Topic 4

• Define biodiversity (4 marks)


  Biodiversity is the number of different species in a habitat (2) and the number of different alleles in a species (2).
• Define species richness (2 marks)

  Species richness is the number of different species (1) in a habitat (1)
• Define diversity index (2 marks)

  Diversity index is the number of different species in a habitat (1) and the number of individuals in a species (1)
• Define endemic (1 mark)

  Endemic - species found in only one specific geographical location (1)
• Define genetic diversity (2 marks)

  Genetic diversity in the number of different alleles (1) in a species (1)
• Define heterozygosity index (2 marks)


  Heterozygosity index is the number of heterozygous individuals (1) over total number of individuals in the population (1)
• Define niche (2 marks)


  Niche is the role of an organism (1) in a habitat (1)
• Give examples of anatomical, behavioural and anatomical adaptations (3 marks)

  ·   Anatomical (physical feature) – camouflage, strong beaks

  ·   Behavioural – living in groups, hibernation, being nocturnal, migration

  ·   Physiological (producing a biological molecule) – slow metabolism (sloths), venom (snake), musk (skunk)
• Explain how natural selection can result in adaptation (4 marks)

  ·   Genetic mutation results in variation in the population (1)

  ·   Selection pressure/ change in environment favours individuals with the advantageous allele (1)

  ·   Individuals with the advantage allele survive, reproduce and pass on the advantageous allele to offspring (1)

  ·   Increasing the allele frequency in the population over time (1)
• Define species (1 mark)

  Individuals interbreed to produce fertile offspring (1)
• Define speciation – formation of new species (2 marks)

  Individuals are no longer able to interbreed to produce fertile offspring (1), they are reproductively isolated (1)
•  Explain how natural selection can result in speciation (5 marks)

  ·   Genetic mutation results in variation in the population (1)

  ·   Selection pressure/ change in environment favours individuals with an advantageous allele (1)

  ·   Individuals with the advantage allele survive, reproduce and pass on the advantageous allele to offspring (1)

  ·   Increasing the allele frequency in the population over time (1)

  ·   This can result in speciation – sympatric (absence of a geographical barrier) or allopatric (in the presence of a geographical barrier) (1)
• Write the two equations of Hardy – Weinberg equation and describe how they can be used to show that natural selection is occurring (3 marks)

  If natural selection is occurring, there would be a change in allele frequency over time (1)

  
• Write the three-domain system proposed by Carl Woese (3 marks)

  Prokarya, eukarya, and archaea (3)
• Write features of bacteria/ prokarya (5 marks)

  ·       No nucleus

  ·       circular, double-stranded DNA

  ·       chromosomal DNA

  ·       plasmid DNA

  ·       70S ribosomes

  ·       pili

  ·       peptidoglycan cell wall

  ·       slime capsule
• Write features of eukaryotes/ eukarya (5 marks)

  ·       Nucleus

  ·       Linear, double-stranded DNA

  ·       Histones

  ·       80S ribosomes

  ·       rough endoplasmc reticulum

  ·       Golgi apparatus

  ·       Membrane bound organelles – nucleus, mitochondria, chloroplasts (plants)

  ·       Cellulose cell wall (plants) or chitin cell wall (fungi)
• Define molecular phylogeny (3 marks)

  · Molecular phylogeny - molecular differences/similarities the sequence of nucleotides in DNA/RNA or the sequence of amino acids in proteins (1)

  · reveal evolutionary/genetic relationship between organisms (1)

  · the more similarities in common, the more related the individuals/ species (1)
• Describe the evaluation of new scientific theories (3 marks)

  • Communicating theory to scientific community (1)
  • Published in peer-reviewed scientific journals (1)
  • Conferences (1)
  • Repeat experiments to confirm/ validate findings (1)
• Describe the role of seed banks (3 marks)

  ·       Conserve genetic diversity​(1)

  ·       Prevents extinction of species  (1)

  ·       Safeguard genes that may prove useful in the future​ (1)

  ·       Allow for reintroduction of species in the future (1)
• Explain the conditions of storing seeds (4 marks)

  ·       Conditions of storage – dry and cold (2)

  ·       To reduce enzyme activity in seeds…preventing germination of seeds​ (1)

  ·       And to prevent microbial growth…preventing decomposition of seeds (1)
• Explain the role of zoos and captive breeding programs (3 marks)

  ·       Increase population size​ (1)

  ·       Conserve / increase genetic diversity​ (1)

  ·       Therefore, prevents extinction of species ​ (1)

  ·       Allow for reintroduction of species in the future (1)
• Define inbreeding depression in a small population (2 marks)

  Inbreeding depression - mating resulting in homozygous recessive individuals (1) with genetic defects (1)
• Describe ways of preventing inbreeding depression (3 marks)

  ·       use of stud books/ records​ (1)

  ·       use of IVF/ surrogates​ (1)

  ·       exchange of animals between zoos (1)