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28 Cards in this Set
- Front
- Back
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What is ecology? |
The study of relationships between organisms and their environment |
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Why are ecosystems described as dynamic? |
Because they are constantly changing |
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What are edaphic factors? |
The conditions of the soil whether it's clay (easily waterlogged), sand (water drains v easily) of loam (which retains water) |
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Why are plants usually affected by abiotic factors more than animals? |
Animals are able to migrate to a different climate and shelter, and have a variety of food sources |
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What is biomass and what does a producer convert light energy into? |
The mass of living material in an organism Chemical energy which is then transferred into food |
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What is the only exception to the biomass pyramid? |
Zooplankton usually has a higher biomass than phytoplankton |
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How can biomass of an area be calculated? |
The organism is killed and placed in an oven so the water evaporates until constant mass is obtained This mass is then multiplied by the number of organisms present in the sampling area |
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What is the disadvantage of finding the dry biomass of an organism? |
Small samples need to be taken to prevent the destruction of organisms making it less representative |
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What is ecological efficiency? |
The efficiency with which biomass or energy is transferred from one trophic level to the next |
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Why do produces only convert a small fraction of sunlight they received into biomass? |
Most of the light is reflected and some of the light has unusable wavelength or is transmitted through the leaf |
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What is gross production? |
The total solar energy that plants convert into organic matter |
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What is net production and how do you calculate it? |
The organic matter/biomass that is left over after the plant has used some of it for respiration Gross production - respiratory losses |
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What is primary and secondary production? |
The generation of biomass in a producer and a consumer |
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Why do consumers convert a very small percentage of biomass from their food into organic tissue? |
Not all of the biomass of an organism is eaten out of indigestible e.g. bones or roots Some of the energy is transferred to the environment as heat from metabolic reactions Some energy is lost from an organism through urine and faeces |
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How do you calculate ecological efficiency? |
(Energy or biomass available after transfer)/ (Energy or biomass available before transfer) X100 |
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How do you calculate the biomass consumed in an area? |
Mass or net production X area of land |
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What is the aim of agriculture in terms of biomass? |
To minimise the number of trophic levels so that less energy is lost between levels and the maximum amount of biomass is eaten by humans |
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What is decomposition? |
The chemical process in which a compound is broken down into smaller molecules or elements |
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What does a decomposer do and what else are they known as? |
They break down dead plant or animal matter which turns organic compounds into inorganic ones by secreting extracellular enzymes Saprotrophs |
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What are detritivores? |
They speed up the decay process by breaking the dead material into smaller pieces which increases SA for decomposers to work on They digest internally |
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What is nitrogen needed for and how is it made useful? |
Amino acids and nucleotides It is combined with O or H atoms to be utilised through bacteria |
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What are the four stages of the nitrogen cycle? |
Nitrogen fixation Nitrification Denitrification Ammonification |
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What are the two types of bacteria involved in nitrogen fixation and what do they contain? |
Azotobacter and rhizobium contain nitrogenase which combines nitrogen with hydrogen to form ammonia |
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Where do the bacteria involved in nitrogen fixation live and what do they gain? |
Azotobacter live freely in the soil and rhizobium live in root nodules in leguminous plants They gain carbohydrates from the plant when it photosynthesis |
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What happens in the nitrification stage and what are the conditions? |
Bacteria in the soil convert NH3 into other useful nitrogen-containing compounds Nitrosomonas oxidise NH4+ compunds into NO2- Nitrobacter oxidise NO2- into NO3- Soil needs to be aerated for oxidation |
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What happens in the denitrification stage? |
In anaerobic conditions in the soil denitrifying bacteria convert NO3- back into N2 as its source of energy |
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What happens in the ammonification stage? |
Decomposers convert nitrogen containing compounds in dead organisms into ammonium compounds |
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What are the three ways in which nitrogen can be fixed? |
Through bacteria, Haber cycle and lightning strikes |
