Use the graph to predict the yield of sorghum grain when the rainfall was 380 mm. Explain how you arrived at your answer.

Transcription

1 1 Sorghum is a grain crop plant. A group of students collected data about the effect of rainfall on the yield of sorghum grain. The data are for 2001 and came from different plots of land in one state in the USA. a i Use the graph to predict the yield of sorghum grain when the rainfall was 380 mm. Explain how you arrived at your answer. ii The students used these data to conclude that higher rainfall causes a greater yield of sorghum. Is this a valid conclusion? Explain your answer. (3 marks) b The table shows the effect of adding nitrogen fertiliser on the yields of three different cereal crops in the USA. Crop Mean yield of grain / tonnes ha 1 Without nitrogen fertiliser With nitrogen fertiliser Maize Sorghum Wheat This resource sheet may have been changed from the original 1

2 i Calculate the percentage increase in yield of maize when nitrogen fertiliser was added. Show your working. ii Nitrogen fertiliser has a different effect on each crop. Suggest an explanation for this different effect. AQA Human Biology, BYA 2, 2008, Unit 2 (Question 8) 2 Intensive rearing of livestock produces large quantities of waste. Some farmers use an anaerobic digester to get rid of the waste. In an anaerobic digester, microorganisms break down the large, organic molecules in the waste. This produces methane, which is a useful fuel. It also produces organic substances that can be used as a natural fertiliser. The diagram shows an anaerobic digester. a i Suggest two advantages of processing waste in anaerobic digesters rather than in open ponds (simple tanks which are open to the environment). This resource sheet may have been changed from the original 2

3 ii The anaerobic digester has a cooling system, which is not shown in the diagram. Without this cooling system the digester would soon stop working. Explain why. b i The over application of fertiliser increases the rate of leaching. Explain the consequences of leaching of fertiliser into ponds and lakes. (3 marks) ii Give one advantage of using natural fertiliser produced in the digester rather than an artificial fertiliser. 3 The following table shows the mean values for net primary production in four ecosystems. Ecosystem Region AQA Biology, 2011, Unit 4 (Question 3) Net primary production/kj m 2 year 1 Natural grassland Temperate Grassland on a farm using intensive farming methods Temperate Deciduous woodland Temperate Rainforest Tropical a i Explain what is meant by the term net primary production. ii Net primary production is higher in tropical rainforest than in temperate deciduous woodland. Give two reasons why. This resource sheet may have been changed from the original 3

4 b The diagram below shows the energy flow through a natural grassland ecosystem. All figures are in kj m 2 year 1 i Name process A. ii What type of organisms will be carrying out process B? iii The percentage efficiency of energy transfer between primary producers and primary consumers is 10.8%. Calculate the percentage efficiency of energy transfer between secondary and tertiary consumers. Show your working. This resource sheet may have been changed from the original 4

5 iv The energy transfer is more efficient between primary and secondary consumers than between primary producer and primary consumer. Suggest a reason why. Explain your answer. Reason Explanation 4 Urea from animal waste can be used as a fertiliser. Some bacteria in the soil secrete the enzyme urease which hydrolyses urea into ammonia. Some of this ammonia is released into the atmosphere. NBPT is an inhibitor of urease and can be added to urea fertiliser to reduce the loss of ammonia to the atmosphere. a A molecule of NBPT has a similar structure to a molecule of urea. Use this information to suggest how NBPT inhibits the enzyme urease. Scientists investigated the effect of NBPT on the release of ammonia from urea fertiliser added to the soil. A control experiment was carried out. This involved adding urea fertiliser only. The graph shows their results. This resource sheet may have been changed from the original 5

6 b i Describe how NBPT affected the loss of ammonia from urea fertiliser. ii Suggest an explanation for the increase in mass of ammonia released over the first four days in the control experiment. This resource sheet may have been changed from the original 6

7 c Suggest how the addition of NBPT to urea fertiliser could result in increased growth of crop plants. (3 marks) AQA Biology, 2011, Unit 4 (Question 3) This resource sheet may have been changed from the original 7