9 a inheritance and selection (whs)

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  • 1. 31/03/2014 Inheritance and Selection W Richards Worthing High School
  • 2. 31/03/2014 Variation Variation is a name given to differences in a species, e.g. dogs: Variation is due to each animal having different GENETIC INFORMATION in their cells.
  • 3. 31/03/2014 Where is this information stored? Section of a chromosome: Genes for eye colour Genes for hair colour Genes for blood group: Different species have different numbers of chromosomes. Humans have 46 (23 pairs) in every cell. Genetic information is stored by genes which are arranged on chromosomes:
  • 4. 31/03/2014 Environmental differences Clearly, not all differences are due to just our genes… Variation due to inheritance only Variation due to environment only Variation due to a bit of both
  • 5. 31/03/2014 Sexual reproduction Sexual reproduction involves two organisms of the same species. Each organism produces a GAMETE. For example, in animals the gametes are the egg and the sperm: When the sperm penetrates the egg the egg is fertilised and cells start to reproduce to form a new individual:
  • 6. 31/03/2014 Sexual reproduction In plants, the gametes are the egg and pollen: Any type of sexual reproduction helps a species to become more varied because the offspring inherit characteristics from both parents. Fertilisation
  • 7. 31/03/2014 Selective breeding I raise cows. Each type of cow is good at a certain job. The Friesian cow produces large quantities of milk, the Jersey cow produces very nice milk and the Hereford cow produces lot of beef. If, for example, I want lots of milk I would only breed Friesian cows with each other – this is SELECTIVE BREEDING. Friesian Jersey Hereford
  • 8. 31/03/2014 Asexual reproduction Plants can reproduce ASEXUALLY. The offspring are genetically ________ to the parent plant and are called _________. Two examples: 1) This spider plant has grown a rooting side branch (“stolon”) which will eventually become __________. 2) A gardener has taken cuttings of this plant (which probably has good characteristics) and is growing them in a ____ atmosphere until the ____ develop. Words – clones, damp, independent, roots, identical
  • 9. 31/03/2014 Cloning 1) Cloning plants: 2) Cloning sheep: