List two abiotic factors that affect the distribution of plant species.

1.  ..................................................................
2.  ..................................................................
 

State one example of secondary succession.

Distinguish between fundamental and realized niches.

Discuss the difficulties of classifying organisms into trophic levels.

temperature / water / light / soil pH / salinity / mineral nutrients
Award [1] for any two abiotic factors.

regrowth following forest fire/fallow land/earthquake / other example of secondary succession

fundamental niche is the potential mode of existence and realized niche is the actual mode of existence;
fundamental niche depends on the adaptation of a species;
competition/predation prevents a species from occupying its entire fundamental niche;
realized niche is usually smaller than fundamental niche;

organisms may fit into more than one trophic level;
omnivores consume organisms from all levels of the food chain;
there may be seasonal changes in trophic levels depending on food supply;
some organisms alter diet with their life cycle (e.g. some amphibians);

Almost all candidates were able to list abiotic factors that affected plant distribution.

While there were many possible examples of secondary succession, many indicated colonization of lava after a volcano erupted which is an example of primary succession.

Candidates were familiar with fundamental and realized niches and thus gained one mark but few could distinguish clearly between them and gain two marks.

Most candidates were able to gain one mark for indicating that organisms may fit into more than one trophic level but few obtained a second mark for discussing such ideas as organisms alter diet with stage in their life cycle or that there are seasonal changes in trophic levels.