B15 - Variation

• Variation: all the differences in the characteristics of induviduals
• Selective breeding:

  1. Choose parents with desireable characteristics
  2. Breed the parents together
  3. Choose the offspring with desired characteristics
  4. Repeat the proccess over many generations until all offspring have desired characteristics
• Advantags of Selective Breeding:

  • Disease resistance in plants
  • Animals produce more meat or milk
  • Large or unusual flowers
  • Increased yield in crops
  • Less hostile animals
• Disadvantages of Selective Breeding:

  • Reduced variation meaning all of a species could be vulnerable to a a disease
  • Can be prone to inherited diesases or defects (inbreeding)
• Process of Genetic Engineering:

  1. Obtain a gene for transferring from a cell
  2. Use an enzyme to isolate the gene
  3. Take a cell with a vector (usually a plasmid or virus cell)
  4. Insert the gene into the vector
  5. The vector is inserted into the organism in an early stage to make sure the organism develops with the characteristic
• Advantages of Genetic Engineering:

  • Potential to overcome inherited disease
  • Faster and more effective than selective breeding
  • Crops tend to have a higher yield
  • Plants can be resistant to herbicides
• Disadvantages of Genetic Engineering:

  • GM plants and animals can spread to other wildlife
  • Health risks on eating GM plants
  • Populations of wild flowers and insects affected