30 10 The diagram shows the flow of energy in an ecosystem. The numbers represent the energy in kJ m−2 yr−1 in each category. primary consumers 6.2 × 103 producers 8.5 × 104 sunlight 7.0 × 106 (a) (i) Calculate the percentage efficiency of energy transfer from sunlight to the producers. (2) Answer .............................................................. % (ii) Give one reason why the energy transfer from sunlight to the producers is less than 100% efficient. 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(b) Plant productivity is affected by the abiotic and biotic factors that exist at different latitudes. The diagram shows latitudes of the Earth. Northern hemisphere 0 Equator 30 30 60 60 90 90 30 30 60 60 90 90 North South The table shows the productivity of plants growing on land at different latitudes in the Northern hemisphere. Latitude / degrees Productivity / g m−2 yr−1 0 to 10 (equatorial conditions) 900 to 1500 30 to 40 (warm temperate conditions) 400 to 800 40 to 60 (cool temperate conditions) 200 to 600 60 to 70 (alpine to arctic conditions) 0 to 200 32 A student concluded that primary productivity is determined by abiotic factors that affect the light-dependent and light-independent stages of photosynthesis. Discuss the validity of this conclusion. 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(Total for Question 10 = 14 marks) TOTAL FOR PAPER = 120 MARKS 34 BLANK PAGE 35 BLANK PAGE 36 BLANK PAGE