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Biodiversity

AQA AS-level BiologyTopic 14 of 1433 lessons

Revision notes for Biodiversity in AQA Biology (7401). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.

  1. A SpeciesA species is a basic unit of classification.
  2. Binomial System of NamingTo ensure all scientists are referring to the same organism, a universal and binomial system of naming is used.
  3. Courtship BehaviourIndividuals can recognise members of their own species by behaviour.
  4. ClassificationThe grouping of organisms is known as classification.
  5. TaxonomyTaxonomy is the process of organising groups of species into a hierarchical classification system.
  6. DomainA domain is the highest taxonomic rank.
  7. KingdomsThe domain Eukarya is divided into four kingdoms: Protoctists, Fungi, Plantae and Animalia.
  8. PhylogenyThe hierarchical classification system is based on supposed evolutionary lines of descent.
  9. Index of DiversityBiodiversity is the term used to describe the variety of living organisms and the variety of ecosystems in a particular area.
  10. Example Index of DiversitySpecies Numbers(n) found in habitat n(n-1) A 12 12(11)=132 B 5 5(4)=20 C 2 2(1)=2 D 7 7(6)=42 E 4 4(3)=12 Σn(n-1) 208 total N = 12 + 5 + 2 + 7 + 4 =…
  11. Species Diversity and EcosystemsAn ecosystem is a community of living organisms (biotic) interacting with each other and their non-living environment (abiotic).
  12. The Impact of AgricultureUsually ecosystems increase in the number of different species as they develop and increase the index of diversity.
  13. Balancing Conservation and FarmingAs the human population increases, there is a need to produce more food by more intensive farming.
  14. Managing EcosystemsThe management of ecosystems includes: maintaining existing hedgerows at the most beneficial height and shape planting hedges rather than erecting…
  15. Investigating DiversityThe theory of evolution is a model used by some scientists.
  16. Comparing DNADNA sequencing can now be done by machines so base sequences can be compared to establish relationships between species.
  17. Comparing mRNAMolecular phylogenetics is the branch of phylogeny that analyses genetic, hereditary molecular differences in DNA, mRNA or amino-acid sequences to…
  18. Comparing Amino-acids SequencesThe similarity of amino-acid sequences in some proteins will reflect how closely two species are related.
  19. SamplingIt is usually impossible to count or measure every individual in a population, so biologists take a sample.
  20. Random SamplingIn random sampling every individual or position in the area has an equal chance of being chosen.
  21. Normal DistributionMany characteristics that show continuous variation, such as height or leaf length, are affected by many genes and by the environment.
  22. Mean, median and ModeThe mean, median and mode are all measures of the average, or central tendency, of a set of data.
  23. Mean and Standard DeviationThe standard deviation measures the spread of data around the mean.
  24. Interpreting Graphs 1Graphs show the relationship between two variables.
  25. Interpreting Graphs 2The rate of a process is the change in the dependent variable per unit time.
  26. Interpreting Graphs 3Many biological graphs are curves, for example the volume of product formed by an enzyme over time.
  27. Interpreting Graphs 4The type of graph depends on the type of data.
  28. Interpreting Graphs 5A scatter graph is used to find out whether there is a relationship between two variables, for example body mass and heart rate in different mammals.
  29. Interpreting Graphs 6Mean values on a bar chart or line graph are often shown with error bars.
  30. Interpreting Graphs 7To read a value from a graph, draw a line from the known value on one axis to the line or curve, then across or down to the other axis.
  31. Interpreting Graphs 8Exam questions often ask for a percentage change using values read from a graph or table. percentage change = (new value − original value) ÷…
  32. Interpreting Graphs 9Some biological quantities cover a very wide range of values, for example the number of bacteria in a culture, which can increase from 10 to 10 000…
  33. Interpreting Graphs 10Exam questions about graphs use different command words, and each needs a different type of answer.

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