Unit 1.3 Flashcards
(19 cards)
First Law of Thermodynamics
States that energy is neither created nor destroyed (principle of conservation of energy)
The second law of Thermodynamics
states that the entropy of an isolated system not in equilibrium will tend to increase over time
Entropy
A measure of the disorder of a system and it refers to the spreading out or dispersal of energy
Example of entropy in photosynthesis and respiration
- Low-entropy solar energy turns into higher-entropy chemical energy
- Chemical energy turns into even higher-entropy mechanical energy and is ‘lost’ as heat
Equilibrium
the tendency of the system to return to an original state following a disturbance
Steady-State Equilibrium
is a characteristic of open systems where the inflow and output of energy is constant over time
Examples of a steady-state equilibrium
A water tank, constant body temperature, etc.
Steady-state equilibrium is stabilized by what feedback?
Negative feedback
Static Equilibrium
An equilibrium in which there is no change over time. It will only adapt a new equilibrium after a disturbance.
Examples of Static Equilibrium
Pile of rocks, building, non-living systems.
What is an example of a system that may undergo long term changes to their equilibrium while retaining integrity in a system?
Succession
Rapid change from human activities can affect
it can disturb system stability and bring unforeseen side-effects
Positive Feedback
- Positive feedback loops are destabilising as they serve to amplify change in the same direction.
- This can drive a system toward a tipping point where a new equilibrium is adopted.
Example of Positive Feedback
Global warming leads to an increase in temperatures > this melts ice caps > the albedo in the region decreases > so more solar radiation is absorbed > leading to more infra-red radiation > leading to an increase in global temperatures… more ice melts etc
Negative Feedback
- Negative feedback loops are stabilising.
- They occur when the output of a process inhibits or reverses the operation of the same process in such a way as to reduce change—it counteracts deviation
- This self-regulation is homeostasis and explains stability in systems.
Example of Negative Feedback
There is an increase in global temperatures > this leads to more evaporation and cloud formation > the clouds reflect more solar radiation back to space > decreasing global temperatures
What is a tipping point and how does it occur?
Inputs may start a positive feedback loop whereby the changes are amplified. Beyond a certain point, a tipping point is reached, and the system moves to a new alternative state in a new equilibrium.
Give an example of a catastrophic tipping point leading to an alternative stable state
Coral bleaching can lead to a stable state where the coral is dead and the reef dies
Global warming may lead to an ice free arctic or “hot-house earth”
Describe a non-catastrophic alternative stable state formation
It can also be the result of random stochastic differences that occur during the development of a system. Succession is thought to be able to result in many alternative stable states depending upon these stochastic differences, i.e. the climax community may be slightly different depending upon the inputs during the process of succession.
