Reproduction In Plants Flashcards
Where is the male gamete contained within the plant
The male gamete is contained within the pollen grain
Where is the female gamete contained within the plant
The female gamete is embedded deep in the tissue of the ovary
What are the different structures of the plant
They have a pollen grain, a stigma, a style, a pollen tube, an ovary and an ovule and this all comes under the carpel
How does fertilisation in plants take place (part 1)
A pollen grain will Land on the surface of the stigma of the flower during pollination. The pollen grain will begin to germinate if they are of the species. A pollen tube begins to grow out from the tube cell of the pollen grain through the stigma into the style. The tip of the pollen tube produces hydrolytic enzymes to digest the tissue of the style so the pollen tube can make its way down between the cells. As the pollen tube grows down towards the ovary the generative cell containing the generative nucleus travels down it.
How does fertilisation in plants take place (part 2)
The nucleus of this cell divides by mitosis to form two male nuclei. The pollen tube grows through the ovary to reach an ovule. Eventually the tip of the pollen tube passes through the micropyle of the ovule. Once the tube has entered the the micropyle the 2 male nuclei are passed into the ovule so that fertilisation can occur.
What do the male nuclei fuse with and what products are formed
They undergo double fertilisation and one male nucleus fuses with 2 polar nuclei to form the endosperm nucleus which is Triploid. The other male nucleus fuses with the egg cell to form the diploid zygote. At this point fertilisation is complete and the development of the seed and the embryo within can begin
What chemical is responsible for pollen tube growth
Calcium
How are pollen grains formed in the anther
Each anther contains four pollen sacs where the pollen grain develops. In each pollen sac there are large numbers of microspore mother cells which are diploid. They divide by meiosis to form haploid microspores which are the gametophyte generation. The gametes themselves are formed from the microspores by mitosis. They contain 2 haploid nuclei the tube nucleus and the generative nucleus. The tube nucleus produces the pollen tube and the generative nucleus fuses with the nucleus of the ovule to form a new individual
How is the egg cell formed
Diploid megaspore mother cells divide by Meiosis to give rise to 4 haploid megaspores three of which degenerate leaving one to continue to develop. The megaspore undergoes three mitotic divisions that result in an embryo sac containing an egg cell(female gamete), two polar nuclei, two synergids and three antipodal cells
What is pollination
Pollination is the act of transferring pollen grains from the male anther of a flower to the female stigma of the same species
What is cross pollination and why is it useful
Cross pollination is when the stigma from one plant receives pollen from other plants and this is done to maximise variation in the offspring
