1.3 - Energy And Equilibria

Question 1

What is the first law of thermodynamics

Answer 1

Energy can neither be created nor destroyed, it can only be transformed from one form to another

Question 2

What forms does energy exist in

Answer 2

Energy exists in many different forms, including light energy, heat energy, chemical energy, electrical energy, and kinetic energy

Question 3

What describes the change in energy

Answer 3

The 2 laws of thermodynamics,

Question 4

What is the principle of conservation of energy

Answer 4

The first law of thermodynamics
- it means that the energy enetering a system equals the energy leaving it

Question 5

What is an example of the principle of conservation of energy

Answer 5

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

Question 6

What is the second law of thermodynamics

Answer 6

They entropy of a system increases over time

Question 7

What is entropy

Answer 7

A measure of the amount of disorder in a system

Question 8

What happens when entropy increases

Answer 8

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

Question 9

What does the second law of thermodynamics tell us about the energy in a system

Answer 9

It explains the desacerase in available energy within a ecosystem

Question 10

Explain the decrease in available energy in a food chain

Answer 10

• 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)

Question 11

Define equilibrium

Answer 11

An equilibrium refers to a state of balance occurring between the separate components of a system

Question 12

Which type of systems extsists in a state of stable equilibrium and what is the characteristics of this

Answer 12

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

Question 13

What is the main type of stable equilibrium know as

Answer 13

Steady state equilibrium

Question 14

When does a steady state equilibrium occur

Answer 14

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

Question 15

What open systems are normally in steady state

Answer 15

Those in nature

Question 16

Use the example of a forest to explain steady state equilibrium

Answer 16

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

Question 17

What is the second type of steady equilibrium

Answer 17

Static equilibrium

Question 18

What is static equilibrium and give an example of

Answer 18

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

Question 19

What is the difference between stable and unstable equilibrium

Answer 19

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)

Question 20

What does a feedback loop do and where are they found

Answer 20

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

Question 21

What are the 2 types of feedback loops

Answer 21

Negative and positive

Question 22

What is a negative feedback loop

Answer 22

Negative feedback is any mechanism in a system that counteracts a change away from the equilibrium

Question 23

When do negative feedback loops occur

Answer 23

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

Question 24

Are negative feedback loops stable

Answer 24

In this way, negative feedback is stabilising - it counteracts deviation from the equilibrium
Negative feedback loops stabilise systems

Question 25

What is a positive feedback loop

Answer 25

Positive feedback is any mechanism in a system that leads to additional and increased change away from the equilibrium

Question 26

When do positive feedback loops occur

Answer 26

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

Question 27

Are positive feedback loops stable

Answer 27

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

Question 28

What is a tipping point

Answer 28

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

Question 29

What happens if a tipping point is reached

Answer 29

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

Question 30

Why is a tipping point very important in a ecosystem or another ecological system

Answer 30

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

Question 31

Can a negative feedback loop affect tipping points

Answer 31

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

Question 32

Why can tipping points be difficult to predict

Answer 32

• 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

Question 33

What is an example of humans pushing something past its tipping point

Answer 33

Icecaps and glaciers

Question 34

What is resilience

Answer 34

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

Question 35

Hat 2 factors can contribute to a systems resilience

Answer 35

Diversity and the size of storages within systems can contribute to their resilience and affect their speed of response to change

Question 36

What type of systems are more likely to reach there tipping point

Answer 36

Systems with higher diversity and larger storages are less likely to reach tipping points

Question 37

Use the example of a ecosystem to explain tipping points ands resilience

Answer 37

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

Question 38

What is an example of a enviroment with a low resilience

Answer 38

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

Question 39

How do humans affect resilience using the example of a rainforest

Answer 39

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