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Animal Survival

Learn about the process of fertilisation and development in animals, both externally and internally. Understand the importance of internal fertilisation and the role of the placenta. Explore the different strategies for survival and reproduction in fish and mammals.

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Animal Survival

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  1. Animal Survival Reproduction

  2. Comparison of Eggs and Sperm

  3. Fertilisation • New vocabulary = gamete = sex cell • Sperm = male gamete • Egg = Female gamete • When a sperm and an egg fuse together, the nuclei fuse and their genetic information mix together. This is called FERTILISATION.

  4. External Fertilisation • Takes place outside the female’s body. • This is inefficient and wasteful. • Must occur in water environment.

  5. Internal Fertilisation • Takes place inside the female’s body. • Female keeps the egg in her body, male deposits sperm directly into females body (in mammals, penis deposits sperm into female vagina) • More efficient and less wasteful (fewer gametes are lost and less gametes are produced) • Some animals then lay eggs for development outside body. In others, the egg (new life) develops insode the female.

  6. Tough but flexible membrane protects the egg and developing embryo after fertilisation Nucleus Cytoplasm contains yolk to feed the developing embryo Development in Fish • G6: State that in fish, eggs are protected by flexible coverings and that embryos obtain food from the enclosed yolk sac.

  7. Yolk sac remains attached providing nourishment until the young fish is able to feed itself Development in Fish • G7: State that in a fish, such as trout, the young emerge from the eggs able to maintain themselves.

  8. Development in Mammals • G8: Describe how the fertilised egg passes down the oviduct and becomes attached to the wall of the uterus, develops in fluid of the amniotic sac and obtains food from the maternal circulation.

  9. Development in Mammals

  10. C1: Explain the importance of internal fertilisation to land-living animals • Internal fertilisation allows animals to live on land. • Eggs are kept within the female body and sperm are deposited directly into the female

  11. C2: Explain the relationship between the no. of eggs/young produced and the amount of protection given during fertilisation and development in fish and mammals None (or limited) None (or limited) Large number Poor Low Young are dependant on parents for food and protection Protected inside mother’s body Few High High G9: State that at birth, the young of mammals are dependant on the adult for care and protection

  12. C3: Describe the structure and function of the placenta • Animal Survival Booklet • Pages 35 - 42

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