Biology topic 7

• Biotic


  living parts of an ecosystem
• Abiotic

  nonliving parts of an ecosystem
• biotic factors examples


  - new predators

  - competition

  - new pathogens

  - food availability
• Abiotic factors examples


  - moisture levels

  - light intensity

  - temperature

  - CO2 levels

  - wind intensity and direction

  - soil pH

  - mineral level in soil
• Define Habitat


  Place where an organism lives
• define population


  All the organisms of one species in a habitat
• define community


  The populations of different species living in a habitat
• Define ecosystem


  The interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment
• Adaptations


  Changes in physical structure, function, or behaviour that allow an organism or species to survive and reproduce in a given environment.
• food chains


  Energy links between different organisms in an ecosystem based on feeding habits.

  
• sampling: quadrats


  Study distribution of small organisms

  1) place quadrat on the ground at a RANDOM point within first sample area. ( do this by using a grid and coordinates)

  2) count all of organisms within quadrat

  3) repeat these 2 steps

  4) work out mean number of each organism per quadrat within first sample are

  5) repeat these steps in a different sample area

  6) compare the 2 results

  
• Transects


  1) mark out a line in the area you want to study using a tape measure.

  2) collect data along the line

  3) to do this you can count all organisms you want that touch the line

  
  

  4) you can use quadrats along this line or at intervals to collect data

  
• environmental aspects affecting distribution

  - water availability

  - change in temperature

  - change in atmospheric gases
• Water Cycle


  The continuous process by which water moves from Earth's surface to the atmosphere and back
• Water Cycle steps


  EVAPORATION/TRANSPIRATION - water becomes water vapour

  CONDENSATION - water cools and condenses to form clouds

  PRECIPITATION - rain from clouds

  RUN OFF - water goes back in to rivers or the sea for the cycle to repeat
• Carbon Cycle


  The organic circulation of carbon from the atmosphere into organisms and back again
• Carbon cycle steps


  1. CO2 removed from atmosphere during photosynthesis

  2. some CO2 is returned through respiration.

  3. plants eaten by animals - carbon become parts of fats/proteins in bodies - moves through food chain

  4. some returned from CO2 from animal respiration.

  5. when these plants/algae die decomposers feed on them - when they respire CO2 is returned to atmosphere

  6. animals produce waste - broken down.

  7. combustion releases CO2

  8. Carbon is continuously cycled throughout the air.
• Decomposition definition


  A chemical reaction that breaks down compounds into simpler products.
• Factors affecting the rate of decay

  temperature

  oxygen availability

  water availability

  number of decay organisms
• Investigating the effect of temperature on decay (1)

  1. Place 20 cm3 of fresh milk into three beakers

  2. Decide the three temperatures you will investigate. Write these onto the sides of the beakers. They may be 5, 20 and 35°C.

  3. Use universal indicator paper or solution to determine the pH of the milk in the three beakers

  4. Cover each beaker in cling film and incubate at the appropriate temperature

  5. Use universal indicator paper or solution to determine the pH of the milk in the three beakers after 24, 48 and 72 hours
• Investigate the effect of temperature on the rate of decay

  1. Use a water bath to heat all of the components to a given temperature.

  2. Mix the milk, sodium carbonate and 5 drops of phenolphthalein indicator. The resulting solution should be purple - alkaline.

  3. add lipase to a test tube label it 'L'

  4. Add lipase to the solution and start timing.

  5. When the solution turns yellow, stop timing.

  6. Repeat using different temperatures.
• Define biodiversity


  the variety of different species of organisms in the world or in a particular habitat or ecosystem.
• Why is biodiversity important

  - ensures ecosystems are stable

  - to help the human species survive.

  - ensure health/food security

  - helps fight disease

  - provides livelihoods.
• Waste management


  Managing wastes to reduce their environmental harm without seriously trying to reduce the amount of waste produced.

  - WATER - sewage and toxic chemicals can pollute water

  - LAND - toxic chemicals (farming) , Nuclear waste buried in ground, Landfill sites

  - AIR - smoke and acidic gases released into atmosphere.
• Greenhouse


  Natural situation in which heat is retained in Earth's atmosphere by carbon dioxide, methane, water vapor, and other gases.

  
  

  Gases act as an insulating layer, this stops some light escaping, heating the environment.

  
• Global Warming Consequences


  - shrinking cryosphere (frozen parts of planet)

  - rising sea levels

  - more powerful hurricanes

  - distribution of animal/plant species

  - change in migration patterns

  - reduce biodiversity
• Uses of Land


  - building

  - quarrying

  - farming

  - waste dumping
• Deforestation causes


  -Conversion of forests to agricultural land to feed people

  -development of cash crops and cattle raising

  -unregulated commercial logging

  -poor soils in humid tropics that do not support agriculture for long
• Deforestation problems


  - Destroys Habitats and Animals

  - Destroys possible medicines

  - Less CO2 absorbed so more in atmosphere - trees are carbon sinks

  - Less biodiversity
• Destroying peat bogs effects

  - Adds more CO2 into atmosphere.

  - Bogs = areas of land that are acidic and waterlogged. Plants don't properly die - build up - form peat.

  - Carbon from plants is stored in peat

  - Peat is often drained to have farmland

  - comes in contact with oxygen - microorganisms start to decompose it - release CO2

  - CO2 released when peat is burned as a fuel

  - destroys some habitats - reduces biodiversity.
• protecting Ecosystems


  - breeding programmes - prevent endangered species form becoming extinct

  - programmes to protect and regenerate rare habitats have been started

  - programmes to reintroduce hedgerows and field margins

  - government introduced programmes to reduce level of deforestation

  - people encouraged to recycle
• pressure on maintaining biodiversity

  - cost money - pay farmers - cost to keep watch on land.

  - could effect employment levels

  - conflict between protecting biodiversity and food security - some pests get killed by farmers.

  - land is in very high demand
• Trophic Levels


  The hierarchical levels of the food chain through which energy flows from primary producers to primary consumers, secondary consumers and so on.

  
  

  PRODUCER > PRIMARY CONSUMER > SECONDARY CONSUMER > TERTIARY CONSUMER

  
• Pyramids of Biomass


  illustrates the relative amount of living organic matter available at each trophic level in an ecosystem

  
  

  REMEMBER TO LABEL WHEN DRAWING

  DRAW TO SCALE

  
• Biomass transfer


  - Transfer of biomass from one trophic level to another

  - biomass is lost between each trophic level (not much)
• How is biomass lost

  - organisms DONT ALWAYS EAT EVERY PART of the organism that they are consuming - e.g. some material that makes up plants and animals is inedible: bone

  
  

  - organisms don't absorb all of the stuff in the food they ingest - the stuff that they don't absorb is egested as faeces

  
  

  - some of the biomass taken in is converted to other substances that are LOST AS WASTE e.g. organisms use lots of glucose in RESPIRATION to provide energy for movement and keeping warm rather than to make more biomass. This process produces lots of waste CO2 and water as by-products. UREA is another waste substance, which is released in urine with water when the proteins in the biomass are broken down
• Factors affecting food security

  - an increasing birth rate

  - changing diets in developed countries

  - new pests and pathogens

  - environmental changes

  - cost of agricultural inputs

  - conflicts
• Overfishing


  - Removing more fish from the oceans than can be naturally produced

  - Fish stocks are declining because of this

  - means less fish for us and ocean's food chains are affected
• ways to maintain fish stocks

  Fishing quotas - limiting the amount of fish that can be caught in certain area

  Net size - regulation for catching certain fish are introduced to reduce the capturing of unwanted fish during fishing as well as capturing of young fish meaning those fish of that breed can reproduce
• How to make food production

  1) Limit movement- less energy used to move around (put in pens/ cage)

  2) Control temp of surroundings- less energy used regulating body temp themselves