B6: Life on Earth

B6: Life on Earth

1. Selective Breeding

   • Mating the Best Organisms for Good Offspring
     • The parent organism with the best characteristics are selected and they're bread with each other. The best of the offspring are selected and bred and this process is repeated over several generations to develop the desired traits.
   • Causes a Reduction in the Gene pool
     • The farmer keeps breeding from the best animals/plants which are closely related which is called inbreeding. It can cause health problems because there's more chance of the organism developing harmful genetic disorders when the gene pool is limited. Can be serious problems if a new disease appears, because there's not much variation in the population.

2. Classification

   • Organising Living Organisms into Groups
     • They used to be classified according to similarities and differences in their characteristics or things you can see in a microscope. These characteristics were used to classify organisms into five groups called kingdoms. They are divided into smaller groups - phylum, class, order, family, genus, species.
   • Developments Lead to Improvements
     • There have been new discoveries made because of technology improving. DNA analysis allows scientists to find out the differences between organisms. DNA is also used to estimate how long ago two species separated from each other, because genetic variants arise by mutations and scientists have estimates for how frequently these mutations can happen. By finding the number of different genetic variants between two species, scientists can estimate when the emergence of new species occurred.

3. Biodiversity

   • Variety of Life in an Area
     • A combination of three different factors.
       • The diversity of living organisms in a particular area
       • The diversity of different genes and alleles in a particular area
       • The diversity of different ecosystems in a particular area
   • Human interactions Can Reduce It
     • Increasing human population - Has grown hugely the last 200 years and is still rising. We need to take up more and land and resources to survive

4. Maintaining Biodiversity

   • Benefits Wildlife and Humans
     • Providing future medicines - Many we use today come from plants. Undiscovered plant species may contain new medical chemicals and if they become extinct, we could miss out on valuable medicines
     • Minimal damage to food chains - If one species become extinct it will affect all species that feed on are eaten by that species, so the whole food chain is affected.
   • Can be Challenging
     • Economic Issues
       • Expensive to conserve species/habitats. Many developing countries are rich in natural resources.
     • Moral Issues
       • Protecting one species may mean killing individuals of another species, which some people think is wrong.
     • Political Issues
       • Some schemes require several different countries to work together and it can be difficult if some countries aren't willing to sign up to an agreement.