1. IB ESS
Guru Charan Kumar
ESS-EOST PRACTICE PAPER
1. Leaching of soil nutrients is an example of
A.
transfer of materials.
B.
transformation of materials.
C.
transfer of energy.
D.
transformation of energy.
2. 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.
3. Which is an example of negative feedback?
A.
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.
4.
Loss of vegetation leading to soil erosion leading to further loss of vegetation.
Unsustainable slash and burn agriculture practices in tropical rain forests.
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
2013

2. IB ESS
Guru Charan Kumar
5. 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
6. 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
7. A system may best be defined as
A.
a set of components that function predictably.
B.
and assemblage of parts and their relationships forming a whole.
C.
a set of components that function unpredictably.
D.
an assemblage of functioning parts without inputs or outputs.
8. 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
2013

3. IB ESS
Guru Charan Kumar
2013
9. 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
10. Inputs to a closed system may be
A.
matter only.
B.
energy only.
C.
matter and energy.
D.
heat only.
11. Which statement best illustrates the second law of thermodynamics?
A.
Potential energy increases as energy moves through a system.
B.
The amount of energy is unchanged as matter moves through a system.
C.
Potential energy decreases as energy and matter move through a system.
D.
Energy cannot leave a system.

4. IB ESS
Guru Charan Kumar
12. The capacity of a system to self-regulate is generally increased by
A.
the presence of positive feedback.
B.
the presence of negative feedback.
C.
low energy inputs in the system.
D.
energy outputs greater than energy inputs in the system.
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
14. Which of the following is an essential feature of a system in steady-state equilibrium?
A.
Positive feedback mechanisms
B.
Negative feedback mechanisms
C.
Balanced inputs and outputs
D.
High diversity
15. Which of the following does not represent an open system?
A.
A lake inside a cave
B.
The entire universe
C.
A tropical island
2013

5. IB ESS
D.
16.
Guru Charan Kumar
A city
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
17. What do outputs from an open system consist of?
A.
Energy only
B.
Matter only
C.
Energy and matter
D.
Neither energy nor matter
18. The diagram below represents the inputs and outputs of water from a lake over a period of time.
2013

6. IB ESS
Guru Charan Kumar
P = precipitation (rain, snow)
E = evaporation from the
falling on the surface of
surface of the lake
the lake
I = inflow from
streams
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
19. Which row shows how energy and materials move through each type of system?
Isolated System
Closed System
2013
Open System
A.
energy flows through
system
materials flow through
system
energy flows through
system
B.
energy does not enter
system
materials flow through
system
energy does not leave
system
C.
energy does not leave
system
energy flows through
system
materials flow through
system
D.
materials do not leave
system
energy flows through
system
materials do not leave
system

7. IB ESS
20. Which statement is correct?
Guru Charan Kumar
A.
A lake is an example of an isolated system.
B.
An open system exchanges energy but not matter with its surroundings.
C.
The most common systems found on Earth are closed systems.
D.
A closed system exchanges energy but not matter with its surroundings.
21. Which statement expresses the second law of thermodynamics?
A.
The amount of energy available to do useful work in a system decreases over time.
B.
Energy can neither be created nor destroyed.
C.
Entropy will always decrease spontaneously in a system over time.
D.
Energy inputs equal energy outputs.
22. 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
23. The graph below shows how a population changed over a period of time.
2013

8. IB ESS
Guru Charan Kumar
Population
Time
Which of the following best describes the regulation process in this system?
A.
Positive feedback
B.
Static equilibrium
C.
Negative feedback
D.
Transformation
24. 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
25. 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
2013

9. IB ESS
Guru Charan Kumar
26. Which of the following is an example of negative feedback?
2013
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
27. How are the flows and storages of matter and energy generally represented in flow diagrams?
Storages
Flows
A.
arrows
boxes
B.
circles
boxes
C.
boxes
arrows
D.
boxes
circles
28. Of what is the diagram below an example?
global warming
ice-caps melt
increased global temperature
A.
Negative feedback
B.
Positive feedback
C.
Steady-state equilibrium
D.
Static equilibrium
less energy refected

10. IB ESS
Guru Charan Kumar
atmospheric
CO 2
increases
warmer
atmospheric
temperature
less CO 2
uptake by oceans
warmer
ocean
temperature
29.
The diagram above is an example of
A.
steady state equilibrium.
B.
positive feedback.
C.
negative feedback.
D.
static equilibrium.
30. Spiders mainly use a web and poisonous fangs to trap and eat insects such as flies. What type of
interaction is this?
A.
Parasitism
B.
Competition
C.
Mutualism
D.
Predation
2013

11. IB ESS
31.
Guru Charan Kumar
Respiratory loss
13 000
Energy input
21 000
Producers
4200
2200
3300
Herbivores
720
Decomposers
1960
Respiratory loss
What are the organisms in X?
A.
Autotrophs
B.
Primary consumers
C.
Secondary consumers
D.
Tertiary consumers
2013
270
380
X
90

12. IB ESS
Guru Charan Kumar
2013
32. The diagram below shows part of an aquatic food web for a lake ecosystem.
Freshwater turtles
Large fish
Small fish
Tadpoles
Aquatic insects
Water fleas
Rotifers
Algae
What is the maximum number of trophic levels represented in this food web?
A.
Three
B.
Four
C.
Five
D.
Six