Define the terms species, population and community.

Species:

Population:  

Community:

Explain the shape of the pyramids of energy that are constructed by ecologists to represent energy flow in an ecosystem.

species: group of organisms that can interbreed to produce fertile offspring;
population: group of organisms of the same species living in the same area at the same time;
community: group of populations living and interacting with each other in an area;

energy flows up from one trophic level to the next (in a community);
energy is lost at each stage by waste products/feces/not all the organism is consumed;
most energy is lost through respiration/heat;
each level on the pyramid is about 10% – 20% of the size of the one below it / 80% – 90% energy lost between levels;
labelled diagram of pyramid of energy (indicating trophic levels);

Candidates either knew these definitions well or did not. It is valuable to stress to candidates that many marks come from command term objective 1 questions, which are overwhelmingly “state” or “define”. These questions require commitment to learn these statements and definitions. Such commitment is always rewarded when candidates meet questions such as these in examinations  

Many candidates were able to describe the flow of energy through ecosystems well with the best answers including diagrams of an energy pyramid with the tropic levels labelled.