Question

Find incorrect statements
A. Rhodospirillum is aerobic  
B. Anabaena and Nostoc are free-living nitrogen fixers  
C. Azotobacter is anaerobic  
D. Beijerinckia is aerobic  

• A. C, D
• B. A, C
• C. A, B
• D. B, D

Hint:

Remember that nitrogen-fixing bacteria like Azotobacter and Beijerinckia are aerobic, whereas Rhodospirillum can be anaerobic depending on the conditions.

Answer 1

The Correct Option is B

Analysis of Statements:

A. Rhodospirillum is aerobic: ❌ Incorrect. 🔹 Rhodospirillum is generally anaerobic under certain conditions and can perform anoxygenic photosynthesis.

B. Anabaena and Nostoc are free-living nitrogen fixers: ✅ Correct. 🔹 Anabaena and Nostoc are cyanobacteria that fix atmospheric nitrogen and are free-living in aquatic or moist environments.

C. Azotobacter is anaerobic: ❌ Incorrect. 🔹 Azotobacter is an aerobic, free-living nitrogen-fixing bacterium.

D. Beijerinckia is aerobic: ✅ Correct. 🔹 Beijerinckia is an aerobic nitrogen-fixing bacterium.

Thus, the incorrect statements are: A and C

✅ Correct Answer: (2) A, C.