2.3 - Flows Of Energy And Matter Flashcards
What happens to some of the energy when it enters earths atmosphere
When solar radiation (insolation) enters the Earth’s atmosphere, some of the energy becomes unavailable for ecosystems due to being:
- Absorbed by inorganic matter
- Reflected back into the atmosphere
What is the pathway of radiation through earths atmosphere and what does it involve
The pathway of radiation through the atmosphere involves a loss of radiation through reflection and absorption, with the following (approximate) percentage losses:
- Reflection from clouds ~ 19%
- Absorption of energy by clouds ~ 3%
- Reflection by scatter from aerosols and atmospheric particles ~ 3%
- Absorption by molecules and dust in the atmosphere ~ 17%
Reflection from the surface of the Earth ~ 9%
How does solar energy end up in producers
- Most incoming solar radiation fails to enter chloroplasts in leaves because it is reflected, transmitted (passes straight through the leaf), or is the wrong wavelength to be absorbed
- Of the radiation captured by leaves, only a small percentage ends up as biomass in growth compounds because the conversion of light to chemical energy is inefficient
- In total, only around 0.06% of all solar radiation falling on Earth is captured by plants
What are the pathways of energy through an ecosystem
- Conversion of light energy to chemical energy
- Transfer of chemical energy from one trophic level to another with varying efficiencies
- Overall conversion of ultraviolet and visible light to heat energy by an ecosystem
- Re-radiation of heat energy to the atmosphere
What is ecological efficiency
The percentage of energy transferred from one trophies level to the next with the average being 10%
Why is energy lost from tropic level to tropic level
Energy losses occur due to various reasons, such as movement, inedible parts (e.g. bone, teeth, fur), waste products (e.g. faeces), and the inefficient energy conversions that occur during the process of respiration
- Ultimately, energy is lost as heat due to the second law of thermodynamics
What happens to light energy as it converts to heat and chemical energy
Energy is converted from one form to another but cannot be created or destroyed due to the first law of thermodynamics
The inputs of the system as a whole, and of any individual trophic level, are equal to the outputs
What is ecological efficiency
The efficiency of energy transfer from one trophies level to the next as a percentage
How do you calculate ecological efficiency
Ecological efficiency = (energy used for new biomass / energy supplied) x 100
Answer this question:
A butterfly lays an egg on a blackberry bush. In its first day, the caterpillar that hatches consumes blackberries containing a total of 35 J of energy. 4.1 J of this energy are used to form new caterpillar biomass. Calculate the ecological efficiency of this step of the food chain.
Ecological efficiency = (energy used for new biomass ÷ energy supplied) × 100
Ecological efficiency = (4.1 ÷ 35) × 100
Ecological efficiency = 11.7 %
Answer this question:
A wheat farmer decides to use biological control against insect pests that are eating her wheat crop. The farmer introduces a species of toad. By eating the insect pests the toads ingest 10 000 kJ m-2 yr-1 of energy. The toads lose 7 000 kJ m-2 yr-1 of this energy as heat from respiration and 2 000 kJ m-2 yr-1 of energy in faeces and urine. Calculate the ecological efficiency of energy transfer from the insects to the toads.
Step 1: Calculate the energy used for toad growth (new biomass)
Toad energy received = 10 000 kJ m-2 yr-1
Toad energy losses = 7 000 + 2 000 = 9 000 kJ m-2 yr-1
Energy for growth = 10 000 - 9 000 = 1 000 kJ m-2 yr-1
Step 2: Substitute the values into the equation
Ecological efficiency = (energy used for new biomass ÷ energy supplied) × 100
Ecological efficiency = (1 000 ÷ 10 000) × 100
Ecological efficiency = 10 %
What do primary producers do during photosynthesis
convert light energy to chemical energy stored within biological molecules
What is gross primary production
the amount of chemical energy stored in the carbohydrates within plants (during photosynthesis)
What is gross primary productivity
The rate at which plants are able to store chemical energy via photosynthesis
Solve this question:
The total chemical energy contained within the grass that grows in a 200 m2 field over the course of one year is found to be 1 000 kJ. Calculate the gross primary productivity of the grass field. Give appropriate units.
Step 1: Calculate the total chemical energy contained within the grass in 1 m2 of the field over the course of one year
1 000 ÷ 200 = 5 (kJ)
Step 2: Give the appropriate units
5 kJ m-2 yr-1
Answer this question :
On average, a patch of arctic tundra covering an area of 1 km2 is estimated to produce a total biomass of 1,500 kg per year. Calculate the gross primary productivity of this patch. Give your answer in g m-2.
Step 1: Calculate the average yearly biomass of 1 m2 of the arctic tundra patch (1 km2 = 1 000 000 m2)
1 500 ÷ 1 000 000 = 0.0015 (kg yr-1)
Step 2: Convert this into grams
0.0015 × 1,000 = 1.5 g m-2 yr-1
What is net primary productivity
Net primary productivity (NPP) is the GPP minus plant respiratory losses (R)
How can net primary productivity be defined
NPP can therefore be defined as the rate at which energy is stored in plant biomass, allowing for respiratory losses
NPP is important because it represents the energy that is available to organisms at higher trophic levels in the ecosystem, such as primary consumers and decomposers
What is the equation for net primary productivity
NPP=GPP-R
Answer this question:
The grass in a meadow habitat converts light energy into carbohydrates at a rate of 17 500 kJ m-2 yr-1. The grass releases 14 000 kJ m-2 yr-1 of that energy during respiration. Calculate the net primary productivity of the grass in the meadow habitat.
Step 1: Work out which numbers correspond to which parts of the equation
The meadow grass converts 17 500 kJ m-2 yr-1 into carbohydrates; this is GPP
The meadow grass releases 14 000 kJ m-2 yr-1 of that energy in respiration; this is R
Step 2: Substitute numbers into the equation
NPP = GPP - R
NPP = 17 500 - 14 000
Step 3: Complete calculation
17 500 - 14 000 = 3 500
NPP = 3 500 kJ m-2 yr-1
What is Gross secondary productivity
Gross secondary productivity (GSP) is the total energy/biomass assimilated by consumers and is calculated by subtracting the mass of faecal loss from the mass of food eaten
What is the equation for GSP
GSP = food eaten - faecal loss
How do you calculate NSP
NSP=GSP-R
Solve this question:
In a patch of woodland, caterpillars ingest 2 000 kJ m-2 yr-1 of chemical energy from the biomass of oak leaves. The caterpillars lose 1 200 kJ m-2 yr-1 of this energy in faeces. They lose a further 600 kJ m-2 yr-1 of this energy through respiration. Calculate the net secondary productivity of the caterpillars.
Step 1: Calculate GSP
GSP = food eaten - faecal loss
GSP = 2 000 - 1 200
GSP = 800 kJ m-2 yr-1
Step 2: Calculate NSP
NSP = GSP - R
NSP = 800 - 600
NSP = 200 kJ m-2 yr-1
What is annual yield
The annual yield for a natural resource (such as a forest) is the annual gain in biomass or energy, through growth
What is the maximum sustainable yield
The maximum sustainable yield is the maximum amount of a renewable natural resource that can be harvested annually without compromising the long-term productivity of the resource (i.e. without a reduction in natural capital)
What resources does max sustainable yield apply to
Crops
Define max sustainable yield
The amount of renewable natural resource that can be harvested annually without compromising the long term productivity of the reosurse
What productivity is max sustainable yield in relation to
In this way, maximum sustainable yield is equivalent to the net primary productivity (NPP) or net secondary productivity (NSP) of a system (as these values represent the amount of energy stored and new plant or animal biomass per year)
What are the 7 stores in a carbon cycle
- The atmosphere (as CO2)
- Sedimentary rocks
- Fossil fuels like coal, oil, and gas; coal is largely carbon
- Soil and other organic matter
- Vegetation (e.g. as cellulose)
- Animals
- Dissolved in the oceans (as CO2)
What are the 6 flows in a carbon cycle
- Consumption (feeding)
- Death and decomposition
- Photosynthesis
- Respiration
- Dissolving
- Fossilisation
How is photosynthesis a store
- Autotrophs use the energy of sunlight to ‘fix’ carbon dioxide, turning its carbon into sugars and other organic molecules
- This removes carbon from the atmosphere
- Terrestrial plants use gaseous CO2 directly from the air
- Aquatic organisms use CO2 dissolved in water
- As much CO2 is fixed from ocean microorganisms, as from terrestrial plants
How is sedimentation a store
- Plants that die are not fully decomposed by saprobionts; their bodies form layers of sediment that can accumulate over millions of years, locking carbon into the ground
- This sediment is a store of energy and can form fossil fuels like peat and coal
- Aquatic organisms that die also form sediments on the sea bed; these can go on to form other fossil fuels like oil and gas
- Shells and other calcium-containing body parts can form sedimentary rocks such as limestone
- The existence of life forms over billions of years has shaped the biosphere, in that their remains are still being recycled
How is respiration a flow
- All life forms respire, including autotrophs
- Heterotrophs rely on respiration for all their energy needs
- Respiration puts CO2 into the atmosphere, in the opposite direction to photosynthesis
- Anaerobic respiration also releases CO2 into the atmosphere, via fermentation by yeast, moulds and bacteria
How is carbon moved through feeding
- Carbon is passed from autotroph to heterotroph during feeding
- Carbon is also passed from primary consumer to secondary consumer
- Biomass transfer always includes the transfer of carbon, the main element in biomass
How is decay and decomposition a flow
- Dead plants and animals are fed upon by detritivores and decayed by saprophytes
- Releasing carbon into the surroundings
- Supplying carbon to the detritivores
- Supplying carbon to the saprophytes
- Waste matter such as faeces and urine is used by decaying saprobionts
- Such processes can release CO2 back into the air
How does human impact affect the carbon cycle
Human activities such as burning fossil fuels, burning, deforestation, urbanisation and agriculture impact the balance of storages and flow within the carbon cycle
Answer this question:
Discuss human impacts on the carbon cycle
Humans have a significant impact on the carbon cycle, mainly through the combustion of fossil fuels and deforestation. Fossil fuels such as coal, oil, and natural gas contain carbon that has been stored underground for millions of years. When these fuels are burned, carbon is released into the atmosphere as carbon dioxide (CO2), contributing to the greenhouse effect and climate change.
Deforestation, especially in tropical regions, also affects the carbon cycle. Trees and other plants absorb CO2 from the atmosphere during photosynthesis, storing carbon in their biomass. When trees are cut down and burned or left to decay, the stored carbon is released back into the atmosphere as CO2.
Other human activities that contribute to carbon emissions include agriculture, transportation, and industry. For example, livestock farming produces methane, a potent greenhouse gas, through enteric fermentation in cows, sheep, and other ruminants. Transportation, especially cars and trucks, burns fossil fuels and releases CO2 into the atmosphere. Industry and manufacturing processes also contribute to carbon emissions through the burning of fossil fuels and other energy-intensive processes.
What are the stores in the nitrogen cycle
- Organisms (organic)
- Soils ( inorganic)
- Fossil fuels (organic)
- Atmosphere (inorganic)
- Water bodies (inorganic)
What are the flows in the nitrogen cycle
- Nitrogen fixation by bacteria and lightning
- Absorption
- Assimilation
- Consumption (feeding)
- Excretion
- Death and decomposition
- Denitrification by bacteria in water logged soils
What are the human impacts on the nitrogen cycle
- increased use of fertilisers
- burning of fossil fuels
- industrial nitrogen fixation
- land use changes
- livestock farming
- wastewater treatment
How does increased use of fertilisers impact the nitrogen cycle
- Fertilisers, especially nitrogen fertilisers, are widely used in agriculture to increase crop yield
However, excess nitrogen can leach into waterways, leading to eutrophication and harmful algal blooms
How does burning of fossil fuels impact the nitrogen cycle
Burning fossil fuels releases nitrogen oxides into the atmosphere, which can lead to the formation of acid rain
Acid rain can increase soil acidity, which can affect the ability of plants to take up nitrogen
How does industrial nitrogen fixation impact the nitrogen cycle
Humans have developed methods to fix nitrogen industrially, for example, in the production of fertilisers and explosives
This has greatly increased the amount of fixed nitrogen available for use in human activities
How has land use change impacted the nitrogen cycle
Conversion of natural landscapes, such as forests and wetlands, into agricultural or urban areas can lead to changes in nitrogen cycling
For example, wetlands are important nitrogen sinks, and their loss can result in nitrogen being released into waterways and the atmosphere
How does livestock farming impact the nitrogen cycle
Livestock farming produces large amounts of manure and urine, which can contribute to increased nitrogen inputs to ecosystems
This can lead to eutrophication and other environmental problems if not managed properly
How does waste water treatment impact the nitrogen cycle
Wastewater treatment plants can be a source of nitrogen pollution if they do not effectively remove nitrogen from treated water before releasing it into the environment
