v a r i a t i o n

• What is evolution?


  Gradual change in any species over time, resulting in new species and extinction of others.
• what species are more likely to survive?

  species that have lots of variation are more likely to survive as they carry many versions of the same gene.
• what is natural selection?

  It is the thought that those who have adaptations better suited for their environment are more likely to survive and reproduce, carrying on the gene. Natural selection is sometimes too slow for organisms to adapt to new environmental conditions, they will become extinct.
• what is gene therapy?

  genes from normal mucus are inhaled into the lungs of those who suffer from cystic fibrosis, some genes may take that gene and produce normal mucus only for a few days.
• gene therapy cons

  The new cells made will not contain the gene meaning it will only last a few days and the inhalation will have to be used ever few days.
• cystic fibrosis

  inherited disease producing thick mucus in the lungs creating a breeding ground for bacteria and slowing down. the exchange in gasses.

  physio has to happen daily.
• the set up of chromosomes

  coded information inside the chromosomes determines the sequence of amino acids. These show the different types of protein produced, some of these are enzymes which controls processes effecting the functioning of the cell. Characteristics are then inherited.
• factors that increases chances of mutations

  UV rays

  X rays

  toxic chemicals

  ionising radiation
• why aren’t mutations noticed?

  they happen in 1 out of a millions cells, white blood cells destroy them, mutations are only herniated through gametes
• asexual reproduction


  1 parent cell, the nucleus divides then the cytoplast divides into two daughter cells, all genetically identical to the parent and there is no variation between the offspring.
• sexual reproduction

  2 parent cells, gametes of the egg and sperm. The offspring is a mix of DNA from both cells, fertilisation creates a new cell with variation.
• effectors of plant growth

  availability/ how much competition for water

  competition for light

  temperature of air/soil

  slopes, ho much light as a result
• what is variation

  differences between animals of the same species
• what is a mutation


  Change in the DNA molecule
• what is the basis of evolution?

  heritable variation
• what creates variations


  their environment and the genes they have
• continuous variation


  controlled by more that one set of genes, normal distribution on a graph.
• discontinuous variation


  usually controlled by one set of genes, distinct grouping on graphs.
• Gene screening

  Gene screening allows to see what diseases can be caused by the inheritance of changed genes. Prenatal also allows to see the diseases before birth.
• Faults in genes


  Genes can contain ‘faults’ or a damaged code in the DNA. If these faults are inherited it causes incurable diseases because these faults are in every cell throughout their body.