. Okay, clear. Now there is one very important topic which is remaining in this chapter is selectable marker is what is selectable marker from which questions are asked every year from which questions are asked every year. Okay, let's see. So, we know that uh we will try to of course insert our gene of interest inside a plasmid. H inside a plasmid. But this reaction happens in a test tube and we are not able to see that whether it is going to cut by restriction enzyme or not. whether it is liating or if the plasmid is u restricted by restriction in the nucleus then whether our gene of interest is inserted inside that plasmid or not enough so these all things we can't see it we just have to add the enzymes and let the reaction to happen but we also can't assume that if we have done all the things then all the things would have been done h we can't assume assume that thing that it it is done and we have to recheck it cross check it by using selectable marker. What are these selectable marker? Selectable marker are basically some genes in the plasmid which tells us that whether our host in which we have inserted our plasmid that contains a plasmid which has our gene of interest or not. Okay. And it is done with the help of two markers or two genes. One is the antibiotic register gene and one is the beta galactoidase genes which is which uh makes us to get sure that whether our gene of interest has been inserted in the plasmid or not. Okay let's see them one by one. Let's see them one by one. So first one is the antibiotic resistance gene. Uh so let's say uh the plasmid in which we are inserting our gene of interest contains a a gene which is which makes uh which makes that plasmid resistant to antibiotic empilinic resistance gene is there. So if we are able to insert our gene of interest in between the ampeilin resistance gene then we know that empilin resistance will be gone and if it is not inserted in that ampi resistance gene then the empilin resistance will not be gone and that's how we do it and know we first try to insert it insert our gene of interest inside that plasmid and then we try to select it use by growing it in the amperine containing medium. If it is able to grow in the amperine containing medium then we know that it is not inserted. But if it has been inserted in the ampin restor gene then it will not the bacteria or the host containing this plasmid will not be able to grow in the medium containing empinine because the empin resistance gene has been inactivated due to insertion of our gene of interest inside it and that is known as insertional inactivation. Clear? Clear. Now let's move ahead and see blue white screening. So this method of antibiotic resistance genes it needs multiple plating which makes it a kos that's why we we use a blue white selection method as a selectable marker. So we have a plasmid known as puc8 and this plasmid contains a lag z enzyme that was used in case of upna lag operon. This lag zet gene it codes for an enzyme known as beta galactosidees enzyme and this beta galactoside it breaks lactose into glucose and galactose but it is also specific to one another substrate known as X gol. It also breaks X gol to produce some it also catabolizes exol to produce some constituents and it produces a byproduct which gives blue color to the to the cell in which this plasmid is present. Okay. So if this lag zed is active then the then the then that colony will give blue color and but if we are able to insert our gene of interest inside this lag zet gene then that will not give a blue color that will that will tend to give a white color because it will it because it will not give a blue color because lag zed gene has been inactivated due to insertion of our gene of interest here. So if it is white then we have got our transformant. If the colony is blue then it is a non-transformant colony. Okay. Now this chapter has one more topic which is very important and it is PCR. question was asked in 2024 IAT exam also and this PCR is basically a method to amplify the gene of interest or to amplify any DNA and a uh basically it's a DNA replication step in a synthetic media which is done by using three steps dennaturation analing and extension in dennaturation we generally give a very high temperature to the DNA 94°C temperature to the DNA so that the hydrogen bonds all the hydrogen bonds in the DNA get broken down and the double stranded DNA be had become a single stranded DNA okay like this now in the next step known as analink known as analink primers are added primers and specific buffers dntps and magnesium dipositive ions are given to the medium so that primers are able to bind to the single strands. Okay. And once they are bound to the single strand, a specific DNA polymerase is added which polymerizes the whole DNA which polymerizes the whole DNA by the polymerization steps using these DNTPS as substrates. Okay. And it is done at 72°C. Now at 72°C normal DNA polymerase will of course get degraded. But this tag polymerase is a specific DNA polymerase which is active at high temperature because it is extracted from a bacteria known as thermos aquaticus which is found at 100°C in the thermal vents. Okay. So this is this is a basic uh process of PCR which involves three steps dennaturation analing and extension at 94°C 50 to 60°C and 72°C respectively. Okay clear now this is a type of exponential growth because 2 to 4 4 to 8 8 to 16 to 32 32 to 64 such type of things are happening here. So that's why it follows an equation known as N is equal to N 2 ^ N where N is the final DNA amount n is a initial DNA count and 2 ^ n there this small n it denotes number of cycles or the number of generations in bacteria it is known as number of generation in DNA it it it is said to be as number of cycles of PCR it has undergone okay now the next or The last unit that we have to cover is of course what is of course ecology. It's a macro study. It's a macro study which studies populations and communities. Okay. So we'll cover the three chapters of ecology in a composite manner. We'll cover the important topics of those three chapters here in this session. Okay. First thing is that how do you calculate whether a population is growing or it is degrowing and know how much is the number of population. It can be simply calculated by noting the these points like number of individuals at time t is equal to number of individuals at time zero from which we started plus birth plus immigration increases the count and death plus immigration decreases the count of population. Okay, this is a simple formula. Now next thing is the population growth curve. A population growth curve can be of two types exponential and logistic. Logistic growth curve is more realistic while exponential is not so realistic. And it's look if you plot a graph between number of individuals with time then the exponential growth curves is a J-shaped curve. It looks like a J- shape and the logistic growth curve it looks as if it is an S-shaped curve. Why logistic growth is more realistic? Because in logistic growth we take into account or we consider that the amount of resources present in our ecosystem are limited which is a truth statement. But here we assume that the amount of resources in the environment present in the ecosystem are limit are not limited are unlimited which is not the true statement. It's a false statement because resources are always limited on this earth. This earth itself is a limited thing. Okay. Now let's compare them one by one. Exponential and logistic growth curve. If you compare it assumes that resources are unlimited. It assumes that resources are limited. Okay. Logistic growth curve. It takes into account carrying capacity but exponential do not have such assumptions. What is carrying capacity? Carrying capacity is the maximum number of individuals that a population can uh support. more than that it can't support. Okay. And the formula our typical formula exponential growth curve it will show a formula of n is equal to n e ^ rt there is something exponential dn upon dt is equal to rn where dn upon dt is the rate of increase or rate of change of the population and n is the number of individual at any given time interval t and r is birth minus death upon time which means birth rate minus death rate or else it is known as intrinsic rate of natural increase. Okay. While the logistic growth curve it shows or it follows a formula dn upon dt is equal to rn k minus n upon k. It looks very similar to exponential growth equation till here but it adds a ratio of k minus n upon k extra here. Okay. It is multiplied by this ratio also. Take next. Next we need to focus on one thing that is the age pyramids. We know that a population let's say human population we are divided into we can be divided into three parts children's reproductively active individuals and old individuals or else pre-productive age reproductive age and post-reroductive age individuals. Okay. If the amount of pre-productive age individuals are most followed by reproductive and post-productive then that population is expanding. If the re-reproductive and reproductive ages are age individuals the numbers are same then they are stable then they are in a stable equilibrium or the pyramid is stabilizing pyramid and if the pre-productive individuals are less and reproductive are more then it is known as declining population because pre-productive individuals should be more in number. Out of these three, the best one is the stable type of pyramid. Okay. Okay. Clear. Let's move ahead. Now the very important point, the very important topic subtopic of this chapter is botic botic interaction. We know that whenever we study a population or a community, we know that we are going to study interaction among two individuals of same species or different species. If the individuals interact um in a positive manner or negative manner or they are neutral to each other and know those type of interactions will be studied here. Okay. So there are mainly as per your syllabus there are six interaction which are written over here. The first one is known as mutualism in which both of the individuals benefit from each other and that is known and that is an obligate type of relationship because both of them will live with each other and they can't live without each other. They can't exist individually. They will always exist in a pair. Take so both of them benefit from each other. Commensalism in which one organism benefits for the other but the other do not have any significant advantage or disadvantage from the other one. Okay. Parasitism it involves it in in this interaction one of them benefits while the other is harmed but that person who is harmed is not killed uh directly or instantly. But in predation same type of interaction is happening. One is getting benefited, one is harmed but the person who is harmed is killed or uh is killed or dies instantly. Okay. In competition both the competing counterparts are negatively affected and in amensalism one is negatively affected but other one is neither positively nor negatively affected. So these are the six interaction that we needed to study. The thing that I told here are the basic principles and if you know these basic principles you will be able to solve questions that will be asked in the exam. But I urge you to study uh the example different examples that are there written in your NCERTT with respect to all these interactions because this topic is very important. Okay. Clear? Like there's a topic of brood parasetism which is mentioned in your book Hannah which occurs between cuckoo and crow. But if you don't know if you haven't studied that example then I think you will not be able to uh mark those questions correctly if such questions will be asked from the example part of this interaction topic. Okay. So, so you should study the examples of all these interactions from your NCERTT. We don't have much time that's why I'm not trying to cover all those examples. I'm just giving you an overview of what kind of interaction are these ones. Okay, clear? Let's move ahead. Now in an ecosystem in an ecosystem we know that plants are the one which produces their food by themselves using sunlight. So they basically they fix sun sunlight or the light energy into chemical energy which are used by their body and which are used by the other uh individuals like harbivores and carnivores directly or indirectly and that energy which is fixed by plants they uh flow in the whole ecosystem. So plant the whatever energy they fix they fix it in the form of biomass and that productivity is known as primary productivity. The total biomass or the total energy that is fixed is known as gross primary productivity. But some amount of energy is used by plant itself. So all the energy is not laid down in the form of biomass. some of it is used as per respiratory losses and the and the remaining energy is known as net primary productivity. So basically net primary productivity is equal to gross primary productivity minus respiratory loss. Okay. And this net primary productivity is the biomass which is available for the consumption to herbivores because harbivores eat eat what they eat plants. So they they will eat what they will eat a plant biomass and the biomass which is available to harve is actually the net primary productivity because a rest has been used by plants itself in respiratory processes. Okay. Now let's move ahead and see food chain. So in our nature we have two types of food chain. One is grazing food chain and the second one is detritus food chain. The grazing food chain is is the simplest food chain which includes plants, herbivores, carnivores, top carnivores. Plants are known as primary producers. Herbivores are primary consumers, secondary consumers are carnivore and tertiary consumers are top carnivores. Okay. Though we are more able to see such kind of food chain in our terrestrial ecosystem but this type of food chain is involved in the energy transfer mechanisms more in oceans not on land. On land the major condute of energy transfer is detritus food chain which starts with decomposers. So it starts with dead and decaying matter which is decomposed by these decomposers. Okay, clear. Let's move ahead. Now the process of decomposition or detritification detrits actually do this process of decomposition. And this decomposition is a five-step process is a five-step process which starts with fragmentation of the dead and decaying matter followed by leeching in which lots of inorganic substances they are swept away deep down the soil which accumulates as an unavailable inorganic substance which is known as leeching. followed by catabolism and after that mineralization and humification happens. In mineralization, all the inorganic matters are solubilized in the soil. And in humification, all the organic substances are laid on the outer rough surface of the soil which is known as humus which is a dark amorphous substance um and it is water repellent. That's why it is able to hold water on the soil. That's why humus rich soil is very beneficial for agriculture because it gives time for the absorption of water um on the surface of soil because it is a water repellent. It do not directly lets the uh water to flow inside the soil. Okay. Now ecological pyramids are also very important topic because um question has been asked from this topic in IT as well as NST. So these ecological pyramids they actually are the pyramids which gives us information about what is there in each trophic level primary consumer, secondary consumer, tertiary consumer or primary producers. H now uh so we can compare the different trophic levels in terms of number of individuals present in them or amount of weight or amount of biomass in that ecosystem or the amount of energy present in that ecosystem. And know if you consider about number and biomass pyramid these pyramids can be upright also. It can look like it can look like this or else they can be inverted also. It can also look like it can also look like this. Okay. So both of them can be inverted and one one examples of inverted biomass inverted ecological pyramids has been written here. Ecological pyramids of numbers can be inverted in tree ecosystem and biomass pyramids can be inverted in pond ecosystem. But energy pyramid is always going to be straight. Okay? Because of this 10% law. We know from 10% law that the amount of energy which is present in the lower traffic level only 10% of that energy is transferred to the next tropic level and only 10% of that is transferred to the further next traffic level. So that's why the lowest tropic level will have the largest energy followed by the subsequent upper one followed by the further upper tropic levels. Okay. Clear? Clear. Let's move ahead. Now the last chapter of ecology is biodiversity and it has one important topic which is known as different type of biodiversities or different type of diversities. So we have three different types of diversities. One is genetic diversity. Second one is species diversity and third one is ecological diversity. Genetic diversity basically is concerned with the variation among the species. Like we know that we all are humans but we have different human races. We have Caucasian population, we have Asian population, we have African population and so we have different variations among one species that is homo sapiens that is known as genetic diversity. One very important point is the presence of a Himalayan plant known as rofia vomatoria which is of different types and it produces different type of chemicals chemical counterparts of one particular chemical that is known as resurpene. Rarpine chemical is used as an anti-cancerous agent but it has a variant. It has different variants and how those variants are produced because these ropia also have different types of subspecies or variants in them. Okay, clear clear. Now if we compare diversity at the species level, we will get to know that there are multiple species present in our ecosystem. Like if we compare western guards with eastern guards, we will come to know that western guards have far more ecologies diversity of amphibians as compared to eastern guards. Okay. So if we compare the number of species in particular places then that will come under species diversity. And the last one is ecological diversity in which we compare ecosystems, the climates and the type of conditions in those different ecosystem. Like if we compare Gulf country with India, we know that Gulf country they mainly have deserts. They only have desert. So there is no ecological diversity in them only desert. But if you compare India, India has Himalayas also, mountains also, we have plains also, we have mangroves also, we have tropical rainforest, we have tropical deciduous forest, we have different kinds of area, we have deserts also. That's why in terms of different types of climatic condition, different types of terrestrial and aquatic habitats. India is a more ecologically diverse country. Okay. Now this biod diversity it can be studied in two manner. Okay. One is species area relationship and other one is latitudinal gradient. If you talk about latitudinal gradient we know that most of the sunlight falls at the equator. And we know that the place where sunlight is the most the sunlight will be absorbed the most by plants. And plants they will produce more amount of biomass there because there is more sunlight. So so equator is the most biodiverse area because of presence of lots of energy and biomass at the equatorial level. But as we start to move towards pole the amount of biodiversity it starts to decrease. And there and this is a trend here. H this is a trend that the amount of biodiversity it keeps on decreases as we as we start to move from equator to poles. Okay, this is one thing. Now species area relationship. If you talk about species area relationship, if you plot a graph between the species and the area, it will look like this. Initially with the increase in area the amount of species will also increase but a a a time will come where you will tend to increase area covered but the species number will not increase at all. Okay. So such kind of uh study between species and area is known as species relationship and it it actually tends to give us this kind of formula which is S is equal to CA to power Z. S stands for species richness and C is a constant. A is area covered. Zed is regression constant or regression coefficient. And regression coefficient also gives us idea of the number of species or the diversity of species at any particular given area. Okay. Now we know that we have lots of biodiversity but that biodiversity we are losing that biodiversity day by day. And what are the major causes behind this biodiversity loss? There are four major causes behind biodiversity loss and these are mentioned over here. First one is habitat loss and fragmentation. So if we if we cut down the forest so habitat of the natural habitat of all the animals and plants are gone. So that's why biodiversity loss is a major cause habitat loss and fragmentation is a major cause of biodiversity loss. Okay. or else over exploitation, illegal poaching, illegal killing of animals. It also leads to biodiversity loss. Alien species invasion like if we introduce any alien species into an indigenous area, then that alien species, it will not have its natural predator here in this new population because its natural predator was present in some other area from where you have brought that alien species. Now in the absence of the natural predator these alien species they start to grow abnormally high and they affect or they start to overexploit the indigenous species and due to which the indigenous species they get wiped away. This is also one of the major cause of biodiversity loss. And the fourth one is co-extinction. Let's say if two individuals or two species are able to survive uh with each other. They can't survive without each other. Okay. Two individuals can't survive without each other. They will both of them will survive only when they are present close to each other or else they will not survive. Okay. Now in that case if one of the counterparts is gone then the other will also get away because because why it will get away it will get away because they were obligate error they were obligate they can't grow without each other okay so if one is gone then other will automatically go away okay so these are the main four causes behind biodiversity loss these are also known as a quartet Okay. Now the last topic of this chapter is biodiversity conservation. So we always try to conserve biodiversity though we are not able to conserve. Uh we can see from what is happening all across the world. Amazonian rainforest is also getting wiped away. But yes we always try to conserve biodiversity at at different levels and know communities. There are many communities which try to conserve bodiversity. government also they put many policies to conserve biodiversity but yes more or less it's a it's a kind of we can say it's a kind of trying we are trying to conserve it but we are not because of different reasons h so let's see how we can conserve biodiversity it can be done in two ways INC2 and XC2. INC2 conservation is basically that mode of conservation in which we actually try to conserve the species or the flora and fauna in the places where they are w getting wiped away. Like illegal poaching is causing like if there is some forest in which illegal poaching is causing decrease in the tiger population then government actually do what? government actually uh rec starts to recognize that area as a national park or a biosphere reserve or a hot spot, biodiversity hotspot, H or a wildlife century and they employ they start to employ the forest rangers and police and all those officers in that forest to conserve the flora and fauna present over there. and and to restrict illegal poaching and hunting of the endangered animals. So in such cases we are trying to protect animals and plants in the area where they tend to grow in their at their site onsite uh conservation. But here in XC2 conservation, we do not go on the site where illegal poaching is taking place or in the forest. We don't go in the forest to conserve the flora and fauna which are being wiped out. In XC2 conservation, we actually try to take those flora and fauna from their natural habitat to our gardens of our homes or to the zoological parks or to the botanical gardens and they grow them there. so that they can grow properly in those defined conditions which are not their natural condition though we try to give them their natural condition the conditions like their natural conditions. Okay. So such kind of thing is known as X2 conservation. In X2 conservation, we also try to conserve the seeds, sperms, semen and a spores of different endangered or critically endangered species who have a high risk of extinction. Okay, we conserve them in liquid nitrogen under 196 under minus 196° C. Okay. So these are some of the methods of conservation of uh biodiversity and with this we are ending up with ecology. Okay. Hope you have enjoyed this session and uh I hope this session will help you a lot in understanding the most important topics of biology important for your IAT exam. But at the end also I am saying this thing that the topics that I have covered they are at most important but the topics which we haven't covered or the factual topics they are also very important because they can straight away give you four marks in just 5 to 10 seconds because you have to just know the answer and tick mark them. Okay. So you have to cover these points these chapters also but you have to cover those chapters also which are factual uh you just need to do some things you don't need to do many things there and know you just have to write all the facts there in your notebook or if you don't want to write them in the notebook then also you can just uh mark them in uh mark them in your book whatever book you follow and just Try to read them every day. Read those underlined things every day and after 8 to 9 days or 1 weeks you will be able to uh see the change that your subconscious has got those facts in your mind. Okay. So you just have to read those facts every day without taking any tension that whether you will be able to remember it or not. Okay. So that things are also important. So with this I'm ending up this session. I hope that this session will help you. Um till then keep reading Hannah keep reading and uh at the end all that I can say is best of luck and keep doing your part of hard work. Okay. Bye-bye.