Biology - module 3

Biology - module 3

1. a species is a group of organisms that can breed together to produce fertile offspring

2. species adapt to their environment - more likely to survive and produce offspring - whole species continue to exist

3. Cactus - round shape - small surface area - reduce water loss - thick waxy layer - store water in thick stem - shallow roots - absorb water over large area

4. Fish - gills - oxygen for respiration - tail fins large surface area to propel through water - streamline body - little resisitance - swim bladder

5. in species there is genetic variation - each look slightly different

   • cause for variation is when genes change - mutations - can be caused outside factors - radiation and chemicals
     • if in body cells - cancer - in sex cells - mutation passed onto offspring - develop new characteristics - some can be harmful or help them to survive

6. natural selection

   • survival of the fittest
   • genetic variation
     • resources to survive limited - individuals must compete - only some will survive
       • some varieties of species will have better chance of survival - increased chance of reproducing to pass on genes
         • greater proportion in next generation have those characteristics to survive
           • over many generations species become better and survive - 'best' features naturally selected and species become more adapted to environment

7. selective breeding

   • humans deliberately choosing features they want in next gen - only in plants and animals
   • natural selection selects features which help survival where selective breeding does not nessessarily

8. Evolution

   • estimate life on earth began 3500 million years ago
   • first living things were very simple - now evolved to be complex and varied
   • new species
     • groups of organisms of same species become isolated from each other so they cant interbreed
       • factors combine to make 2 groups so different they are different species
         • different mutations create new features in 2 groups of organisms
         • natural selection - if features beneficial - spread through pop
         • environmental factors - develop different adaptations to different conditions
   • fossil records and DNA provide evidence for evolution
     • fossils shows species getting more complex over time
     • DNA controls characteristics and mutates and changes over time - similarites and differnces in DNA help to work out evolve
   • charles darwin - theory of evolution - natural selection - made observations and creative thinking
     • Lamarck - if characteristics were used a lot - become more developed - those acquired characteristics be passed onto offspring - but acquired characteristics dont have genetic basis - unable to pass onto next generation

9. biodiversity

   • variety of life on earth
   • number of different species on earth
   • range of different types of organisms
   • genetic variation between organisms in the same species
   • maintaining biodiversity - stop species from extinction - important
     • more plants available - more resources for new crops
     • medicines - discover - use chemicals in living things
     • rate of extinction increasing
       • correlation in world pop growth and species extinction - suggests a lot to do with human activity
       • hunting or destroying habitat or introducing new species which they cant compete with
   • classification - similarites and differences in characteristics, genes, physical features
     • five different kingdoms - bacteria, fungi, algae, plants, animals
       • each kingdom divided into more groups etc until species
       • number of types of organisms decreases but number of characteristics in common increases
     • shows us evolutionary realtionships

10. organisms are dependant on other organisms and environment for survial

    • factors essential for life - light, food, oxygen and co2, water
    • if any factor in short supply - difference species have to compete - some wont survive - limit size of pop
    • interdependance
      • any change in any environment can have a knock on effect on organisms
    • rapid change in envornment can cause species to become extinct - environmental conditions - cant adapt - new competitor, disease, predator - organism in food web becomes extinct

11. Energy in an ecosystem

    • energy from the sun is the source of energy for nearly all life on earth
      • plants use a small % of light energy from the sun during photosynthesis. energy stored y converting into chemicals make up plant cells
        • energy is transferred between organisms in ecosystem when animals eat plnts and animals - energy is also transferred when decomposers and detritivores feed on parts of dead organisms and waste
          • energy is lost at each stage - respiration, heat and waste
            • food chains are not usually lobger than 5 as so much energy is lost not enough to support more organisms
    • efficiency = energy available to the next stage / energy that was available to the previous stage X 100

12. nitrogen cycle

    • atmosphere 78% nitrogen - very unreactive - cant be used directly
    • nitrogen used for proteins for growth
    • plants get their nitrogen from the soil but needs to be turned into nitrates. animals only get proteins by eating plants or animals
    • nitrogen fixation - process of turning n2 from air into nitrogen compounds in soil which plants can use
    • lightning - lots of energy - nitrogen and oxygen react to give nitrates - goes into soil
    • nitrogen fixing bacteria form atmos into soil
    • decomposers break down proteins in dead plants, animals, urea and waste into ammonia - ammonia turned into nitrates by nitrifying bacteria in soil
      • decomposers - decompose proteins and urea - turn into ammonia
      • nitrifying bacteria - turn ammonia in decay into nitrates that can be absorbed by roots
      • nitrogen fixing bacteria - turn n2 into nitrogen compounds that plants can use
      • denitrifying bacteria - turns nitrates back into n2 - not beneficial

13. carbon cycle

    • co2 in the air - only arrow going down - as photosynthesis
    • plants convert co2 from air into sugars, carbohydrates, fats, protiens
      • animals eat plants - eating passes carbon compounds into animlas
        • animal and plant respiration releases co2 back into air
          • animals and plants die or excrete and decompose - co2 released from decomposition - decomposers that break down waste release co2 from respiration
            • combustion of fossil fuels releases co2 into air

14. sustainability

    • meeting the needs of todays population without harming the environment so that future generations can still meet their own needs
    • human activities can damage the environment - environment wont be the same for future gens
    • limited resources will eventually run out - future gen wont be able to use
    • maintain biodiversity - future gens wont bee able to benefit from then extinct species that could help with medicines etc
    • packaging
      • use renewable materials
      • use less energy - less fossil fuels
      • less pollution - biodegradable - more susutainable - will rot away easily
      • making and transporting use energy

15. measuring environmntal changes

    • non living indicators
      • temperature - thermometers - could indicate climate change
      • nitrate level - change in water - increase suggests pollution
      • co2 - change in air - increase could be down to human activity - suggest global warming
    • living indicators
      • lichen - air pollution - sensitive to sulfur dioxide - indicates how clean air is - increase means air is clean
      • mayfly nymphs - water pollution - sensitive to oxygen levels in water - more mayfly means clean water
      • phytoplankton - water pollution - pop increases when nitrate and phospates in water increase - so when there os pollution