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Define an open system.
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All Flashcards in Topic 2.5
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2.5.130 cards
Define an open system.
An open system exchanges both energy and matter with its surroundings.
Energy + matter exchange
State the first law of thermodynamics.
Energy cannot be created or destroyed; it can only be transformed from one form to another.
Transformed
Define an open system.
An open system exchanges both energy and matter with its surroundings.
Energy + matter exchange
State whether energy cycles in ecosystems.
Energy does not cycle; it flows through ecosystems and is lost as heat.
Flows, not cycles
State whether energy cycles in ecosystems.
Energy does not cycle; it flows through ecosystems and is lost as heat.
Flows, not cycles
State the first law of thermodynamics.
Energy cannot be created or destroyed; it can only be transformed from one form to another.
Transformed
State the main input and the main output of energy in ecosystems.
Main input is sunlight; main output is heat.
Sun in, heat out
State the main input and the main output of energy in ecosystems.
Main input is sunlight; main output is heat.
Sun in, heat out
State the second law of thermodynamics.
Every energy transfer is inefficient; some energy is dissipated as heat, so less usable energy remains.
Inefficient + heat
State the second law of thermodynamics.
Every energy transfer is inefficient; some energy is dissipated as heat, so less usable energy remains.
Inefficient + heat
State the first law of thermodynamics.
Energy cannot be created or destroyed, only transformed.
Transformed
State the first law of thermodynamics.
Energy cannot be created or destroyed, only transformed.
Transformed
Explain why energy does not cycle in ecosystems.
Energy flows through ecosystems and is eventually lost as heat, so it cannot be recycled.
Lost as heat
State the second law of thermodynamics.
Energy transfers are inefficient and some energy becomes heat.
Inefficient + heat
Explain why less energy is available at higher trophic levels.
Energy is used for respiration, movement and maintenance and much is lost as heat, so only a small proportion becomes new biomass.
Respiration + heat
Explain why energy does not cycle in ecosystems.
Energy flows through ecosystems and is eventually lost as heat, so it cannot be recycled.
Lost as heat
State the second law of thermodynamics.
Energy transfers are inefficient and some energy becomes heat.
Inefficient + heat
Explain why less energy is available at higher trophic levels.
Energy is used for respiration, movement and maintenance and much is lost as heat, so only a small proportion becomes new biomass.
Respiration + heat
State two phrases that commonly gain marks in thermodynamics answers.
Use “energy is transformed” for the first law and “transfers are inefficient with heat loss” for the second law.
Exact mark phrases
Define an open system in ecology.
An open system exchanges energy and matter with its surroundings.
Energy + matter
Outline the basic pathway of energy through an ecosystem.
Sunlight is captured by producers, transferred by feeding through consumers, and leaves the system as heat at each step.
Capture → transfer → heat
Outline the basic pathway of energy through an ecosystem.
Sunlight is captured by producers, transferred by feeding through consumers, and leaves the system as heat at each step.
Capture → transfer → heat
Define an open system in ecology.
An open system exchanges energy and matter with its surroundings.
Energy + matter
State two phrases that commonly gain marks in thermodynamics answers.
Use “energy is transformed” for the first law and “transfers are inefficient with heat loss” for the second law.
Exact mark phrases
Explain how the second law helps explain short food chains.
Heat loss at each transfer reduces usable energy at higher trophic levels, limiting the number of trophic levels supported.
Heat loss limits levels
Explain why higher trophic levels contain less energy.
Energy is lost as heat at each transfer so less usable energy remains to build biomass at higher levels.
Heat loss
Explain why eating at lower trophic levels is often more energy efficient.
Fewer energy transfers means less heat loss, so more of the original energy supports food production.
Fewer transfers
Explain why higher trophic levels contain less energy.
Energy is lost as heat at each transfer so less usable energy remains to build biomass at higher levels.
Heat loss
Explain why eating at lower trophic levels is often more energy efficient.
Fewer energy transfers means less heat loss, so more of the original energy supports food production.
Fewer transfers
Explain how the second law helps explain short food chains.
Heat loss at each transfer reduces usable energy at higher trophic levels, limiting the number of trophic levels supported.
Heat loss limits levels
2.5.250 cards
Define cellular respiration.
Cellular respiration is the process that releases energy from glucose in cells, usually using oxygen.
Releases energy from glucose
Define photosynthesis.
Photosynthesis is the conversion of light energy into chemical energy stored in glucose.
Light → glucose
State two reasons energy is lost between trophic levels.
Energy is lost as heat from respiration and in waste/uneaten material (faeces, bones, plant fibre).
Heat + waste/uneaten
Define energy efficiency in a food chain.
Energy efficiency is the percentage of energy transferred from one trophic level to the next.
Percent transferred
State the process that traps solar energy as chemical energy.
Photosynthesis.
Light trapped
Define photosynthesis.
Photosynthesis is the conversion of light energy into chemical energy stored in glucose.
Light → glucose
Define cellular respiration.
Cellular respiration is the process that releases energy from glucose in cells, usually using oxygen.
Releases energy from glucose
State two reasons energy is lost between trophic levels.
Energy is lost as heat from respiration and in waste/uneaten material (faeces, bones, plant fibre).
Heat + waste/uneaten
Define energy efficiency in a food chain.
Energy efficiency is the percentage of energy transferred from one trophic level to the next.
Percent transferred
State the process that traps solar energy as chemical energy.
Photosynthesis.
Light trapped
State the process that releases energy from glucose in cells.
Cellular respiration.
Releases energy
State what happens to energy during respiration.
Some energy is transferred to ATP for life processes and a significant amount is released as heat.
Heat released
Define incomplete consumption.
Incomplete consumption is when not all parts of an organism are eaten, so energy in those parts is not transferred.
Not all eaten
State the approximate value of the 10% rule.
On average, about 10% of energy at one trophic level becomes biomass available to the next level.
~10% passes on
Define incomplete consumption.
Incomplete consumption is when not all parts of an organism are eaten, so energy in those parts is not transferred.
Not all eaten
State the inputs and outputs of photosynthesis.
Inputs: carbon dioxide and water. Outputs: glucose and oxygen.
CO2 + H2O → glucose + O2
State the approximate value of the 10% rule.
On average, about 10% of energy at one trophic level becomes biomass available to the next level.
~10% passes on
State the process that releases energy from glucose in cells.
Cellular respiration.
Releases energy
State the inputs and outputs of photosynthesis.
Inputs: carbon dioxide and water. Outputs: glucose and oxygen.
CO2 + H2O → glucose + O2
State what happens to energy during respiration.
Some energy is transferred to ATP for life processes and a significant amount is released as heat.
Heat released
State whether cellular respiration occurs in plants.
Yes. Plants respire continuously to release energy for life processes.
Plants respire
State where photosynthesis occurs in plant cells.
Photosynthesis occurs in chloroplasts.
Chloroplasts
Explain why energy transfer efficiency is low.
Energy is used for respiration, movement and maintenance and is lost as heat and waste rather than becoming new biomass.
Heat + waste
State two major pathways for energy loss between trophic levels.
Heat loss from respiration and losses in waste/uneaten material.
Heat + waste
Explain why energy transfer efficiency is low.
Energy is used for respiration, movement and maintenance and is lost as heat and waste rather than becoming new biomass.
Heat + waste
Define inefficient digestion.
Inefficient digestion is when not all ingested food is absorbed; energy leaves the body as faeces.
Not all absorbed
State whether cellular respiration occurs in plants.
Yes. Plants respire continuously to release energy for life processes.
Plants respire
Define inefficient digestion.
Inefficient digestion is when not all ingested food is absorbed; energy leaves the body as faeces.
Not all absorbed
State two major pathways for energy loss between trophic levels.
Heat loss from respiration and losses in waste/uneaten material.
Heat + waste
State where photosynthesis occurs in plant cells.
Photosynthesis occurs in chloroplasts.
Chloroplasts
State the approximate proportion of energy transferred to the next trophic level.
About 10% (order-of-magnitude).
~10%
Explain how low efficiency affects food chain length.
Low transfer efficiency leaves too little energy at higher trophic levels to support many levels, so chains are short.
Too little energy higher up
Explain how low efficiency affects food chain length.
Low transfer efficiency leaves too little energy at higher trophic levels to support many levels, so chains are short.
Too little energy higher up
Explain why respiration reduces energy transfer between trophic levels.
Organisms use energy for metabolism and release much of it as heat, so less becomes new biomass available to the next level.
Less biomass formed
Explain why photosynthesis is important for energy flow in ecosystems.
It traps solar energy and stores it as chemical energy in biomass that can be transferred through food chains.
Traps sunlight into biomass
State the main form in which energy leaves organisms during transfer.
Energy leaves mainly as heat released during respiration.
Heat from respiration
Explain why photosynthesis is important for energy flow in ecosystems.
It traps solar energy and stores it as chemical energy in biomass that can be transferred through food chains.
Traps sunlight into biomass
State the main form in which energy leaves organisms during transfer.
Energy leaves mainly as heat released during respiration.
Heat from respiration
State the approximate proportion of energy transferred to the next trophic level.
About 10% (order-of-magnitude).
~10%
Explain why respiration reduces energy transfer between trophic levels.
Organisms use energy for metabolism and release much of it as heat, so less becomes new biomass available to the next level.
Less biomass formed
Explain why higher trophic levels usually have lower biomass.
Less energy becomes new biomass at each transfer because most is lost as heat and waste, so biomass decreases at higher levels.
Less energy for growth
Explain why higher trophic levels usually have lower biomass.
Less energy becomes new biomass at each transfer because most is lost as heat and waste, so biomass decreases at higher levels.
Less energy for growth
Explain how respiration illustrates the second law of thermodynamics.
Respiration releases heat, showing that energy transfers are inefficient and usable energy decreases.
Heat = inefficiency
State how energy enters most ecosystems.
Energy enters mainly as sunlight and is captured by producers via photosynthesis.
Sunlight captured
State how energy enters most ecosystems.
Energy enters mainly as sunlight and is captured by producers via photosynthesis.
Sunlight captured
Explain how respiration illustrates the second law of thermodynamics.
Respiration releases heat, showing that energy transfers are inefficient and usable energy decreases.
Heat = inefficiency
Explain why biomass generally decreases up a food chain.
Because only a small proportion of energy becomes new biomass at each trophic transfer; most is lost as heat and waste.
Less energy for growth
Explain why diets based on lower trophic levels can be more energy efficient.
Fewer trophic transfers means less energy is lost as heat before reaching humans.
Fewer transfers
Explain why biomass generally decreases up a food chain.
Because only a small proportion of energy becomes new biomass at each trophic transfer; most is lost as heat and waste.
Less energy for growth
Explain why diets based on lower trophic levels can be more energy efficient.
Fewer trophic transfers means less energy is lost as heat before reaching humans.
Fewer transfers
2.5.322 cards
Define a pyramid of numbers.
A pyramid of numbers shows the number of individual organisms at each trophic level.
Counts individuals
Define ecological pyramids.
Ecological pyramids are diagrams that represent trophic levels using numbers, biomass, or energy, with producers at the base.
Numbers, biomass, energy
Define a pyramid of numbers.
A pyramid of numbers shows the number of individual organisms at each trophic level.
Counts individuals
Define a pyramid of energy.
A pyramid of energy shows energy flow per unit area per unit time at each trophic level.
Energy flow rate
Define a pyramid of energy.
A pyramid of energy shows energy flow per unit area per unit time at each trophic level.
Energy flow rate
Define a pyramid of biomass.
A pyramid of biomass shows the total dry mass of organisms at each trophic level.
Dry mass per level
Define biomass.
Biomass is the total dry mass of living organisms in a given area, representing stored chemical energy at a trophic level.
Dry mass in an area
Define a pyramid of biomass.
A pyramid of biomass shows the total dry mass of organisms at each trophic level.
Dry mass per level
Define ecological pyramids.
Ecological pyramids are diagrams that represent trophic levels using numbers, biomass, or energy, with producers at the base.
Numbers, biomass, energy
Define biomass.
Biomass is the total dry mass of living organisms in a given area, representing stored chemical energy at a trophic level.
Dry mass in an area
Why can a pyramid of numbers be inverted?
One large producer, such as a tree, can support many consumers like insects, making the level above wider.
One supports many
Why is a pyramid of energy always upright?
Energy is lost as heat at every trophic transfer, so less energy is available at higher levels.
Heat loss
Why is a pyramid of energy always upright?
Energy is lost as heat at every trophic transfer, so less energy is available at higher levels.
Heat loss
Explain why biomass is measured as dry mass rather than fresh mass.
Water content varies widely and does not contain usable chemical energy, so drying allows fair comparison of stored energy between organisms and trophic levels.
Water varies; no usable energy
Why can biomass pyramids be inverted in aquatic ecosystems?
Producers like phytoplankton have low standing biomass but reproduce rapidly, supporting larger consumer biomass.
Fast turnover
Why can a pyramid of numbers be inverted?
One large producer, such as a tree, can support many consumers like insects, making the level above wider.
One supports many
Why are producers always at the base of ecological pyramids?
Producers capture incoming energy, usually sunlight, and convert it into biomass that supports all higher trophic levels.
Energy enters at producers
Explain why biomass is measured as dry mass rather than fresh mass.
Water content varies widely and does not contain usable chemical energy, so drying allows fair comparison of stored energy between organisms and trophic levels.
Water varies; no usable energy
Why are producers always at the base of ecological pyramids?
Producers capture incoming energy, usually sunlight, and convert it into biomass that supports all higher trophic levels.
Energy enters at producers
Why can biomass pyramids be inverted in aquatic ecosystems?
Producers like phytoplankton have low standing biomass but reproduce rapidly, supporting larger consumer biomass.
Fast turnover
What general trend do ecological pyramids show?
They show that numbers, biomass, and available energy usually decrease at higher trophic levels.
Less higher up
What general trend do ecological pyramids show?
They show that numbers, biomass, and available energy usually decrease at higher trophic levels.
Less higher up
2.5.438 cards
Define productivity in ecosystems.
Productivity is the rate at which new biomass is produced in an ecosystem, usually by producers through photosynthesis.
Rate of biomass production
State what productivity measures: a total or a rate?
Productivity measures a rate: how quickly new biomass is produced.
It is a rate
Define productivity.
Productivity is the rate at which new biomass is produced in an ecosystem.
Rate of biomass
Define productivity in ecosystems.
Productivity is the rate at which new biomass is produced in an ecosystem, usually by producers through photosynthesis.
Rate of biomass production
State what productivity measures: a total or a rate?
Productivity measures a rate: how quickly new biomass is produced.
It is a rate
Define productivity.
Productivity is the rate at which new biomass is produced in an ecosystem.
Rate of biomass
State the relationship between GP, NP, and respiration.
Net productivity equals gross productivity minus respiration: NP = GP − R.
Subtract respiration
State the relationship between GP, NP, and respiration.
Net productivity equals gross productivity minus respiration: NP = GP − R.
Subtract respiration
State the difference between gross and net productivity.
Gross productivity is total energy captured; net productivity is what remains after respiration losses.
Before vs after respiration
Define gross productivity (GP).
Gross productivity is the total biomass or energy gained by producers through photosynthesis before losses to respiration.
Total captured
Define gross productivity (GP).
Gross productivity is the total biomass or energy gained by producers through photosynthesis before losses to respiration.
Total captured
State the difference between gross and net productivity.
Gross productivity is total energy captured; net productivity is what remains after respiration losses.
Before vs after respiration
State the formula for net productivity.
NP = GP − R.
Subtract respiration
Define net productivity (NP).
Net productivity is the biomass or energy remaining after respiration losses, available for growth, reproduction, and transfer to the next trophic level.
Available after respiration
State the formula for net productivity.
NP = GP − R.
Subtract respiration
Define net productivity (NP).
Net productivity is the biomass or energy remaining after respiration losses, available for growth, reproduction, and transfer to the next trophic level.
Available after respiration
Explain what respiration represents in productivity calculations.
Respiration represents energy used by organisms for metabolism and life processes, released mainly as heat.
Energy used + heat
State the core relationship between NP, GP and respiration.
Net productivity equals gross productivity minus respiration: NP = GP − R.
NP = GP − R
Explain what respiration represents in productivity calculations.
Respiration represents energy used by organisms for metabolism and life processes, released mainly as heat.
Energy used + heat
State the core relationship between NP, GP and respiration.
Net productivity equals gross productivity minus respiration: NP = GP − R.
NP = GP − R
State which type of productivity is available to consumers and why.
Net productivity is available to consumers because it is the biomass remaining after producers use energy for respiration.
Consumers use NP
Explain why net productivity decreases at higher trophic levels.
Energy is lost as heat through respiration at each transfer, so less energy remains to form new biomass at higher levels.
Heat loss each transfer
Explain why net productivity decreases at higher trophic levels.
Energy is lost as heat through respiration at each transfer, so less energy remains to form new biomass at higher levels.
Heat loss each transfer
State which type of productivity is available to consumers and why.
Net productivity is available to consumers because it is the biomass remaining after producers use energy for respiration.
Consumers use NP
What type of organisms are responsible for most productivity?
Producers such as plants and algae are responsible for most productivity because they convert sunlight into chemical energy through photosynthesis.
Plants and algae
What type of organisms are responsible for most productivity?
Producers such as plants and algae are responsible for most productivity because they convert sunlight into chemical energy through photosynthesis.
Plants and algae
Why is productivity described as a rate rather than a total?
Productivity measures how quickly new biomass is produced over time, not the total amount present.
Speed of production
Why is productivity described as a rate rather than a total?
Productivity measures how quickly new biomass is produced over time, not the total amount present.
Speed of production
Explain what happens to energy lost through respiration.
Energy used in respiration is released as heat to the environment and cannot be passed to the next trophic level.
Lost as heat
Explain what happens to energy lost through respiration.
Energy used in respiration is released as heat to the environment and cannot be passed to the next trophic level.
Lost as heat
Which productivity value is transferred to the next trophic level?
Net productivity is transferred because it represents biomass remaining after respiration.
Only NP transfers
Which productivity value is transferred to the next trophic level?
Net productivity is transferred because it represents biomass remaining after respiration.
Only NP transfers
Give one reason why productivity limits food chain length.
Energy is lost at each trophic transfer, so progressively less energy is available to support higher trophic levels.
Less energy higher up
Give one reason why productivity limits food chain length.
Energy is lost at each trophic transfer, so progressively less energy is available to support higher trophic levels.
Less energy higher up
Explain why high respiration reduces net productivity.
More energy is used for life processes and released as heat, leaving less energy available to form new biomass.
More respiration = less NP
Explain why high respiration reduces net productivity.
More energy is used for life processes and released as heat, leaving less energy available to form new biomass.
More respiration = less NP
State one factor that can increase productivity in an ecosystem.
High light availability, suitable temperature, and sufficient nutrients can all increase productivity.
Light, heat, nutrients
State one factor that can increase productivity in an ecosystem.
High light availability, suitable temperature, and sufficient nutrients can all increase productivity.
Light, heat, nutrients
Topic 2.5 study notes
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