Sexual Reproduction in Flowering Plants

1. Plant Reproduction Sexual Reproduction in flowering plants (3 min) http://www.youtube.com/watch?v=1OFF2qYvLag&safe=active Crash Course: Sexual Reproduction in Plants (10 min) http://www.youtube.com/watch?v=ExaQ8shhkw8&safe=active

2. Sexual Reproduction • Flowering Plants (Angiosperms) • Most successful and abundant modern day plants • Reproductive structures found in flowers • Seeds are enclosed with a “fruit” while developing

3. Flower Structure • Stamens: • Male portion of flower • Filament stalk with anther tip produces pollen grains • Often more than one • Thick walled pollen grains contain 2 monoploid gametes

4. Pistil: (carpel) • Female portion of flower • Usually located in the center of the flower • Stigma: at top of pistil, has sticky surface to receive pollen grains • Style: fleshy tube supporting stigma, connecting it to ovary • Ovary: contains ovules (monoploid gametes) that develop into seeds • The ovary itself will develop into the “fruit”

5. Rings of modified leaves surround the reproductive organs of the flower • Sepals: • form a ring around the base of the flower • Enclose and protect the flower bud before it blooms • Petals: • often brightly colored to attract pollinators

6. Pollination • Transfer of pollen from anther to stigma • Self Pollination: flower pollinates itself • Cross Pollination: pollen is taken from one plant to another (get more genetic variation) • Agents of Pollination: • Wind, birds, bats, bees, butterflies, wasps, flies, ants • Plant often adapted to attract a specific pollinator with showy petals, aromas and nectar The Biggest Flower in the World: (3 min) http://www.youtube.com/watch?v=FHaWu2rcP94&safe=active

7. Fertilization • Pollen grains land on stigma and grow pollen tubes that grows down through the style to the ovary and enter the ovule • Double Fertilization Occurs: • One sperm fertilizes egg to make diploid zygote • One sperm fertilizes 2 polar bodies forming triploid endosperm (3n) • This becomes the tissue that stores food for the embryo

8. 1 minute: http://videos.howstuffworks.com/discovery/30701-assignment-discovery-seed-dispersal-video.htm Fruits and Seeds • Each ovule develops into a seed • Ovary walls thicken around the seed and develop into the fruit

9. Seed Structure • Seed Coat: • tough protective coating • Has a scar where it was attached to the ovary • Cotyledon: • stores food for early growth of embryo when seed germinates • Epicotyl: • develops into stems and leaves • Hypocotyl: • develops into roots

10. Seed Dispersal • Dispersal: • Plants have many adaptations to help them scatter their seeds • Fruit dries and bursts open (snapdragon) • Carried by wind (dandelion) • Carried by water (coconut) • Burrs, hooks • Fruits eaten by birds or other animals and pooped out • Seed Dispersal:http://www.youtube.com/watch?v=rhp5k5ptSx0&safe=active

11. Seed Germination • Germination: “seed hatching” • Seeds need water, oxygen, proper temperature Germination: (1 min) http://science.howstuffworks.com/life/30704-assignment-discovery-germination-of-a-seed-video.htm