1974137
Description
Flashcards by sferrier96, updated more than 1 year ago
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Created by sferrier96
over 9 years ago
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| Question | Answer |
| name three effects of nitrogen fertilisers | reduced species diversity leaching eutrophication |
| how are fertilisers linked to reduced species diversity? | nitrogen-rich soil favours the growth of one particular species. This species out-competes other species hence species diversity is decreased. |
| What is meant by leaching? | the process by which nutrients are removed from soil |
| describe how leaching occurs | nitrates in the soil dissolve in water and drain into lakes and rivers |
| what factors affect the rate/amount of leaching that occurs | amount of nitrates already in the soil soil type and structure the amount of rainfall the amount of water used by crops and plants |
| What is meant by eutrophication? | the process by which nitrate (nutrients) build up in bodies of water. |
| describe the process of eutrophication | 1. nitrate concentration increases as a result of leaching 2. algae grow on the surface of the water = algal bloom 3. algae absorbs light hence preventing it from reaching deeper into the water. 4. photosynthetic plants die 5. saprobiotic organisms grow exponentially and demand for oxygen increases. 6.aerobic organisms die because oxygen concentration falls. |
| Explain how the leaching of nitrates from farmland into rivers may lead to a large increase in biochemical oxygen demand (BOD). (5 marks) | nitrate limiting factor for plant growth; increased growth of plants/algae/protoctists; nitrate needed by plants for protein synthesis; competition for light/effect of competition (e.g. plants underneath die); plants die, providing food supply for microorganisms/number of microbes increases; use of oxygen for respiration of microorganisms |
| Suggest and explain how any other environmental factor could influence the rate of leaf decomposition. (2 marks) | Soil water content; water needed for hydrolysis |
| What is the difference between the ways in which microbial decomposers and detritivores obtain their nutrients? (2 marks) | Decomposers secrete enzymes / onto organic matter/ food/ extracellular breakdown; Detritivores ingest / eat/ take in organic matter/food first; |
| The radioactive phosphate was absorbed by the plant and incorporated into organic compounds. Name two phosphorus-containing organic compounds and describe their importance in plants. (4 marks) | Phospholipid; Part of cell membrane; or ATP/ADP; ATP as source of energy for specific process; ADP needed to produce ATP/needed in specific process; or Nucleic acids/DNA/RNA; Carry genetic information/involved in protein synthesis; |
| Explain how each of the following could account for falling nitrate concentration. 1. algal growth 2.biological denitrification (2 marks each) | 1.Absorption / uptake by algae (not: ‘used’ or ‘used in growth); Use in protein / amino acid synthesis. 2. Breakdown to nitrogen; by denitrifying bacteria / named example, e.g. Pseudomonas. |
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