2Comparison of Eggs and Sperm Produced by FemalesProduced by MalesSmaller number producedLarger number producedMuch larger than spermMuch smaller than eggsAre not ‘self propelled’Have ‘tails’, so can swimContains food reservesHave very limited food reserves
3Fertilisation FERTILISATION. New vocabulary = gamete = sex cell Sperm = male gameteEgg = Female gameteWhen a sperm and an egg fuse together, the nuclei fuse and their genetic information mix together. This is calledFERTILISATION.
4External Fertilisation Takes place outside the female’s body.This is inefficient and wasteful.Must occur in water environment.
5Internal 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.
6Development in FishG6: State that in fish, eggs are protected by flexible coverings and that embryos obtain food from the enclosed yolk sac.Tough but flexible membrane protects the egg and developing embryo after fertilisationNucleusCytoplasm contains yolk to feed the developing embryo
7Development in FishG7: State that in a fish, such as trout, the young emerge from the eggs able to maintain themselves.Yolk sac remains attached providing nourishment until the young fish is able to feed itself
8Development 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.
10C1: 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
11C2: Explain the relationship between the no C2: Explain the relationship between the no. of eggs/young produced and the amount of protection given during fertilisation and development in fish and mammalsNo. of eggsChances of fertilisationProtection of eggsParental protection of youngChances of successful developmentFishMammalsLarge numberNone (or limited)None (or limited)PoorLowProtected inside mother’s bodyYoung are dependant on parents for food and protectionFewHighHighG9: State that at birth, the young of mammals are dependant on the adult for care and protection
12C3: Describe the structure and function of the placenta Animal Survival BookletPages