Foundation - 1.2 Systems

Question 1

Systems

Answer 1

An assemblage of constituent parts as well as the interactions and relationships which make up these parts, which together make up an entity

Question 2

Systems approach

Answer 2

Term used to describe a method of simplifying and understanding a complicated set of interactions

Question 3

Two ways of studying systems

Answer 3

• reductionist approach
• holistic approach

Question 4

Reductionist approach

Answer 4

Breaking a system down into its parts and studying each individually
* can be useful for partially understood systems

Question 5

Holistic approach

Answer 5

Looks at the system’s processes and interactions as a whole

Question 6

Flows

Answer 6

Provide inputs and outputs of energy and matter
* they can either be transfers or transformations

Question 7

Transfers

Answer 7

A change in location but no change in matter

Question 8

Transformations

Answer 8

A change in chemical nature, a change in state or a change in energy as well as a change in location

Question 9

Storage

Answer 9

Represented by rectangles, usually with their size being proportional to the storage itself

Question 10

Emergent properties

Answer 10

A property of a system but not of the individual parts of the system

Question 11

Main types of systems

Answer 11

• Open
• Closed
• Isolated (hypothetical)

Question 12

Open systems

Answer 12

Both energy and matter are exchanged between the systems and its surrounding
* usually organic (living) systems that interact with surroundings
* e.g. most ecosystems, as well as our bodies

Question 13

Closed systems

Answer 13

Energy, but no matter, is exchanged between the systems and its surroundings
* usually inorganic
* e.g. the Earth (and its atmosphere) could be considered one, though its debated

Question 14

Isolated systems

Answer 14

Neither energy nor matter are exchanged between the system and its surroundings
* do not exist naturally, theoretical concept (though universe could be one)

Question 15

Scales of systems (with examples)

Answer 15

• Small-scale ecological system: bromeliad (plant in rainforest) forms microcosm of life
• Large-scale ecosystem: entire rainforest where countless species interact within a complex web of relationships
• Giant, self-contained system: the Earth’s atmosphere

Question 16

Gaia hypothesis

Answer 16

Proposed by James Lovelock (1970s)
* Presented Earth as a single, self-regulating system

Question 17

Tipping point

Answer 17

The minimum amount of change within a system that will destabilise it, causing it to reach a new equilibrium or stable state

Question 18

Positive feedback loops

Answer 18

The product of a reaction leads to an increase in that reaction, again and again

Question 19

Regime shift

Answer 19

The formation of a new equilibrium as a result of positive feeback loops

Question 20

Steps of reaching a tipping point

Answer 20

1. The system is subject to some kind of pressure
2. This pressure pushes the system towards a tipping point
3. The tipping point is reached
4. Positive feedback loops accelerate the shift into a new state
5. Change is often irreversible or a high cost is required to return it to previous state

Question 21

Reasons why tipping points are difficult to predict (name 3)

Answer 21

• Often delays of carying length involved in feedback loops which add complexity of modelling systems
• Not all components change abrubtly at the same time
• May be impossible to identify a tipping point until after it has been passed
• One activity in one part of the globe may lead to a system reaching a tipping point elsewhere on the planet

Question 22

Resilience

Answer 22

Ability of a system to maintain stability and avoid tipping point

Question 23

Factors affecting stability of system (name 3)

Answer 23

• Disturbance frequency and intensity
• Size of storages
• Species diversity, interactions (competition)
• Trophic complexities (how many system components are there)
• Rate of nutrient or energy influx (how fast nutrients and energy are moving in and out of system)

Question 24

Model

Answer 24

A simplified version of reality
* can be analysed or tested to learn about how the system works and predict its behaviour

Question 25

Strengths of models (name 3)

Answer 25

* Models simplify complex systems * Models allow predictions to be made about how systems will react in response to change * System inputs can be changed to observe effects and outputs without the need to wait for real-life events to occur * Easier to understand than the real system * Results can be shared between researchers and communicated to the public * Results can warn us about future environmental issues

Question 26

Limitations of models (name 3)

Answer 26

* Can be oversimplified or inaccurate * Results depend on the quality of data of inputs * Results become more uncertain the further they predict into the future * Different models can show vastly different outputs even if they have the same inputs * Results can be interpreted differently by different people * Can be very complex

Question 27

Static equilibrium

Answer 27

No inputs or outputs (of energy or matter) to the system and therefore the system shows no change over time * no natural systems are such

Question 28

Unstable/dynamic equilibrium

Answer 28

Even small disturbances can cause the system to suddently shift

Question 29

Negative feedback

Answer 29

When the output of a process inhibits or reverses the operation of the same process in such a way as to reduce change * stabilising as they counteract deviation

Question 30

Positive feeback

Answer 30

When a disturbance leads to an amplification of that disturbance, destabilising the system and driving it away from its equilibrium