12. Biodiversity

• what is a habitat?

  Where an organism lives
• What is a population?

  All the organisms of one species in a habitat
• What is community?

  All the organisms of all species in a habitat
• What is species diversity?

  Number of different species and number of individuals in each species
• What is species richness?

  Number of species
• Index of diversity

  D = N(N-1) / sum of n(n-1)

  N = total num of organisms of all species

  n= total number of organism of one soecies
• What does a high value of diversity index indicate?

  High diversity. A stable site
• What does a low value of diversity index indicate?

  Low diversity
• How can We collect a random sample

  Grid the area and generate random coordinates, place, a quadrat on the coordinate use, at least 20 quadrats
• How does agriculture provide ideal conditions for crop photosynthesis?

  Fertilises add to provide minerals and fields are irrigated
• Why does removal of hedgerows from fields cause a decrease in diversity

  Low variety of habitats and use of pesticides
• What are some conservation techniques for farming

  Hedges rather than fences

  dont drain the fields

  organic fertilisers
• What is genetic diversity

  number of different alleles of genes in a population
• What are the causes of genetic diversity?

  Mutations, meiosis and random fusion of gametes
• What is meiosis

  Formation of gametes.
• What are the two steps of meiosis

  M1 - homologous pairs separate

  M2 - centromere breaks and chromatids separate
• What does meiosis form

  4 daughter cells that are genetically different
• How does meiosis lead to variation

  Independent segregation - any one from a pair of homologous chromosomes can enter a gamete with any other

  crossing over - chromatids cross over at the chiasmata and exchange alleles, leads to new combinations