Option C: Ecology and conservation (Core topics) :C.4 Conservation of biodiversity SL Paper 3

Date	November 2017	Marks available	2	Reference code	17N.3.SL.TZ0.14
Level	Standard level	Paper	Paper 3	Time zone	TZ0
Command term	Explain	Question number	14	Adapted from	N/A

Question

Data from the International Union for Conservation of Nature (IUCN) indicates that the population numbers of many mammal species are decreasing. The chart shows reasons for the decrease and the number of species in each category of danger.

[Source: Michael Hoffmann et al. 2011. The changing fates of the world’s mammals. Philosophical Transactions of the Royal Society B, Volume 366, issue 1578. DOI: 10.1098/rstb.2011.0116. By permission of the Royal Society.]

Calculate how many species are classified as endangered due to hunting and trapping.

[1]

State one reason mammals can continue to survive even if they are extinct in the wild.

[1]

Outline how deforestation can affect the richness of biodiversity in an ecosystem.

[1]

Explain the impact of plastic waste on Laysan albatrosses (Phoebastria immutabilis).

[2]

Markscheme

14/15/16

Do not accept intermediate values eg: 14.5

zoos/nature reserves/captive breeding/ex situ conservation/farming/husbandry/pets

deforestation reduces richness by destroying habitat/loss of food/shelter/nesting sites

a. adults/young ingest plastic «which is indigestible»

b. plastic damages/fills stomach «can lead to starvation and death»

c. plastic blocks intestine so food cannot be digested «can lead to starvation and death»

d. adults/young can become entangled in plastic and so they drown/choke/suffocate

Allow other verifiable effect of plastic

“Can kill the birds” is too vague and worth [0]

[Max 2 Marks]

Date	May 2017	Marks available	4	Reference code	17M.3.SL.TZ2.18
Level	Standard level	Paper	Paper 3	Time zone	Time zone 2
Command term	Explain	Question number	18	Adapted from	N/A

Question

Explain the use of indicator species to assess the condition of the environment.

Markscheme

a. indicator species are organisms that indicate health of ecosystem/level of pollution

b. they exist in higher relative numbers under certain environmental conditions
OR
if certain environmental conditions are not found, indicator species die/reproduce

c. are very sensitive/highly tolerant species

d. provides quantitative information on the quality of the environment around it

e. named example of indicator species and susceptibility
Must state a named species. eg: Lichens used to detect air quality.

f. indicator species are used to calculate biotic index

Date	May 2017	Marks available	4	Reference code	17M.3.SL.TZ1.16
Level	Standard level	Paper	Paper 3	Time zone	Time zone 1
Command term	Discuss	Question number	16	Adapted from	N/A

Question

Freshwater invertebrates were sampled by students at three sites along a river in central France. The animals were identified and counted. The diversity of each site can be compared using Simpson’s reciprocal index.

Simpson’s reciprocal index is given by the following formula:

Calculate the diversity of site C. Working should be shown.

[2]

Site A has a higher Simpson’s reciprocal index than Site B showing that its diversity is higher.

Explain the reason that ecologists consider Site A to have a higher diversity than Site B, despite both sites having six different species present.

[2]

Discuss the advantages and disadvantages of in situ conservation methods.

[4]

Markscheme

b. = 3.56 «allow 3.55»

a. the species in Site A are more evenly represented than site B

b. site B has a large number of one species «but very few in the other 5»

c. Simpson’s reciprocal index is a measure of species evenness as well as species richness

Advantages:
a. conservation in the natural habitat / ecosystem

b. the species will have all the resources that it is adapted to

c. the species will continue to evolve in their environment / can maintain genetic diversity

d. the species have more space so a bigger breeding populations can be kept

e. it is cheaper to keep an organism in its natural habitat

f. established food webs/ species interactions can be maintained

Disadvantages:

g. it is difficult to control illegal exploitation «eg poaching»/harder to monitor populations

h. the area may need restoring / may be required for other purposes

i. alien species are difficult to control

j. species close to extinction are harder to conserve

k. management/protection may represent a significant cost

Date	November 2016	Marks available	1	Reference code	16N.3.SL.TZ0.14
Level	Standard level	Paper	Paper 3	Time zone	TZ0
Command term	Outline	Question number	14	Adapted from	N/A

Question

In 1997 in South Africa, a decision was made to decrease the use of mosquito-killing pesticides due to their negative effect on the environment. Mosquitoes are known to be responsible for the spread of malaria. In 2001 the decision was reversed and the use of pesticides was increased. The graph shows the estimated numbers of people with malaria in each year.

Outline the trend in the number of people with malaria during the period when the use of pesticides was decreased in South Africa.

[1]

One pesticide used in killing mosquitoes was DDT. Considering its harmful effects, discuss whether the decision to reintroduce it was justified.

[4]

Markscheme

the number of people with malaria increased

a. choice has to be made between damage to environment or increase in malaria

b. DT may lead to biomagnification/bioaccumulation in food chains
OR
taken up by species in lower trophic levels becoming more concentrated at higher trophic levels

c. causes harm to consumers at end of food chain
OR
example «eg: thin egg shells of falcons»

d. DDT is shown to be effective in reducing malaria

e. possible partial solution to be selective in areas sprayed with DDT

f. may kill insects that are not pests

Date	November 2016	Marks available	2	Reference code	16N.3.SL.TZ0.13
Level	Standard level	Paper	Paper 3	Time zone	TZ0
Command term	Evaluate	Question number	13	Adapted from	N/A

Question

The number of plants in two fields of approximately the same size was counted.

Compare and contrast the richness and the evenness of the two fields.

[2]

A calculation of Simpson’s reciprocal index was undertaken on each field with the following results.

Evaluate these results.

[2]

A calculation of Simpson’s reciprocal index was undertaken on each field with the following results.

Evaluate these results.

[2]

Markscheme

a. same richness as they have the same number of species/total of individuals

b. field 1 has more evenness as more even distribution of numbers among the species. Allow vice versa.

a. the higher the number the more diverse/biodiverse is the field
OR

b. field 1 shows greater diversity/biodiversity (as it has a higher value)

a. the higher the number the more diverse/biodiverse is the field
OR

$D = \frac{N (N - 1)}{\sum n (n - 1)}$

b. field 1 shows greater diversity/biodiversity (as it has a higher value)

Date	May 2013	Marks available	1	Reference code	13M.3.SL.TZ2.20
Level	Standard level	Paper	Paper 3	Time zone	Time zone 2
Command term	Outline	Question number	20	Adapted from	N/A

Question

Explain the niche concept.

[3]

Outline one reason for the extinction of a named animal species

[1]

Markscheme

a. niche is an organism’s ecological role/mode of existence;
b. niche is how organism uses abiotic and biotic resources;
c. depends on where organism lives/habitat;
d. depends on organism’s nutrition/feeding activities;
e. depends on interactions (competition/herbivory/predation/mutualism) with other organisms;

name of species and what caused it to become extinct (both needed)
The named species must be extinct and not endangered.
eg:
passenger pigeon (became extinct when) hunted as a source of food
Note: dinosaur is not a named species.

Date	November 2013	Marks available	1	Reference code	13N.3.SL.TZ0.21
Level	Standard level	Paper	Paper 3	Time zone	TZ0
Command term	State	Question number	21	Adapted from	N/A

Question

$D = \frac{N (N - 1)}{\sum n (n - 1)}$

State what $N$ and $n$ stand for in this formula.

$N$ :

$n$ :

[1]

b.i.

Discuss three reasons for the conservation of biodiversity in rainforests.

[3]

b.ii.

Markscheme

$\begin{array}{l} N : & total number of organisms of all species found/in population; \\ n : & number of organisms of a particular species; \end{array}}$ (both needed)

b.i.

ethical: life should be respected / cultural importance for (local human indigenous) population / (human indigenous) population’s ability to live sustainably within ecosystem might be affected / richness for future generations;

ecological: native species might be replaced by alien species / extinction of one species can lead to the extinction of many others / interdependency of species may be disrupted/negative effects on food chains /soil erosion/floods occur with deforestation / rainforests act as a carbon sink which helps reduce global warming;

economic: medicines or materials not found yet / genes of wild species need to be preserved / ecotourism improves local economy/encourages local conservation / plant sources of pharmaceuticals lost if species extinct / crops may be improved with alleles from wild plants;

aesthetic: loss of beauty of wild / inspiration for artists;

(Words in italics alone are not worth marks)

b.ii.

Date	May 2010	Marks available	1	Reference code	10M.3.SL.TZ2.21
Level	Standard level	Paper	Paper 3	Time zone	Time zone 2
Command term	State	Question number	21	Adapted from	N/A

Question

State the name of a statistical method used to quantify changes in biodiversity.

Markscheme

Simpson diversity index

Date	May 2010	Marks available	5	Reference code	10M.3.SL.TZ2.3
Level	Standard level	Paper	Paper 3	Time zone	Time zone 2
Command term	Discuss	Question number	3	Adapted from	N/A

Question

State a source of vitamin D in a human diet.

[1]

Discuss exposure to sunlight as a source of vitamin D.

[2]

Discuss reasons for conservation of biodiversity of a named ecosystem.

[5]

Markscheme

fatty fish e.g. mackerel/tuna/sardines/herring etc.;
liver;
eggs;
fortified dairy products;

sunlight stimulates skin to synthesize vitamin D;
less sun exposure/insufficient vitamin D leads to skeletal deformities/rickets;
UV radiation increases the incidence of skin cancer/melanoma;
vegans/vegetarians are more likely to lack vitamin D so need more exposure to sunlight;

name of ecosystem:
e.g. (tropical) rainforest;
ethical reason:
every species has a right to life, regardless of whether it is useful/non useful to humans;
potential of undiscovered medicines;
ecological reasons:
better use of the rainforest may occur by respecting the existing balance in concert with the indigenous people;
native species are adapted to local conditions whereas invasive species are less likely to be in balance;
species in the rainforest are interdependent so loss of species threatens the rest of the community;
deforestation of rainforests increases soil erosion/silting of rivers/flooding/CO2 atmospheric levels;
economic reasons:
ecotourism is a potential source of income;
aesthetic reasons:
loss of beauty of the system;
artists are inspired by the images/flowers/animals of rainforests;
heritage/cultural reasons:
maintenance of the rainforest preserves human cultural diversity;
Do not award more than [2 max] for each category of reasons e.g. not more than [2] for ecological reasons.