1.
The Gaia Hypothesis proposes that our planet functions as a single organism that maintains
conditions necessary for its survival by feedback mechanisms. It was formulated by James
Lovelock in the mid-1960s. In his recent book The revenge of Gaia, he suggests that we have
passed the “tipping point” on global warming and that feedback mechanisms will speed up the
rate of global warming.
(a)
State what type of system the Earth is and what the inputs and outputs are
(3)
(b)
Using positive and negative feedback models explain the process of climate change.
(7)
(c)
Scientists use computer simulations to model the effects of changes in the temperature of
the Earth. Discuss the advantages and disadvantages of this modelling.
(4)
Expression of ideas (2)
(Total6 marks)
2. Of what is the diagram below an example?
ice-caps melt
global warming
less energy refected
increased global temperature
A.
Negative feedback
B.
Positive feedback
C.
Steady-state equilibrium
D.
Static equilibrium 8806-6410
(Total 1 mark)
3. Which is an example of negative feedback?
A.
An increase in air temperature increases the rate of melting of the Earth’s ice caps, thus
decreasing the reflection of solar radiation.
B.
An increase in a herbivore population, leading to overgrazing and thus to a decline in the
herbivore population.
C.
An increase in human birth rate compared with death rate leading to exponential increase
in the human population.
D.
A loss of vegetation leads to soil erosion and thus further loss of vegetation occurs.
(Total 1 mark)
1
4.
Which row correctly gives examples of transfer and transformation processes?
Transfer
Transformation
A.
Decomposition
Organic matter entering the ocean
B.
Evaporation
Decomposition
C.
Evaporation
Organic matter entering the ocean
D.
Organic matter entering the ocean
Evaporation
(Total 1 mark)
5.
A desert with very low precipitation and little vegetation is an example of which type of
system?
A.
Open
B.
Closed
C.
Isolated
D.
Closed and isolated
(Total 1 mark)
6.
Which of the following is an example of negative feedback?
A.
Loss of vegetation, leading to soil erosion, leading to further loss of vegetation
B.
Animals failing to reproduce when food is abundant
C.
More carbon dioxide favouring plant growth, so plants absorb more carbon dioxide
D.
A population of small mammals in a forest decreasing due to a fire
(Total 1 mark)
7.
Which system represents a herd of elephants living on the African grassland?
A.
An open system
B.
A closed system
C.
An isolated system
D.
An autotrophic system
(Total 1 mark)
2
8.
Which of the following best describes the result of positive feedback in a system?
A.
The system changing further in the same direction
B.
The system remaining stable
C.
The system changing in the opposite direction
D.
The system remaining unchanged
(Total 1 mark)
9.
Which of the following contains only transfer processes?
A.
Melting of ice caps; evaporation of sea water
B.
Run-off of water from land to rivers; dead organic matter entering a lake
C.
Formation of water droplets in clouds; volcanic eruptions
D.
Leaching of soil nutrients; freezing of lake water
(Total 1 mark)
10.
(a)
Define the term feedback.
......................................................................................................................................
......................................................................................................................................
(1)
(b)
Explain, with the help of an example, the term negative feedback in relation to an
ecosystem.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
(Total 4 marks)
3
11.
The diagram below represents the inputs and outputs of water from a lake over a period of time.
P = precipitation (rain, snow)
falling on the surface of
the lake
I = inflow from
streams
E = evaporation from the
surface of the lake
Lake
R = run-off in a stream
flowing out of the lake
S = loss by downward movement into the rocks
Assuming there is neither a rise nor a fall in the level of the lake, and there are no other inputs or
outputs, what is the value of R?
A.
P+I–E–S
B.
I+P+E+S
C.
(S + E) × (I + P)
D.
I+P+E–S
(Total 1 mark)
12.
As disease spreads through a population, numbers fall. As the result of a reduction in contact
between individuals, the rate of spread of the disease is reduced. This is followed by a recovery
in numbers.
This is an example of
A.
positive feedback
B.
negative feedback
C.
demographic transition
D.
entropy
(Total 1 mark)
4
13.
The downward leaching of nutrients within the soil profile is primarily an example of which of
the following?
A.
Transformation of energy
B.
Transfer of energy
C.
Transfer of materials
D.
Transformation of materials
(Total 1 mark)
14.
Consider these statements concerning the flow of energy through ecosystems:
Statement 1: The amount of energy that is available to living things decreases as it is
transformed and passed along food chains.
Statement 2: As energy is transformed along food chains, no energy is destroyed.
Which is a correct evaluation of these statements?
Statement 1
Statement 2
A.
Demonstrates the first law of thermodynamics
Demonstrates the second law of
thermodynamics
B.
Is unrelated to the laws of thermodynamics
Demonstrates the second law of
thermodynamics
C.
Demonstrates the second law of
thermodynamics
Demonstrates the first law of
thermodynamics
D.
Demonstrates the second law of
thermodynamics
Is unrelated to the laws of
thermodynamics
(Total 1 mark)
15.
A stable ecosystem will be in . . . (I) . . . equilibrium, achieved largely through mechanisms
of . . . (II) . . . feedback.
Complete this statement.
(I)
(II)
A.
Steady state
Positive
B.
Static
Negative
C.
Steady state
Negative
D.
Static
Positive
(Total 1 mark)
5
16.
Leaching of soil nutrients is an example of
A.
transfer of materials.
B.
transformation of materials.
C.
transfer of energy.
D.
transformation of energy.
(Total 1 mark)
17.
The Second Law of Thermodynamics states that in any
A.
open system, entropy tends to increase spontaneously.
B.
open system, entropy tends to decrease spontaneously.
C.
isolated system, entropy tends to increase spontaneously.
D.
isolated system, entropy tends to decrease spontaneously.
(Total 1 mark)
18.
Which of the following contributes most effectively to self-regulation within a system?
A.
Rapid transfer of materials
B.
Inputs of energy being greater than outputs
C.
Negative feedback mechanisms
D.
Positive feedback mechanisms
(Total 1 mark)
6
19.
The diagram below shows energy transfer in a cow.
energy respired,
lost as heat R
secondary
productivity
SP
energy
assimilated
energy
consumed
C
energy lost
in urine U
energy lost
in faeces F
energy
consumed
C
Secondary Productivity (SP) is
A.
C + R.
B.
C – (R + U + F).
C.
C – (U + F).
D.
C + R + U + F.
(Total 1 mark)
7
20.
The diagram below shows energy transfer in a cow.
energy respired,
lost as heat R
secondary
productivity
SP
energy
assimilated
energy
consumed
C
energy lost
in urine U
energy lost
in faeces F
energy
consumed
C
If C = 4000 kJ day–1 and SP = 200 kJ day–1, the efficiency of conversion is
A.
50 %.
B.
10 %.
C.
5 %.
D.
2 %.
(Total 1 mark)
8
21.
In the diagram below all values are in kJ m–2 yr−1
Net Productivity of carnivores
12
Carnivores
Respiration and other losses
Z
Consumed by carnivores
Y
Decomposers and other losses
320
Net Productivity of herbivores
400
Herbivores
Respiration and other losses
X
Consumed by herbivores
W
Decomposers and other losses
32 000
Net Productivity of producers
40 000
Producers
[Ian Bradbury, The Biosphere, (John Wiley & Sons Ltd., 1991). Reproduced by permission of Wiley-Blackwell.]
The carnivores’ productivity as a percentage of primary productivity is
A.
0.003.
B.
0.03.
C.
0.3.
D.
3.
(Total 1 mark)
9
22.
In the diagram below all values are in kJ m–2 yr−1
Net Productivity of carnivores
12
Respiration and other losses
Z
Carnivores
Consumed by carnivores
Y
Decomposers and other losses
320
Net Productivity of herbivores
400
Respiration and other losses
X
Herbivores
Consumed by herbivores
W
Decomposers and other losses
32 000
Net Productivity of producers
40 000
Producers
[Ian Bradbury, The Biosphere, (John Wiley & Sons Ltd., 1991). Reproduced by permission of Wiley-Blackwell.]
The values of W, X, Y and Z are
W
X
Y
Z
A.
72 000
8400
720
92
B.
8000
8400
720
92
C.
8000
7600
80
92
D.
8000
7600
80
68
(Total 1 mark)
10
23.
Which is an example of negative feedback?
A.
Loss of vegetation leading to soil erosion leading to further loss of vegetation.
B.
A decline in a large predator population after they have eaten most of their prey
population.
C.
Melting of permafrost in the tundra due to climatic change leading to further release of
methane, causing further change.
D.
Unsustainable slash and burn agriculture practices in tropical rain forests.
(Total 1 mark)
24.
Which of the following factors would prevent the ecosphere being classified as a closed system?
A.
The input of solar energy
B.
The re-radiation to space of heat energy
C.
The arrival of rocks as meteorites from space
D.
The unstable state of its equilibrium
(Total 1 mark)
25. A lake with a stream flowing into it, but with water lost only by evaporation, is an example of a
system which is
A.
isolated.
B.
stable and closed.
C.
unstable and closed.
D.
open.
(Total 1 mark)
11