Reproductive choices: Inheritance, variation and evolution: Biology: GCSE (9:1)

• Sexual reproduction


  The production of new living organisms by fusing gametes and by combining the genetic material of two individual parents

  
• Asexual reproduction

  The production of new living organisms that are genetically identical to the parent, does not involve the fusion of gametes

  
• Binary fission

  A method of asexual reproduction that is carried out by single-celled organisms such as bacteria

  
• Advantages of sexual reproduction


  Produces variation, variation provides a survival advantage by natural selection, selective breeding can be used to increase food production
• Advantages of asexual reproduction

  Saves energy and time, only one parent needed, faster than sexual reproduction, many identical offspring can be produced
• Advantageous variation


  Sexual reproduction can produce variation in the offspring which can put some individuals at an advantage

  
• Natural selection


  If an environment changes, variation can allow for natural selection where the fittest individuals are more likely to reproduce

  
• Selective breeding


  Natural selection can be sped up artificially by humans via selective breeding to increase food production

  
• Energy efficient

  Asexual reproduction conserves energy and saves time as only one parent is needed, so an organism does not have to search for a mate

  
• Seasonal choices


  Some organisms change reproductive method depending on environmental and seasonal conditions
• Favourable conditions

  Asexual reproduction typically occurs when environmental conditions are favourable, so many identical offspring can quickly be produced

  
• Susceptible to environmental change

  Asexual organisms lack variation, meaning an entire population could be wiped out by a disease or sudden environmental change
• Identical offspring


  The result of asexual reproduction where the process of mitosis leads to genetically identical individuals or clones

  
• Non-identical offspring


  The result of sexual reproduction where the process of meiosis leads to individuals with genetic variations

  
• Genetic variation


  Differences in the DNA between individuals which can result in different displayed characteristics

  
• Strawberry plants

  Can reproduce asexually by the formation of runners or can reproduce sexually using flowers to produce fruits and seeds

  
• Daffodils

  Can reproduce asexually by bulb division or sexually through flowering and pollination

  
• Malarial parasite

  Reproduces asexually in the human host and sexually in the mosquito

  
• Fungi


  Can reproduce asexually by spores but can also reproduce sexually to give variation