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reproduction in plants - Coggle Diagram
reproduction in plants
name and function
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stamen
-anther+filament
-male organ
-2 lobs each containing 2 pollen sacs
-pollen sacs contain pollen grains
-when matured, anther splits open and pollen grains are released
-anther contains vascular bundle to provide necessary nutrients for gamete development
-filament is the stalk that holds anther in place
petal
-brightly coloured scented with nectar to attract insects for pollination
-nectar guides to attract insects deep into the petal
-provide platform for insects to land
-protect stamen and carpel
carpel
-ovary+style+stigma
-ovary develops into fruit after fertilisation
-produces and protects one or more ovules
-ovule develops into seed after fertilisation. produces female haploid gamete(ovum)
-style is the stalk that connects the stigma to the ovary
-it holds the stugma in the suitable position to trap pollen grains
-stigma is the swollen end of the style
-it secretes a sugary fluid ti stimulate germination
pollination
self pollination
-transfer of pollen grains from anther to the stigma of the same or another flower of the SAME plant
advantages:
-only one parent needed
-beneficial genes most likely to be passed down
-higher probability of pollination occurring due to close proximity of anther and stigma
-less pollen and energy wasted
disadvantages:
-less genetic variation, less well adapted to environmental changes
-probability of harmful recessive alleles being expressed is higher
cross pollination
transfer of pollen grains from the anther of one plant to the stigma of ANOTHER plant of the same spieces
advantages:
-inherit beneficial qualities from both parents
-greater genetic variation
-likelihood of harmful recessive alleles being expressed is lower
disadvantages:
-two parents required
-dependant on external factors--insects/wind
-lower probability of pollination
-more energy and pollen wasted
insect pollination
-when insects visit flower, they land on petal and follow the nectar guide into the flower
-they force their way in between the two wing petals to collect nectar
-the insects back forces the keel petals upwards, exposing the stigma and anthers
-stigma and anthers brushes against the hairy back of the insect
-pollen grains from the anther stick to the insects back
-pollen grains on the insects back from the previous plant are transferred to the stigma
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fertilisation
-after pollination, pollen grains settle on mature stigma
-stigma secrets sugary fluid which germinates the pollen grain
-a pollen tube grows out from each pollen grain and male gametes enter the pollen tube
-pollen tube grown down the style into the ovary
-as pollen tube grows, it secrets an enzyme to digest the surrounding tissue of the stigma and style
-the pollen tube enters tge ovule through the micropyle
-within the ovule,the tip of the pollen tube absorbs sap and bursts, releasing 2 male gametes
-the nucleus of one male gamete fuses with the nucleus of the ovum