variation and natural selection

• What is variation?

  Differences in the characteristics of individuals in a population.
• What is evolution?

  A change in the inherited characteristics of a population over time through natural selection.
• What is speciation?

  When two populations of one species become so different that they can no longer breed and reproduce fertile offspring.
• What is the process of evolution by natural selection? VCSI

  • Genetic variation in population due to mutation.
  • There is competition between individuals due to large number of offspring and limited resources.
  • Those with the advantageous characteristics are better suited to survive and they breed.
  • The offspring will then inherit the beneficial alleles.
• What is the process of speciation?

  • A part of the species population is isolated.
  • Genetic variation arises because of random mutations in the population producing different alleles and phenotypes.
  • Because of the habitat variation and different abiotic factors different characteristics are beneficial for each of the populations.
  • The better adapted individuals survive, reproduce and pass on the advantageous allele fertile offspring.
  • After many generations species have become too different to produce fertile offspring if they breed.
• What is antibiotic resistance?

  When bacteria are not killed by the presence of an antibiotic.
• What is MRSA?

  A species of bacteria that is resistant to some types of antibiotics.
• How are fossils formed?

  • In the correct conditions some parts of organisms do not decay.
  • The decayed parts are replaced by materials as they decay.
  • Traces of organisms like footprints may also be preserved.
• What are factors that may cause extinction?

  • Physical - catastrophic event, drought, climate change.
  • Biological - lack of food, new disease, new predators.
• What is the evolution of antibiotic resistance?

  • Mutations in bacterial pathogens produce new strains.
  • Some strains might be resistant to antibiotics and so are not killed.
  • These surviving strains are able to reproduce.
  • Over time the population of the resistant strains increases.
  • Then the resistant strain is able to spread and so the treatment is ineffective.
• How can the rate of development of antibiotic resistant strains be reduced?

  • Appropriately prescribed antibiotics.
  • Completing the course of antibiotics so all bacteria is killed.
  • Restricted agricultural use of antibiotics.