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Plant Reproduction (Pollination (Insect pollination (Flowers are usually…
Plant Reproduction
Pollination
Is the transfer of pollen grains from the anther of one flower to the stigma of the same flower or another flower of the same kind.
Birds, insects or the wind help in the transfer of pollen grains
Insect pollination
Flowers are usually large, brightly colored and scented to attract insects, anthers don’t hang out of the flowers, stigma is sticky in order to catch pollen grains. (E.g. Balsam, Rose, Wild orchid)
When an insect video visits a flower to feed on the nectar, pollen grains from the anther stick to the insect's hairy body. The pollen grains are brushed off onto the stigma of the same flower or another flower that the insect visits.
Wind pollination
Flowers are usually small and dull colored with no scent, anthers hang out of the flowers so that pollen grains are easily shaken free and carried by the wind, stigma is large and feathery in order to catch the pollen grains floating in the air. (E.g. Grass, maize, oak
The filament sways in the slightest wind and pollen grains are shaken free. The pollen grains are carried by the wind and land on the stigma of another flower.
Types of pollination
Self-pollination, which occurs within the same flower or between flowers of the same plant, does not depend on birds, insects and the wind (advantage)
Cross-pollination, which occurs between flowers of separate plants of the same kind, their young okang mah combine the good qualities of both parent plants and may be better able to adapt to its environment, better quality seeds may be produced (advantages)
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Germination
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Requires warmth, oxygen and water
When a seed germinates, the root appears first. This allows more water to be absorbed, as well as to provide some support as the young plant grows, at this stage, the young plants uses the food stored in seed leaves for energy.
The shoot appears after the root. When the first leaves of the shoot appear, the young plant can carry out photosynthesis to make its own food
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Structure of a flower
A flower helps flowering plants to reproduce, so it is important in reproduction.
Most types of plants like hibiscus have both male and female parts on a single flower. Some types of plants like maize have male parts (stamen) and female parts (carpel) on separate flowers while a few like asparagus have the male and female flowers developing on separate plants.
Flower parts
Anther, which produces pollen grains and stores them in pollen sacs while filament holds the anther up (male parts)
Stigma, which receives pollen grains while style connects stigma to the ovary (female parts)
Ovary, which protects the ovule and becomes the fruit after fertilization has taken place while ovule becomes the seed after fertilization has taken place (female parts)
Petal, which attracts pollinators such as birds and insects to the flower while flower stalk holds the flower up so that it can be easily detected by pollinators
Fertilization
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After pollination, each pollen grain produces a pollen tube. The male reproductive cells are found inside the tip of the pollen tube, the pollen tube enters the ovule that contains an egg cell. Fertilization occurs when both the reproductive cells fuse.
After fertilization, most of the flower parts such as the petals, style and stigma usually wither and drop off, except the ovary. The ovules in the ovary start to develop into seeds while the ovary enlarges and gradually becomes the fruit. When the ovary is ready to be released, it is said to have ripened.
Seed Dispersal
To prevent overcrowding, which can lead to competition for nutrients, sunlight, spec and water and so that they can grow in a new and more favourable place
Types of dispersal
Animal: Fleshy, juicy, fragrant, sweet or brightly colored fruit,hard and indigestible seeds, have hooks to catch on the fur of passing animals
Water: Fruit is waterproof, can float on water and has fibrous husk
Wind: Fruit is light, dry, small, have wing-like or parachute-like structures that allow them to be easily carried by the wind
Splitting: Have fruit walks that split open with a sudden force when ripe, shooting the seeds out in different directions