topic 9

• What is an individual?

  a single organism
• What is a population?

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

  All the organisms of different species living in a habitat
• What is an ecosystem?

  A biological community of interacting organisms and their physical environment of abiotic factors.
• What is interdependence?


  Animals and plants depending on one another for survival: food, shelter etc
• What is mutualism?


  A relationship between two organisms where both benefit.
• Give an example of mutualism


  bee gets pollen from flower reproducing flowers along the way, and flower gets pollinated
• What are parasites?


  an organism that lives and feeds in or on another creature. Only the parasite benefits from this relationship
• What are abiotic factors?

  Non-living factors of the environment
• What are biotic factors?

  living factors
• What abiotic factors affect communities?

  temperature, amount of water, light intensity, levels of pollutants
• What biotic factors affect communities?

  competition and predation
• What is competition?


  the struggle between organisms to survive as they attempt to use the same limited resources
• What is predation?


  An interaction in which one organism kills another for food.
• How can you use quadrats to study the distribution of small organisms

  1)randomlyselect (random number generator, coordinates) some points to sample in the sample area2) place 1m^2quadratson each point, and count the number of organisms that you are investigating in each3) find the average amount per quadrat4) to find an estimate for the total population, multiply the average amount of organisms per quadrat by the area of the sample area in m^2

  If asked for equipment, list aquadrat, calculator(random number…) and anidentification key
• How can you study distribution of an organism along a gradient?

  1) use abelt transect- mark out a line across the area you want to study, with a changing abiotic factor along the line, like light intensity, or soil pH2) collect data along the transect usingquadratsplaced next to each other, or at regular buildings4) you could also record other data, like the mean height of the plant you are investigating in each quadrat5) see if the change in the data you took correlates with the abiotic factor that changes on your belt transect
• What is the name for the first organism in a food chain?


  producer
• What is the name for the second organism in a food chain?

  primary consumer
• What is the name for the third organism in a food chain?

  secondary consumer
• What is a trophic level?


  Each step in a food chain or food web
• Why do food chains usually have fewer than 5 trophic levels

  There would not be enough energy available to continue to rise through the trophic levels. There is not enough energy stored in the biomass to support another organism.
• How can energy be lost in a food chain?

  transferred by heat, excreted, egested
• What is the formula for efficiency?

  Useful energy out/total energy in
• What does a pyramid of biomass show?


  how much the organisms at each trophic level would weigh if you put them all together
• Describe the carbon cycle

  1)green plants use CO2 in the air to make carbohydrates,l fats and proteins

  2) eating passes the carbon compounds in the plants along to animals in a food chain

  3) Both plant and ahimal respiration while the organisms are alive releases CO, back into the air.

  4) Plants and animals eventually die and decompose, or are killed and turned into useful products.

  5) When plants and animals decompose they're broken down by microorganisms, like bacteria and fungi. These decomposers release CO, into the air by respiration, as they break down the material.

  6) Some useful plant and animal products, e.g. wood and fossil fuels, are burned (combustion). This releases CO2 back into the air

  7) Decomposition of materials means that habitats can be maintained for organisms that live there, bc nutrients are returned to the soil, and waste material doesn't just pile up
• Describe the water cycle

  1) Energy from the Sun makes water evaporate from the land and sea, turning it into water vapour. Water also evaporales from plants - this is known as transpiration

  2) The warm water vapour is carried upwards (as warm air rises). When it gets higher up it cools and condenses to form clouds.

  3) Water falls from the clouds as precipitation (usually rain, but sometimes snow or hail) onto land. where it provides fresh water for plants and animals.

  4) It then drains into the sea, before the whole process starts again.
• What is desalination?


  A process to remove salts from salt water
• Describe thermal desalination


  1) Salt water is boiled in a large enclosed vessel, so that the water evaporates

  2) The steam rises to the top of the vessel, but the salts stay at the bottom.

  3) The steam then travels down a pipe from the top of the vessel and cools and condenses back into pure water.
• Describe reverse osmosis

  1) Salt water is first treated to remove solids, before being fed at a very high pressure into a vessel containing a partially permeable membrane.

  2) The pressure causes the water molecules to move in the opposite direction to osmosis - from a higher salt concentration to a lower salt concentration.

  3) As the water is forced through the membrane, the salts are left behind, removing them from the water.
• What are the four types of bacteria in the nitrogen cycle?

  decomposers, nitrifying bacteria, denitrifying bacteria, nitrogen-fixing bacteria
• What do decomposers do (N2 cycle)?

  decompose proteins and urea and turn them into ammonia. Ammonia forms ammonium ions in solution that plants can use
• What do nitrifying bacteria do (N2 cycle)?

  turn ammonia in decaying matter into nitrites and then into nitrates. Different species of nitrifying bacteria are responsible for producing nitrites and nitrates
• What do denitrifying bacteria do (N2 cycle)?

  turn nitrates back into N2 gas. This does not benefit living organisms. They are often found in waterlogged soil.
• What do nitrogen-fixing bacteria do? (N2 cycle)

  turn atmospheric N2 into ammonia, which forms ammonium ions
• Describe crop rotation

  kThis is where, instead of growing the same crop in a field year after year, different crops are grown each year in a sycle. The cycle usually includes a nitrogen-fixing crop (e.g. peas or beans), which helps to put nitrates back into the soil for another crop to use the following year.
• Describe fertilisers

  Spreading animal manure or compost on fields recycles the nutrients left in plant and animal waste and returns them to the soil through decomposition. Artificial fertilisers containing nitrates (and other mineral ions needed by plants) can also be used, but these can be expensive and can cause environmental problems
• Why are legumes useful to farmers?

  There are nitrogen-fixing bacteria which live in their roots, so by doing a crop rotation with legumes, the farmers can replenish the amounts of nitrates in the soil.
• What is eutrophication?

  When raw sewage or fertilisers containing nitrates are released into a river and the microorganisms in the water increase and use up all or the oxygen there.
• What indicator species can indicate clean waters, with lots of oxygen?

  stonefly larvae, freshwater shrimps
• What indicator species can indicate polluted waters?

  bloodworms and sludgeworms indicate a very high level of water pollution because they are adapted to polluted conditions