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 |
(a)[1]
Classify these bacteria as photoautotrophs or chemoautotrophs.
(b)[2]
Explain how the bacteria can produce carbon compounds in the condition where biomass increased. Refer to both the carbon source and the energy source.