sexual reproduction in plants and animals. interpret diagrams of formation of egg and sperm. explain...
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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 Stamen Pollen Ovary
Sperm Pistil Testes
Gonads Embryo
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 Reproduction Sexual Reproduction
One parent Two 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:Advantages Disadvantages
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.
Advantages DisadvantagesSexual 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”
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