Natural Selection and Genetic Modification

• What is evolution?

  A gradual change in inherited traits
• What causes evolution to occur?

  It occurs due to natural selection
• What are the steps of the theory of natural selection?

  1. Genetic variation exists due to mutations
  2. Selection pressures exist (e.g. competition)
  3. Random mutation gives a selective advantage
  4. Organism is better adapted and survives
  5. Organism reproduces, passing on beneficial alleles
  6. Frequency of advantageous alleles increases
• Why does competition exist between organisms in a habitat?

  Resources required for survival are limited
• How does antibiotic resistance illustrate evolution?

  1. Genetic variation exists due to mutations
  2. Antibiotics act as a selection pressure
  3. Mutations give bacteria antibiotic-resistance
  4. Resistant bacteria survive when antibiotics are used
  5. Bacteria reproduce, passing on resistance
  6. Frequency of resistant alleles increases
• Why is studying antibiotic resistance beneficial for understanding evolution?

  Bacteria reproduce rapidly, allowing observation
• How do fossils provide evidence for evolution?

  • Older fossils contain simpler organisms
  • Newer fossils contain more complex organisms
  • Fossils can be organized chronologically
• What did Darwin study to develop his theory of evolution?

  A variety of organisms on the HMS Beagle
• What is the title of Darwin's published work on natural selection?

  'On the Origin of Species'
• How did Wallace contribute to the theory of evolution?

  He proposed a similar theory with different mechanisms
• What evidence did Wallace gather to support natural selection?

  Studying warning coloration in butterflies
• What concept did Darwin propose related to natural selection?

  The idea of 'survival of the fittest'
• How has the theory of evolution by natural selection impacted modern biology and society?

  • Enables classification of organisms into taxa
  • Influences modern medicine (antibiotic treatments)
  • Highlights importance of genetic diversity for conservation
• What fossils have provided evidence for human evolution?


  • 'Ardi' - 4.4 million years old
  • 'Lucy' - 3.2 million years old
  • Leakey's 1.6 million year old fossils
• What clues does 'Ardi' provide about human evolution?

  • Shows traits of both humans and apes
  • Ape-like: long arms, large big toes
  • Human-like: structure suggests upright walking
• What clues does 'Lucy' provide about human evolution?

  • More human-like traits than 'Ardi'
  • Leg and foot structure adapted for walking
  • Brain size closer to that of an ape
• How does the development of stone tools provide evidence for evolution?

  • Correlation between complex tools and brain size
  • Primitive tools are older than complex tools
  • Brain size increased alongside tool advancements
• How did Leakey's findings contribute to evidence for human evolution?

  He discovered many hominid fossils
• What did the fossil 'Turkana Boy' show?

  Traits comparable to modern-day humans
• What methods do scientists use to date tools?

  • Carbon-14 dating for carbon-containing materials
  • Stratigraphy using sediment layer ages
• What is a pentadactyl limb?

  A limb with five digits in animals
• How does the pentadactyl limb provide evidence for evolution?

  It suggests descent from a common ancestor
• What is classification?

  Organisation of organisms into groups
• What is taxonomy?

  Classification of organisms into taxa
• Name the five kingdoms.

  Animals, plants, fungi, protists, prokaryotes
• What happens to the number of organisms in each taxon as you move down the hierarchy?

  The number of organisms decreases
• What is the problem with grouping organisms based on anatomy and behavior?

  • Unrelated organisms may appear similar (e.g., sharks and dolphins)
  • Related species may look different in various habitats (e.g., queen ants, worker ants)
• What advancements have led to reconsideration of the five kingdoms classification system?

  • Microscopes
  • Biochemistry
  • DNA and RNA analysis
• Describe the three domains system of classification.

  • Divided into three groups: Archaea, Bacteria, Eukarya
  • Hierarchical structure: domain, kingdom, phylum, class, order, family, genus, species
• Which domain do eukaryotic organisms belong to?

  Eukarya
• Which domains do prokaryotic organisms belong to?

  Archaea and Bacteria
• Describe the domain Bacteria.

  • Consists of true bacteria
  • Example: E. coli
• Describe the domain Archaea.

  • Consists of primitive microorganisms
  • Contains extremophiles adapted to extreme conditions (e.g., hot springs)
• What is selective breeding?

  The process of breeding organisms with desirable traits
• What is the main advantage of selective breeding?

  Creates organisms with desirable features
• What are the main steps involved in selective breeding?

  1. Identify a desired characteristic
  2. Select parent organisms with desired traits
  3. Breed selected offspring with desired traits
  4. Repeat until all offspring have desired traits
• Where else is selective breeding useful besides agriculture?

  In medical research and sports
• What are the disadvantages of selective breeding?

  • Reduction in the gene pool
  • Inbreeding can cause genetic disorders
  • Development of physical problems
  • Selection of harmful recessive alleles
• How can plants be cloned?

  • Taking plant cuttings
  • Tissue culture
• What is tissue culture?

  A method of growing living tissue in a medium