1.3 - Energy And Equilibrium

Question 1

State the first law of thermodynamics

Answer 1

Energy can neither be created nor destroyed; it can only change form.
Also know as the law of conservation of energy

Question 2

What happens to energy within the first law of thermodynamics

Answer 2

In ecosystems energy enters the system in the form of sunlight, its converted into biomass via photosynthesis, passes along the food chain as biomass, is consumed and ultimately leave as heat. Heat is released because of the inefficient transfer of energy. The total amount of energy has not changed but the amount of available energy has reduced

Question 3

What is the second law of thermodynamics

Answer 3

In any energy conversion there is less usable energy at the end of the process than at the beginning. Energy goes from a concentrated form into a more dispensed form. Entropy increases

Question 4

How does the energy change in the second law of thermodynamics referring to a food chain

Answer 4

At each tropic level the energy that is passed along is dispensed to different forms such as growth, movement and heat (this reduces the amount of energy available for the next level)

Question 5

Define entropy

Answer 5

A measure of the disorder in a system

Question 6

Define equilibrium

Answer 6

The tendency of a system to return to its original state following a disturbance

Question 7

Compare “static equilibrium” and “steady state equilibrium”

Answer 7

In static equilibrium there is no change over time. Most non living systems are in a state of static equilibrium. A steady state equilibrium is a characteristic of an open system where there are continuos inputs and outputs of energy and matter. The system as a whole stays the same.

Question 8

Give an 3 examples of steady state equilibrium

Answer 8

• a country population: a place will have births and deaths, but will ultimately remain unchanged
• climax ecosystem: there are no long term changes. Inputs and outputs are balanced
• human body temperature?: when it rises we sweat too coll down, stays at 37 degrees

Question 9

State 3 examples of static equilibrium

Answer 9

• a hat on a hook: the hat is not in motion, remaining in equilibrium. There are no inputs or outputs creating change
• pile of rocks: forces within the system are balanced - no output or input
• building: no change in the system

Question 10

Compare stable equilibrium and unstable equilibrium

Answer 10

In stable equilibrium the system tends to return to the same equilibrium after the disturbance whereas in an unstable equilibrium it returns or moves to a new equilibrium

Question 11

Is a simple ecosystem or a more complex ecosystem more likely to maintain a stable equilibrium when faced with disturbance? Exaplain your answer, using examples

Answer 11

The more diverse and complex an ecosystem, the more resilient it tends to be as there are many interactions between different species and so equilibrium can be maintained. For example the Daintree rainforest in Queensland is a mature forest so it’s highly diverse. If a disease were to wipe out one species of trees the forest would be able to return to the original equilibrium by making new interactions. A simple ecosystem would not.

Question 12

Define negative feedback

Answer 12

Feedback that counteracts any change away from equilibrium, contributing to stability

Question 13

Outline an example of negative feedback

Answer 13

Global temperatures rise causing more ice caps to melt. This increases the water vapour in the air + more clouds. More solar radiation is reflected by the clouds decreasing global temperatures

Question 14

Define positive feedback

Answer 14

Results in a further increase or decrease change in response to change in the system. Moves the system away from its original equilibrium towards instability

Question 15

Outline “the vicious cycle of poverty” as an example of positive feedback

Answer 15

Low income -> decreased access to to education -> lower job prospects -> less income

Question 16

An IB student has a lot of work to do and gets stressed. As a result, they might struggle to focus on their work, and delay in completing it. The workload piles up more and more because they aren’t getting through it, making them more stressed.
What type of feedback mechanism is being described here? Explain your answer.

Answer 16

Positive feedback - end result is a new equilibrium with the student less able to do work

Question 17

Describe the term resilience

Answer 17

Refers to the tendency of a system to avoid tipping points and maintain stability through steady state equilibrium. Returns to initial state following a disturbance

Question 18

Describe the term tipping point

Answer 18

When small changes in a system add up together and tip the equilibrium over a threshold to a new unstable equilibrium

Question 19

Explain how the size of storges and the diversión y of a system can affect its resilience

Answer 19

The more diverse and complex an ecosystem the more resilient it tends to be as there are more interactions between species. The bigger the storage the less significant a small change would be

Question 20

State and explain the resilience of the stated system:
A large forest ecosystem with high biodiversity

Answer 20

High
There are more interactions between organisms if the biodiversity is high. If there is a change eg. A decrease in population of a particular species through disease, those organisms that feed on it will have alternative food sources to turn to. The system will remain mostly unchanged

Question 21

State and explain the resilience of the stated system:
A large field with only corn growing with small numbers of insects feeding on the corn

Answer 21

Low
A monoculture of corn can be wiped out by a disease - small gene pill reduced resistance to disease. Also vulnerable to pests

Question 22

State and explain the resilience of the stated system:
An isolated village community in the gobi desert with a population of around 1000 people

Answer 22

Low/moderate
Small, isolated population has low genetic diversity. This makes population vulnerable to disease. Food quality is poor with migration the reliance is increased to moderate

Question 23

State and explain the resilliance of the stated system:
The community of shanghai, china. Population roughly 24,000,000

Answer 23

High
Large population implies large genetic diversity. Access to varied resources. Disease does spread quickly due to high population density

Question 24

Explain how the extensive use of fossil fuels, resulting in increased atmospheric levels of greenhouse gases hours gases might affect the resilience of a ocean food web

Answer 24

Low resilliance. More co2 and so2 due to fossil duel combustions leads to acid rain and ocean acidification. Reduces the ability of circumstances to form shells and leads to coral bleaching. Both result in the deceased of species diversity.

Question 25

Describe the tipping point of increased greenhouse gases and evaluate the consequences

Answer 25

with increase in greenhouse gases there will be an increase in ocean acidification leading to a decrease in circumstances as a food source - the tipping point would be reached when the circumstances are no longer able to survive due to thinking of their shells. Ocean food web would need to find an alternative food source. A diverse ecosystem means that most species would be able to adapt to the change.