Ecology

• describe how ammonium ions can be converted to nitrate ions in the soil?


  nitrifying bacteria

  turn ammonia into nitrites and then nitrates
• what is the use of nitrates in plants?

  make proteins

  from amino acids
• suggest why crops still grow when no nitrate fertiliser is added?

  nitrogen fixing
• suggest why two fish of the same size may produce different masses of nitrogenous waste?

  different diet
• describe the process of eutrophication and the effects that it can have on the environment?

  fertilisers leeched into rivers

  rapid growth of algae

  blocks light

  no photosynthesis

  plants below die

  decomposers (bacteria)

  respire

  anoxic

  animals die
• deforestation affects the carbon cycle. Explain these effects?

  less photosynthesis

  more carbon dioxide

  burning of trees produces carbon dioxide
• the nitrogen in a nitrate ion in the soil can become the nitrogen in a protein molecule in an animal - explain how this happens?

  absorption by root hair cell

  active transport

  assimilation

  eaten

  digested

  protease
• suggest two advantages of using animal waste as a fertiliser rather than using a chemical fertiliser?

  less eutrophication

  readily available

  cheaper
• suggest three reasons why mountain hares may prefer to eat the plants in some habitats rather than plants in other habitats?

  more nutritious

  less predators

  more food/plants
• the scientists use a large number of quadrats to make sure the data collected is reliable - describe a procedure they should follow to make sure the data collected using quadrats is valid?

  repeat

  place quadrats randomly
• describe the possible consequences of an enhanced greenhouse effect?

  global warming

  ice caps melt

  flooding

  climate change

  habitat destruction

  migration

  extinction
• suggest two ways to reduce the build up of greenhouse gases in the atmosphere?

  reduce deforestation

  reduce burning of fossil fuels
• explain what is meant by the term decompose?


  break down a dead organism

  done by bacteria or fungi
• suggest why oryx are less active in the summer than in winter?

  avoid water loss

  avoid overheating

  less food available
• suggest why a farmer might choose to use a chemical pesticide in hig paddy field?

  kills pests
• describe how a pyramid of biomass from the same data would differ from the pyramid of numbers?


  pyramid shape

  different organisms have different masses
• explain why not all the energy in a producer passes to the primary consumer?

  energy for respiration

  energy used in movement

  energy lost in egestion and excretion
• what is meant by the term population?

  all of the organisms of the same species
• explain what is meant by the term trophic level?

  levels in food chain from producer to consumer
• suggest two reasons why humans are removing rainforest?

  construction

  making paper
• explain how deforestation can change the balance of gases in the atmosphere?

  more carbon dioxide

  less photosynthesis

  less oxygen
• suggest how deforestation can change the soil structure?

  soil erosion

  leeching
• suggest why the release of sterile male tomato leaf miners has been successful in controlling the leaf miner?

  no sperm

  fewer eggs fertilised
• what is meant by greenhouse gas?

  gases that trap heat
• what is a community?

  different species
• suggest two reasons why more of our fish are supplied by fish farming rather than from traditional fishing?

  can control mass

  genetically modify

  high yield
• give two advantages of using biological control rather than pesticide to reduce the number of fire ants?

  no need to reapply

  lasts longer
• what is an ecosystem?

  all the biotic and abiotic factors
• what is meant by biodiversity?

  measure of the variety of different species in an ecosystem
• why is biodiversity good?

  decreases the interdependance between species