Topic 1 Practice Questions – Marking Scheme
(a)
(b)
feedback:
the return of part of an output of a system (or subsystem) as an input,
so as to affect succeeding outputs/OWTTE;
1
Answers must have a definition, some explanation of negative
feedback and an example (which need not be as detailed as that
below) to achieve full marks.
negative feedback:
feedback that tends to damp down, neutralize or counteract any
deviation from an equilibrium and promotes stability/OWTTE;
example:
increase in number of predators (e.g. owls) → decrease in small
mammals (e.g. mice, voles, shrews) → increase in small
mammals → increase in predators;
explanation:
understanding of ecological relationships/processes;
3 max
For the final mark the answer must show some understanding of
ecological relationships or processes, such as predation, disease,
breeding success. This material may be incorporated in the
example. Some or all of the information may be given in the
form of a diagram.
[4]
(a)
(i)
(ii)
(b)
(c)
The Gaia philosophy envisages the entire planet
as a living, self regulating organism;
1
an open system exchanges energy and material,
a closed system exchanges energy but not material;
1
sunlight converted by producers;
producers eaten by consumers;
some energy released as heat;
consumers eaten by other consumers;
detrital decay;
(i)
For example coral reefs:
coral reefs increasingly seen as an economic
resource rather than a subsistence resource;
coral reefs have been used for increasingly
intensive fishing;
source of building materials;
sites for tourism;
pollution sink;
cultural and technological change for example
in fishing industry (dynamite fishing);
political motives behind promoting tourist opportunities;
3 max
(ii)
under increasing population pressure;
has led to overfishing (unsustainable);
loss of biodiversity;
damage to extremely vulnerable polyps;
and knock-on effects throughout the ecosystem;
4 max
For example:
conservation areas / national parks;
restricting resource use or allowing resource
use at a sustainable level within the park;
will have economic implications;
can be difficult to police;
ocean is an open system;
indigenous people need to retain control;
victim of your own success;
3 max
[12]
(a)
(i)
(ii)
(b)
feedback that tends to damp down/neutralize/counteract
any deviation from an equilibrium, and promotes stability;
1
feedback that amplifies/increases change (it leads to
exponential deviation away from equilibrium);
1
most ecosystems contain inbuilt checks and balances;
without internal balance an ecosystem would spiral out of control;
without negative feedback no ecosystem could be self-sustaining;
1 max
(c)
smoke
coal
cold water
Three correct [2], one or two correct [1].
steam / water vapour / water
energy /
electricity
warm water
2 max
[5]