Question

From the following lists, choose the incorrect combination: 

List-I	List-II	List-III
A	Photoautotroph — Atmospheric \(CO_2\)	Chlorobium
B	Chemoautotroph — Inorganic compounds	Salmonella
C	Photoheterotroph — Organic source	Rhodospirillum
D	Chemoheterotroph — Organic compounds	Xanthomonas

• A. A
• B. B
• C. C
• D. D

Hint:

Salmonella is a chemoheterotroph. Whenever Salmonella appears with chemoautotroph, the statement is incorrect.

Answer 1

The Correct Option is B

Concept: Microorganisms are classified according to their source of energy and source of carbon.
• Photoautotrophs use light energy and \(CO_2\).
• Chemoautotrophs use inorganic substances and \(CO_2\).
• Photoheterotrophs use light and organic carbon.
• Chemoheterotrophs use organic compounds.

Step 1: Examine Combination A. Chlorobium is a photosynthetic bacterium. It can be considered photoautotrophic. Thus Combination A is correct.

Step 2: Examine Combination B. Salmonella is not a chemoautotroph. It is a chemoheterotrophic bacterium obtaining both energy and carbon from organic compounds. Therefore this combination is incorrect.

Step 3: Examine Combination C. Rhodospirillum is a photoheterotroph. This combination is correct.

Step 4: Examine Combination D. Xanthomonas is chemoheterotrophic. This combination is also correct.

Step 5: Final conclusion. Only Combination B is incorrect. Hence option (B) is correct.