20. Human influences on ecosystems
A section of Biology, 0610
Listing 10 of 393 questions
For Examiner's Use In South America, forests have been cut down to provide land for cattle grazing and for growing crops, such as soya beans. shows an area before deforestation and after the planting of soya. Occasionally small areas of forest are left if the land cannot support agriculture. Suggest the disadvantages of removing the forest from all but small areas of land. Much of the soya is used to feed farm animals rather than to make foods that humans can eat. Explain the advantages of using soya as food for humans rather than for farm animals. For Examiner's Use Much of the cleared forest in South America is used as land for cattle grazing. The clearing of forest and keeping large numbers of cattle have severe effects on the environment, especially the atmosphere. Outline the effects of forest clearance and cattle farming on the atmosphere. Yields from crops grown on soils like those in are likely to decrease over time. State reasons for the likely decrease in yields. Forest products are used in the manufacture of paper. Explain the environmental advantages of recycling paper.
0610_s12_qp_31
THEORY
2012
Paper 3, Variant 1
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For Examiner's Use shows a goliath beetle, Goliathus giganteus. State two features, visible in , that show that Goliathus giganteus is an arthropod. For Examiner's Use Use the key to identify each species. Write the letter of each species, B to H, in the correct box in the key. One, A, has been done for you. Key 1 Wings present go to 2 Wings absent go to 7 2 Back legs adapted for jumping Schistocerca gregaria A Back legs not adapted for jumping go to 3 3 Two pairs of wings go to 4 One pair of wings Drosophila melanogaster 4 Wings with hairs go to 5 Wings with no hairs go to 6 5 Hairs on back wings longer than width of back wing Ephestia cautella Hairs on back wings shorter than width of back wing Batrachedra amydraula 6 Thorax with spots Rhynchophorus ferrugineus Thorax with no spots Oryctes agamemnon 7 Three pairs of legs Microcerotermes diversus Four pairs of legs Oligonychus afrasiaticus For Examiner's Use Pesticides can be sprayed onto date palms to kill pests. This can damage the environment. Outline the damage to the environment that may be done by spraying pesticides. An alternative to using pesticides is biological control. The Senegalese grasshopper is a serious pest in West Africa. A fungal parasite of grasshoppers is used as a means of biological control. Spores of the fungus are sprayed onto populations of grasshoppers. An investigation was carried out to compare this biological control with a pesticide. Three fields were treated as follows: • sprayed with fungal spores • sprayed with pesticide • not sprayed Explain why one field was not sprayed. For Examiner's Use The population density of grasshoppers was recorded for 22 days after spraying. The results are shown in . mean population of Senegalese grasshoppers / number per m2 time / days time of spraying field not sprayed field sprayed with pesticide field sprayed with fungal spores Describe the effects of the two sprays on the populations of grasshoppers. You will gain credit if you use data from to support your answer. pesticide fungal spores For Examiner's Use Explain the differences between the effects of the pesticide and the fungal spores on the grasshoppers, as shown in .
0610_s12_qp_33
THEORY
2012
Paper 3, Variant 3
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Some integrated farming systems involve making best use of all available resources without the use of large inputs of energy in the form of fossil fuels. A study looked at what happened to the light energy that was the major energy input to farms in the Zhujiang delta in China. The farms are based on a dyke-pond system as shown in . dyke elephant grass vegetables phytoplankton mulberry trees pond fish Elephant grass, vegetables and mulberry trees are grown on the dykes in between the ponds. The elephant grass is grown and then cut to feed the fish. Vegetables and fish are used for human consumption. Silkworms feed on the mulberry trees. Phytoplankton are the main producers in the pond and are eaten by the fish. Explain the meaning of the term producer. Use the information provided in the passage on page 18 and in to complete a food web for the farm. Some of the producers have been drawn for you. phytoplankton in the pond mulberry trees vegetables In the study the researchers discovered that the vegetables absorbed 1560 MJ m–2 per year of light energy. The energy which was transferred from the vegetables to humans was 3 MJ m–2 per year. Explain what happens to the energy that is absorbed by the vegetables but is not transferred to humans. Suggest the advantages to a farmer of including ponds stocked with fish in an integrated farming system.
0610_s15_qp_33
THEORY
2015
Paper 3, Variant 3
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Questions Discovered
393