Tuesday, April 24, 2018

4.1 Sexual and Asexual Reproduction

Asexual and Sexual Reproduction
■ Reproduction: production of a new generation of individuals(offspring) from pre-existing ones(parents).
■ Importance: ensure the continuity or perpetuation of the species.
■ Types of reproduction

Sexual reproduction

Asexual reproduction
Audio:



Sexual Reproduction
■ The production of offspring by the fusion of specialised sex cells(gametes)
■ The male gamete(sperm) fuses with the female gamete (ovum or egg) by a process known as fertilisation.
■ This results in the formation of a zygote. The zygote develops into a new individual.
■ Living organisms which carry out sexual reproduction: humans, all vertebrates, insects and flowering plants.
Audio:



■ Types of fertilisation:

Internal fertilisation
  • The sperms are deposited in the female reproductive tract and fertilisation occurs within the body of the female. 
  • The zygote develops internally and live individuals are born. 
  • Occurs in insects, reptiles, birds and mammals.

External fertilisation
  • Limited almost entirely to aquatic organisms, sperms and eggs are shed into the water in great numbers simultaneously. 
  • Only a small number of the eggs are fertilised by sperms. 
  • Occurs in most fish amphibians and aquatic plants.
Audio:











No comments:

Post a Comment