Sexual Reproduction in Plants and Animals

Interpret diagrams of formation of egg and sperm. Explain fertilization in animals and plants. Compare advantages / disadvantages of asexual and sexual reproduction KEY WORDS StamenPollenOvary Sperm PistilTestes GonadsEmbryo

Gametes produced in reproductive organs called gonads. Male gonad called testes. SPERMATOGENESIS

Only 1 egg cell receives enough cytoplasm to survive. Female gonads called ovaries. OOGENESIS

Meiosis is necessary for gametes to be produced. Once fertilization has occurred, mitosis is used to reproduce the single cell until an embryo is produced and eventually birth occurs. The zygote must receive food, moisture, warmth and protection.

The embryo develops and matures through mitosis.

Plants: Male gamete – pollen (from stamen) Female gamete – egg (from pistil) Pollen transferred to pistil. Fertilizes many eggs producing zygotes. Develop into seeds. Ovary develops into fruit.

Asexual ReproductionSexual Reproduction One parentTwo parents Meiosis - gametes One offspring Combination of both parents genes. High variation due to gamete production and fertilization. Mitosis - daughter cells Two offspring Genetically identical to parent. No variation unless due to mutations.

Asexual Reproduction: AdvantagesDisadvantages Less chance for evolution Can lead to overcrowding and competition for survival. Genetically identical organisms are more vulnerable to disappearing because of a catastrophe or disease. No need to find a partner Less energy is required to reproduce. Offspring are well adapted to the environment because of the success of the parent. Fast – can take over an area quickly by reproducing.

AdvantagesDisadvantages Sexual Reproduction: Slow – finding a partner and producing gametes takes time. Lots of energy used to make gametes and attract a mate. The genetic results of meiosis and often fertilization, are unpredictable Genetic "errors" happen more frequently because meiosis is more complex than mitosis. Increases genetic variation in a species - more evolution Only the “strongest ” will be able to reproduce allowing the best qualities to be passed on to new generations. Variations guarantee that a higher proportion will survive in cases of catastrophe or disease. Two parents to watch over offspring

In sexual reproduction: “Only the strong survive” Most species have developed ways to ensure that the “best” genetics are passed on to future generations. Things that enhance reproductive success are called – adaptations.

Examples of adaptations that enhance reproductive success: Behavioural caring for their young mating calls / dances fighting Those best able to modify their behaviour or appearance are most likely to survive and reproduce. Physical bright colours / size pheromones multiple offspring

1.List some adaptations that humans have deveoloped to show they are “strong” and to attract a mate for reproduction. - build their muscles 2.List 10 slang terms for male genitalia. - “daddy buttons”