Ecosystems Flashcards
How does temperature affect ecosystems?
- Affects enzymes controlling metabolic reactions
- Warmer temperatures may allow plants and ectothermic animals to develop faster
- Changes in temperature can trigger migration and/or hibernation in some animal species
- Changes in temp can trigger leaf fall or dormancy in some plants
What are edaphic factors?
- Relate to soil type
- Different soil types have different particle size, which affect the organisms that are able to survive in them
How can human activities like agriculture manipulate the transfer of biomass through ecosystems?
- Creates simple food chains by reducing the number of trophic levels
- They ensure that as much of the energy as possible is transferred into biomass that can be eaten by humans
What is ecological efficiency and how can it be calculated?
- The percentage efficiency at which biomass or energy is transferred from one trophic level to the next
- energy or biomass available after transfer / energy or biomass available before transfer x 100
What are the basic trophic levels in a food chain?
- Producers - make their own food
- Primary consumers - consume producers
- Secondary consumers - consume primary
- Tertiary consumers - consume secondary
What do decomposers do?
- Break down complex materials in dead organisms into simpler ones
- This releases nutrients back into the ecosystem
How is net and gross primary production calculated?
NPP = GPP - respiratory losses
- GPP is the quantity of solar energy that plants convert to organic matter and store as chemical energy
What are some ways energy can be lost from biomass?
- Some energy is lost through photosynthetic reactions
- Not all biomass is digestible by consumers
- Some energy lost to the environment as heat during movement or respiration
- Some energy lost in excretory materials like urine and faeces
What is ammonification?
The conversion of organic nitrogen-containing compounds into substances like ammonia by decomposers
What is nitrification?
- Conversion of ammonia or ammonium ions into nitrites (by nitrosomas) and then nitrates (by nitrobacter)
- Two stage oxidation process
- Nitrate ions can then be absorbed by plants
What is nitrogen fixation?
- Nitrogen gas is converted into nitrogen containing compounds like ammonia
- By rhizobium and azotobacter
- Bacteria in the soil perform this, then convert the ammonia into amino acids
What is detrification?
- Where denitrifying bacteria convert soil nitrates into gaseous nitrogen
- Anaerobic process
What happens if organic matter accumulates in regions without decomposers?
The carbon they contain may become trapped, forming fossil fuels over millions of years
How does global warming affect the levels of carbon dioxide containing compounds in the ocean and atmosphere?
- Global warming reduces the amount of carbon dioxide that can dissolve in oceans, as at higher temps less gas can dissolve in water
- So more carbon dioxide is released into the atmosphere
What is a pioneer community and some of they key characteristics of a pioneer species?
- First stage of succession in which pioneer species colonise an inhospitable environment and make it more suitable for other species
Pioneer species can usually - - reproduce asexually
- germinate rapidly
- photosynthesise
- fix nitrogen from the atmosphere
- tolerate extreme conditions
