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Biology_Edexcel_A-snab_Alevel

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  1. the-circulatory-system
    8 主题
  2. diet-and-health
    11 主题
  3. gas-exchange-cell-membranes-and-transport
    8 主题
  4. nucleic-acids
    3 主题
  5. proteins
    10 主题
  6. inheritance
    7 主题
  7. cell-structure-and-organisation
    7 主题
  8. cell-division
    3 主题
  9. reproduction-and-inheritance
    4 主题
  10. differentiation-and-variation
    5 主题
  11. biodiversity
    9 主题
  12. resources-from-plants
    10 主题
  13. ecosystems-and-energy-transfer
    7 主题
  14. photosynthesis
    7 主题
  15. climate-change
    10 主题
  16. evolution
    3 主题
  17. forensics
    3 主题
  18. microorganisms-and-immunity
    11 主题
  19. muscles-and-movement
    3 主题
  20. respiration
    7 主题
  21. homeostasis
    4 主题
  22. exercise
    4 主题
  23. response-to-the-environment
    8 主题
  24. the-brain-behaviour-and-disease
    10 主题
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Comparing Biodiversity Between Habitats

  • Once the abundance of different species in an area has been recorded, the results can be used to calculate the species diversity for that area

    • Species diversity looks at the number of different species in an area but also the abundance across the different species

  • An index of diversity is a measurement that describes the relationship between the number of species present and how each species contributes to the total number of organisms that are present in that community

The index of diversity formula

  • The formula is:

straight D space equals space fraction numerator straight N left parenthesis straight N minus 1 right parenthesis over denominator Σn left parenthesis straight n minus 1 right parenthesis end fraction

  • Where:

    • n = total no. of organisms for a single species in the community

    • N = total no. of organisms in the community

    • Σ = sum of

  •  The larger the number obtained, the higher the level of diversity

Calculating the index of diversity

  • To calculate:

    • Step 1: Calculate N(N-1) to find value A

    • Step 2: Calculate n(n-1) for each species and add all these numbers together to find value B

    • Step 3: Divide value A by value B

Worked Example

Samples of different insect species in a back garden were collected using sweep nets and identification keys. Use the data recorded to calculate the index of diversity.

Index of diversity question table

The total number of organisms(N) in this community would be: 7 + 34 + 6 + 21 + 12 + 37 + 7 + 19 + 59 = 202

The formula is:

straight D space equals space fraction numerator straight N left parenthesis straight N minus 1 right parenthesis over denominator Σn left parenthesis straight n minus 1 right parenthesis end fraction

Answer:

Step one: Calculate N(N-1) to find value A

N(N-1) = 202(202-1)

N(N-1)= 202(201)

N(N-1) = 40602

Step two: Calculate n(n-1) for each species and add all of these numbers together to find value B 

See table below

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