The diagram shows the structure of a type of bacterium and details of the response of the bacterium to light. [Figure 2.1: Diagram showing the structure of a type of bacterium and details of its response to light, including fibres for movement, light receptors, and structures containing a chemical similar to chlorophyll.]

1. (a)(i)Use information in the diagram to suggest: the sequence of events that takes place when the bacterium is provided with light from the direction shown[3]
2. (a)(ii)Use information in the diagram to suggest: the advantage to the bacterium of responding to light in this way.[2]
3. (b)There are similarities between the functions of parts of the bacterium and the functions of structures found in the human eye. Suggest which structure in the human eye has a function similar to each of the following regions of the bacterium. A B[2]
4. (c)The type of bacterium shown in the diagram fixes nitrogen. Describe the role of bacteria in nitrogen fixation.[2]
5. (d)(i)The enzyme that these bacteria use to fix nitrogen is destroyed in the presence of oxygen. Suggest why destruction of this enzyme is likely to occur in the type of bacterium in the diagram.[2]
6. (d)(ii)Suggest one adaptation that such bacteria may have developed to prevent the destruction of this enzyme.[1]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.