Free Biology NEET Video Lectures for Sexual Reproduction In Flowering Plants

00:00:02 [Music] [Applause] [Music] [Applause] [Music] hello everybody and this is Dr Vishal tredi from Department of bio sens and bio engineering IIT goha and today we are going to discuss about a new topic and the name of this topic is the sexual reproduction in flowering plant so before discussing about the integrate mechanism of the reproduction in flowering plant let's discuss what are the different modes of uh reproduction in the plant system so uh in the plant system the reproduction can be by two

00:01:08 mode one is called asexual reproduction and the second one is called as sexual reproduction what is mean by the asexual reproduction is that the vegetative part of the plant will give rise to the new plant so in the asexual reproduction the uh plant reproduce itself and does not required the help of the specialized organ or the specialized system so in this case of mode the uh the plant part give rise to new plant where in which there's no sexual uh organs are required for example the root give rise

00:02:22 to new plant so the alternate name of the sexual reproduction could be that vegetative propagation you can have stem giving du plant uh and example in this category is potato example in this category is the sweet potato similarly if you have leaves they may give rise to the new plant uh an example in this is bopal okay so in this kind of plant in this kind of uh a aexual in this kind of reproduction mode the uh uh there's no specialized uh sex organs are required whereas in the case of sex sexual

00:03:30 reproduction the sexual reproduction requires two different types of organ one is called male sex organ and the second one is called as female sex organ uh it could be present in one individual or it could be present in two individuals so accordingly the plant can be of unisexual or plant can be bisexual irrespective of the State uh presence of these sex organ then the male sex organ or the female sex organs are going to produce the gites so in this case it is going to be male gites in this case it is going

00:04:25 to be the female gameit and then the male and female gamits are going to fuse with each other and they will form the zygote and then zygote will develop into the embryo and that embryo will develop into the new plant in this whole process the male sex organ goes far by uh uh a division known as meosis so the male sex organ is going to be duped in both the cases whereas the male or the female gametes are going to be hloy when they will fuse again the zygote is going to be deployed and accordingly the

00:05:19 embryo as well as the new plant is going to be deployed in nature so what you can see that in this kind of sexual reproduction mode first of all you need a very very specialized organs one for the male male uh one is male sex organ the other one is female sex organ male sex organ is going to produce the male gametes the female sex organ is going to produce the female gametes and then these two gametes are going to be fused and the formation of male and female gametes are occurring through a specialized mechanism which involves the

00:05:57 meosis and the other kind of processes and that actually reduces the number of chromosome which are associated with the male and female gametes and that actually eventually will fuse by a process known as fertilization to form the zygote and then zygote will evolve or develop into the embryo and the embryo will develop into the new plant now the first and the foremost question comes that what is the advantage or the disadvantage of plant for are going to the sexual reproduction because as you can see that the asexual

00:06:34 reproduction is very very simple and uncomplicated for example any asexual in any sexual reproduction mechanism although we have not discussed in detail about the asexual reproduction here but there are many more other modes of asexual reproduction and the uh asexual reproduction is ideally be very very simple compared to the mechanism which are involved in developing the sex going for the sexual reproduction even then the plants have evolved to do the sexual reproduction so the first question comes

00:07:09 what is the advantage of a plant to go for the sexual reproduction as the mechanism suggest the sexual reproduction involves the U involves the very very specialized um male sex organ as well as a female sex organ and they will form the male and female gites which fuse together so because of that they are always being uh used as a mechanism to generate the different types of uh traits or they are actually used to acquire the different types of traits okay you can imagine that there is a plant one and you can have a plant

00:08:13 two okay this plant is uh insect resistance this plant is uh for example having a colored flower so this plant is very good for pollination this plant is very good in protecting himself from insect okay now if the plant one and plant two suppose the male the plant one is male and plant B is females okay so female individual of plant two the male individual of plant one come together so they will form the male gamit this one is going to form the female gamit okay and then eventually they will going

00:09:34 to go for fertilization and they will form a zygote followed by embryo followed by new new plant okay so in this case what you will see that after the fertilization when the zygote is going to form it is going to have two different character one is it is going to be insect resistance the number two it is going to be having a beautiful flower or I'll say colored flower so now this plant the new plant which which is actually a hybrid plant if I say so this hybrid plant is actually going to be a new species and

00:10:49 this hybrid plant is going to have the resistance against insect number one and it is going to be more attractive for pollination this means this plant or this hybrid plant species which is evolved by these two plants for example in this case the plant one is actually insect resistance but it is lacking a very very beautiful colored flower so because of that the pollination of this particular species is going to be very low the poll pollination frequency is going to be very low and that's how the

00:11:44 number of copies which are going to be produced by plant one is going to be very less compared to similarly the plant two the plant two it has a very very uh beautiful flowers so the pollination efficiency is very high but it is sensitive for the insect attacks okay so in that case the plant two is also susceptible for the insects and that's why the plant two species is also not very very uh it's not going to propagate but because they can follow a sexual reproduction mechanisms they can

00:12:18 actually generate a hybrid variety and these hybrid variety can be used can have the new species and this new species actually will have the resistance against the insect and it also can have a very very high efficiency of pollination so that is the First Advantage the first advantage of sexual reproduction is that it allows the recombination of genetic material to acquire neut trates okay now these Nut trates could be in terms of having a beautiful flower uh this beautiful flower could be in terms of uh having a a combination of

00:13:23 uh different types of colors in the flower petal itself or it could be uh in terms of of having a entirely different kinds of flower so that actually is going to help in the pollination okay and the pollination is very important for the success of sexual reproduction in plant number B since they are talking about the new treats uh traits it also can be in the new traits in terms of helping the formation of embryo and formation of embryo and seeds seeds and the embryo which are having the higher level of viability

00:14:15 then number three we have already discussed a a case of insect resistance but it could be the resistance against any kind of environmental Factor it could be any environmental Factor like um the uh water it could be for air it could be against the pollen uh pollution uh it could be against the wind and it could be against the all sorts of infectious things insects uh molds and other kind of stuff okay the other uh Advantage is that the sexual reproduction always allows the keeping the uh uh keeping the

00:15:14 uh maintaining the genetic pool Okay so means you might have seen that the male sex organ as well as the female sex organ is actually going with a meosis division and that is causing the generation of male male gametes as well as the female gametes and both of these male gametes or the female gametes are heids and when they come together they will the deploy this means there is always a uh maintenance of the genetic pool means there always a maintenance of the genetic material means it started with the deployed

00:16:06 species and it always ends up into the deployed species so that particular kind of continuity always been maintained in the case of sexual reproduction now if there are so many advantages there are also disadvantages of going for the sexual reproduction what are the disadvantages of sexual reproduction one of the major disadvantage of sexual reproduction is that it is very very complicated okay it is involves many steps few of the step I have shown that how the male sex argon as well as the female sex argon forms the gits git have

00:17:05 to fused they go for then they will form the zygote then dyode will form the embryos and embryo will then form the um will present in the seed then seed will grow and germinate and give you the new plant so that actually has a many steps and if there is any kind of uh problem or if any of these steps will not go for go successfully then the whole process of sexual reproduction will not go number three is the sexual sexual reproduction uh mainly being dependent on formation of male and female gites and the formation

00:17:43 of and then their dispersal within the environment so that the male gtes reaches to the female gtes and the uh do the fertilization and these kind of processes require lot of it will always be dependent not only on the plant it always depends on the uh the the factors which are uh working in working around the plant and uh for example the insects animals and other kind of environmental factors so that's how it actually depends on many factors for for example the pollin pollination so if the pollination is not going to

00:18:32 happen even if it uh then the male and female gamits will not come and fuse and form the zygotes so because of that it always been depends on the many types of uh uh outside the plant factors for example the uh the animals or the insects which have to carry the male gites from the one uh plant to another plant and then help in uh doing the fertilization uh number four as we said you know these are the good advantages that they are actually acquiring the resistance or acquiring the traits which are good for the plant

00:19:15 but they can also acquire the traits which are not good for the plant so traits not good for the plant so these are the advantages as well as the disadvantages of the plants goes for the sexual reproduction but there are many more advantages than the disadvantages because the plant are uh going for uh the sexual reproduction and that is actually uh uh evolving over the course of time to reduce these factors reduce these event these disadvantages okay so let's see how the sexual reproduction or in journal the

00:20:07 reproduction is being evolved within the different plant groups to take care of to to focus more on the sexual reproduction as well as on the other hand to reduce the chances of its failure so we have El we have we have uh bryter we have teroy then we have gnos pums and then ultimately we have angos pumps these are the Primitive plants okay or I'll say primitive plant like okay whereas these are this is the seed bearing plant the first time when the SE uh seed has been appeared and these are

00:22:02 the flower bearing plants okay so how the the reproduction mechanism Works in this in this case the uh whether it is El bra or ter in fact in in the case of fungi also U what we have is we have two different species one is called the one is called ghy and the other species is called spite okay so ghy is forming the gites okay and these gites are then going for the fusion and they are forming the zygote okay and then zygote is evolving into uh uh a cell body known as the sporo sporo sporo then goes for

00:23:35 the uh division okay and it forms the different types of spce the so sporo sporo is deployed whereas the ghy is hloy and this Mion is mitosis okay so the ghy goes for the mitotic division and then it forms the gtes it could be male or female gamits they will fuse and form the zygote then zygote will go for uh the mitotic division and it will grow and form the sporophyte sporophytes then will go for the meosis to form the spores and and then these spes will grow and form the uh gy okay so they are heids so as soon as there will be a

00:24:44 meosis in the sporophyte it will go for the Spore formation and the spores are haid in nature and they will grow by a mitotic division to give you the holoid gimy okay so in these this kind of primitive uh reproduction mechanisms the uh plants are mostly being uh going with the so these two gy or the sporophytes are two individual different plants uh species they could become come together also but in many of these cases because these are the Primitive plants uh they are always growing to uh separately so and the communication or

00:25:30 the development from the gy to spori or spori to gide is always involving the always happening outside the plant it's not happening inside the plant and so because of that there are lot of disadvantages there are a lot of disant means that suppose the ghy has formed the gites those gites may get may may will fuse with each other only in the external environment so this Fusion is going to happen in the outside the plant means either in the water or air or any other kind of in medium so if that

00:26:06 Medium is going to destroy these gametes because for example the external environment is not good for U the uh the fusion then these gites are going to dead okay even if suppose the gites got fused the zygote is formed zygote may not evolve into the spori because they may also get damaged once the spori is formed the sporophytes will go for the mosis spores are formed spores may not develop into the ghy so because of that the maintaining the sexual reproduction cycle in these kind of plant is very

00:26:42 very very limited so most of these plants actually goes for the uh asexual mode or the vegetative propagation because the sexual reproduction is still under very very primitive State there are uh more chances of uh failure rather than the getting a very very well defin very very specialized Machinery so that it could happen in a efficient manner and give you the success in terms of sexual reproduction so these kind of problems have been overcome by in the gymnos pumps so in the case of gymnos pum which is actually the first plant uh

00:27:21 where the seeds are being appeared okay and these seeds uh bearing plants are actually seeds are present in the uh specialized structures known as the cones so these specialized structures are known as The Cone and uh in this case what happened is gymnos sperm is also forming the uh uh you know male gites as well as the female gites and now the fale and female are fusing forming the zygote zygote is then eventually will develop into embryo and this embryo is present in the form of a seed and this

00:28:16 seed is not being throw into the environment okay it's this seed is being stored in a specialized Machinery known as The Cone and this cone actually protects the seed from the adverse environmental condition and because of that the success of the sexual repetion goes up in the case of gymnosperm but still these kind of classes of molecules these kind of classes of plants have not evolved the male or the female sex organs in a very very uh defined way so because of that still there is a uh there is a failure at the stage of where

00:29:00 the male sex organ as well as the female sex organs are forming the gites but these gites are facing problem in terms of getting the fused Fusion so those kind of problems are being taken care by the ngos sperm and that's why the engos sperms are considered to be the most evolved plants present on the earth so in this case what they have done they are have taken the male as well as the female sex organs and then they have put these male and female sex organ into a combined structure and that combined

00:29:35 structure is known as the flower and that's why the flowers appearance of flower is only happening in the case of angop sperms there are no reports uh uh previously that the flowers are present in the case of gymnos sperms so what is the advantage of flower the advantage of flower is that it contains the male as well as the female sex organ in a well defined structure or in a well defined Manner and it is also being enclosed into a structure so because of that the male or female sex organs are protected

00:30:18 from uh the environmental damages and on the other hand because the male and female organs are present in a well defined structures uh they their formation of male gamits and the female gamits is more and on the other hand the fusion of these male and female gamits and the formation of seeds and formation of fruits is all happening on the this flower within this flower and because of that the efficiency of sexual reproduction is going up in the case of the angos sperms the flower is not being involved in a single day it flower is

00:31:01 being evolved uh by considering the uh the problems what gymnosperms were facing uh because the gymnosperms are having all the male and the female sex organs open the there were chances when the male or the female gits are getting damaged so because of that the concept of flower came up and that flower came flower is evolved into the angio p com s by a very very specialized scheme how the flower is evolved so this is uh just the hypothetical scheme which has not been ever proved by doing the experimental

00:31:46 mechanisms so in this kind of um uh the hypothetical scheme what people have proposed that the earlier the on the leaves itself the sporangia is present okay so what is mean by sporangia is that the it is actually the sex organs but these kind of sporangia were unprotected they were not enclosed so because of that what happened is these leaves started curling inside okay so they will started curling like this and sporangia is getting enclosed within this Leaf okay and then ultimately these leaves started curling

00:32:36 further up further up and as a result you started de developing the flower like this okay where the sporangia is present in the center and then this got evolved into a flower like structure and the spangas are present in the center and this is what the typical flower is look like you can see that this is the individual leaves individual petals and in the center you have the male or the female sex organs which are arranged and this is what the typical flower or the Primitive flower is look like and that is the mechanism by which

00:33:22 the flower is evolved but as I said this is a hypothetical model to explain the flower formation or the flower development or flower Evolution within the angop sperms but there's no experimental or the systematic uh experiments are being conducted to prove or the disprove this kind of mechanisms but irrespective of any of these mechanisms uh the flower is evolved where they it is having a very very well defined structures with a very very well defined arrange M of the different uh male or the female sex organs so let's

00:34:03 see how the different types of molecule different types of plant parts flower parts are being arranged on the flower so as you can see on the PowerPoint slide you can see a structure of a flower so what you can see actually a flower with uh consist of a flow a typical flower is consist of the floor four four rolls means the four circles in which the flower parts are arranged what are these four uh Parts the outer part is known as the uh okay so outer part is known as the uh the uh the cix okay then in within the cix we have the

00:34:52 Cora and then within the Cora we have the male sex organ which is called as the stem or the osum and then we have the uh gyum or the carpal which is the innermost uh innermost part so starting from the Kix the Kix this is the outermost role of the flower leaves the individual Leaf segment of a calx is known as the seel they are mostly the calx are green in color and their main job is to protect the flower from getting the dehydration but in some cases the uh the leaves are the SEL are also being also being present as a

00:35:38 different color and in those cases the calx is called as the petaloids so the when the calx is green in color it is called as a seel when the calx is present in any different color it is called as the petaloid as I as I discussed before the main function of the calx is to prot protect the inner part of the plant uh especially when it is present in the form of buts uh by the uh uh by the loss of water from the inner part of the plant so you can imagine that the FL flower is always been present in the

00:36:14 form of bird and one the bird is uh at that time the calx is actually is the outermost uh closing of the flower and it actually protects the plant from losing the water the other function of the calx especially when the calx is colored in colored uh rather than the green color uh it attracts the it attracts the insects as well uh in uh as soon as the flower bird opens the calx sometime get fall from the flower or in some cases it remain remain associated with the plant so so it is particular up to the

00:37:00 different PL flower whether the calx will remain associated with the flower throughout the its Journey from the uh from the bird opening to the fruit formation or in some cases it may fall uh the second row of the plant uh flower part is known as the Corolla the Corolla uh is a in inner inner reel of the Flow Part next to the calx the flowers are is the individual leaves of the Corolla is known as the petals these are uh colored they are not in green color they are of different colors and they sometime they

00:37:41 are also fragrance so that it becomes they they should attract the insects and the other animals for the pollination their main job is to attract the insects as well as the other animal for the pollination the uh uh the Cora or the seel or the calx actually are the non-essential or the sterile part of the plant uh FL flower and they are not being taken part into any kind of sexual reproduction uh they are also forming a outer envelop so that they can protect the andrum or the gyum uh next to the uh

00:38:24 Cora we have the andrum this is the third role of wheel uh floral appendages that arises uh inner side to the Cora the individual appendages within the endium is known as the stemon which represent actually the male sex organs so endrum or the stamin is the male sex organ it has two parts one is called anther and the other part is called the filament and the and the part which connects the enter to the filament is called as the connect active uh each stemon is consist of uh uh each the anther is the part

00:39:05 where uh where the where it has a pollen pollen sack so in some cases it has two poen sac and the uh or the four poen Sac within the poen sac they contains the pollen grain and these pollen grains are the are the male sex uh gametes which actually travels from the one plant to another plant the function of the male sex organ is to generate the male sex gites and then the male sex gametes can go from one plant to another plant and they will go for the fertilization similarly they have the gyum the gyum or the uh it is

00:39:51 the innermost role of the flower aages known as the carpals so carpal is actually the female sex organ it contains three part one is called stigma style or the inner part is the ovary the ovary uh is actually the uh main sex uh or main sex organ where the fertilization take place and it actually produces the egg which participate into the uh fertilization event and then the uh fruit development as well as the seed development actually take place within this part the other part the the style or the stigma is only being a medium

00:40:31 through which the uh pollen grains travel within the uh female sex organ so uh accordingly because the so as you can see in a flower diagram the are the structures of a flower uh there are two four reels okay uh calx Cora andrum and gyum so the flower could be classified based on whether they have have uh these four uh parts so if they contain the all these four parts they are called as the complete flower if any of these four parts are missing they are called as the incomplete flower um in addition to that

00:41:12 the flowers could be of two different types the flower could be of uh flower could be of two different types uh one is called the male flower or the female flower depending on on whether they contain only the male sex organ or the female sex organ but the flower could be of bisexual in nature as well so so as you can see uh as we have discussed actually that the uh so you can see that the flower okay so this is the CX Corolla this is the stemon or andrum and this is the gyum okay so if you can arrange and

00:42:28 see that these are the four wheels which are present within the flower structures but these four structures could be explained or could be written in the form of a formula so when you write these kind of arrangement of these four flower part into a uh into a into a form of a formula then it is called as the floral formula in the floral formula uh what you can use so you can you can use the defined terms for each and every part of the plant and then you can define whether the pl what is the arrangement of these

00:43:16 different plants so as you can see on the PowerPoint slide we can you can see that the uh for example for if the plant has the calx you can write the K and if it contains for example the five SEL then you can write the K5 okay similarly if it contains Corolla the Cora for Corolla you can write C and it can suppose it contains six petals then you can write C6 for andrum you have to write a and if it contains five stemon means it if it contains the five pollen tubes then you can write the A5 similarly for gyum you

00:43:55 can write G and if it contains carpal then you can write the G5 I have given the two examples where in one example I have given the mustard so what you can see is actually that it is a male and female uh plant so it is actually a bisexual plant means it contains both the osum and gyum within the plant then it contains the Cora where the arrangement is 2 plus 2 whereas the Corolla is 4 and the andrum is 2 + 4 means the two are outside and four are inside and then it has a gyum which is uh two actually and as you can see they

00:44:37 have been enclosed within the bracket means the gyum is uh is together or the fused similarly for habiscus I have written this is the K5 C5 a infinite and G5 so K5 means uh the Corolla r five and these called foras are fused similarly the Cora Cora is five but they are not fused and a is oscium and it contains the infinite number of stemons and that's why the number is infinite and then it contains G5 means gyum is five but those are fused to form a uh uh a single petal a single pollen tube so this is all about the flower and

00:45:26 its arrangement what is mean by the floral diagram is that if you write so this is actually the F floral formula that you can write the the arrangement in the on the on a 2d in a in a 1D structure but if you want to write you can actually make a diagram of the arrangement of the stamin and Cora and in that case it is called as the floral diagram so for the study of taxonomy or for the study of different flowers we know use these two uh formula or as well as the diagram to represent the particular plant or

00:46:04 particular flower and uh that actually helps in understanding or getting the complete property of that particular flower or the family so what is the function of a flower or as I said what is the utility of evolving a very very primitive sex organ or sex seual reproduction into a very very specialized sexual Machinery because it has evolved into a flower and what is the function of a flower number one the primary function of a flower is to protect the sex organs number two uh attract the insects

00:47:03 and other animals so flower is doing two jobs one it is protecting the sex organs so they will be there is a more efficiency of produce uh by the sex organs to produce the respective male or the female gamits on the other hand since attracts the uh the insects and the other animals the the travel of these male gamits or the female male gametes from the one flower to another flower is also very high number three it allows the development of fruits so uh now what we are going to discuss we are going to discuss

00:48:00 that different parts of the flowers and so in the coming lecture we are going to discuss about the four major part one is we are going to talk about the KX we are going to talk about the Corolla we are going to start by the stemon or the enrum and we are also going to talk about the gyum or the female sex orgon okay so and in addition we are also going to discuss couple of questions related to this topic thank you for