Transcript
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Asexual Reproduction
• Asexual reproduction is natural “cloning.” Parts of the plant, such as leaves or stems, produce roots and become an independent plant.
• Talk about some benefits and some drawbacks to asexual reproduction.
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Sexual Reproduction
• Sexual reproduction requires fusion of male cells in the pollen grain with female cells in the ovule.
• Talk about some advantages and drawbacks to sexual reproduction.
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Terms to know:• Haploid: having a single set of
chromosomes in each cell.
• Diploid: having two sets of chromosomes in each cell.
• Mitosis: cell division, which produces two genetically identical cells.
• Meiosis: reduction division, which produces four haploid reproductive cells.
Angiosperms (flowering plants)• Plants that protect their seeds within the body
of a fruit.• Make up ¾’s of all plants, including:
– Trees, shrubs, herbs, grasses, water plants…
Male Reproductive Structure
The stamen consists of two parts: Anther and Filament
The anther is where meiosis occurs to produce haploid pollen
The filament is a stalk that supports the anther
Female Reproductive StructureThe pistil consists of
the stigma, style and ovary
The sticky stigma receives the pollen from the anther
The pollen grows a tube down through the style
Meiosis occurs in the ovary to produce haploid ovules
Reproductive Structures
• Petals: colorful
structures that attract pollinators.
• Sepals: surround and protect the flower bud.
Pollination
Wind, insects or other animals transfer pollen from the anther of one flower to the stigma of another
Flowers vary depending on pollination mechanism
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Pollination is the transfer of pollen from the anther to the stigma
• This is an example of cross-pollination as the pollen travels from one flower to a different flower. This is desirable in plants as it promotes variation.
Flower Structure Pollination Fertilisation Seed Dispersal Germination Test
Click to view the animation
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Self-pollination occurs when pollen falls from the anther onto the stigma of the same flower
• Self-pollination is not desirable as it reduces variation
• Click to show animation of self-pollination
Flower Structure Pollination Fertilisation Seed Dispersal Germination Test
Pollination VectorsWind Pollination: Dull, scentless flowers with reduced petalsBees/Butterfly Pollination: Bright
color, nectaries, scent. They sip nectar, get pollen on coats, transfer pollen from flower to flower
Bird Pollination: Nectaries, brightcolors, tube-like flowers
Moth Pollination: White petals, open at night
Fly Pollination:Rank odor, fleshcolored petals
• Pollen Grain • Anther Sac
Pollen grains contain two haploid cells produced through meiosis.1- The Tube cell – will grow the pollen tube. 2- The Generative cell – will go through mitosis to create two sperm cells.
OvaryEach ovule within an ovary has a micropyle (an opening for the pollen tube). The ovules’ megasporangium undergo meiosis to produce four haploid cells (3 die leaving 1 megaspore)The megaspore undergoes mitosis 3 times to produce 8 haploid cells within the embryo sac.
Fertilization
{ After pollen lands on the stigma, a pollen tube grows down through the style to ovary
{ Generative cell creates the two sperm nuclei
{ Double fertilization occurs: { one sperm fertilizes the egg{ one sperm the two polar nuclei together
Result of Double Fertilization
{ The sperm nucleus and egg nucleus join to form a 2n (diploid) embryo
{ The other sperm nucleus and the two polar nuclei join to form a 3n (triploid) endosperm. The endosperm is the food supply for the embryo.
{ First link
Seed and Fruit Development
{ After fertilization, the petals and sepals fall off flower
{ Ovary “ripens” into a fruit
{ The ovule develops into a seed
Seed Dispersal Mechanisms-Allow plants to colonize new areas and avoid
shade of parent plant
Wind Dispersal - Flight mechanisms, like parachutes, wings, etc. Ex. Dandelion, maples, birch
Animal Dispersal - Fleshy fruits which animals eat, drop undigested seeds in feces or burrs which stick to animals’ coats