Energy and Equilibria

Question 1

What is the First Law of Thermodynamics?

Answer 1

The First Law of Thermodynamics is the principle of conservation of energy. It states that energy in an isolated system can be transformed but not created or destroyed

Question 2

What can the Principle of Conservation of Energy be modelled by?

Answer 2

The energy transformations along food chains + energy production systems

Question 3

What is the Second Law of Thermodynamics?

Answer 3

The Second Law of Thermodynamics states that the entropy of a system increases over time.
Entropy is a measure of the amount fo disorder within a system
An increase in entropy arising from energy transformations reduces the energy available to do work

Question 4

What does the Second Law of Thermodynamics explain?

Answer 4

The Second Law of Thermodynamics explains the inefficiency and decrease in available energy along a food chain

Question 5

Are energy conversions ever 100% efficient?

Answer 5

Energy conversions are never 100% efficient

Question 6

How efficient are plants at converting solar energy to stored sugars?

Answer 6

Depending on the type of plant, the efficiency at converting solar energy to stored sugars is about 1-2%

Question 7

How efficient are herbivores at absorbing nutrients?

Answer 7

Herbivores only assimilate (absorb nutrients) about 10% of the total plant energy they consume

The rest is lost in metabolic processes + escaping from carnivores

Question 8

How efficient are carnivores at absorbing nutrients?

Answer 8

A carnivore’s efficiency is only around 10% due to metabolic processes + chasing their prey

Question 9

How much energy is passed on to the next trophic level?

Answer 9

Only 10% of energy is passed on to the next trophic level

Question 10

What is efficiency ?

Answer 10

The useful energy, work or output produced by a process divided by the amount of energy consumed being the input to the process

Question 11

How do you calculate efficiency?

Answer 11

Useful output / input

Question 12

What is equilibrium ?

Answer 12

Equilibrium is the tendency of a system to return to an original state following a disturbance

Question 13

What is steady state equilibrium?

Answer 13

Where there are continuous inputs + outputs of energy but the system as a whole remains in a constant state

Kept in check by negative feedback

e.g. maintenance of constant body temp.

Question 14

What is static equilibrium?

Answer 14

There is no change over time, but when disturbed it will adopt a new equilibrium

e.g. rocks or buildings

This cannot occur in living systems as life involves exchange of energy + matter with the environment

Question 15

What happens in a stable equilibrium after a disturbance?

Answer 15

In a stable equilibrium, the system returns to the SAME equilibrium after a disturbance

Question 16

What happens in an unstable equilibrium after a disturbance?

Answer 16

In an unstable equilibrium, the system returns to a NEW EQUILIBRIUM after a disturbance

Question 17

What is a feedback loop?

Answer 17

A feedback loop is when information that starts a reaction in turn may input more energy that starts another reaction

Question 18

Feedback loop mechanisms can either be:

Answer 18

• Positive

- Negative

Question 19

What is positive feedback?

Answer 19

• Change a system to a new state
• Destabilising as they increase change
• New equilibrium adopted

Question 20

Give an example of a positive feedback loop

Answer 20

1. RISING GLOBAL TEMPERATURES (lead to)
2. Melting ice caps
3. Dark soil exposed
4. More solar radiation absorbed
5. Drop in albedo
6. RISING GLOBAL TEMPERATURES

Question 21

What is negative feedback?

Answer 21

• Return equilibrium to original state

- Stablising as they reduce change

Question 22

Give an example of a negative feedback loop

Answer 22

1. RISING GLOBAL TEMPERATURES (lead to)
2. Melting ice caps
3. More water available for evaporation
4. More clouds
5. More solar radiation reflected by clouds
6. FALLING GLOBAL TEMPERATURES

Question 23

What does the resilience of a system measure?

Answer 23

The resilience of a system measures how it responds to a disturbance. The more resilient the system, the more disturbance it can deal with

Question 24

Name 7 factors affecting ecosystem resilience increase

Answer 24

• More diverse + complex ecosystem
• Greater species diversity
• Greater genetic diversity
• Larger ecosystem
• Climate // in tropical forests fast growth rate vs. Arctic slow growth
• Faster rate of reproduction
• Humans can mitigate threat to ecosystem

Question 25

When is an ecological tipping point reached?

Answer 25

An ecological tipping point is reached when an ecosystem experiences a shift to a new state in which there are significant changes to its biodiversity

Question 26

What are 3 characteristics of tipping points?

Answer 26

• Involves positive feedback
• Changes are long lasting
• Changes are hard to reverse

Question 27

Give an example of a tipping point being reached

Answer 27

Coral reef death - If ocean acidity levels rise high enough, the reef coral dies and cannot regenerate