Define the terms fundamental niche and realized niche.

Fundamental niche: ..................................................... ..............................................

Realized niche: ..................................................... .....................................................

Explain why the carnivores in an ecosystem tend to be fewer in number and have a smaller biomass than the herbivores in the same ecosystem.

Explain why carnivores tend to be more affected by biomagnification than organisms lower down the food chain.

Fundamental niche:
the potential niche / the niche the organism could occupy under ideal conditions / the full mode of existence given the adaptations of the species / OWTTE;

Realized niche:
the actual niche / the niche restricted by competition and environmental variables / the niche resulting from the limits placed on the species / OWTTE;
Responses must distinguish between the two types to gain credit.

energy transfer along the food chain is less than 100 % efficient;
10 % energy transfer between trophic levels;
nutrient transfer is less than 100 % efficient;
each carnivore needs to consume many prey organisms;
tendency for size of organisms to increase as trophic level increases;

mercury / DDT / other named example;
biomagnification is the accumulation of chemicals through the food chain;
chemicals that undergo biomagnification are stored/not broken down (in the bodies of the organisms that consume them);
chemicals are passed (unaltered) from one trophic level to the next;
chemicals become more concentrated in the bodies of each (subsequent) trophic level;
organisms higher up the food chain consume larger amounts of the chemical;

Few could give accurate definitions of the two niches.

This proved to be another weak area, as not many candidates could link the decrease in numbers to the loss of energy between trophic levels in an ecosystem.

Most candidates did not seem to understand that the term biomagnification refers to the passing of chemicals along the food chain, or that the chemicals are stored in the bodies of the organisms that consume them. Consequently, there were few good answers to this question.