Reproductive Strategies

animal and human reproduction

HideShow resource information

Advantages of sexual reproduction:

  • Each induvidual is genetically unique
  • Some will survive a change in the environment


  • 2 parents are needed and the induvidual could be widely dispersed
  • Not all offfspring ideally adapted to their environment

Advantages of asexual reproduction:

  • Only one parent needed
  • Rapid proliferation of offspring
  • allows exploitation of favourable conditions


  • genetically identical same susceptibility to environmental change and disease
1 of 7

Aquatic organisms

  • Water bodies often large and population low
  • Produce large number of gametes,through external fertilisation in which many are wasted therforeonly som will survive
  • Sessile organisms often have motile larvae which settle and develop into adults

Parental care

Variable:Not at all so some die,some defend their territory.It is usually pre-birth.(

2 of 7



  • Vertebrates show evolutionary transit from aquatic to terrestrial
  • external fertilisation
  • Can live on land but return to water to breed
  • Clasping increases chances of fertilisation
3 of 7



  • Sperm transferred while male and female in close proximity
  • reptiles and birds lay shelled eggs - amniotic - embryo nourished by yolk
  • Many eggs are laid so some will survive
  • Development outside parents body
4 of 7

Birds - parental care

bird.jpg image by drawn4u ( care

  • Hatched:lots of careas young develop
  • Less eggs laid more care
  • E.g flamingoslay one egg- lots of care.Displays of courtship are elaborate.Parents produce protein rich milk until young can feed itself.
5 of 7



  • Successful animals
  • Impact humans:Pests of crops,act as vectors of disease;parasites,pollinators f crops
  • Lay eggs
  • Internal fertilisation
  • 2 types of lifecycle:metamorphic and incomplete metamorphisis
6 of 7

Flowering plants


  • Primitive plants need water for fertilisation
  • Angiosperms are flowering plants that ud=se wind or insects to transfergametes for fertilisation
  • evolution of seed with food store enables embryo to develop untill leaves emerge and photosynthesis starts
  • seeds have a testa resistant to adverse conditions
7 of 7


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Human, animal and plant physiology resources »