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  1. 1. ECOLOGY
  2. 2.  organisms in relation to their environment  this includes the relationship of organisms with:  each other  non-living components of their environment organisms
  3. 3.  Polar  Temperate  Tropic Temperate Polar Tropic
  4. 4.  control each other’s population size
  5. 5. Biotic factor living organisms e.g. predators, competitors, parasites Abiotic factor non-living factors which influence organisms e.g. light, temperature, soil, rainfall
  6. 6.  is the particular locality in an environment in which an organism lives SPACE FOOD WATER
  7. 7. rock pools (limpets, barnacles, top shells) soil burrows (earthworms)
  8. 8.  is the group of individuals of the same species living in a particular area at the same time
  9. 9.  includes all the populations of all the species within an ecosystem
  10. 10.  is a natural unit composed of living and nonliving components whose interactions result in a stable self-perpetuating system
  11. 11.  is a community of organisms in conjunction with the nonliving components of their environment (things like air, water and mineral soil), interacting as a system
  12. 12. ponds an oak tree a field a rockpool the sea
  13. 13. same species
  14. 14. different species Camels, goats and sheep compete for food.
  15. 15. a) Distinguish between intraspecific and interspecific competition. (2) b) Explain why intraspecific competition is likely to be more intense than interspecific competition. (1) Members of a species use the same resources but different species use different resources.
  16. 16. c. i) List TWO resources that animals compete for. (2) space, food, water, mate
  17. 17. ii) List TWO resources that plants compete for. (2) Space, light, water, ions in soil, carbon dioxide
  18. 18. d) What is the effect of competition on the growth of a population? (1) Reduces the growth rate of a population.
  19. 19. Before 1859 there were no wild rabbits in Australia but in 1859 some domestic rabbits escaped from their pen, when it was swept away by a flood. These rabbits ran wild and bred at such a rate that parts of Australia soon became overrun with them. The following graph shows how the population of rabbits increased with time.
  20. 20. a. Describe and explain the growth of the rabbit population at stages 1, 2 and 3. (12) STAGE 1: Slow increase in population. Few individuals able to reproduce. Rabbits need to acclimatise. STAGE 2: Rapid increase in population. Many individuals able to reproduce. Resources are abundant.
  21. 21. a. Describe and explain the growth of the rabbit population at stages 1, 2 and 3. (12) STAGE 3: Population stable. Resources become limited and can support a certain number of individuals.
  22. 22. b. Discuss the effect of the observed growth rate of rabbits on agricultural activity in Australia. (2) Rabbits fed upon crops and caused damage to agriculture. c. Suggest how the observed growth rate of rabbits affected the natural ecosystem in Australia. (2) Many wild plants were eaten leading to loss of plant species, more soil erosion as soil was no longer covered by vegetation.
  23. 23. a) PRODUCERS – autotrophic plants b) CONSUMERS – heterotrophic organisms, mainly animals c) DECOMPOSERS – saprophytic bacteria & fungi – break down dead matter to return nutrients to the soil
  24. 24. Distinguish between a community of plants and a population of plants. (2) Distinguish between producers and consumers. (4)
  25. 25.  is the role or job of an organism within the community
  26. 26.  the movement of food energy from one organism to the next Trophic level = feeding level 1st Trophic level 2nd Trophic level PRODUCER PRIMARY CONSUMER 3rd Trophic level SECONDARY CONSUMER 4th Trophic level TERTIARY CONSUMER Top carnivore
  27. 27.  Ecosystem: Field grass aphid leaves ladybird caterpillar sparrow  Ecosystem: Oak tree oak tree insect larvae thrush  Ecosystem: Freshwater pool algae tadpole waterbeet le hawk
  28. 28.  are made up of many food chains linked together  give a more complex picture of how animals feed  are more stable than food chains
  29. 29. 5 1. There are …… primary consumers. 2. The top carnivore owl is the ……… .
  30. 30. 3. Suppose all the woodmice died from a poison, i) the acorn would (increase / decrease).
  31. 31. 3. Suppose all the woodmice died from a poison, i) the acorn would (increase / decrease).
  32. 32. 3. Suppose all the woodmice died from a poison, i) the acorn would (increase / decrease). ii) the weasel would (increase / decrease).
  33. 33. 3. Suppose all the woodmice died from a poison, i) the acorn would (increase / decrease). ii) the weasel would (increase / decrease).
  34. 34. 4. Draw a food chain with 5 links from this food web. oak leaf greenfly ladybird shrew owl 5. In this food web, the shrew can be either secondary tertiary a ………………. or a ……………….. consumer.
  35. 35. The following organisms can be found in the same habitat: weasel, rabbit, greenfly, green plant, caterpillar, small bird and ladybird. Construct a food web to include all the organisms found in the list above.
  36. 36. weasel, rabbit, greenfly, green plant, caterpillar, small bird and ladybird weasel small bird Weasel eats small mammals & birds. rabbit ladybird greenfly green plant caterpillar
  37. 37. a) Pyramid of Numbers b) Pyramid of Biomass c) Pyramid of Energy
  38. 38.  shows the total number of individuals at each trophic level
  39. 39.  indicates the weight of all individuals at each trophic level  biomass is the weight of living material
  40. 40. Pyramid of Numbers Pyramid of Biomass Ladybird Aphid Rosebush Rosebush Aphid Ladybird
  41. 41. From the food web write a food chain including four trophic levels. (2) [Any food chain as long as 4 trophic levels are present]
  42. 42. b) In the space below draw a pyramid of numbers for the food chain you answered in ‘a’. (In your diagram label each trophic level). (3)
  43. 43.  shows the transfer of energy from one trophic level to the next
  44. 44. Pyramid of Energy
  45. 45. 1. excretion 2. moving about 3. keeping the body warm 4. egestion 5. respiration
  46. 46. Give a reason why the number of trophic levels seldom exceeds 5. (1) Great (90%) losses in energy at every trophic level.
  47. 47. Approximately what percentage of all the energy present at one trophic level is transferred to the next higher trophic level? (1) Only 10% of the energy is transferred to the next trophic level.
  48. 48. Why is energy not recycled in ecosystems? (1) Lost as heat to the surrounding environment.
  49. 49. ENERGY FLOW Light SUN energy Biotic component Heat energy nutrients Abiotic component Flow of ENERGY is LINEAR but flow of NUTRIENTS is CYCLIC.
  50. 50.  the shorter the food chain, the more people can be fed REASON: the 90% ‘wastage’ of energy that occurs between each trophic level is cut down
  51. 51. Green light is reflected by the leaf.
  52. 52. Only 1% of the light falling on a leaf is used in photosynthesis. What happens to the rest? 30% evaporates water from plant 20% is reflected from plant 40% warms up soil, air and vegetation [transmitted]
  53. 53.  respiration : is not available for the next trophic level  growth: is passed on the next trophic level
  54. 54.  over half of the energy in the grass the cow eats, is passed out of the body in faeces
  55. 55. Excretion and death Nutrients in living organisms Absorption by living things Nutrients in dead bodies and waste Decomposition by bacteria and fungi Nutrients in environment available for use
  56. 56.  all living things need carbon to make:  carbohydrates  fats  proteins
  57. 57. CO2 in air 0.03% 1. Respiration 2. Decomposition 3. Combustion 1. Photosynthesis
  58. 58. carbon dioxide gas photosynthesis plant respiration animal respiration combustion decay carbon compounds in animals animal nutrition carbohydrates in green plants death death fossilisation carbon compounds in dead organic matter (humus) coal
  59. 59. 1) More fossil fuels are being burnt than in the past. 2) Large areas of forest are being removed and so less CO2 is removed from the air.
  60. 60. How can the greenhouse effect be: 1) an advantage to plants? Plants grow more as photosynthesis increases due to a higher temperature. 2) a disadvantage to plants? More chances to wilt as more water is lost by evaporation.
  61. 61.  plants & animals need nitrogen to make: proteins  plants cannot use atmospheric nitrogen From where do plants get the nitrogen they need? Nitrogen 78% Gases in air.
  62. 62. Mention THREE ways by which these ions can end up in the soil. 1. Erosion 2. Burning fossil fuels (generates nitric oxide) 3.
  63. 63. Nitrates in soil 1. Lightning 2. Nitrogen-fixing bacteria 3. Nitrifying bacteria 1. Absorption by plants 2. Leaching 3. Denitrifying bacteria
  64. 64. NITROGEN (in the air) Denitrifying bacteria lightning Nitrogen-fixing bacteria SOIL NITRATES taken up by plants Nitrifying bacteria Plant protein Dead organisms and faeces NITRITES Animal protein Nitrifying bacteria excretion decomposition AMMONIA
  65. 65. LIGHTNING  causes N2 & O2 to combine at high temperatures and nitrogen oxides form  these oxides are washed into the soil by rain where they form nitrates O2 & N2: most abundant gases in air.
  66. 66. NITROGEN-FIXING BACTERIA  absorb nitrogen gas from the air and ‘fix’ it into a form which the plant can use to build protein  change nitrogen gas into ammonium compounds Root nodule full of bacteria.
  67. 67. NITROGEN-FIXING BACTERIA live: 1) freely in the soil e.g. Clostridium 2) in the root nodules of leguminous plants (e.g. peas, beans, clover) e.g. Rhizobium Root nodules
  68. 68. Mutualism:  is the relationship between nitrogen fixing bacteria and leguminous plants Bacteria gain: 1. Food 2. Shelter Plant gains: Ammonium compounds
  69. 69. SYMBIOSIS:  is a relationship between two organisms MUTUALISM:  is a type of symbiosis  is a close relationship between two different organisms where both benefit from each other
  70. 70. When leguminous plants decay:  the nitrogen which the bacteria have fixed goes into the soil where it can be used by plants Nitrogen-fixing bacteria are very useful because they increase the amount of useful nitrogen compounds in the soil.
  71. 71. Clover Beans Peas 1.can live in soils poor in nitrates 2.are used in crop rotation to increase nitrates in soil
  72. 72. NITRIFYING BACTERIA  change ammonia into nitrites and then into nitrates  this is called nitrification  ammonia is present in:  dead remains  animal waste
  73. 73. Organic nitrogen in dead bodies or animal waste Bacillus Decay ammonia Nitrification Nitrosomonas nitrite Nitrification Nitrobacter nitrate
  74. 74. 1) Absorption by plants root hairs provide a large surface area for absorption salts are absorbed by:  diffusion  active transport
  75. 75. 2) Leaching is when salts are lost from the soil and reach the groundwater Nitrates
  76. 76. 3) Denitrifying bacteria live in water-logged soil carry out denitrification by changing nitrates into nitrogen gas e.g. Pseudomonas Why do farmers dig up the land? To improve drainage and aeration thus denitrification does not occur.
  77. 77. Distinguish between nitrification and denitrification. (5) Nitrification is carried out under aerobic conditions but denitrification under anaerobic conditions. In the process of nitrification, ammonia is converted into nitrites and then into nitrates. In denitrification, nitrates are converted into nitrogen gas.
  78. 78. During a fieldwork activity a biology student used a pitfall trap for sampling animals. The diagram above shows the pitfall trap. a) List ONE advantage and ONE disadvantage of this method. Advantage: cheap; easy to set up; no maintenance needed; animals remain alive (1) Disadvantage: animals eat each other; flooding of pitfall trap if it rains (1)
  79. 79. The photo below shows a student using another sampling technique. The photo below shows a student using another sampling technique. a) Name the piece of apparatus being used to sample plant density and diversity in the field. (1) Quadrat
  80. 80. The following photo shows three biology students during fieldwork in a woodland area. Explain why the sampling equipment shown in the diagram cannot be used for animals. (1) Animals move out of the quadrat and so cannot be counted.