1.3 - Energy And Equilibria Flashcards
What is the first law of thermodynamics
Energy can neither be created nor destroyed, it can only be transformed from one form to another
What forms does energy exist in
Energy exists in many different forms, including light energy, heat energy, chemical energy, electrical energy, and kinetic energy
What describes the change in energy
The 2 laws of thermodynamics,
What is the principle of conservation of energy
The first law of thermodynamics
- it means that the energy enetering a system equals the energy leaving it
What is an example of the principle of conservation of energy
The transfer of energy in food chains within ecosystems demonstrates the principle of conservation of energy
Energy enters the system (the food chain or food web) in the form of sunlight
Producers convert this light energy into biomass (stored chemical energy) via photosynthesis
This chemical energy is passed along the food chain, via consumers, as biomass
All energy ultimately leaves the food chain, food web or ecosystem as heat energy
What is the second law of thermodynamics
They entropy of a system increases over time
What is entropy
A measure of the amount of disorder in a system
What happens when entropy increases
entropy increases (through inefficiencies in energy transformations) the energy available to do work decreases
This is because the transformation and transfer of energy is any system is never 100% efficient
In other words, in any energy conversion, the amount of useable energy at the end of the process is always less than the amount of energy available at the start
What does the second law of thermodynamics tell us about the energy in a system
It explains the desacerase in available energy within a ecosystem
Explain the decrease in available energy in a food chain
- In a food chain, for example, energy is transformed from a more concentrated (ordered) form (e.g. light energy the Sun), into a more dispersed (disordered) form (heat energy)
- Initially, light energy from the Sun is absorbed by producers
- However, even at this initial stage, energy absorption and transfer by producers is inefficient due to reflection, transmission (light passing through leaves) and inefficient energy transfer during photosynthesis
- The energy that is converted to plant biomass is then inefficiently transferred along the food chain through respiration and production of waste heat energy
- xuwaay`2qwaAs a result of these inefficient energy transfers, food chains are often short (they rarely contain more than five trophic levels)
Define equilibrium
An equilibrium refers to a state of balance occurring between the separate components of a system
Which type of systems extsists in a state of stable equilibrium and what is the characteristics of this
Open systems (such as ecosystems) usually exist in a stable equilibrium
- This means they generally stay in the same state over time
- They can be said to be in a state of balance
- A stable equilibrium allows a system to return to its original state following a disturbance
What is the main type of stable equilibrium know as
Steady state equilibrium
When does a steady state equilibrium occur
A steady-state equilibrium occurs when the system shows no major changes over a longer time period, even though there are often small, oscillating changes occurring within the system over shorter time periods
These slight fluctuations usually occur within closely defined limits and the system always return back towards its average state
What open systems are normally in steady state
Those in nature
Use the example of a forest to explain steady state equilibrium
For example, a forest has constant inputs and outputs of energy and matter, which change over time
As a result, there are short-term changes in the population dynamics of communities of organisms living within the forest, with different species increasing and decreasing in abundance
Overall, however, the forest remains stable in the long-term
What is the second type of steady equilibrium
Static equilibrium
What is static equilibrium and give an example of
There are no inputs or outputs (of energy or matter) to the system and therefore the system shows no change over time
No natural systems are in static equilibrium - all natural systems (e.g. ecosystems) have inputs and outputs of energy and matter
Inanimate objects such as a chair or desk could be said to be in static equilibrium
What is the difference between stable and unstable equilibrium
A system can also be in an unstable equilibrium
Even a small disturbance to a system in unstable equilibrium can cause the system to suddenly shift to a new system state or average state (i.e. a new equilibrium is reached)
What does a feedback loop do and where are they found
Most systems involve feedback loops
These feedback mechanisms are what cause systems to react in response to disturbances
Feedback loops allow systems to self-regulate
What are the 2 types of feedback loops
Negative and positive
What is a negative feedback loop
Negative feedback is any mechanism in a system that counteracts a change away from the equilibrium
When do negative feedback loops occur
Negative feedback loops occur when the output of a process within a system inhibits or reverses that same process, in a way that brings the system back towards the average state
Are negative feedback loops stable
In this way, negative feedback is stabilising - it counteracts deviation from the equilibrium
Negative feedback loops stabilise systems
What is a positive feedback loop
Positive feedback is any mechanism in a system that leads to additional and increased change away from the equilibrium
When do positive feedback loops occur
Positive feedback loops occur when the output of a process within a system feeds back into the system, in a way that moves the system increasingly away from the average state
Are positive feedback loops stable
In this way, positive feedback is destabilising - it amplifies deviation from the equilibrium and drives systems towards a tipping point where the state of the system suddenly shifts to a new equilibrium. Positive feedback loops destabilise systems
What is a tipping point
A tipping point symbolises the minimum amount of change within a system that will destabilise it, causing it to reach a new equilibrium or new stable state.
It is a critical threshold in a system
What happens if a tipping point is reached
If a tipping point is reached, any further small change in the system will have significant knock-on effects and cause the system to move away from its average state (away from the equilibriu
Why is a tipping point very important in a ecosystem or another ecological system
In ecosystems and other ecological systems, tipping points are very important as they represent the point beyond which serious, irreversible damage and change to the system can occur
Can a negative feedback loop affect tipping points
Positive feedback loops can push an ecological system towards and past its tipping point, at which point a new equilibrium is likely to be reached
Eutrophication is a classic example of an ecological reaching a tipping point and accelerating towards a new state
Why can tipping points be difficult to predict
- There are often delays of varying lengths involved in feedback loops, which add to the complexity of modelling systems
- Not all components or processes within a system will change abruptly at the same time
It may be impossible to identify a tipping point until after it has been passed - Activities in one part of the globe may lead to a system reaching a tipping point elsewhere on the planet (e.g. the burning of fossil fuels by industrialised countries is leading to global warming, which is pushing the Amazon basin towards a tipping point of desertification) - continued monitoring, research and scientific communication is required to identity these links
What is an example of humans pushing something past its tipping point
Icecaps and glaciers
What is resilience
Any system, ecological, social or economic, has a certain amount of resilience
This resilience refers to the system’s ability to maintain stability and avoid tipping points
Hat 2 factors can contribute to a systems resilience
Diversity and the size of storages within systems can contribute to their resilience and affect their speed of response to change
What type of systems are more likely to reach there tipping point
Systems with higher diversity and larger storages are less likely to reach tipping points
Use the example of a ecosystem to explain tipping points ands resilience
For example, highly complex ecosystems like rainforests have high diversity in terms of the complexity of their food webs
If a disturbance occurs within one of these food webs, the animals and plants have many different ways to respond to the change, maintaining the stability of the ecosystem
Rainforests also contain large storages in the form of long-lived tree species and high numbers of dormant seeds
These factors promote a steady-state equilibrium in ecosystems like rainforests
What is an example of a enviroment with a low resilience
In contrast, agricultural crop systems are artificial monocultures meaning they only contain a single species. This low diversity means they have low resilience - if there is a disturbance to the system (e.g. a new crop disease or pest species), the system will not be able to counteract this
How do humans affect resilience using the example of a rainforest
Humans can affect the resilience of natural systems by reducing the diversity contained within them and the size of their storages
Rainforest ecosystems naturally have very high biodiversity
When this biodiversity is reduced, through the hunting of species to extinction or the destruction of habitat through deforestation, the resilience of the rainforest ecosystem in reduced - it becomes increasingly vulnerable to further disturbances
