Multiple Choice Questions (MCQ) topic quiz
Ecosystems
Instructions and answers for teachers
These instructions cover the learner activity section which can be found on page 16.
This Lesson Element supports OCR A Level Biology A (H420) and Biology B (Advancing
Biology) (H422).
When distributing the activity section to the learners either as a printed copy or as a
Word file you will need to remove the teacher instructions section.
The Activity
This Lesson Element is a teaching and learning resource containing 20 multiple choice
questions (MCQs) on the theme of ecosystems. Some questions might require synoptic
thinking, using knowledge and ideas from various topics across the full A Level content.
This resource can be used to test and consolidate understanding at the end of a topic or to
revisit and refresh knowledge at a later point in the course.
Introduction
Multiple choice questions allow rapid coverage of a wide range of sub-topics.
Contrary to a widespread belief among students, multiple choice questions are not
necessarily easy – they can be easy, moderate or difficult.
The questions are written so that the incorrect answers are plausible distractors based on
common errors or misconceptions.
The questions in this quiz cover topics mainly from specification section:
Biology A
6.3 Ecosystems
Biology B (Advancing Biology)
4.3 Photosynthesis, food production and populations.
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1
© OCR 2017
Multiple Choice Questions (MCQ) topic quiz - answers
1
The table shows the results of a study into a food chain involving four species, R, S,
T and U, in an area of woodland.
number of
individuals
biomass of one
individual /
arbitrary units
energy value per
unit mass /
arbitrary units
R
10 000
0.100
1.0
S
5
10.000
2.0
T
500
0.002
1.8
U
5
300 000.000
0.5
species
What is the order of energy flow in this food chain?
A
TRUS
B
TSRU
C
URST
D
USRT
Your answer
2
C
The ecological role (1) of hermit crabs (2) includes scavenging in rock pools (3).
What ecological terms are represented by the numbers 1, 2 and 3?
1
2
3
A
niche
community
ecosystem
B
trophic level
species
habitat
C
niche
species
ecosystem
D
trophic level
community
habitat
Your answer
Version 1
2
C
© OCR 2017
3
What conversion is carried out by nitrifying bacteria as part of the nitrogen cycle?
A
Ammonium compounds are converted to nitrites and nitrates.
B
Atmospheric nitrogen is converted to nitrates.
C
Nitrates are converted to atmospheric nitrogen.
D
Nitrates are converted to ammonium compounds.
Your answer
4
A
The graph shows the changes in three quantities in a typical ecosystem as it goes
through a succession to its climax.
What do the three lines represent?
gross primary
production of
biomass
biomass leaving as
respiratory loss
total biomass
accumulated
A
1
2
3
B
1
3
2
C
2
3
1
D
3
1
2
Your answer
Version 1
3
A
© OCR 2017
5
Limiting factors affect population size.
Which of these factors acts independently of the density of the population?
A
air temperature
B
disease
C
food supply
D
territory size
A
Your answer
6
The competitive exclusion principle is based on experimental evidence but aims to
explain an observation about real ecosystems.
Which observation is explained by the competitive exclusion principle?
A
Only one species can occupy a particular niche.
B
Pioneer plants are not found in an established community.
C
The diversity of a habitat increases as succession proceeds.
D
Similar ecosystems develop under similar environmental conditions.
Your answer
Version 1
4
A
© OCR 2017
7
An experimental pond was set up by placing water containing a little plant fertilizer in
a tank and leaving it outside. Various organisms, X, Y and Z, were subsequently
found in the tank and their inter-relationships were observed.
The graph shows how their populations changed over time.
Which line of the table identifies the trophic levels of X, Y and Z?
X
Y
Z
A
predator
prey
primary consumer
B
prey
predator
primary producer
C
primary consumer
primary producer
prey
D
primary producer
primary consumer
predator
Your answer
Version 1
5
D
© OCR 2017
8
The table compares how three animals use the energy in their food.
percentage of
energy in food
that is absorbed
percentage of
energy absorbed
that is respired
percentage of energy
absorbed that is
incorporated into new
tissue
grasshopper
50
47
3
rabbit
37
24
13
trout
86
56
30
animal
What can be concluded from this data?
A
The rabbit uses more energy in respiration.
B
The trout uses a lower proportion of its absorbed energy in respiration than the
other animals.
C
The grasshopper is inefficient because it is an ectotherm.
D
The trout has the potential to grow the fastest.
Your answer
Version 1
6
D
© OCR 2017
9
The Haber process fixes atmospheric nitrogen to make nitrate fertiliser. The graph
shows the effect of adding inorganic nitrate fertiliser on the yield of maize.
What conclusion can be drawn from the graph?
A
Nitrate fertiliser may be supplemented by the action of nitrogen fixing bacteria.
B
Beyond 130 kg ha-1 it is uneconomic to add nitrate fertiliser.
C
Environmental damage can result from the overuse of nitrate fertiliser.
D
Yield is directly proportional to the mass of nitrate fertiliser added.
Your answer
Version 1
7
B
© OCR 2017
10
Two animal species, L and M, are found in the same area of mixed moorland and
forest.
 In the spring and summer L and M eat the same plant food.
 In the winter, species L eats nuts in the forest while species M eats heather roots
on the moorland.
 Species L and M are preyed upon by the same predator.
 Although M’s numbers are initially reduced more by this predation, M’s population
recovers because M breeds faster than L.
Using this information, what can be concluded about species L and M?
A
They occupy entirely different communities, niches and ecosystems.
B
They are part of the same community but occupy different niches.
C
They occupy the same habitat but are at different trophic levels.
D
They are in the same community but are unrelated in the ecosystem.
Your answer
11
B
A forestry company aims to increase the output of wood, energy and biochemicals
from its woodlands without compromising woodland biodiversity, health and
resilience.
What principles are informing the company’s aims?
Principle 1: preservation
Principle 2: conservation
Principle 3: sustainable development
A
1, 2 and 3
B
Only 1 and 2
C
Only 2 and 3
D
Only 1
Your answer
Version 1
8
C
© OCR 2017
12
The table shows the number of breeding pairs of two species of wading birds on a
Scottish island at the start and end of a seventeen year period.
number of breeding pairs of wader birds
wading bird species
1983
2000
lapwing
1104
1364
redshank
486
733
What is the percentage change in the number of breeding pairs of lapwings?
A
19 %
B
23 %
C
33 %
D
51 %
B
Your answer
13
A water meadow contained cuckoo flower, an important food plant for the caterpillar
of the orange tip butterfly. A student wishes to estimate the abundance of these
species in the meadow, and also the number of predatory beetles that might eat the
caterpillars.
Which line of the table identifies appropriate methods for estimating the abundance of
these organisms in the meadow?
cuckoo flower
orange tip
caterpillar
predatory beetle
A
random quadrats
light trap
light trap
B
systematic quadrats
pitfall trap
pitfall trap
C
random quadrats
random quadrats
pitfall trap
D
systematic quadrats
systematic quadrats
light trap
Your answer
Version 1
9
C
© OCR 2017
14
A study was made of a rock pool for a period of four hours from the time it was
exposed by the morning tide going out. A pH probe showed that the pH of the water
in the rock pool increased during this time.
What could explain the change in pH?
Statement 1: Animals in the rock pool became more active and produced more
carbon dioxide.
Statement 2: Seaweeds in the rock pool increased their rate of photosynthesis
Statement 3: Temperature increased, reducing the volume of carbon dioxide
dissolved in the water.
A
1, 2 and 3
B
Only 1 and 2
C
Only 2 and 3
D
Only 1
Your answer
15
C
Human activity can cause these changes to occur in natural ecosystems:
Change 1: the destruction of ancient communities
Change 2: the replacement of indigenous communities by new animal and plant
associations
Change 3: reduction in biodiversity.
Which changes occur when a bog is drained to provide agricultural land?
A
1, 2 and 3
B
Only 1 and 2
C
Only 2 and 3
D
Only 1
Your answer
Version 1
10
A
© OCR 2017
16
The table compares the plant biomass required to produce 1kg of meat or fish for
human consumption in the form of beef, chicken or salmon.
meat or fish for human
consumption
plant biomass required to produce 1 kg
of meat or fish (kg)
beef
8.7
chicken
1.9
salmon
1.6
Which statements are supported by the data?
Statement 1: Salmon farming uses finite resources more efficiently than beef
farming.
Statement 2: Food security would be enhanced if chicken farms replaced a
proportion of beef farms.
Statement 3: The feed conversion ratio of mass of biomass supplied to mass of
product is higher for fish than for chicken.
A
1, 2 and 3
B
Only 1 and 2
C
Only 2 and 3
D
Only 1
Your answer
Version 1
11
B
© OCR 2017
17
The bar chart shows the relative number of sightings of three species of mammal in
two areas of Ireland.

Red squirrels are indigenous to Ireland.

Grey squirrels are an introduced species with similar habitat and food
requirements to red squirrels.

Pine martens are an indigenous predator of squirrels.
Which statements are supported by this data and information?
Statement 1: Pine martens reduce squirrel abundance.
Statement 2: Red and grey squirrels show interspecific competition.
Statement 3: Pine martens prey preferentially on grey squirrels.
A
1, 2 and 3
B
Only 1 and 2
C
Only 2 and 3
D
Only 1
Your answer
Version 1
12
A
© OCR 2017
18
Which land management practices maintain a deflected succession?
Practice 1: Grazing sheep on Snowdonia.
Practice 2: Burning patches of heather on lowland heaths.
Practice 3: Rotational coppicing of hazel trees.
A
1, 2 and 3
B
Only 1 and 2
C
Only 2 and 3
D
Only 1
Your answer
Version 1
13
A
© OCR 2017
19
The Galapagos Islands are an environmentally sensitive location. The graph shows
how the number of human residents and tourists on the Galapagos Islands has
changed over a period of sixty years. Human activity threatens some animal and
plant populations on the Galapagos.
Which statements concerning the Galapagos Islands are true?
Statement 1: Exponential growth in the number of residents stopped in 2000.
Statement 2: Residents outnumbered tourists in 1990.
Statement 3: Conservation efforts should focus on reducing the number of tourists
by 90% in the next ten years.
A
1, 2 and 3
B
Only 1 and 2
C
Only 2 and 3
D
Only 1
Your answer
Version 1
14
D
© OCR 2017
20
The flow diagram shows the main events of the carbon cycle.
Which line of the table correctly identifies processes 1, 2, 3 and 4?
1
2
3
4
A
combustion
breathing
photosynthesis
reproduction
B
respiration
death
respiration
death
C
combustion
respiration
photosynthesis
death
D
respiration
metabolism
respiration
reproduction
Your answer
C
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© OCR 2017
Multiple Choice Questions (MCQ) topic quiz
Exchange surfaces
Learner Activity
1
The table shows the results of a study into a food chain involving four species, R, S,
T and U, in an area of woodland.
species
number of
individuals
biomass of one
individual /
arbitrary units
energy value per
unit mass /
arbitrary units
R
10 000
0.100
1.0
S
5
10.000
2.0
T
500
0.002
1.8
U
5
300 000.000
0.5
What is the order of energy flow in this food chain?
A
TRUS
B
TSRU
C
URST
D
USRT
Your answer
2
The ecological role (1) of hermit crabs (2) includes scavenging in rock pools (3).
What ecological terms are represented by the numbers 1, 2 and 3?
1
2
3
A
niche
community
ecosystem
B
trophic level
species
habitat
C
niche
species
ecosystem
D
trophic level
community
habitat
Your answer
Version 1
16
© OCR 2017
3
What conversion is carried out by nitrifying bacteria as part of the nitrogen cycle?
A
Ammonium compounds are converted to nitrites and nitrates.
B
Atmospheric nitrogen is converted to nitrates.
C
Nitrates are converted to atmospheric nitrogen.
D
Nitrates are converted to ammonium compounds.
Your answer
4
The graph shows the changes in three quantities in a typical ecosystem as it goes
through a succession to its climax.
What do the three lines represent?
gross primary
production of
biomass
biomass leaving as
respiratory loss
total biomass
accumulated
A
1
2
3
B
1
3
2
C
2
3
1
D
3
1
2
Your answer
Version 1
17
© OCR 2017
5
Limiting factors affect population size.
Which of these factors acts independently of the density of the population?
A
air temperature
B
disease
C
food supply
D
territory size
Your answer
6
The competitive exclusion principle is based on experimental evidence but aims to
explain an observation about real ecosystems.
What observation is explained by the competitive exclusion principle?
A
Only one species can occupy a particular niche.
B
Pioneer plants are not found in an established community.
C
The diversity of a habitat increases as succession proceeds.
D
Similar ecosystems develop under similar environmental conditions.
Your answer
Version 1
18
© OCR 2017
7
An experimental pond was set up by placing water containing a little plant fertilizer in
a tank and leaving it outside. Various organisms, X, Y and Z, were subsequently
found in the tank and their inter-relationships were observed.
The graph shows how their populations changed over time.
Which line of the table identifies the trophic levels of X, Y and Z?
X
Y
Z
A
predator
prey
primary consumer
B
prey
predator
primary producer
C
primary consumer
primary producer
prey
D
primary producer
primary consumer
predator
Your answer
Version 1
19
© OCR 2017
8
The table compares how three animals use the energy in their food.
percentage of
energy in food
that is absorbed
percentage of
energy absorbed
that is respired
percentage of energy
absorbed that is
incorporated into new
tissue
grasshopper
50
47
3
rabbit
37
24
13
trout
86
56
30
animal
What can be concluded from this data?
A
The rabbit uses more energy in respiration.
B
The trout uses a lower proportion of its absorbed energy in respiration than the
other animals.
C
The grasshopper is inefficient because it is an ectotherm.
D
The trout has the potential to grow the fastest.
Your answer
Version 1
20
© OCR 2017
9
The Haber process fixes atmospheric nitrogen to make nitrate fertiliser. The graph
shows the effect of adding inorganic nitrate fertiliser on the yield of maize.
What conclusion can be drawn from the graph?
A
Nitrate fertiliser may be supplemented by the action of nitrogen fixing bacteria.
B
Beyond 130 kg ha-1 it is uneconomic to add nitrate fertiliser.
C
Environmental damage can result from the overuse of nitrate fertiliser.
D
Yield is directly proportional to the mass of nitrate fertiliser added.
Your answer
Version 1
21
© OCR 2017
10
Two animal species, L and M, are found in the same area of mixed moorland and
forest.
 In the spring and summer L and M eat the same plant food.
 In the winter, species L eats nuts in the forest while species M eats heather roots
on the moorland.
 Species L and M are preyed upon by the same predator.
 Although M’s numbers are initially reduced more by this predation, M’s population
recovers because M breeds faster than L.
Using this information, what can be concluded about species L and M?
A
They occupy entirely different communities, niches and ecosystems.
B
They are part of the same community but occupy different niches.
C
They occupy the same habitat but are at different trophic levels.
D
They are in the same community but are unrelated in the ecosystem.
Your answer
11
A forestry company aims to increase the output of wood, energy and biochemicals
from its woodlands without compromising woodland biodiversity, health and
resilience.
What principles are informing the company’s aims?
Principle 1: preservation
Principle 2: conservation
Principle 3: sustainable development
A
1, 2 and 3
B
Only 1 and 2
C
Only 2 and 3
D
Only 1
Your answer
Version 1
22
© OCR 2017
12
The table shows the number of breeding pairs of two species of wading birds on a
Scottish island at the start and end of a seventeen year period.
number of breeding pairs of wader birds
wading bird species
1983
2000
lapwing
1104
1364
redshank
486
733
What is the percentage change in the number of breeding pairs of lapwings?
A
19 %
B
23 %
C
33 %
D
51 %
Your answer
13
A water meadow contained cuckoo flower, an important food plant for the caterpillar
of the orange tip butterfly. A student wishes to estimate the abundance of these
species in the meadow, and also the number of predatory beetles that might eat the
caterpillars.
Which line of the table identifies appropriate methods for estimating the abundance of
these organisms in the meadow?
cuckoo flower
orange tip
caterpillar
predatory beetle
A
random quadrats
light trap
light trap
B
systematic quadrats
pitfall trap
pitfall trap
C
random quadrats
random quadrats
pitfall trap
D
systematic quadrats
systematic quadrats
light trap
Your answer
Version 1
23
© OCR 2017
14
A study was made of a rock pool for a period of four hours from the time it was
exposed by the morning tide going out. A pH probe showed that the pH of the water
in the rock pool increased during this time.
What could explain the change in pH?
Statement 1: Animals in the rock pool became more active and produced more
carbon dioxide.
Statement 2: Seaweeds in the rock pool increased their rate of photosynthesis
Statement 3: Temperature increased, reducing the volume of carbon dioxide
dissolved in the water.
A
1, 2 and 3
B
Only 1 and 2
C
Only 2 and 3
D
Only 1
Your answer
15
Human activity can cause these changes to occur in natural ecosystems:
Change 1: the destruction of ancient communities
Change 2: the replacement of indigenous communities by new animal and plant
associations
Change 3: reduction in biodiversity.
Which changes occur when a bog is drained to provide agricultural land?
A
1, 2 and 3
B
Only 1 and 2
C
Only 2 and 3
D
Only 1
Your answer
Version 1
24
© OCR 2017
16
The table compares the plant biomass required to produce 1kg of meat or fish for
human consumption in the form of beef, chicken or salmon.
meat or fish for human
consumption
plant biomass required to produce 1 kg
of meat or fish (kg)
beef
8.7
chicken
1.9
salmon
1.6
Which statements are supported by the data?
Statement 1: Salmon farming uses finite resources more efficiently than beef
farming.
Statement 2: Food security would be enhanced if chicken farms replaced a
proportion of beef farms.
Statement 3: The feed conversion ratio of mass of biomass supplied to mass of
product is higher for fish than for chicken.
A
1, 2 and 3
B
Only 1 and 2
C
Only 2 and 3
D
Only 1
Your answer
Version 1
25
© OCR 2017
17
The bar chart shows the relative number of sightings of three species of mammal in
two areas of Ireland.

Red squirrels are indigenous to Ireland.

Grey squirrels are an introduced species with similar habitat and food
requirements to red squirrels.

Pine martens are an indigenous predator of squirrels.
Which statements are supported by this data and information?
Statement 1: Pine martens reduce squirrel abundance.
Statement 2: Red and grey squirrels show interspecific competition.
Statement 3: Pine martens prey preferentially on grey squirrels.
A
1, 2 and 3
B
Only 1 and 2
C
Only 2 and 3
D
Only 1
Your answer
Version 1
26
© OCR 2017
18
Which land management practices maintain a deflected succession?
Practice 1: Grazing sheep on Snowdonia.
Practice 2: Burning patches of heather on lowland heaths.
Practice 3: Rotational coppicing of hazel trees.
A
1, 2 and 3
B
Only 1 and 2
C
Only 2 and 3
D
Only 1
Your answer
Version 1
27
© OCR 2017
19
The Galapagos Islands are an environmentally sensitive location. The graph shows
how the number of human residents and tourists on the Galapagos Islands has
changed over a period of sixty years. Human activity threatens some animal and
plant populations on the Galapagos.
Which statements concerning the Galapagos Islands are true?
Statement 1: Exponential growth in the number of residents stopped in 2000.
Statement 2: Residents outnumbered tourists in 1990.
Statement 3: Conservation efforts should focus on reducing the number of tourists
by 90% in the next ten years.
A
1, 2 and 3
B
Only 1 and 2
C
Only 2 and 3
D
Only 1
Your answer
Version 1
28
© OCR 2017
20
The flow diagram shows the main events of the carbon cycle.
Which line of the table correctly identifies processes 1, 2, 3 and 4?
1
2
3
4
A
combustion
breathing
photosynthesis
reproduction
B
respiration
death
respiration
death
C
combustion
respiration
photosynthesis
death
D
respiration
metabolism
respiration
reproduction
Your answer
Version 1
29
© OCR 2017