Outline the diversity of Eubacteria according to cell wall structure.

State the role of Rhizobium and Nitrobacter in the nitrogen cycle.

Rhizobium:        ...........................................................

Nitrobacter:        ...........................................................

Explain the use of bacteria in bioremediation.

can be Gram-positive or Gram-negative;
Gram-negative have a thinner wall/less peptidoglycan/converse;
Gram-negative have an outer layer of lipopolysaccharide and protein;

Rhizobium: converts atmospheric nitrogen to ammonia / nitrogen fixation;
Nitrobacter: oxidizes nitrite into nitrate / nitrification;

bacteria remove contaminants from the environment;
by using them as energy sources;
(or) by converting them to a soluble/ harmless form;
example of bioremediation (e.g. Pseudomonas is used to clean up oil spills);

Most were able to get a mark for indicating that bacteria can be Gram-positive or Gram-negative. Many were able to obtain a second mark for indicating the different compositions of their cell walls.  

Candidates tended to either get the roles of both bacteria in the nitrogen cycle correct or both wrong.

While many had a general idea of the use of bacteria in bioremediation, few were able to give an actual example.