1. Animal Survival
Reproduction

2. Comparison of Eggs and Sperm
Produced by Females
Produced by Males
Smaller number produced
Larger number produced
Much larger than sperm
Much smaller than eggs
Are not ‘self propelled’
Have ‘tails’, so can swim
Contains food reserves
Have very limited food reserves

3. Fertilisation 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. Development in Fish
G6: 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 fertilisation
Nucleus
Cytoplasm contains yolk to feed the developing embryo

7. Development in Fish
G7: 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

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
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
No. of eggs
Chances of fertilisation
Protection of eggs
Parental protection of young
Chances of successful development
Fish
Mammals
Large number
None (or limited)
None (or limited)
Poor
Low
Protected inside mother’s body
Young are dependant on parents for food and protection
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
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