AQA A2 Biology - Chapter 6 Nutrient Cycles

Charlotte Lloyd
Flashcards by Charlotte Lloyd, updated more than 1 year ago
Charlotte Lloyd
Created by Charlotte Lloyd almost 6 years ago


AQA A2 Biology Unit 4 - Chapter 6 Nutrient Cycles

Resource summary

Question Answer
Which processes produces carbon dioxide from carbon containing compounds? Combustion Decay Respiration
Which process removes carbon dioxide from the atmosphere? Photosynthesis
What is the greenhouse effect? Solar radiation is absorbed by the atmosphere/earth but is not reflected/remitted back into space due to 'greenhouse' gases which trap/absorb heat thus causing the warming of the atmosphere
What are some of the consequences of global warming? The global temperature has increases due to the amount of greenhouse gases having increased; Caused: Melting of polar ice caps, Rise in sea levels, More extreme weather Impact on food production
What is ammonification and which organisms carry it out? Production of ammonia from ammonium containing compounds; Carried out by saprobiotic microbacteria which feed on ammonium compounds producing ammonium ions in the soil
What is nitrification and when does it occur? Conversion of ammonium ions into nitration ions; In an oxidation reaction; Only occurs when oxygen is available
What is nitrogen fixation, and which two types of micro-bacteria carry it out? Conversion of nitrogen gas to nitrogen containing compounds; Carried out by free-living or mutualistic bacteria
What is denitrification? Conversion of nitrates to nitrogen gas
Why are fertilisers needed? Replenish minerals lost through extensive farming; these minerals are needed for growth
Distinguish between the two types of fertilisers: Natural (organic) fertilisers - consist of dead and decaying plants/animals as well as animal waste Artificial (inorganic) fertilisers - mined from rocks and deposits and then converted into different forms: All fertilisers contain nitrogen, phosphorus and potassium
How do fertilisers increase productivity? Provide essential minerals for growth; More growth = higher productivity
What are the positive effects of nitrogen based fertilisers? Nitrogen needed for growth: More nitrogen = more growth Bigger plants = more photosynthesis Improved crop productivity
What are the detrimental effects of nitrogen bases fertilisers? Reduced species diversity - nitrogen rich soils favour fast growing plants which out-compete other species; Leaching - pollution of the water ways; Eurotrophication - caused by leaching
What is leaching and what does it cause? Process by which nutrients are removed from the soil, Rain water dissolves any soluble nutrients and carry them deep into the soil (away from plant roots), Then enter the water ways: Pollute drinking water and causes eurotrophication which kills fish
Explain how eurotrophication can kill fish - mainly in fresh water Usually nitrate level is a limiting factor; Nitrate conc increases algae grows exponentially = algal bloom; Prevents light penetrating to the lower depths, light become limiting factor so plants and algae die; Saprobiotic bacteria grow exponentially; Use up oxygen in the water; Oxygen conc becomes limiting factor for aerobic populations - fish die; Anaerobic organisms increase exponentially - further decompose dead organisms releasing toxic waste; Water now putrid
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