Investigating Diversity (Required Practical)

• How could genetic diversity be investigated within and between species?

  • Measurable or observable characteristics
  • DNA base sequences
  • mRNA base sequence
  • Amino acid sequence
  • Gene technologies
• The frequency of measurable and visible characteristics can be compared between individuals
• What is an example of comparing measurable and visible characteristics?

  The differences in height within an age group or the differences in the brain size between humans and monkeys
• Comparing visible characteristics has generally been replaced by genetic techniques
• The sequences of bases in the DNA can be compared between individuals, where the greater the differences in base sequences between two individuals, the more distantly related the individuals.
• The greater the difference in base sequences of DNA?

  The more distantly related the individuals
• What is an example of comparing DNA base sequences?

  An individual will have a DNA base sequence that is more similar to their fathers than a random member of the population
• The sequences of bases in mRNA can be compared between individuals, where the greater the differences in the base sequences between two individuals, the more distantly related the individuals
• The greater the difference in the mRNA base sequence?

  The more distantly related the individuals
• The sequence of amino acids in proteins can be compared between individuals to determine whether they are related
• The greater the difference in the amino acid sequence of individuals?

  The more distantly related the individuals
• Gene technologies are used to investigate genetic diversity by studying the genome, gene technologies are a recent development that have dramatically changed the way genetic diversity can be studied.
• Before gene technologies were invented, genetic diversity could be measured by comparing visible characteristics between organisms.
• How was diversity investigated before gene technologies?

  Comparing visible characteristics between organimsms
• The frequency of characteristics in a population was used as an indirect measure of diversity
• What is an example of visible characteristics being used to compare genetic diversity?

  The number of different coat colours of horses and the number of individual horses with each coat colour
• Gene technologies allow the alleles (and thus genetic diversity) in an individual to be directly measured
• How do gene technologies investigate genetic diversity?

  Allow the alleles in an individual to be directly measured
• Alleles are the different versions of a gene, and what gives rise to genetic diversity in a population
• What are alleles?


  Different versions of a gene
• What gives rise to genetic diversity in a population?

  Alleles
• An example of using gene technologies would be: the number of different alleles for a single gene and the number of individuals with each allele, which directly shows genetic diversity
• How can variation in a habitat be measured?

  In a quantitative investigation
• The variation within a habitat can be measured in a quantitative investigation
• To ensure the results from a quantitative investigation are accurate, the following practices should be used:

  • Random sampling
  • Large sample sizes
  • A mean
  • Standard deviation curves
• What is sampling?


  Taking measurements from a limited number of individual organisms from a larger population
• To ensure that a sample is a reliable representation of the population, the sample needs to be large and unbiased
• Random sampling investigates the variation in a population without spending a large amounts of time counting every individual within the population
• Why is random sampling used?

  It ensures the sample accurately represents the total variation of the species and that bias is reduced
• How can random sampling be used to reduce bias?

  Assigning individual numbers (such as coordinates) to an area and randomly selecting them using a random number generator
• Randomly selecting areas on a field for example is used to determine the random placement of quadrats in the sample area.
• Large samples ensure that the sample is representative and reduce the probability that any patterns are due to chance
• Why should large samples be used?

  Ensure that the sample is representative and reduce the probability that any patterns are due to chance
• How can the effect of chance be used when investigating diversity?

  Large sample sizes, this usually means placing many quadrats or repeating transacts, depending on the method being used
• How are large sample sizes used?

  Placing many quadrats or repeating transacts, depending on the method
• What are transects used for?

  Studying how abiotic factors affect biodiversity
• What is an example of a transect investigation?


  Taking samples from around and far away from a tree
• How to carry out a sample?

  • Collect a random sample of … from the population(s)
  • Use grid coordinates and a random number generator to select sample areas without bias
  • Ensure to collect a large sample from the population to be representative (placing lots of quadrats)
  • Calculate a mean and a standard deviation to interpret the results
• The mean provides an average for all the values collected in a sampling study
• Why is the mean used in sampling studies?

  Can show if there is variation between samples