B13 Energy And Ecosystems Flashcards
What are producers in a food web
Plants
How can the amount biomass be measured
Measured in terms of mass of carbon or dry mass of tissue per given area.
Energy transfer
Between each trophic level in a food web the majority of the energy is lost due to respiration and excretion. The remaining energy is used to form the biomass.
What is eutrophication
when nitrates leached from fertilised fields stimulate growth of algae in pond.
Eutrophication process
excessive growth of algae creates blanket on surface of H2O which blocks out light.
As result plants below cannot photosynthesis and die.
Bacteria within water feed and respire on dead plant matter.
results in increase in bacteria, which are all respiring and using up O2 within water.
Eventually, fish and other aquatic organisms die due to lack of dissolved O2 in water.
What is leaching
when water-soluble compounds are washed away, often into rivers or ponds.
What could happen if the nitrogen fertiliser leach into water
causes eutrophication.
Natural fertilisers
Pro = cheaper, and often free if the farmer owns animals.
Con =exact minerals and proportions cannot be controlled.
Artificial fertilisers
are chemicals created to contain exact proportions of minerals.
Inorganic substances are more water soluble, and therefore more of these ions dissolve in water surrounding soil.
Whilst this is an advantage to the plant for absorbing the nitrates and phosphates, downside is that their high solubility means that larger quantities are washed away with rainfall and therefore have a greater impact on the environment.
Fertilisers
are added to soil to replace nitrate and phosphates ions lost when plants harvested and removed from nutrient cycles as crops.
fertilisers can be:
• natural (manure)
• artificial (inorganic chemicals).
The nitrogen cycle key processes
I. Saprobiotic nutrition and microbes
2. Ammonification
3. Nitrification
4. Nitrogen fixation
5. Denitrification
What’s GPP
Gross primary production (GPP)
is chemical energy store in plant biomass, in given area or volume.
It is the total energy resulting from photosynthesis.
What’s NPP
Net primary production (NPP) is the chemical energy store in plant biomass taking into account the energy that will be lost due to respiration (R).
NPP calculation
NPP = GPP - R
The NPP is the energy left over that is available to the plant to create new biomass and therefore available to the next trophic level in a food web.
NPP & gpp
How productive an ecosystem is depends on the abiotic and biotic factors. Plenty of water, light, warmth and green plants will maximise the rates of photosynthesis and therefore result in more carbohydrates being produced in the plants. This can be quantified using GPP and NPP.
Net production of consumers
To work out the net production of consumers (N), such as animals, the formula below can be used:
N=I-F+R
= the chemical energy store in ingested food(energy in ingested food)
F = the chemical energy lost to the environment in faeces and urine (energy lost in faeces and urine)
R = respiratory losses.(energy lost in respiration)
Rates of productivity
Rates of productivity are recorded using the units kJ ha-l year-I.
• kj is the unit for energy, but these units also includes per unit area and per year.
• It is recorded as per unit area to standardize the results to enable environments to be compared-it takes into account that different environments will vary in size.
• The units are also per year to take into account the impact seasons will have on rain, light and heat - it provides an annual average to allow fair comparisons between environments.
THE IMPORTANCE OF THE NITROGEN
CYCLE
The air is 78% nitrogen, however plants and animals cannot obtain nitrogen through gas exchange.
• Nitrogen gas (N,) contains a triple bond. NEN
• Microorganisms are needed to convert nitrogen gas into nitrogen containing substances that plants and animals can absorb.
Which biological molecules contain N
Proteins
ATP
Nucleic acids
Why are mycorrhizae are beneficial for plant growth?
I. The fungi increase the surface area for water and mineral absorption
2. The mycorrhizae acts like a sponge so holds water and minerals around the roots.
3. This makes plants more drought resistant and able to take up more inorganic ions.
Their part in the nutrient cycles is therefore improving the uptake of relatively scarce ions, such as phosphate ions.
This is a mutualistic relationship.
What are mycorrhizae
Mycorrhizae are fungal associations between plant roots and beneficial fungi
What is phosphorous used for in organisms
• DNA/RNA
• АТР
• Phospholipid bilayer
It is therefore an essential element for life.
Phosphorous cycle
This cycle is different to the carbon and nitrogen, in that phosphorus is not found as a gas and therefore not in the atmosphere.
Instead it is mainly found as a phosphate ion, in mineral form in sedimentary rocks.
