Question 1
Paper 2Medium3 marksA bacterial culture was grown in darkness in a medium in which carbon dioxide was the only source of carbon. The same amount of iron was supplied in each culture, but in different forms. All other conditions were identical.
| Form of iron supplied | Change in bacterial biomass after 48 hours |
|---|---|
| Iron(II) compounds | Increase |
| Iron(III) compounds | No increase |
Classify these bacteria as photoautotrophs or chemoautotrophs.
Explain how the bacteria can produce carbon compounds in the condition where biomass increased. Refer to both the carbon source and the energy source.