Download ecosystem answers

ECOSYSTEM ANSWERS
1.
(a)
(b)
(i)
All (living) organisms/populations found in an ecosystem/in a habitat/in an
area; (NOT just ‘all species present’/’no. of spp.’)
1
(ii)
Habitat (/environment) + community (/described)/
abiotic and biotic factors in a defined area/named area;
1
(i)
9 – 25°C
1
(ii)
biotic factor:
food/predators/presence of mate/competition/
disease;
abiotic factor:
water current/tides/nature of substratum/O2 (conc) /
pH/toxins/light;
2
(Total 5 marks)
2.
(a)
Wood mouse;
(b)
Decomposers/bacteria/fungi/saprophytes/saprotrophs/detritivores;
(c)
Colonisation/pioneer species/examples from fig/seeds/fruits;
soil formation/improvement/change by organism;
succession/eq;
process repeated to climax community/forest;
diversity is reduced;
(d)
MAX. 3
{trees form food source for many species/wide range of primary consumers;
{(primary consumers/named example/are eaten by other species)
{idea that trees are the basis of food chains/food webs;
productivity of area is reduced (with loss of trees);
so fewer organisms can be supported;
habitats are lost/ecological niches are lost (with each tree species lost);
MAX. 3
(Total 8 marks)
3.
(a)
(i)
Lepus;
(1)
(ii)
Lagomorpha;
(1)
(b)
(i)
Distribution / habitat overlaps / found in the same place;
(1)
(ii)
Geographical isolation / separation / barrier;
Adapted to slightly different conditions / environment / different selection
pressure;
Mutation in one population / different mutations;
(Max 2)
(Total 5 marks)
4.
(a)
Allow two marks for 617;
allow one mark if arithmetical error in calculation;
(2)
(b)
(i)
Moose numbers rose in absence of predators / with plenty of food;
depletion of food / spread of disease / climatic change / resulted in fall / death;
(2)
(ii)
Caused the moose numbers to stabilise at lower level / equivalent;
(1)
(Total 5 marks)
5.
(a)
Habitat as place where an organism lives/where a species lives;
environment as surrounding/abiotic portion of ecosystem;
(2)
(b)
The greater the distance from the city centre, the less the sulphur
dioxide concentration and the more species of lichens/converse;
traffic/industry generates sulphur dioxide/few species are able to
tolerate high SO2 concentrations;
(2)
(c)
(i)
Correct answer (2.6) gains two marks;
allow one mark if answer incorrect but  interpreted correctly;
(2)
(ii)
Diversity would decrease as you move towards city centre/converse;
few species are able to tolerate high sulphur dioxide concentration;
(2)
(Total 8 marks)
6.
(a)
(i)
Understanding of  n(n-1);
correct answer of 2.85;
(2)
(ii)
Diversity gives both number of individuals and number of species;
avoids difficulties of large number of rare species;
(2)
(b)
Sample with quadrats/other acceptable method;
random placing;
count number of individuals of each species;
(3)
(c)
(i)
Figure 1 shows no correlation/relationship between bird species diversity
and plant species diversity;
Figure 2 shows positive correlation/as plant structure diversity increases so
does bird species diversity;
(2)
(ii)
Succession;
longer the field left uncultivated, greater proportion of shrubs and trees;
(2)
(iii)
Provides more niches;
different species of birds feed/nest at different heights/in different places;
(2)
(d)
(Continues to increase and then) levels out;
as climax is reached;
maximum plant structural diversity;
(Max 2)
(Total 15 marks)