[Music] hello Matrix welcome it's finally your time to shine on learn extra live with Looney and Aslam hi Asam hi Loney how are you doing oh good how are you how's the break good yeah yeah to fine great great what are we doing for the mric today what are we doing today we are doing some exciting stuff Looney we are going to be able to tell you what makes you okay in other words why are your eyes the color they are why are your eyes the shape they are okay I don't want to get to more details all right cool mindset has you hearded we're going to tell you what makes you so make sure you hit us up on Facebook and on Twitter learn XR you can download the show notes the videos and the schedules on learn. mindset. quick reminder to all you guys we now have something special for you guys for all of you who don't have a PDF VI and you can't download download the notes on your smartphones we have a view option now to view the notes so make sure you check out our Facebook page because I will post the download option for the notes that you can download and the view option for the notes that you can view but it's the same notes guys same thing that Isam is going through just in different platforms so that we can cater for everyone so I hope you guys enjoy the show Asam thanks Lun good uh that's very helpful stuff there remember you got to post your comments and your questions on the Facebook page all the time so we Loney and I can help you keep that going guys well talking about genetics and inheritance inheritance today's time when we hear the word inheritance we thinking about money and when is my when are my great grandparents going to leave something for me Looney how much are they going to leave for me for this stuff imagine when Madiba passed away everybody's waiting to listen to the will what did I get out of this inheritance The Inheritance we talking about however has no price invaluable no money can buy this inheritance that we are talking about is the inheritance in the form of characteristics that you inherit from your parents or you pass on to your children how often do you not go to a place and the PE people around they look at your child ah look just like the mother or I he just looks like you or she looks like you exact carbon copy what does that mean it simply means that that child has inherited characteristics more from one parent than the other but at the same time notice that in a family would be able to even though they all come from the same parent hopefully from the same set of parents hopefully we would be able to say that this is Samir this is y that is Muhammad that is sa whatever these are characteristics that we have inherited yet each individual is unique so that we can recognize that individual so in terms of that let's see where we going with this topic a lot of right in on the what do we have to do things but these things are all incidental learning you're going to learn it as we develop the lesson please don't forget that in the notes you're having the multiple choice questions you having the onew answers in other words the biological terms you're having the multiple matching and some other short questions sometimes those exercises are there to help you to master especially the terminology because that type of question is ideal to uh reinforce the terminology so don't neglect that don't only look at what we are doing on the screen and on the show you have to complete the lesson as a package by going over the other work as well so please don't forget that okay so where are we going to we're looking at definitions of the word genetics white we haven't used before genetics ICS inheritance which we've already touched on variation we've also touched on this in meosis then we must also outline the experiments conducted by Mandel we'll talk about him a little bit in more detail later differentiate between each of the following now here we have what we call sets of terms and you must know the difference often Learners confuse the one with the other what's the difference between chromatin and chromosomes chromatin is the whole bundle that you see there and the individual threads that make up this chromatin Network are known as chromosomes right and then from there the chromosomes are made up of chromatids some of your meosis work coming back to you genes and Al genes are units of inheritance and genes are found on the homologous chromosomes there will be one factor on one of the uh homologous pair and another Factor on the other one the two together are called a gene and each of these two factors are called Al because they form one gene they must occupy the same spot on the relevant homologous chromosomes we'll talk talk about that a little later and we spoke about it in meosis phenotype and genotype again we'll come through that just now as well just to uh highlight quickly the genotype is your genetic makeup which we can't see because it's inside your body in the genes we generally talk about homo zygus and heterozygous which we will come through just now as well dominant and recessive guys those are English words dominant to dominate to be stronger recessive to be weaker in that case and let's see how that plays out in our lesson later thereafter you must be able to state mandal's law of dominance what did Mandel say about dominance there we go these terms that we spoke about homozygous heterozygous another word for homozygous or another term pure breeding or true breeding and heterozygous also hybrid now remember we said that a gene is made up of two Ali that are found on the same Locus on the homologous chromosomes okay adjacent homologous chromosomes we said that earlier now if the two Al remember the two Ali will code for the same characteristic you can't have one of the two Ali coding for eye color and Looney the other Al next to that on the same Locus coding for bum size imagine what would happen we would get bum in the eye or eye in the bum I don't even want to think I can't imagine what it look like so the if the one a is coding for eye color the other one must also be coding for eye color notice I didn't say they have to be identical I said they must be coding for the same thing so if they coding for the same thing they could be identic that means if the one is coding for blue eye the other one can also code for blue eye if they are identical we say that they are homozygous homo the same and if they are different if one of those aliens are coding for brown eyes and the other one is coding for blue eyes we say that the individual is heterozygous for that condition remember we can't say this is a heterozygous individual no we say that this individual is heterozygous or homozygous for a particular characteristic you could be homozygous for one characteristic eye color and for the shape of your eye you may be heterozygous for that or the color of your hair Etc good then we must Define also what's a monoh hybrid cross and a die hybrid and look at the prefixes there mono D mono One D two monohybrid cross deals with one characteristic at a time and Di hybrid two characteristics at a time so for example I said to you earlier eye color if we're just looking at eye color in an individual we want to see how this individual passes on or inherits from his parents the color of his or her eyes then we looking at one characteristics at a time characteristic at a time so this is a monohybrid cross however if we now switch and we want to look at eye color and height at the same time now we're looking at two characteristics at the same time so it becomes a DI hybrid cross the DI hybrid cross is slightly more difficult to work out than a monohybrid cross then we must also be able to show the format to show a genetic cross whether it's monohybrid or dihybrid we must also next law of Mandel State Mandel's princip principle or law of segregation then we must be able to solve monohybrid genetics problems for today and from that solution of that problem we must determine the proportion and the ratio of genotypes and phenotypes did I complete that when I started something the top you see I did not sometimes my memory works for me I know I left something out it forced me to go back we were talking about Geno genotype and we said that it's the genetic makeup and then I jumped to homozygous and ezygas and I forgot to go back so what is phenotype notice the the the the sound coming from phenotype phenotype the f f sound so phenotype is talking about the features that means the outward expression of the genetic makeup let's say I am heterozygous for brown eyes so het zygus is my genotype we can't see that if I look at you if you look into my eyes I can see the world in your eyes L your boyfriend tells you that then tell him I said Khan wants to know where's that Jetta that they stole from him 10 years ago because he can see the whole world in your eyes Okay so please just ask him when he tells you the next time don't forget so you can look into my eyes you can't tell me Aslam you are heterozygous or homozygous you can tell me Aslam you got brown eyes so that is what you can see that's my outward appearance so that is referred to your phenotype the genotype Gene inside heterozygous or homozygous that's where we needed to finish that one so there we are with that uh what we need to do that's quite a lot a mouthful let's look at the Challenge questions the one is seemingly very simple because it's a multiple choice question which of the following is the most likely outcome of of a cross between two heterozygous tall PE Plants okay and they're giving you the Alternatives there I'm not going to read that you have it with you and it's no NE not necessary to read all of that question two curly hair and straight hair are coded for by Al in humans explain why my parents with curly hair can have children with only curly hair while interesting Looney straight head parents can have ch children that have straight hair or curly hair so we're saying if the parents if you take two parents and they only they both have curly hair only all the children will have curly hair but if we take two straight head parents they is a possibility they'll have straight head children and curly think about homozygous heterozygous think about dominant and recessive when you tackling this one use a genetic diagram to illustrate your answer so you must be able to show us genetically why this is so a summary of what we're doing today genetics is what we are looking at we got to look at Mandel first first of all we got to look at terminology which incidentally we did while I told you what we're going to do I went through all the terminology that you need to know or almost all anyway and we must look at monohybrid crosses Mandel we got to go into a little bit of history of what he did how he did it why he did it and terminology I've told you and how to set out firstly a monohybrid cross and how to solve a problem again guys you cannot solve this problem without the terminology and you cannot do it either without knowing how Mandel has set these things out what did he say his law of dominance his law of segregation there's our friend Gregor Mandel an Austrian monk who is known as the father of genetics because he was the first person to actually investigate and provide uh acceptable uh suggestions hypothesis at a time of how how inheritance is brought about he studied these characteristics in plants in a PE plant the seed the flower the Pod the stem and he found that the seeds were either gray or yellow they were either round or wrinkled uh the the calans were either yellow or green and the P was either full or constricted or the the stem was long or short so there was no in between so as he's walking past these plants all the time in the Monas when he's going to his classes and so on he's seeing this says Ah but something's perfect thing to make a hypothesis right observation he saw something this led to a question why is this so and from that question he's saying I think the following I hypothesize the following and then he does an investigation and his results from the investigation must either support his hypothesis and then accept it or reject his hypothesis identical ideal for our studies an example of a cross very simple flowers with white FL plants with white flowers and purple what happened all The Offspring in the first generation all were purple and then if we took these and we crossed them Bendel found that there were three a proportion of three is to one three white purple and white uh one white and that's shown to you in this diagram I will come back to that later I just want to conclude this segment with this last part and that is the format when you're working out a genetics problem this is the format you must use all the time so I want you to look at that and consider it it's also in your notes so you can look at the same format in your notes it's no sense going through that because we're going to be doing many problems and I will remind you about this and we'll touch on it when we come back after the break Looney all right my SES you are going to take a very quick break so don't go anywhere we'll see you straight after this hey hey hey welcome back guys Aslam guys uh don't you just see how Looney's name fits with her personality she always has a tune when we start when we end it's always with a tune it's never just straight forward hi guys how are you Hi how are you I wonder how she talks at home we'll have to find out from my parents thanks Loney let's carry on guys we were busy with the summary earlier uh let's just round up on this diagram sorry about that okay sometimes okay so we saying that if we take these pods here and we we we cross the thing and we'll have that type of thing this is just a pictural diagram to show you what will happen what's happening here now okay there we go all right now what I'm more interested in is this guy this guy is the important thing notice the format guys oh what's happening what is happening am I pressing something okay notice something here when you put this format and you use this format correctly you're going to get two out of six even though your answer is incorrect as long as you use the correct format so 2 out of 6 is 33.3 so you cannot waste that opportunity now how what what what what's happening with my tongue L something's going on you you put the tune into my tongue so what am I talking about the format we start any genetic Problem by writing the word P1 or if they ask you for the second generation it will be P2 so what does that mean one means it's the first p means parents first parents from there we have two headings phenotype and genotype I prefer to put phenotype on top because our problem is based on the genotype so it's no sense having the genotype above and then working out the problem under it if you have it the other way it's not a sin or a penalty but it's more convenient to work this way so phenotype in other words in this particular example we're taking an organism that's white and an organism that's black and the genotype for that because the question would have told you it's homozygous dominant and homozygous recessive and then you will get this what's coming out of this now if the organism is dominant for example in this example white is dominant then we use a capital letter to show dominance uppercase letter big letter whatever you want to call it and for recessive we use a small one recessive weak okay so that's what's happening there notice in this particular exam uh example white is dominant but we're using letters b now you can argue why don't we use W you can use the W but imagine using W capital W small W can you see the problem the problem is when somebody's marking this and if you don't make your Small's small and your Big's big you're going to have a problem when they marking so you rather not use letters of the alphabet that are so similar in uppercase and lower case use letters that are different so that you can see clearly this is an uppercase and a lower case so capital letters are used for dominant and lowercase letters are used for recessive when an organism is homozygous then obviously the two a must be identical if it's capital B then both must be capital B if they small B then both must be uh small B now what happens to these ails these ails are found on the parent now when the parent is going to produce Offspring by sexual reproduction then before that happens the sperm or egg must form and for that to happen meosis must take place now notice how we're linking genetics to meosis when meosis takes place what did you learn that each sperm or each egg gets only one of these characteristics or one of these aliens why because the sperm and the Egg have half of the chromosomes that the adult parent had reduction division so that's why what we do then we show the gameit gameit and what we do for the gameit we simply take these genotypes and we separate them notice we have semicolons there to show that they are separated what we mean is that is in a different sperm that's in a different sperm that's in a different egg that's in a different egg that's what has happened they have separated now they are gamings now what will happen next when sexual reproduction takes place fertilization will take place and when fertilization takes place there's a recombination in a different way of these same aliens this one and this one can't cross because they are both sperm sperm and sperm don't fertilize the sperm must fertilize with the egg so that doesn't happen that does not happen rather this one must cross with that one there's a possibility or it can cross with that one there's a possibility and so to for the other one it can cross with that one or it can cross with that one but you notice with the line line crosses it becomes hectic and you can make mistakes so what scientists have D formed is what we call a punet square so instead of using line diagram they use a punet square by the way in the exams you can use line or you can use pet whatever you comfortable I would advise you to use a pet Square because it's neater and it has more clarity and less confusing now how do we use a punet square we draw the table with three rows and three columns in the upper row the first row we write and and this again you can use it either way you want to but this is what I do whatever is on the right we put it on top whatever is on the left we put it on the left or on the side so we've taken those two BBS and we put them on that left side and we taken the two small BBS and we put them on the right hand side now all you do that and that together will give you bb capital B small B and in this particular case because all the offspring are the same we don't have to repeat the exercise we simply say that's a story there and now after fertilization has taken place you're getting The Offspring first FAL generation that means this is the first set of Offspring if you were doing the second generation that F1 would change to F2 okay and there we have that answer there all are B with a small B that's a genotype or you could say 100% hetro zygous or and phenotype 100% white spent enough time there let's go straight to the questions then a plant with red flowers is crossed with a plant with white flowers okay let's get another color red flowers notice what I'm doing I'm underlining the keywords this is your homework before you answer the question or you can make notes on the side of the question all the seeds when grown produce plants with red flowers assuming that the flower color is controlled by a single pair of Al which alil is dominant and which is recessive now we're testing your knowledge on whether you know what is dominant and recessive if red was mated with white and all were red what does it tell you which is the stronger one obvious it's going to be red red is dominant and white is recessive 1 point2 if a dominant alil for tall plants dominant Ali for tall plants is represented by the letter d what letter should represent the corresponding recessive alien remember dominant uppercase recessive same letter lower case and therefore your answer would be small D 1.3 distinguish between the terms homozygous and heterozygous and we've done this before so we're going to just show it to you on the screen homozygous having identical aliens at the same Locus on both members of a pair of homologous chromosomes one from your mother one from your father on both of those the aliens are identical if they're coding for blue eyes they must both be coding for blue eyes heterozygous having only one word is changing here different having different aliens at the same Locus remember the rest of the sentence is the same don't learn the thing twice one is same one is different 1.4 explain why Mandel chose P plants for his investigation on inheritance now this is history you needed to read about it and it's doesn't change it's not the higher level it's straightforward Recall why did he use p p plums and the reason were they were cheap and they were easy to grow easy to cultivate also they have easily discernable characteristics or trays what does that mean they either all it's not tall medium short it's tall or short white or purple nothing in between so it was easy to do they grow fast so he could have multiple Generations in a short space of time and this improves the reliability of his results remember increasing sample size right and many seeds are formed at a time again the sample size is also increased there they are easily self and cross-pollinated how did he ensure how did he ensure that the plants were true breeding and that's straightforward first he allowed the wants to self-pollinate for many generations only those that were true breeding how will he know that they true breeding he will know that they true breeding that if he took red fls with red flowers and they kept breeding them among themselves that all the generations only showed red and he took white and only white came out there right or purple or whatever color that you're talking about that's what in this case it's not red right it's purple and white then he took these plants and he pollinated the flowers himself and why could he do this is because the PE plant has a closed flower normally it self pollinates because no insect or other Vector can get any pollen in so what he could do he could open the flower and dust off pollen from one plant to the other he could self-pollinate it how did he ensure that his results were reliable I asked that just now it's obvious he used a big sample he didn't do one and two plants he did many plants and he he repeated the experiment several times remember reliability increases with a bigger sample and by repeating the investigation because reliable means that if anybody else does the experiment they must get the same result this is reliability that means if we repeat we must get the same result validity on the other hand is talking about the method if the method is correct what is kept constant Etc we didn't let anything else interfere our results recorded properly Etc good we move on to number two Gregor Mendel uh experiments with P plants to study inheritance of four plant seed shape whatever for each straight he crossed homozygous tall plants with homozygous dwarf plants The Offspring obtained in the F1 generation were then interbed to form the F2 what we've been talking all the time he did the same for each of the other trays the results obtained for the F2 generation are shown in the table so after he has done his work this is the result that he found plant height tall whatever this that whatever it's giv you figures here okay and it gives you a ratio on the other side and you'll notice that two are not completed X and Y good so you've read the passage what is the expected phenotype ratio for a tray involving two heterozygous plants if we take any two azygous plants and we want to know what is the uh result going to be You can predict it it will always be more or less 3 is to one three of the dominant and one of the recessive from the extract from the results calculate X and Y also states which Pro tray provided a ratio closest to the expect here's your expected yeah 3 is to one right show all working simple I'm not going to go into the calculations you can do this on your own for C shape these were the figures that were there 5474 over 1850 of the recessive one so it came to 2A 96 is to1 ratio 2 96 is to 1 not a fraction a ratio okay not a proportion that of so many this was there this is a ratio when you are comparing two how are they comparing in the whole then we had y seed color 6022 over 2001 and the answer came to 3 comm1 to 1 our answer is 3 is to one so which one is closer obviously is the one that says 3 comma 01 to one is closer so closest seat color 3 comma 01 to1 that's how you answer that question now the question goes further give a possible reason why the ratio selected in question 2 going towards closest to the theoretical now let's go back to this to figures that are given look at the figures 5474 and 1850 here you got 6022 and 2001 there was a bigger sample used here so therefore that is one possible reason why it was closer it has a largest sample size this is now testing you your reliability the closer to the answer the more reliable it's going to be obviously isn't it using the results State whether the alil for round seed or wrinkled seeds is dominant and you would have seen the results and your answer would obviously be round the seeds state two factors that Mandel controlled during these breeding experiments and just now we we asked some questions about it and it's coming back to by you now first of all he had to make sure that when he started with his plants they must be true breeding home homozygous in P1 and in the second stage when you're getting this second ratio the plants had to be heterozygous you can't take a heterozygous plant and cross it with a homozygous plant you're going to have problems you're not going to get the same ratio your whole problem changes or rather your result changes write down Mandel's law of segregation now simply asking you a simple straightforward question write down this law of segregation and what did Mandel's law of segregation ation say it said that during gameid formation remember he didn't say it exactly like this we are now seeing it in terms of our knowledge of meosis and the rest of it during gay me formation members of each alil pair remember during in normally in your body these alil pairs align next to each other in homologous chromosomes but when game meets form the members of each of these Al pirs separate so that each git will only have one Ali for a particular trait remember Mendel first he said something to the effect that for every characteristic there are two factors that bring about that characteristic in today's time we are saying for every characteristic in your body or in every cell there are two Al that control that particular characteristic in an adult both are found but in the sperm and in the egg in gays only one of a pair is found in there why because meosis ensured that those chromosomes split and they move to opposite poles so when the cells formed they had half the chromosome number and therefore in that half you could have only had one of those two alals the other one is with the with the other with the other chromosome or the other sperm or egg good a sheep homozygous for white wool are crossed with sheep homozygous for black wool all the offspring are white what does it tell you guys let's do homework now sheep homozygous for white they are homozygous that's homework and white wool they across with sheep homozygous and black so we know that both the Sheep are homozygous and one is white and one is black when they crossed all the offspring are white you have to ask your question now ask yourself the question which is dominant obviously if we put homozygous white and Homo is black and if all the offspring are white that means white is dominant so this is the homework you're doing while you're working out this problem use the letters b and b to represent a genetic cross to show the results and show the expected results if the F1 were to inter breed so already you know for white it's capital B and for black it's small B and because the question said homozygous you would to have capital b capital B and small B small B for your starting point can you understand my drive in getting you to understand the concept of doing homework before you answer the question it's very easy just go and answer the question but you don't separate homozygous dominant homozygous recessive genotype phenotype you need to use the terminology to write these little notes while on the question paper while you are busy reading this don't wait to read the whole thing as you're going along underline write the symbol for it Etc and you get it done that way especially when they give you longer case studies guys it's a lot of information and you can get confused in between more about this after we come back Lun all right mindsets we are going to take a break a quick shout out to he's a new mindset and asked me to send him a shout out so thank you so much for joining us and for writing on our page and for asking questions we'll see you straight after the break mindsets [Music] thanks luny welcome back guys I'm hoping you getting grips to what we are doing here there's quite a lot of questions coming on the page so that's interesting I'm glad you're doing that so now remember guys again let's go back to the question we saying that as you're going along you're saying homozygous white and homozygous black and that uh the one question that came up there that I picked up and it's nice to discuss it here why are we using B and not W I explained that earlier isn't it that if you use W because the W's the W's are so close the the lower case and upper case look very similar and if you write big both it becomes confusing to Mark so it's rather you use a letter that have totally different upper and lower cases so but you provide a key in this case you didn't have to provide a key because they told you to use capital B and small small P right now and another question is how do we know which is dominant if they don't tell you which is dominant you got to read look at this question it said we had homozygous white and homozygous black and all the offspring are white if we put homozygous black and white and all the offspring are white that means white is showing out better than black now I got a simple rule that I use when it comes to the law of dominance what is the law of dominance the law of dominance states that when when we put two different characteristics together and in the phenotype the one characteristic is masked or Shadow you can't see it you can only see the one like in this case we put two characteristics together those with white wool and those with black wool in the first generation we find that the one is masked we don't see any black they're all white that means that black has been masked by white the one that is masking or shadowing the other one is dominant this is the law of dominance don't confuse it with the law of segregation where they separate here we saying that one is strong and one is weaker and the one that stronger is showing out in The Offspring we'll only notice which one is dominant when we look at the phenotype you can't look at the genotype on its own and see that okay unless they tell you capital B and small B so that's two of your questions that we've answered there now let's look at how we will answer this question and that's what it's all about they want to know both Generations so we start off with the first one again we need to use the format P1 phenotype white and black notice it's very similar to our example that we did earlier capital b capital B small B small B why because they were homozygous meosis takes place to separate the gits into different I mean the the the aliens into different gamage we then cross these whatever is on the left keep it on the left whatever is on the right whatever is on the left keep it on the left whatever is on the right put it on top remember because it's multiplication it doesn't matter if you add it this way and that way the answer will still be the same 5 * 4 is 20 4 * 5 is also 20 so that's the story there okay so we get this answer here now another learner asked if we don't put fertilization why do they penalize us because this is part of the format you're getting one mark for P1 and F1 if they in the right place you're getting another Mark for meosis and fertilization if they in the right place now if your answer is completely wrong and you had the format right out of six you're going to get two already so don't waste that opportunity look at the format and use it so this one is easy all are black and all are white now what happens if we then take the P2 in other words the The Offspring become the second generation now so there remember they were all heterozygous so we show them as heterozygous and they were all white we separate them may look that the format has not changed only the letters have changed so what happens is meosis takes place to separate the game meets again and whatever is on the left it's still on the left whatever in this case it doesn't matter because it the same anyway now watch what happens you're not going to get all azygous now because that capital B and that capital B gives you capital b capital B that capital B and that small B gives you capital B small B this one and that one give you small B capital b or capital B small B same thing and the last one gives you small B small B so what happened they all disappeared the black ones and in the second generation they reappear that homozygous black that we started with comes back but notice 1 2 3 they are all white so genotype we're getting one homo dominant one homozy is dominant because it's capital letters two heto b b b small b b small B two heto and one homo recessive good and we getting the ratio 75% black 25% white uh sorry 75% white 25% black if they ask for percentages they could have just asked for the simplest ratio you would then say 3 is to 1 and that is how you answer that question guys I'm hoping that has helped you we will deal with your questions let's look at first of all the uh the uh the uh challenge question first of all what have we agreed upon during the show about two heterozygous individuals when we get two heterozygous individuals in other words capital T small T capital T small T our ratio at the end should be 3 is to one and if tall is because you know that he deal dealt with tallness in P plants and tallness was shown to be dominant there should be three tall and one uh short that's coming out there so you got to look at your your your your phenotype let's look at now how we can eliminate first of all you can't get a ratio where there's three things there there's no medium it's either tall or short so out you go secondly we're saying that tall is dominant so they must be more tall than short so this one is out because this one has less tall and more short now we go to this one now you used to use your calculator and without using your calculator you can see that these two totals are very close to each other so that can't be the answer the answer would be that one because that would be closest to 3 is to 1 and that's why your answer would be be B so although it's a multiple choice question you had to do a little bit of work to get there one is you had to work out that punet square but you should be knowing by now if we take hetro and hetro we're going to get 3 is to one and also you had to know that the question is talking about phenotype they're telling you about tallness and shortness not about genotype in genotype you'll get 1 is to 2 is to 1 Etc the next question says curly hair and straight are coded for by aliens and humans and so on I'm not going to read that now let's see how we can answer that because curly and curly give you only curly they can't give you straight the only possible thing that we can think about is that Curly seems to be recessive why we say that because when we cross them we're finding that it's only giving us this combination and therefore all the children will be curly whereas the straight head for a straight head to give you a curly hair child it means that the parents both parents must have both characteristics you with me what do I mean by that that means they must have the characteristic for curliness and straightness because if you got curly and curly and you get children with straight hair if you did not have this characteristic H you got to worry maybe somebody was busy there at home H think about that but that's not the case the point is is that straight head is dominant and therefore it can exist in the heterozygous case I told you earlier I got a simple rule when the cat is away the mice will play so if something is dominant whether it's there in one letter or two letters if the capital c is there in cap in in in in one or two notice C is also not a good one to use I'm using it because I can draw it this way whether the C is in two capitals or in one of them the cat is there cat the strong one then the mice will play so only if the cat is away the mice will play yeah the mice can play here you can see curly here why because there's no tray or characteristic or a for for straight hair so that's why we can say that this is the only possible explanation that we can get given in this close environment that that's what's happening so again not that even though we talking about curling and straight and all that we still using the same format we still using the same format over to you Loney all right just do this let's get some space what this is from Tab S Tab say yes I want to know about self-pollination what does it mean what is self-pollination self-pollination my dear simply means in a flower which is obviously uh bisexual or hemaphrodite that means it has both male and female parts in it the pollen from that same flower fertilizes the ovam from that ovary in the same flower this is called self-pollination okay all right am I right by the way cross-pollination then would mean if pollen from one flower is used to fertilize an egg from another flower generally of another plant also sometimes all right this is from Joseph am I right to say that two homozygous parents will always produce heterozygous Offspring Joseph wants to know that whenever we have two homozygous parents will it always give us a heterozygous Let's test his Let's test his story what if we deal our story about uh black and white sheep where we had homo zus black and Homo zygas White and the answer was all heterozygous 100% does his story hold true here yes it does but he didn't state in his question whether he was talking about homozygous dominant and homozygous recessive he simply said when we come when we when we made two homozygous what happens if we take BB and BB they both homozygous but they both dominant now in this case you're not going to get herro zgas because you only have one characteristic and that is capital B so all your Offspring is going to be that way or if we take BB and small BB and we're going to get small BB cheese coming that way okay only the people at home will understand what I mean by BB cheese okay okay and then pal is asking will they penalize you if you don't write feralization definitely they will you will lose one Mark you need one mark for P1 and F1 and you're getting another Mark for meosis and fertilization not if you just write it if I fertilization on top and may is at the bottom I'm not going to get the one mark because it's the wrong idea what is that showing it's showing that you understood meosis and you understood reproduction and you're putting them together now during production of game me meosis must take place when those GS come back together fertilization is the only process that bring them back together okay all right oo now it's disappearing all right just one thing while Looney is looking there I just want to go back to this so the conclusion here for uh Joseph's question when we cross homozygous dominant with homozygous recessive yes The Offspring will all always be heterozygous and when we cross to hetus parents you will always always always always get the result of 1 is to 2 is to 1 genotype one homos zygous dominant BB two heterozygous by heterozygous you notice we don't say dominant or recessive because when the cat is away the mice will play here in this case in heterozygous the cat is there so it's by common sense that that is dominant it's going to be white in our example and one homozygous recessive genotype and phenotype always is 3 is to one or 75% is to 25% how is that working in this case it was white is to Black depending on the example whatever the dominant one will have more and the recessive one will have less L all right with what you just saying guel is asking when you are crossing heterozygous and heterozygous is it always 25% of the recessive say and 75% of the dominant always not going to change they must both be heterozygous now you do some sums on your own to get your idea to around this so we've already given homo and Homo recessive and dominant then we gave hetro Andro now you work out on your own I'm giving you some homework what about if we take a hetero and we combine it with a homo dominant one scenario that's the third scenario now and the fourth scenario what if we take a ha thr and we combine it with a homo recessive what are the possible you have to work out a punet square quickly without the whole format to get to that then that will tell you for scenario one this will always be the answer 2 3 4 that's the four scenarios that you can only get all right and then is asking for question three why did you draw a planet Square while the question requested a genetic cross is it still a genetic cross a gen notice we don't say line diagram nor do we say pet Square the examiners are saying draw a genetic diagram a genetic diagram or a genetic cross or a diagram can be shown with a line diagram or with a punet square let's draw that quickly for you there's your bb and here's your small B small B for gays meosis takes place we get gay mees and that and that gives you b b that and that give you another one BB that one give you BB2 and that one give you bb4 so that's a line diagram upon a square there we go BB all will be BB okay that's what you can do either you're getting the credit as long as you use it and you do it properly and you give your genotype and phenotype ratio in the end and with that guys I'm hoping we had an awesome show Looney thank you so much Asam for the lesson mindset is at home thank you for tuning in we'll see you next week same time same place but for now it's a goodbye don't be scared we'll be waiting for you next week yes don't be scared we'll see you next week guys