Topic 5 - Energy Transfer in Ecosystems Flashcards
What is an ecosystem ?
all the living organisms in an area and all the non living conditions.
What are producers ?
Organisms that make their own food, e.g. plants and algae produce their own food through photosynthesis.
what is the function of photosynthesis in plants?
to release energy for growth and to make useful organic compounds.
what is the biomass of a plant ?
the biological molecules in a plant it can be measures in terms of mass of carbon, or dry mass of tissue per given area.
How is energy transferred through an ecosystem ?
when living organisms eat other organisms.
what is dry mass ?
the mass of the organism with the water removed.
how would you measure dry mass ?
- a sample of an organism is dried in an oven set to a low temperature.
- the mass is weighted at regular intervals until the weight is constant so you know that all water is removed.
- typical unit is km m^-2
how can you estimate the amount of chemical energy in biomass ?
- in a calorimeter.
- a sample of dry biomass is burnt and the energy released is used to heat a known volume of water.
- the chnage in temperature of the water is used to calculate the chemical energy of the dry biomass.
what is the calculation for efficiency of energy transfer ?
(energy out / energy in) x 100
What is the calculation for net primary consumption ?
net primary production = gross primary production - respiratory loss.
NPP = GPP-R
what is net primary production
the energy available to the plant for growth and reproduction
what is the equation for net production of consumers
net production of consumers = chemical energy store - (energy loss by faeces/urine - respiratory loss).
N=I - (F +R )
what is the function of decomposers
they breakdown dead or undigested material, allowing nutrients to be recycled.
how do farmers reduce energy loss in plants
- simplifying food webs by eliminating organisms that compete with the organisms being farmed.
- weeds- compete with plants for resources (herbicides)
- insects - damage leaved, eat crops, cause disease (insecticides)
how can farmers reduce respiratory loss
restricting movement - small pens
heating - indoors and heated
what is a natural ecosystem
one that has not been chnaged by human activity.
Nutrients ar recycled through food webs, but human activity often disturbs the cycle of nutrients
what are saprobionts
decomposer bacteria
what do saprobionts do ?
feed on the remains of dead plabts and animals and on their waste producs, breaking them down. This allows for chemical elements in their remains to be recycled.
How do saprobioints digest waste
Saprobiotic nutrition through Extracelular digestion - they secrete enxymes and digest food externally, then absorb the nutrients they need. Organic molecules are broken down into inorganic ions.
what is mycorrhizae
- fungi forming a symbiotic relationship with the roots of plants.
- The fungi are made of long thin strands called hyphae which connects to the plants roots.
- The hyphae increase the surface area of the plants roots, helping the plant absorb ions from the soil (e.g. phosphorous).
- Hyphae also increases the uptake of water.
- In turn, the fungi obtain organic compounds such as glucose from the plant.
what do plants and animals need nitrogen for
to make proteins and nucleic acid (DNA and RNA)
why do plants and animals need bacteria to convert nitrogen gas to nitrogen containing compounds
They cannot use nitrogen in the form of gas
what is the nitrogen cycle
the process of converting nitrogen to a usable form and then passing it between different living organisms and the non living environment
what are the 4 processes in the nitrogen cycle
nitrogen fixing, ammonification, nitrification and denitrification
Explain the process of nitrogen fixing
reduction
* nitrogen gas in the atmosphere is turned into nitrogen containing compounds by combining nirogen with hydrogen.
* They have ezymes called nitrogenase.
* Biological nitrogen fixing is carried out by bacteria in the root nodules of legummes, which convert nitrogen into ammonia which forms ammonium ions in solutions that can be used by plants.
* They form a mutualistic relationship with the plant as they provide the plant with nitrogen compounds and the plant provides them with carbohydrates.
What happens during ammonification
Nitrogen compounds from dead organisms or animal waste are turned into ammonia by saprobionts which goes onto form ammonium ions.
What is nitrification
oxidation
* ammonium ions in the soil are changed into nitrogen compounds that can be used by plants (nitrates).
* Nitrifying bacteria chnage ammonium ions into nitrites.
* Other nitrifying bacteria changed nitrites into nitrates.
What is denitrification
reduction
* nitrates in the soil are converted into nitogen gas by denitrifying bacteria - they use nitrates in the soil to carry out respiration and produce nitrogen gas.
* This makes soil less fertile.
* This happens under anaerobic conditions where there is no oxygen, e.g. waterlogged soils.
what is the phosphorous cycle
shows how phosporus is passed through an ecosystem
What do plants and animals need phosporus for
to male biological molecules like phospholipids, DNA and RNA.
What is the process of the phosphorus cycle
- Phosphate ions in rocks are released into the soil by weathering.
- Phosphate ions are taken into the plants through the roots. Mycorrhizae increases the rate at which phosphorus can be assimilated (absorbed and used).
- Phosphate ions are transferred through the food chains as animals eat the plants and in turn are eaten by other animals.
- Phosphate ions are lost from the animals in waste products.
- When plants and animals die, saprobionts are involved in breaking down the organic compounds, releasing phosphate ions into the soil for assimilation by plants. Microoganisms also release phosphate ions into soil by urine and facease.
- Weathering of roks also releases phosphate ions into seas, lakes and rivers. This is taken up by aquatic producers such as algae and passed along in food chains to birds.
- The waste produced by birds contains lots of phosphate ions into the soil and is used as a natural fertiliser.
How are nutrients lost by harvestation
when crops are harvested, they’re removed from the field, decreasing the mineral ions of the soil in the nitrogen or phosphorous cycle.
What are artificial fertilisers
inorganic fertilisers - contain pure chemicals as powders or pellets
what are natural fertilisers
organic matter - manure, composted vegetables, crop residues and sewage sludge.
what do fertilisers do
replace the lost miners ions and nutrients from farming, so more energy can be used for growth, increasing efficiency of energy transfer.
what eutrophication
- mineral ions leached from fertilised fields stimulate the rapid growth of algae in ponds and rivers.
- Large amounds of algae block light from reaching plants.
- Eventually the plants die as they cannot photosynthesise enought,
- Saprobiots feed on the dead plant matter, increasing the number of bacteria and reucing the oxygen concentration available in the water due to aerobic respiration.
- Fish and other aquatic organisms die because there is not enough dissolved oxygen.
give an example of saprobiotic feeders
fungus
