Biology 9700 · AS & A Level · Testing for biological molecules
Testing for biological molecules — practice question
In oceans, the nitrogen cycle includes some bacteria that are different from those on land. One ocean bacterium is Nitrococcus mobilis, and it carries out this step in the nitrogen cycle: $\text{NO}_2^- \rightarrow \text{NO}_3^-$.
(a(i))[1]
Name the stage of the nitrogen cycle in which this reaction takes place.
(a(ii))[2]
Describe how nitrogen in nitrate is returned to the atmosphere as nitrogen gas.
(b(i))[2]
Phytoplankton are microscopic photosynthetic organisms and the chief producers in ocean ecosystems. They live in the upper layers of the oceans, where enough light can pass through the water. Define the term ecosystem.
(b(ii))[1]
Define the term producer.
(b(iii))[1]
Define the term habitat.
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “nitrification” …