Flashcards for AQA A Level Biology Chapter 13- Energy and Ecosystems
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Course
Chapter 13- Energy and Ecosystems
Institution
AQA
Contain all you need to know for this chapter of the course. Are detailed and concise, and work best with Anki, but can be used with quizlet. They are in the form of a txt document that can be imported into anki or quizlet. Some images are missing due to the format, so these images will have to be ...
What are producers? Photosynthetic organisms that manufacture organic
substances
What are consumers? Organisms that gain their energy by feeding on other
organisms
What are the three classes of consumer and what do they mean? Primary- first of
the chain of consumers. They eat green plants <div>Secondary- eat primary
consumers </div><div>Tertiary- eat secondary consumers </div>
What are saprobionts? A group of organisms that break down the complex materials
in dead organisms into simple ones, releasing valuable minerals and elements into a
form that can be absorbed by plants
What is a trophic level? The stages in a food chain or web
What is biomass? The dry mass of living material in a specific area at a given
time
What is biomass measured in? gm<sup>-2</sup>
Why is biomass measured as dry mass? The water content can vary, meaning
differences in biomass between two areas can be due to water differences and not
differences in organic matter
Why is energy lost between trophic levels? "Plants lose it because most of the
sun's energy is reflected back into space<div>Animals lose it because:</div><div>-
Some of the organism is not consumed </div><div>-Some energy is lost in
faeces</div><div>-Some energy is lost in heat energy and movement </div>"
What is net primary productivity? The chemical energy available to a primary
consumer from a plant following respiratory losses
How do you calculate NPP? NPP = GPP - respiratory losses
How do you work out the net production of consumers? N = ingested food - (energy
lost in faeces and urine + energy lost in respiration)
Why do food chains have a limited number of trophic levels?Due to energy being lost
between trophic levels, by the time you get to a fourth or fifth trophic level,
there is not enough energy to support a breeding population at a higher trophic
level
What is the nitrogen cycle? "<img src=""image-
18ad6847ea5524c25a379c3c3460952582a205e2.png"">"
What is ammonification? The production of ammonia from dead organisms and faeces,
done by saprobionts
What is nitrification? The oxidation of nitrogen compounds from<div>-Ammonia to
nitrite ions </div><div>-Nitrite ions to nitrate ions</div><div>The process
requires nitrifying bacteria</div>
What is nitrogen fixation? The process of converting nitrogen gas in the air
into nitrogen compounds in the soil
What are the two kinds of bacteria that can perform nitrogen fixation? Free
living nitrogen fixing bacteria- these bacteria are just in the soil, and use the
nitrogen to make amino acids, which are released once the bacteria
dies<div>Mutualistic nitrogen fixing bacteria- these bacteria live in nodules on
the roots of some plants, and give amino acids to the plant in exchange for
carbohydrates from the plant</div>
What is denitrification? The process of converting soil nitrates into nitrogen
gas, performed by denitrifying bacteria
Why does denitrification only happen in anaerobic conditions? Denitrifying
bacteria are anaerobic bacteria
What is the phosphorous cycle? "<img src=""image-
04882cd954d2738c2fc7d0e59a54c490899f5272.png"">"
What is mycorrhizae? Fungi that grow on plant roots to increase its surface
area. Have a mutualistic relationship with the plant
Why do nitrogen containing fertilisers cause reduced species diversity?
Species that grow faster in the presence of nitrogen rich soil will
outcompete other plants
What is leaching? The dissolving of fertilisers in water
What is the effect of leaching? It can make water toxic for humans, causing
cancer
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