plant reproduction asexual reproduction asexual reproduction is natural “cloning.” parts of the...
TRANSCRIPT
Plant Reproduction
Asexual Reproduction
• Asexual reproduction is natural “cloning.” Parts of the plant, such as leaves or stems, produce roots and become an independent plant.
Sexual Reproduction
• Sexual reproduction requires fusion of male cells in the pollen grain with female cells in the ovule.
Plant Life Cycle
Alternation of Generations
• Plants have a double life cycle with two distinct forms:
• Sporophyte: diploid, produce haploid spores by meiosis.
• Gametophyte: haploid, produce gametes by mitosis.
Non-flowering plants
• Mosses, ferns, and related plants have motile, swimming sperm.
• What kind of environmental conditions would be required for reproduction in these plants?
Moss Life Cycle
Fern Life Cycle
• Moss life cycle:
• http://www.youtube.com/watch?v=o1z0Vfo62Lg
• Fern life cycle:
• http://www.youtube.com/watch?v=Fhk-Y0duNjg
Conifers
• Conifers (also non-flowering plants) have reduced gametophytes.
• Male gametophyte is contained in a dry pollen grain.
• Female gametophyte is a few cells inside of the structures that become the seed.
Conifer life cycle
Conifer pollination
• Conifers are wind-pollinated plants.
• Chance allows some pollen to land on the scales of female cones.
• Pollen germinates, grows a pollen tube into the egg to allow sperm to fertilize the egg.
• Life Cycle: http://www.youtube.com/watch?v=WPfRV8NWkk4
Plant Reproduction Song
• http://www.youtube.com/watch?v=35vPjdTNRU0
Flowers
Flower Parts
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 Structure
The 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
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
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
Angiosperm Life Cycle
Gametogenesis: Male
Gametogenesis: Female
Double Fertilization
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
Flower to Fruit
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
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
Gravity Dispersal - Heavy nuts fall to ground and roll
ex. acorns
Water Dispersal - Plantsnear water create floating
fruitsex. coconuts