inheritance and evolution

• domain

  kingdom

  phylum

  class

  order

  family

  genus

  species
• Charles Darwin came up with the idea of evolution
• evolution is the slow continual change in the inherited characteristics of a population over a very long time through a process of natural selection
• evolution can result in the formation of a new species
• all living things on Earth have developed from the first simple live forms 3,000,000,000 years ago
• individuals with phenotypes most suited to the environment are more likely to survive, breed and pass on alleles for the successful phenotypes to the next generation
• evolution explains that all life is descended from a common ancestor
• there is usually variation within the population of a species
• variation comes from mutations that cause a new phenotype
• species gradually evolve by a process of natural selection
• natural selection


  the individuals in a population with inherited features best suited to the environment are the most likely to survive reproduce and pass on the features to the next generation
• overtime a species can change it's appearance and sometimes even become two different species
• bacteria strains can develop resistance to antibiotics due to natural selection
• antibiotic resistance

  • not taking a full course of antibiotics
  • over using antibiotics
  • using antibiotics for the wrong diseases
• MRSA is resistant to most antibiotics
• species poorly adapted to their environment will not survive and will go extinct
• factors that can cause extinction

  • new disease
  • new predators
  • new, more successful competitors
  • changes to the environment over geological time
  • a single catastrophic event
• fossils provide record of organisms that lived a long time ago
• fossils provide evidence that animals and plants change over long periods of time
• a fossil is the preserved remains or trace of a dead organism
• fossils


  dead animals and plants preserved in

  • amber
  • peat bogs
  • tar pits
  • ice
  • casts or impressions (foot prints)
• hard body parts can be covered in layers of leaves and sediment that over time hardens and become rocks and the parts are gradually replaced by minerals
• selective breeding

  1. parents are chosen with the desired characteristics
  2. they are bred together
  3. from the offspring, those with the desired characteristics are bred together
  4. this continues over many generations until all the offspring show the desired characteristics
• humans use selective breeding for

  • disease resistance in food crops
  • animals produce more meat or milk
  • domestic dogs with gentle nature
  • large or unusual flowers
• inbreeding can lead to a reduced gene pool making it more difficult to produce new varieties in the future
• inbreeding causes organisms to be prone to certain diseases or inherited defects
• genetic engineering 


  the technique for changing the genetic information of a cell
• bacteria have additional small pieces of information in their cells
• genetic engineering is a process which involves modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic
• genetic engineering

  1. human cell with insulin gene
  2. gene is cut from DNA using an enzyme/lysozyme
  3. bacteria with plasmid
  4. plasmid is cut using and enzyme/lysozyme
  5. gene is inserted into plasmid
  6. the plasmid is the vector that puts the gene into the bacterium
  7. plasmid multiplies in the bacterium rapidly by binary fission producing insulin
• new species can arise as a result of isolation (two populations become geographically separated)
• plants can be cloned by tissue culture using sterile agar jelly and plant hormones and nutrients
• tissue culture is more expensive and difficult than taking cuttings of plants
• cloning methods in animals

  • embryo transplant
  • fusion cell cloning
• embryo transplant

  1. a developing embryo is removed from a pregnant animal before the cells have started to specialise
  2. the cells are separated and grown in a laboratory for a while
  3. they are transplanted into host mothers
  4. when offspring are born they are identical to reach other
• fusion cell cloning


  the replacing of the nucleus of an unfertilised egg with the nucleus of a different cell from an embryo or adult cell
• food security 


  having enough food to feed a population
• biological factors threatening food security

  • increase birth rate
  • changing diets
  • new pests/pathogens
  • environmental change
  • conflicts/war
  • availability of water/food
• how is energy lost in the food chain

  • during respiration providing energy for movement
  • maintain body temperature
  • waste products
• how can energy loss in food chains be reduces

  • reduce number of steps (plants more efficient than animals)
  • reduced energy used by animals in movement (keep animals in crowded environments)
  • reduce energy lost maintaining temperature (keep animals in heated environments)