6.3.1 Ecosystems Flashcards
Ecosystem
A dynamic set of interactions between the living populations of organism and its abiotic environment..
State biotic factors that affect can affect population size.
3 Ps:
Parasitism
Predation
Pathogens (communicable disease)
Competition:
Intraspecific and interspecific
Describe the different types of competition
Intraspecific:
Competition in a population between species that are the same.
Interspecific:
Competition between species that are not the same.
Describe abiotic factors that can affect an ecosystem.
Light (in plants):
More light allows more plants as they photosynthesise more.
Competition can occur due to differing light availability.
Water availability (affects plants more):
Lack of water leads to water stress and plants wilting
Water is needed for photosynthesis
Temperature:
This affects enzymes in metabolic conditions
Seasonal change can cause migration and hibernation in animals and seed dormancy and flowering in plants.
What is biomass and how can the biomass of an organism be calculated.
Biomass:
The dry weight of all organic matter in an organism.
Calculating biomass:
- Measure the mass of an organism.
- Place the organism in an oven and heat very low at a low temperature to allow evaporation of water.
- Heat organism until no mass change occurs.
- Measure the final mass —> Biomass.
How is the energy contained in a biomass calculated?
Energy can be calculated by how much heat is released from combustion.
The dry biomass of an organism is heated in the presence of saturated oxygen in a calorimeter.
The energy given off in the reaction is recorded.
Pyramid of numbers.
Ecological pyramid that shows the number of individuals in a trophic level.
This is not the most representative as organism differ in mass
Pyramid of biomass
Ecological pyramid that shows the weight of biological matter at each trophic level.
Pyramid of energy
Ecological pyramid that shows the energy content of biological matter at each trophic level.
This is the most efficient as it accurately reflects energy available at the next trophic level.
Niche
A population's role in its ecosystem. This includes: Its feeding role in the food chain. The type of food a population consumes. Its microhabitat. Its reproductive method
Detritus
Dead and waste matter not eaten by consumers
Nitrogen fixation
The process in which nitrogen gas, N2, is converted to ammonia.
N2–> NH3
Ammonia reacts with water to form ammonium ions.
Nitrogen fixation only occurs in aerated soil as it is an oxidation process.
There are nitrogen fixing bacteria present in the soil and some in the root nodules in plants.
What genus of nitrogen fixing bacteria are in the soil.
Azotobacter:
They use nitrogenase to convert nitrogen gas to ammonia.
The genus of nitrogen fixing bacteria are present at the root nodule of legumes.
Rhizobium:
They have a mutualistic relationship with leguminous plants.
Rhizobium get carbohydrates made by the plant in photosynthesis.
The leguminous plants gain amino acids from the nitrogen fixed by Rhizobium.
Nitrification and the bacteria involved in the process.
The process of converting ammonia into nitrite (NO2-) and nitrates (NO3-)
This involves nitrifying bacteria free in the soil:
Nitrosomonas: converts ammonia into nitrites
Nitrobacter: converts nitrites into nitrates.
Denitrification
The process of converting nitrates in the soil, back to nitrogen gas in the air.
This involves the enzyme nitrate reductase:
This is an anaerobic process that takes place in waterlogged soil.
Ammonification
The process carried out by decomposers:
Converts nitrogen containing compounds in dead matter (proteins, nucleic acids), urine (urea) and faeces, into ammonium compounds.
Processes in the nitrogen cycle remove nitrogen from the air.
Nitrogen fixation: Conversion of nitrogen gas into ammonia.
Lightning: Electrical current which splits nitrogen in the air to ammonia.
Processes in the nitrogen cycle add nitrogen back into the air.
Denitrification: The breakdown of nitrates back into nitrogen gas back bacteria.
Difference between decomposers and detritivores.
Decomposers:
An organism that feeds on and breaks down dead organic matter into inorganic ions like ammonium. They perform external digestion by secreting extracellular enzymes.
Includes fungi and bacteria.
Detritivores:
Organisms that feed on detritus. They break down detritus into smaller pieces that increases surface area for decomposers.
They perform internal digestion: using extracellular enzymes internally.
Include: earthworms, woodlice.
Processes that remove carbon dioxide from the air. (2)
CO2 dissolving in oceans:
The sea is a sink. Carbon dioxide dissolves and forms inorganic ions which plants can using, such as carbonates.
Photosynthesis:
Photosynthetic organism convert CO2 into organic matter like: carbohydrates, protein and lipids.
Processes that add carbon dioxide back into the air. (3)
Combustion of fossil fuels:
Fossil fuels contain organic matter which is released in the formed of carbon dioxide when undergoing complete combustion
Respiration performed by all producers, consumers and decomposers:
Organic molecules broken down to release ATP. CO2 is released as a waste product.
Decomposition:
Decomposers break down organic material to release CO2.
Death in the carbon cycle.
When producers and consumers die, they are broken down by decomposers.
Organic matter is converted back into carbon dioxide and release in the air.
If there are not decomposers present then organic matter in not broken down. It can become trapped under soil over thousands of years and become fossils, oil or natural gas.
Feeding in the carbon cycle.
Carbon molecules are passed down the food chain.
Producers—> 1 Consumers—> 2 Consumers—> 3 consumers etc
