Calculate the Simpson’s diversity index for the insect species found in Figure 1.

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

Identify two possible reasons why species B and C were not present in the litter layer when it was resampled six months later.

Identify one abiotic factor which may affect the population of insects in a forest.

Describe a method measuring changes in the abiotic factor you have identified in 2(b)(i).

Distinguish between a mutualistic relationship and a parasitic relationship.

$\frac{36\left(36-1\right)}{5\left(5-1\right)+2\left(2-1\right)+6\left(6-1\right)+1\left(1-1\right)+22\left(22-1\right)}$;

Index = 2.45;

[2]

logging/deforestation has occurred and habitats have been lost;
change in season and those species have migrated/hibernated;
different life cycles of insects so they are not in this form at this time;
sampling error the insect is found in a different micro-habitat;
extinction due to inability to adjust to change in abiotic features, such as pollution event/climate change/fire;
extinction due to biotic factors, eg disease / predation;
random/stochastic event and they have not been collected during the survey;

Accept any other reasonable point.

[2 max]

climate;
water supply;
temperature;
humidity;
pH;

Accept other reasonable responses.
Do not allow biotic factors eg predation.

[1 max]

eg temperature.
decide on sample site/sampling technique;
use thermometer/temperature probe to record temperature at regular intervals over time;

[2]

mutualistic both species benefit;
whereas in a parasitic one only the parasite benefits, (usually the host is only affected slightly);

[2]

A large number of candidates gained both marks for this questions. Common error was mis-interpretation of the equation used to calculate Simpson Diversity Index.

Most candidates obtained some marks for this questions. Marks were often lost for answers covering only one marking point or answers being too vague e.g. death of species without suggesting the reason such as predation.

Most candidates correctly answered this question. The most popular response was ‘temperature’. Common error was to name a biotic factor.

The majority of candidate answered this question well. Occasionally the candidates described testing a parameter different to the one named in 2(b)(i).

This question was generally well answered. Some responses lacked the detail required e.g. parasitic relationship is detrimental to the host and beneficial to the parasite.