Grade 11 eost paper

GURU CHARAN KUMAR/IB ESS 2012

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End of Semester Test November 2012

Grade: 11

Subject: Environmental Systems & Societies

Level: SL

Paper: 1

Duration: 1hour 30 minutes

Date: 21.11.2012

Maximum Mark: 80

Candidate Name: ______________________________

Subject Teacher: Guru Charan Kumar / Mesha Das

Instructions to Candidates

Section A: answer all of Section A in the spaces provided.

Additional Material

This question paper consists of 16 printed pages.


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Page 3 of 16

SECTION A

1) The graph below shows the interdependence of population size of two species of mites.

Eotetranychus sexmaculatus serves as the food supply for Typholodromus occidentalis.

[Source: C B Huffaker, (1958), Hilgardia, Volume 27, pages 343–383.

Reprinted by permission of University of California Press.]

(a) Predict when the next population maximum of T. occidentalis will occur. Show your

working.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

...................................................................................................................................... (2)

(b) Determine the numbers of both organisms on September 30.

T. occidentalis: ............................................................................................................

E. sexmaculatus: ......................................................... . .............................................. (1)

(c) (i) Identify the five day period for which the rate of increase of E. sexmaculatus is

at its maximum.

........................................................................................................................... (1)

(ii) Determine when the difference in numbers between both populations is at a

maximum.

........................................................................................................................... (1)

(d) (i) Calculate the time lag between the maximums of both species in the period

from October 5 through November 5.

E.

sexm

acu

latu

s

5 15 253010 20

July August September October November December January February

5 15 253010 20

5 15 253010 20

5 15 2510 20

5 15 253010 20 5 15 25

3010 205 15 25

3010 205 15 25

3010 20

2500

2000

1500

1000

500

0

50

40

30

20

10

0

E. sexmaculatus(prey)T. occidentalis

(predator)

T.

occ

iden

tali

s


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...........................................................................................................................

........................................................................................................................... (1)

(ii) Suggest a reason for this time lag.

...........................................................................................................................

........................................................................................................................... (1)

(e) (i) Describe the role that negative feedback might play in this species interaction.

...........................................................................................................................

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...........................................................................................................................

........................................................................................................................... (2)

(ii) Explain why the global human population is less prone to negative feedback

control than other organisms.

...........................................................................................................................

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........................................................................................................................... (3)

(f) Outline two examples of feedback in global warming.

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...................................................................................................................................... (2)

(Total 14 marks

2) Figures 1 and 2 represent the food webs for two ecosystems.

Figure 1. Terrestrial Grassland

Figure 2. Marine Food Web

Sunlight

Grass

autotroph

Herbivore

heterotroph

Carnivore

heterotroph

Death

Inorganic

material

Decay

and mineralization

Human

Baleen whaleSmall-toothed

whale

Sperm whale

Elephant

seal

Leopard seal

Squid

Crabeater

seal

Seabird

Fish

Carnivorous plankton

Phytoplankton

Herbivorous

plankton

Krill


Page 6 of 16

[Source: Tudge, C (1991) Global Ecology, The Natural History Museum, pp. 112–113]

(a) (i) State, giving three reasons, which of the food webs, Figure 1 or Figure 2, is

likely to be more stable.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (3)

(ii) Deduce what would happen to the ecosystem in Figure 1 if rabbits were

removed.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(iii) Predict two changes that may occur if foxes were removed from the food web in

Figure 1.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)


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Figure 3. Antarctic Marine Food Web

[Source: Trudge C (1991) Global Ecology, The Natural History Museum, pp. 113]

(b) In Figure 3, the size of the circle represents the relative biomass of each animal

species within the food web.

Identify which of the diagrams in Figure 4 below best illustrates what would happen to

the food web balance in Figure 3,

(i) if humans hunted for seals and fish.

........................................................................................................................... (1)

(ii) if humans harvested krill.

........................................................................................................................... (1)

(Total 9 marks)

Baleen whales

Krill

Fish

PenguinsSquid

Seals


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3) (a) Explain the 2 difference between an open system and a closed system.

...........................................................................................................................

........................................................................................................................... (2)

(b) The first and second laws of thermodynamics suggest that energy is neither made or

lost, merely transformed. Using a named ecosystem, outline how this occurs.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(c) (i) Explain how socio-political and economic pressures have caused or are causing

the degradation of a named area of biological significance.

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........................................................................................................................... (3) (Total 7 marks)


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4) a) Examine the diagram below. It is not intended to represent any particular ecosystem

and the organisms are not shown to the same scale. Choose one of the organisms

shown in the diagram.

Write its name here .....................................................................................................

[Source: Adapted from Adds, J et al. The Organism and the Environment, 2nd edition (1997), page 81]

For the organism you have chosen, describe and evaluate a method for estimating its

abundance.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

marsh plantaquatic

invertebrate

aquatic snailmussel

midgelarvae

phytoplankton

amphibian

aquatic plants

mammal

bird

fish

aquatic plant

tree


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......................................................................................................................................

......................................................................................................................................

...................................................................................................................................... (5)

(b) Explain why it might be important to know the abundance of the species of organisms

in an ecosystem in assessing that ecosystem’s diversity.

......................................................................................................................................

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......................................................................................................................................

...................................................................................................................................... (2)

(c) State how you would attempt to identify an organism with which you were unfamiliar.

......................................................................................................................................

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......................................................................................................................................

...................................................................................................................................... (2)

(d) (i) Name and briefly describe an ecosystem of which you have made a special

study.

...........................................................................................................................

........................................................................................................................... (1)

(ii) Describe one human activity that might influence your chosen ecosystem.

...........................................................................................................................

........................................................................................................................... (1)

(iii) State one abiotic factor that might be changed by this human activity.

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(1)

(iv) Explain how this human activity might change the abiotic factor.

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........................................................................................................................... (2)

(v) Outline how you would measure changes in this abiotic factor.

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........................................................................................................................... (2)

(e) (i) Explain, with an example, what is meant by the term Trophic levels.

...........................................................................................................................

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........................................................................................................................... (2)

(ii) Explain how you would measure the changes in the species diversity of an

ecosystem.

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...........................................................................................................................

........................................................................................................................... (2)


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(Total 20 marks

5) The following is a schematic diagram of an “ecotron”. This is a walk-in chamber with

computer controlled climatic conditions for studying small communities representative of

natural ecosystems.

[Source: modified from NERC www.cpb.bio.ic.ac.uk/ecotron/ecotron.html]

(a) State whether this is an open, closed or isolated system. Give one reason for your

answer.

......................................................................................................................................

...................................................................................................................................... (1)

(b) Identify and explain two ways in which the inputs to the system would differ from the

outputs while communities are growing within the ecotron.

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...................................................................................................................................... (4)

(c) If a fall in temperature of the system is detected by the sensors, mechanisms will be

automatically initiated to increase the temperature. State which kind of feedback this

demonstrates.

...................................................................................................................................... (1)

airtight transparent

ceiling

irrigation system

plant, animal

and decomposer

communities

air pump

lighting

air outlet

sensors

Scale: 1m


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(d) (i) Outline how the second law of thermodynamics can explain the pyramid shape

associated with most food chains including that found in the ecotron.

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........................................................................................................................... (2)

(ii) In this context, explain why food chains studied in the ecotron are generally

limited to no more than three trophic levels.

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........................................................................................................................... (2)

(Total 10 marks)


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6) a) Define the term biodiversity.

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...................................................................................................................................... (2)

(b) Simpson’s diversity index is D =

(i) State what the symbol n represents in the above equation.

...........................................................................................................................

........................................................................................................................... (1)

(ii) Suggest what a high D value indicates about an ecosystem.

...........................................................................................................................

........................................................................................................................... (1)

(iii) Predict the effect on the value of D if the number of organisms of one species

increased but the total number of organisms of all other species in an ecosystem

remained constant.

...........................................................................................................................

........................................................................................................................... (1)

(iv) Suggest one reason for a low D value in an ecosystem.

...........................................................................................................................

........................................................................................................................... (1)

(c) (i) Outline a method for estimating plant biomass within a named ecosystem.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

)1(

)1(

nn

NN


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........................................................................................................................... (3)

(ii) Outline a method for estimating the abundance of small mammals in a tundra

environment.

...........................................................................................................................

...........................................................................................................................

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...........................................................................................................................

........................................................................................................................... (2)

(Total 11 marks)

7) The figure below shows the range of tolerance to temperature for a fish population.

[MILLER, Living in the Environment, 7E. © 1992 Brooks/Cole, a part of Cengage Learning, Inc.

Reproduced by permission. www.cengage.com/permissions]

(a) (i) Outline what the figure above shows about fish density and temperature.

...........................................................................................................................

Optimum range

Zone of

physiological

stress

Zone of

intolerance

Zone of

intolerance

Zone of

physiological

stress

No

organisms

Few

organisms

Few

organisms

No

organismsAbundance

of organisms

Lower limit

of tolerance

Upper limit

of tolerance

Temperature HighLow


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...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(ii) Explain what is meant by a limiting factor in the context of the fish population

in this lake.

...........................................................................................................................

........................................................................................................................... (1)

(iii) State, giving a reason, whether temperature is a density-dependent or density-

independent factor in the regulation of fish populations.

...........................................................................................................................

........................................................................................................................... (1)

(b) Temperature is an abiotic feature of an ecosystem. List four other abiotic factors of an

ecosystem.

......................................................................................................................................

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......................................................................................................................................

...................................................................................................................................... (2)

(c) With reference to one abiotic factor you have named in (b), outline and evaluate a

method for measuring this factor.

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...................................................................................................................................... (3)

(Total 9 marks)

Grade 11 eost paper

Education

guru charan kumarib

population maximum

maximum mark

eotetranychus sexmaculatus

sexmaculatus preyt

typholodromus occidentalis

global human population

negative feedback control