ibbiohlassign012ecologypart2

IB HL BIO – Eco Part 2 Assignment of 22

IB HL Biology – Ecology Part 2 Assignment

1. (a) State three factors that can affect the distribution of animal species.

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(b) Discuss why an index of diversity could be useful in monitoring environmental change.

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(c) Outline the conservation role of one named international agency.

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(Total 5 marks)

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2. Discuss reasons why the biodiversity of rainforests should be conserved.

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3. Foraminifera are small protozoans found in the sediment of all marine ecosystems. Several thousand species of foraminifera live in the Earth's oceans. Because a large number of individuals can be found in a small amount of sediment and because they exist worldwide, foraminifera are useful in examining the distribution of species. The bar graph below summarises data gathered from five coastal regions around North America. Those species occurring in all five regions are considered to be ubiquitous and those species occurring in only one area are considered to be endemic. The species of foraminifera were placed into three classes based on the number of times each species occurred at the five coastal regions.

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1 0 0

0

O ccu rren ces(n u m b e r o f tim es sp ec ie s see n in a re g io n )

P ac ific A rc tic A tlan tic G u lf o fM ex ico

C arib b ean

U U U U U

E

E

E

E

E

N u m b er o f sp ec ie s

> 3 22 -3 21 -2

[Source: Buzas and Culver, BioScience (1991), 41, pages 483–489]

(a) Calculate the percentage of endemic species occurring in the Pacific region.

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(b) Among the five regions, deduce the region where it would be easiest to find most of the ubiquitous species.

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(c) Compare the occurrence of endemic species in the Pacific and Caribbean regions.

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(d) Suggest, giving a reason, which of the Pacific, Atlantic or Caribbean regions will have a greater extinction rate.

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(e) Identify which region has the lowest species diversity.

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(Total 7 marks)

4. (a) Distinguish between in situ and ex situ conservation.

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(b) List three examples of ex situ measures that could be used to conserve endangered species.

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(c) Discuss the international measures needed to conserve endangered species of fish.

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(Total 7 marks)

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5. In the south-west of the USA, dams were built across rivers in the early 1900s to stop natural flooding. As a result, a non-native tree Tamarix ramosissima (salt cedar) gradually replaced the native Populus deltoides (cottonwood) as the dominant woody species. Flooding is being re-established to reverse the invasion of Tamarix.

Studies were done to investigate the relative competitive abilities at the seedling stage using different densities of the two species. Seedlings were grown in pots at different densities and mixtures of the two species. A three dimensional model was developed to show the effect of the densities of each species on Populus mass (graph A) and height (graph B). Densities represent the number of seedlings per 20-cm-diameter pot.

[Source: A Sher, D Marshall and S Gilbert, (2000) Conservation Biology, 14, pages 1722–1754]

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(a) Considering the pots where Populus is growing without Tamarix, describe the change in mass and height of Populus with increased density of Populus seedlings.

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(b) Describe how Tamarix density affects Populus height.

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(c) Suggest two factors that could have allowed Tamarix to dominate in non-flood conditions.

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(Total 6 marks)

6. (a) Distinguish between parasitism and mutualism.

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(b) Outline the management of nature reserves.

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(Total 4 marks)

7. The following equation is the Simpson diversity index.

)1(

1

nn

NND

N is the total number of organisms of all species found and n is the number of individuals of a particular species.

The Simpson diversity index of two communities was measured and the results obtained are shown below.

Community A: D = 12.3 Community B: D = 25.7

(a) Outline the use of the Simpson diversity index for the above communities.

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(b) Explain what is meant by the niche concept.

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(Total 5 marks)

8. The Food and Agricultural Organization (FAO) gathered information to determine if marine ecosystems were being damaged by overfishing. The total fish captured in each of three oceans from the years 1960 to 2000 was compared to the overall world marine capture.

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9 0

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F ish ca tch /× 1 0 to n n es6

1 9 6 0 1 9 7 0 1 9 8 0 1 9 9 0 2 0 0 0Year

W o rld m arin efish cap tu re

P ac ific

O cean

A tlan tic

O cean

In d ian

O cean

[Source: R Buckley (editor), World Fishing: Beyond Sustainability, (2002),Understanding Global Issues Limited, pages 8–9]

(a) Calculate the percentage of the world catch that came from the Atlantic Ocean in 1990.

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(b) Compare the data from the Pacific Ocean with that from the Atlantic Ocean.

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(c) Suggest one reason in each case for the change in the quantity of fish captured in the Atlantic and Indian Oceans from 1980 to 1990.

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(Total 6 marks)

9. (a) Describe the use of ex situ conservation measures.

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(b) (i) Define the term niche.

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(ii) Explain the niche concept using a named organism.

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(Total 8 marks)

10. Discuss the difficulties in obtaining quantitative data needed to promote fish conservation.

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11. (a) State the use of the Simpson diversity index.

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(b) Outline the role of the WWF in conservation measures.

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(c) Discuss international measures that would promote the conservation of fish.

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(Total 6 marks)

12. Ecosystems require an input of energy, water and nutrients to maintain themselves. Nutrients may be reused through recycling within ecosystems.

Nutrient cycling within an ecosystem has been studied in many biomes. One factor studied is the mean residence time (MRT), which is the amount of time needed for one cycle of decomposition (from absorption by organism to release after death). The table below gives the mean residence time for certain nutrients in four different biomes. In addition, the plant productivity is also shown. (Plant productivity gives an indication of the quantity of biomass potentially available to consumers.)

Mean residence time / years

Biome Carbon Nitrogen Phosphorus Potassium Calcium Magnesium Plant productivity /

g Cm–2

yr–1

Sub-arctic forest 353.0 230.0 324.0 94.0 149.0 455.0 360

Temperate forest 4.0 5.5 5.8 1.3 3.0 3.4 540

Chaparral 3.8 4.2 3.6 1.4 5.0 2.8 270

Tropical rainforest

0.4 2.0 1.6 0.7 1.5 1.1 900

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[Source: W H Schlesinger (1991), in M Bush, Ecology of a Changing Planet (1997), Prentice Hall, page 67]

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(a) (i) State which nutrient shows the shortest mean residence time in a temperate forest.

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(ii) Identify the biome in which potassium has the longest mean residence time.

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(b) Compare the mean residence time for nutrients in the temperate forest and chaparral.

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(c) Evaluate the relationship between the mean residence time and plant productivity for the different biomes.

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(d) Suggest one reason for the difference in mean residence time of nutrients in the tropical rainforest and the sub-arctic forest.

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(e) Define the term ecosystem.

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In addition to nutrients, other atmospheric elements may also enter the ecosystem. Radioactive cesium-137 was released into the atmosphere by atomic bomb tests in 1961. The cesium-137 was deposited in the soil and on to plants. The graph shows the amount of radioactivity found in the tissues of lichens (an alga and a fungus growing together), caribou (a member of the deer family) and the Inuit (people of Alaska and Northern Canada) in the Anaktuvuk Pass of Alaska.

In u it

C a rib o u

L ich e n s

Ju n e1 9 6 1

Ju n e1 9 6 2

Ju n e1 9 6 3

Ju n e1 9 6 4

Ju n e1 9 6 5

Ju n e1 9 6 6

D ec D ec D ec D ec D ec

In c re a s in g rad io ac tiv ity/ n C i g – 1

[Source: W G Henson, “Cesium-137 in Alaska Lichens, Caribou and Inuit.” Health Physics, (1967), 13,pages 383–389, Pergamon Press; reproduced with permission from the Health Physics Society]

(f) Describe the level of cesium-137 in the Inuit from 1962 through to 1965.

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(g) The three organisms form a food chain. Deduce the trophic level of

(i) lichens. ...............................................................................................................

(ii) the Inuit. ...............................................................................................................(2)

(h) Suggest a reason for the difference in the amount of cesium-137 found in lichens, caribou and the Inuit.

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(Total 13 marks)

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13. Describe the causes and effects of the increased greenhouse effect.(Total 6 marks)

14. Outline how increased UV radiation can affect life on Earth.

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15. Explain how methane is produced from biomass.

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16. Outline the biological consequences of acid rain.

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17. Explain evolution of a species by natural selection in response to environmental change.(Total 7 marks)

18. Describe how sexual reproduction promotes genetic variation within a species.(Total 4 marks)

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19. Marine iguanas (Amblyrhynchus cristatus) are herbivorous lizards that are endemic to the Galapagos islands in the Pacific Ocean. They warm their bodies by basking on rocks next to the sea and then dive into the water to feed on algae. Microorganisms in their guts help to digest the algae. In 1998, the algae disappeared from most areas as a result of El Niño, an occasional disturbance to conditions in the ocean around the Galapagos islands.

When marine iguanas are subjected to stress, levels of the hormone corticosterone rise in their blood. Biologists measured blood corticosterone levels in randomly selected individuals on six of the Galapagos islands, in May 1998 and again in May 1999. The marine iguanas’ mass and body length were measured at the same time. A body condition index was calculated from the mass and body length. Individuals with an index of 30 or less are extremely thin. The fattest individuals have an index of 60-70. The scattergraph below shows the body condition index and blood corticosterone levels of individuals on Santa Fe, one of the six islands sampled. Two regression lines are shown, for body condition indices above and below 35.

K ey

1 9 9 8

1 9 9 9

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3 0

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1 0

0

C o rtico s te ro n e/n g m l – 1

2 0 3 0 4 0 5 0 6 0 7 0

B o d y co n d itio n in d ex

[Source: Romero and Wikelski, Proceeding of the National Academy of Sciences (2001), 98,pages 7366–7370. Copyright 2001 National Academy of Science, USA]

(a) (i) Compare the body condition indices of marine iguanas in 1998 with the indices in 1999.

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(ii) State a reason for an increase in body condition index between 1998 and 1999.

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(b) No individuals were found with a body condition index of less than 20 in either year on any of the islands. Suggest a reason for this.

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(c) (i) Describe the relationship between body condition index and blood corticosterone level in 1998

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(ii) Suggest a reason for the relationship.

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The biologists found that by measuring the mean blood corticosterone level of a population of marine iguanas, they could predict the percentage survival of the population over the following year. The graph below shows the relationship between blood corticosterone level and percentage survival.

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C o rtico ste ro n e / n g m l – 1

P ercen tag e su rv iv a l


On 17 January 2001, an oil tanker ran aground on San Cristobal, one of the Galapagos islands. Three million litres of oil were spilt. Corticosterone levels were measured immediately before

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and after the oil spill in the blood of marine iguanas on Santa Fe. The level before the oil spill

was 4 ng ml–1. Afterwards it was 11.5 ng ml–1.(d) Using the data in the graph, predict the change in percentage survival caused by the oil

spill.

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The populations of marine iguanas were being monitored on Santa Fe and on Genovesa, another Galapagos island that was unaffected by the oil spill. Some of the marine iguanas had been permanently marked on each island. The bar chart below shows the numbers of marked individuals recaptured before the oil spill in January 2001 and eleven months afterwards in December 2001.

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N u m b er o f m a rk ed ig u an as

G en o v esa S an ta F e

Jan 2 0 0 1D ec 2 0 0 1


(e) The percentage change in the population on Genovesa between January and December 2001 was + 4 %. Use the data in the bar chart to calculate the percentage change over the same period on Santa Fe. Show your working.

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The level of oil contamination on Santa Fe was low and it is unlikely that it was directly toxic to the marine iguanas.

(f) Suggest two reasons for an oil spill affecting the chances of survival of marine iguanas other than by poisoning them.

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(g) Evaluate the use of blood corticosterone level to predict survival rates of marine iguanas.

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(Total 15 marks)

20. (a) Compare genetic and cultural evolution.

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(b) State two physical features that define humans as primates.

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(Total 5 marks)

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ibbiohlassign012ecologypart2

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conservation role

index of diversity

biology ecology

bio eco

international agency

distribution of animal

biodiversity of rainforests