3.9 Methods of Sexual Reproduction

1. 3.9 Methods of Sexual Reproduction (Sec 3.3 pg 83)

2. We have talked about the many ways that asexual reproduction happens. Did you know that there are many ways that organisms use sexual reproduction to reproduce?

3. Conjugation • Used by organisms that also use binary fission. • They form a bridge (tunnel) between their membranes and exchange DNA. • Can increase diversity.

4. Hermaphrodites • Used by species that rarely encounter each other. • Cannot fertilize themselves. • Both parents can produce offspring.

5. Flowering plants • Many contain both male and female reproductive organs and are hermaphrodites. • male parts are called stamen, it has an anther which produces pollen (plant sperm) • female parts are called the pistil, it has the sticky stigma that receives the pollen and moves it to the ovary. • Pollen is transferred via insects, winds, birds, or other animals. • If they pollinate a different flower it is called cross-pollination. If they pollinate themselves it is called self-pollination. • Some plants have male flowers and female flowers, or male and female cones.

6. External fertilization • Many aquatic animals use this method. The female fish releases her eggs into the water. The male fish then releases his sperm over the eggs to fertilize them. • The offspring are susceptible to predators.

7. Internal fertilization • If the sperm has to be deposited into the female to encounter the egg it is called internal fertilization. • Most terrestrial (land) animals use this method and some aquatic (water) species like sharks and whales use this method.