reproduction

• what is sexual reproduction 


  where genetic information from two organisms(mother+father) is combined to produce offspring which are genetically different to either parent
• what do the mother and father produce in sexual reproduction

  -gametes by meiosis

  -gametes fuse/fertilise to make zygotes which divide to make an embryo which half the number of chromosomes from each parent
• in humans, each gamete contains 23 pairs chromosomes- half the number than in a normal cell so when egg and sperm fuse together they give full 46 chromosomes 23 from each parent
• what is asexual reproduction 


  when there is only 1 parent so the offspring is genetically identical to the parent (clone)
• what is the process that asexual reproduction happens by


  mitosis
• adv of asexual reproduction

  -well adapted to environment

  -produces large number of identical offspring

  -requires less energy
• adv of sexual reproduction

  -genetic material comes from both parents, producing variation

  -if environment changes, some offspring are more likely to survive than others did to differences

  -gives survival advantage through natural selection
• what are some environmental changes that may effect survival of species

  -infectious disease

  -competitor

  -climate change