M5 - Energy and Ecosystems Flashcards
(30 cards)
What are consumers?
Living organisms that feed on other living organisms.
What are producers?
Autotrophic organisms (plants, some protists and some bacteria) that make glucose from CO2 and H2O using light energy.
What are Saprobionts?
Organisms that feed on dead organic matter, releasing molecules, minerals and energy that the become available to other living organisms in that ecosystem.
What is a trophic level?
The level at which an organism feeds in a food chain.
In a food chain there are various trophic levels (e.g. producers, _____, _____ etc consumers).
Energy ultimately comes from the ____ and is transferred through the ecosystem through _____. Energy is lost at each trophic level through a variety of ways, but eventually all energy is lost as ____.
primary
secondary
biomass
heat
How is energy lost between trophic levels?
- Heat
- Inedible (e.g. bones/bark)
- Indigestible (e.g. cellulose) - is egested
- Excretion - metabollic waste (e.g. urea)
- Respiration
HIIER
What is biomass? Why is it measured as opposed to normal mass? What type of energy is locked up in biomass?
The dry mass of an organism.
Water content varries during the day/year and water has no significant energy content.
Chemical energy.
What are two types of decomposers? What do they do?
Detritivores - (e.g. earthworms) break down biomass and TAKE IN the remains.
Saprobionts (e.g. fungi and bacteria) complete the process by breaking down the biomass competely - EXCRETING nutrients.
What is the practical experiment to estimate the chemical energy store in biomass?
- Take a sample from an area of known size, weigh it and dry it in an oven below 100 degrees.
- Continue to weigh until the mass no longer changes.
- Burn a known mass in a calorimeter in pure O2. The chamber is insulated to prevent heat loss and the water temperature is measured with a thermometer.
- We know the energy required to increase 1g of water by 1 degrees (specific heat capacity) so can calculate the energy released.
What is primary productivity and what does it depend on?
The rate at which energy is stored in producers .
Depends on:
- Amount of sunlight
- Ability to use energy to synthesise organic compounds
- Other growth factor (e.g. mineral ions)
What happens to solar energy that does not end up reaching producers?
What happens to solar energy that falls on leaves but is not converted into organic matter?
It is absorbed by rocks or water.
- Reflected
- Transmitted through the leaf (misses chloroplasts)
- Wrong Wavelength - not all wavelengths are absorbed or used for photosynthesis.
What is the equation for Net Primary Productivity? What is it available for?
NPP = GPP - R
Photosynthesis (Gross Primary Productivity) - Respiration
NPP is available for growth, reproduction and other trophic levels.
What is the equation for net production of consumers?
N = I - (F+R)
Chemical energy in ingested food - faeces, urine and respiratory loss to environment
How do farmers reduce respiratory losses from livestock?
- Keeping livestock indoors - less energy lost keeping warm.
- Restrict movement and supply food - less energy used moving and finding food.
- Harvest young animals just before adulthood - more energy used for muscle growth in young animals
- Treat livestock with antibiotics - reduce energy loss to pathogens
- Reduce losses to other consumers - (e.g. kill crop pests, keep foxes away from chickens, keep rabbits away from food supply)
What is the equation for efficiency of energy transfer between trophic levels?
energy available after transfer / energy available before transfer x 100
Saprobionts (e.g. ____) secrete ______ _______ on to organic molecules and ____ the products of digestion. Digestion is therefore __________.
Inorganic molecules excreted by decomposers (e.g. _____ and ______) are made available to _______ via _____ cycles.
fungi
hydrolytic enzymes
absorb
extracellular
CO2 and ammonia
producers
nutrient
What are the 4 stages of the nutrient cycle?
- Nitrogen Fixation
- Ammonification
- Nitrification
- Denitrification
What are 3 ways in which nitrogen gas is converted to nitrogen-containing compounds?
- Lightening (nitrogen + oxygen –> nitrogen oxides)
- Industrial processes (e.g. Haber process)
- Fixation by micro-organisms
What happens when nitrogen is fixated by free-living microorganisms/bacteria?
Bacteria reduce nitrogen to ammonia, which can be used to make amino acids.
Nitrogen rich compounds released when they die and decay.
What happens when nitrogen is fixated by mutalistic bacteria? Where does this bacteria live?
Mutalistic bateria live in root nodules of leguminous plants.
Nitrogenase coverts Nitrogen to Ammonia using H+ and ATP and then converted to NH4+ (ammonium ions) to be used by plants. The process requires anaerobic conditions.
The plant uses ammonium ions to make amino acids.
What happens in ammonification? Give examples of nitrogen containing compounds.
Saprobionts feed on faeces and dead organisms releasing ammonia (which then forms ammonium ions) into the soil.
Ammonia is produced from organic nitrogen-containing compounds (e.g. urea, protein, vitamins, nucleic acids).
LEARN NITROGEN CONTAINING COMPOUNDS EXAMPLES
What happens in nitrification?
Ammonium ions are oxidised to nitrites which are oxidised to nitrates - both carried out by nitrifying bacteria.
What happens in denitrification?
Anaerobic denitrifying bacteria reduce soil nitrates into nitrogen gas.
Describe the phosphorous cycle
Phosphates in sedimentary rock deposits.
Weathering and erosion of rocks releases phosphate ions which are dissolved into water (sea, lakes, soil).
Phosphates taken up by plants and incorporated into their biomass.
Plants (containing phosphates) eaten by animals and released by excretion.
Dead plants and animals broken down by saprobionts. Phosphate ions in bones and shells are slow to breakdown - rock deposits and water.
