Life cycle of Angiosperm||Life cycle of an Angiosperm in simple steps

The life cycle of Angiosperm. If you want the Life cycle of the flowering plant then you have come to the right place. Here you will find the life cycle of an Angiosperm in simple steps. 

Life Cycle of Angiosperm.

Angiosperm

The life cycle of flowering plant with double fertilization.

The angiosperms the flowering plants in this we'll look at the parts of the flower pollen development, egg development pollination, fertilization, seed development and finally fruit development. We'll start with parts of the flower. When we look at the flower we see down here we have the sepals that were covering the flower when it was just a bud protecting in the growing bud. we have the petals we'll talk about the function of petals. later we have the anther and the filament which together make the stamen. Now, this is the male structure of a flower. It's where pollens are produced in the middle we have this base-like structure and at the top of which is called the stigma. The long thin neck is called the style and the bottom the swollen part is the ovary together these three parts make up the carpel and this is the female part of the flower now what I've drawn here is what's generically called the perfect flower has both male and female parts. Some flowers might only have female structures and other flowers only have male structures. but to simplify have just kind of done a generic flower. Here look at the male side first with pollen development in the stamen if we look inside the anther we see diploid cells. remember when you're looking at a flowering plant you're seeing the sporophyte generation or the diploid generation these cells inside the anther are called microspore mother cells.

 They're not spores they're the mother cell. Two spores specifically the microspores so to become a haploid spore we have to undergo meiosis and inside the anther then we build microspores. Now if we recall our alternation generation life cycles which is the basis of all plants. Life cycles spores will become the gametophyte generation so these spores will grow by mitosis to form pollen grains. Remembering that the pollen grain is the male gametophyte in flowering and seed plants. So if we blow one of these up and look closer here's the male gametophyte or the pollen inside the pollen. There are two distinct cells:

1. The tube cells 

2. Generative cells

1. Tube cell will make a tube to the style 

to the ovary to aid in fertilization we'll look at that shortly.

 2. Generative cells will generate the sperm cells so this is the gametophyte. This is not the male gamete pollen is not tree sperm. It is the gametophyte but it will be transferred from one plant to the other. So here's a look at the whole process of pollen development inside the anther the microscope mother cell. Undergoing meiosis to make the haploid microspores the microspores developing into the pollen grain all that happening in the stamen. Now let's get back to our flower. Now let's look at what's happening on the female side of things. Inside the carpel, if we zoom in if we could look inside the ovary we would see many structures. Sometimes more than one sometimes just one these structures are egg-producing structures. They're called ovules. So inside the ovary, there are ovules now for simplicity's sake I'm just going to draw what happens in one of you'll. So in an ovule inside the ovary again there's a diploid cell. This is the sporophyte generation this is the megaspore mother cell. It's going to give rise to the megaspore so this diploid cell undergoes meiosis forming haploid megaspores. 

Now, most of the time all the megaspores except for one disintegrates only one megaspore survives there's our one megaspore the spore that will become the gametophyte. So it'll divide and it goes through three rounds of mitotic division so three nuclear divisions. So our one nuclei become two and the two become four and the four become eight and then something very interesting. These eight nuclei are divided into themself through cytokinesis. But we have seven cells formed. Eight nuclei but only seven cells how about something like this. This is what it looks like this is the female gametophyte. Now we look in here let's see what we see we have this cell which I've drawn in a different color to make it easy to see but that's the egg one of these haploid nuclei will be the egg we have this special cell. That has two haploid nuclei in it and it's the endosperm mother cell. It will give rise to the sperm. It's an N plus n cell and then these other five cells. These other five haploid cells become nerds which is all my favorite word's they're unimportant cells. They're going to disintegrate. These two included but I want to draw my arrow is all over the place but the sinner did so, we have this structure inside the ovule so here's the whole side of the female reproductive structures of egg development. So the megaspore the mother cell becomes the megaspore. One of them survives and divides to make this structure inside the ovule prepared for the sperm. So we have pollen made in the anther and the eggs are ready inside the ovule. So what do we need next? We need pollination we have to get the pollen from an anther to a stigma. How can that happen well wind a lot of pollen is wind-born and even water can move pollen. But what do we think about when we think about flowers and angiosperms the thing that's unique and different between Aeneas burns and gymnosperms is the use of yeah biotic vectors which is a fancy way of saying pollinators living things that move pollen from one. Now it's time to answer our question what is the evolutionary significance of petals nectar the fragrance of flowers to attract pollinators. Now think about how important pollinators are to angiosperms in fact there's been coevolution of flowers and animals to ensure or aid this process of the plant. Providing some nutritional value to the animals and the animals, in turn, moving the pollen from one flower to another to aid in reproduction. So here comes the pollen lands on the stigma pollination once we have this we're ready for the next step.

Fertilization 

Double fertilization in Angiosperm.

 I'm going to zoom in again to the carpel and here I put the pollen grain on top of it. We can see the tube cell in the generative cell and we're ready for the process of fertilization we have our egg but we don't have our sperm we have pollen so this is what happens. The tube cell is going to create a tube down through the style to the ovary then the generative cell is going to generate two sperm that travel down the tube. When they get here they're going to have a double fertilization event one of the sperm is going to fuse with the egg to make the zygote the second sperm is going to fuse with the mother cell to make a trip would sell that's that we're going to be the beginning of our endosperm our nutritive tissue. Since there are two fusion events we call this double fertilization this is different between the gymnosperms and angiosperms.