- Remind pupils of the differences in the number of eggs produced by animals where fertilisation is external and those where it is internal. Provide pupils with stimulus material and secondary sources and ask them to identify patterns in the number of eggs, internal and external fertilisation or development, aftercare, growth pattern and chance of offspring surviving to maturity in the species used.
- Discuss the advantages of retaining the young in the body and feeding the young on milk after birth,
eg continuous access to nutrients, protection from predators. Show pupils video clips of other mammals' offspring immediately after birth and ask them about their experience of newly born pets. Establish that newborn humans are more dependent than some other species. Help pupils to agree some broad generalisations from the data considered.
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- state that mammalian young are fertilised internally and develop in the uterus
- explain that an advantage of internal development over external is that there is a greater chance of developing eggs surviving to become independent young
- draw conclusions about mammalian reproduction,
eg some mammals have large numbers of offspring with a relatively small investment in aftercare, others have fewer offspring with a high degree of aftercare
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