Self Fertilization in Flowers Essay

Self-fertilization in flowers get described as the coming together of female and male gametes that are sex cells that have been produced by the same bulb. This process can be broken down into four steps. First, the pollen that is male gametes are carried by wind or water and reach the female gametes, and later germination occurs that leads to the penetration of the ovary into the ovules, and that is when fertilization occurs. To understand how this kind of propagation happens we have to know about first filial generation and second filial generation.F2 (second filial generation) generation can get described as the outcome that comes about when two F1 (first filial generation) get crossed. The first filial generation comes from P generation (parental generation) that is it's an offspring of the paternal age.

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When two First filial generation flowers get cross-pollinated, they form second filial generation flowers. For example, Mendel cross-pollinated two pea plant flowers, a white and purple flower that resulted in four purple flowers bringing about First filial generation but when he let the four purple flowers self-pollinates, the result of it was three purple flowers and a white flower bringing about the second filial generation.

To understand all these, we have to follow the genotype and phenotype of the flowers. Genotype can get defined as the genetic composition of every living organism concerning many traits, a single feature or a set of attributes transferred from parent to offspring. The phenotype can get described as the physical appearance of any living organism regarding its genotype or surroundings.

In the punnet square, we will show the genotype and phenotype ratio of the purple and white flowers. The pure breeding flowers we will take them as parents, that is the purple bearing flower and the white bearing flower with their genotypes being 'PP and pp' respectively. The capital p represents the dominant color of the bulb while the small p represents the recessive color of the flower.

Let's first draw the first filial generation in punnet squares to understand how the second generation comes about and also to get their ratios.

P P

P Pp Pp

p Pp Pp

Here we see that all of the first filial generation flowers have the color purple that is Pp which is the genotype of all these flowers in this generation. To view the how the second filial generation comes s about we will draw another punnet square. Here we will self-pollinate two flowers from the first filial generation.

P p

P PP Pp

p Pp pp

The conclusion we get from this is that a quarter of the total numbers of flowers are purple while another quarter has white flowers. The remaining half of the total flowers are pink flowers. We can, therefore, conclude that the ratios of the genotype and phenotype are:

Genotype ratio = 1: 2: 1 (PP: Pp: pp)

Phenotype ratio = 1:2:1 (purple: pink: white)

Another possible result of the second filial generation shows when Mendel when he experimented on the height and color of flowers. The conclusion of this experiment showed that tall is dominant to dwarf and the color purple was dominant to the color white. He used a tall purple flower and a white dwarf flower as the parental generation. When these two get crossed, they only produced tall purple flowers but when the tall purple flowers self-pollinated they produced tall white flowers, tall purple flowers, dwarf purple flowers and little white flowers. This inheritance law is known as the independent assortment law that says that 'an alternative form of a gene can mix randomly with another to form a different gene.'

The conclusion that made from all this is that no medium sized plants are arising from the first filial generation and second filial generation. It also shows that although there were no small flowers in the first filial generation, it does not mean it has disappeared but got only hidden because it later comes out in the second filial generation. What another thing will learn from this is that the tallness factor is dominant to the shortness factor and it can only get seen in the absence of the tallness factor. Although Mendel knew nothing about chromosomes and genes, his experiments show that characteristics can get passed from generation to generation and it is only fair to believe that the same happens when it comes to flowers.

Factors are passed from one plant to another through gametes, for example, a plant can receive a significant consideration from the tall plant and a small element from the short. It shows that gametes only have a pair of features and that is why a particular characteristic can only contain a couple of factors. All these experiments have helped explain the origin or what happens when people, plants, and animals reproduce. Although not all characteristics get passed to the immediate offsprings in the first filial generation, those traits have not disappeared, but the dominant factor has somewhat hidden them, and in the second filial generation they come to be seen.

These scientific findings are used all over the world in the explaining of genetics in flowers and how it came about.

Another example that shows the self-pollination in flowers get seen when two parental flowers of the color red and white get crossed. The color red in this experiment is the dominant one while the color white is the recessive one meaning that the color red will be the one that will get seen more than the color white. The letters 'RR' and' or' represent the genotype of these flowers. When the two are cross-pollinated they produce the first filial generation flowers that have the dominant color red. Later the flowers from the first filial generation are, and this is where the color pink get produced. It happens because a quarter of the total flowers are red, another quarter is white, and the remaining half produces pink flowers. We get to see that the genotype ratio and the phenotype ratio in this experiment are the same that is 1:2:1. Although the color pink cannot get explained, it shows that the trait of the color white which is recessive comes back in the second filial generation meaning that it had not disappeared but only get hidden due to the color red being dominant.

References

Kent, m. (2000). Advanced biology. New York: Oxford University Press.

Micheal Roberts, m. r. (2000). Advanced biology. United Kingdom: Nelson 2000.