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3.4.5 Energy Transfers – Maximising Productivity

3.4.5 Energy Transfers – Maximising Productivity. L.O: to describe the techniques for increasing productivity in animals and plants to state the advantages and disadvantages of these techniques Starter: Past Exam Q:

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3.4.5 Energy Transfers – Maximising Productivity

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  1. 3.4.5 Energy Transfers – Maximising Productivity L.O: to describe the techniques for increasing productivity in animals and plants to state the advantages and disadvantages of these techniques Starter: Past Exam Q: 8 (b) Energy is transferred through an ecosystem. Describe how and explain why the efficiency of energy transfer is different at different stages in the transfer. (6 marks)

  2. Past Exam Question Jan 2010 8 (b) Energy is transferred through an ecosystem. Describe how and explain why the efficiency of energy transfer is different at different stages in the transfer. (6 marks)

  3. Answers 1 Some light energy fails to strike/is reflected/not of appropriate wavelength; 2 Efficiency of photosynthesis in plants is low/approximately 2% efficient; 3 Respiratory loss / excretion / faeces / not eaten; 4 Loss as heat; 5 Efficiency of transfer to consumers greater than transfer to producers/approximately 10%; 6 Efficiency lower in older animals/herbivores/ primary consumers/warm blooded animals/homoiotherms; 7 Carnivores use more of their food than herbivores;

  4. If I am the answer…what is the question? 1 Slaughtered when still growing/before maturity/while young so more energy transferred to biomass/tissue/production; 2 Fed on concentrate /controlled diet /controlled conditions/so higher proportion of (digested) food absorbed/lower proportion lost in faeces / valid reason for addition; 3 Movement restricted so less respiratory loss / less energy used; 4 Kept inside/heating/shelter / confined so less heat loss / no predators; 5 Genetically selected for high productivity;

  5. Past Exam Question Jan 2010 8 (c) Explain how the intensive rearing of domestic livestock increases net productivity. (4 marks)

  6. http://www.youtube.com/watch?v=rEkc70ztOrc&feature=plcp

  7. Mini Presentations • Pesticides • Biological Control • Integrated Pest Control • Fertilisers

  8. Mini Presentations Suggested Format: Slide 1: Name of technique Slide 2: What that technique is Slide 3: Advantages (why it’s used to maximise productivity) Slide 4: Disadvantages Slide 5 (extension) : Case Study / Examples Remember to keep text on the slide to a minimum please!

  9. Past Exam Question Jan 2011 Q) Managed ecosystems such as wheat fields are prone to pest infestations. Describe the advantages and disadvantages of using biological agents to control pests. (5 marks)

  10. Answers Advantages 1. Specific (to one pest); 2. Only needs one application/ reproduces; 3. Keeps/maintains low population; 4. Pests do not develop resistance; 5. Does not leave chemical in environment/on crop / no bioaccumulation; 6. Can be used in organic farming; Disadvantages 7. Does not get rid of pest completely; 8. May become a pest itself; 9. Slow acting/ lag phase/ takes time to reduce pest population;

  11. http://www.youtube.com/watch?v=gX1FLXEo96g

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