Only some bacteria and blue green algae (cynobacteria) have the capacity to fix atmospheric nitrogen.
• Bacteria: Azotobacter, Rhizobium, Frankia etc.
• Blue green algae: Nostoc, Oscillatoria, Anabaena etc.

Correct Option: B

Only some bacteria and blue green algae (cynobacteria) have the capacity to fix atmospheric nitrogen.
• Bacteria: Azotobacter, Rhizobium, Frankia etc.
• Blue green algae: Nostoc, Oscillatoria, Anabaena etc.

In (E.coli) double stranded DNA is present.

Correct Option: C

In (E.coli) double stranded DNA is present.

Sex-factor or F-factor in bacteria results in high frequency conjugation. It allows bacteria to produce sex pilus necessary for conjugation.

Correct Option: B

Sex-factor or F-factor in bacteria results in high frequency conjugation. It allows bacteria to produce sex pilus necessary for conjugation.

Some of the blue green algae can tolerate extremes of temperature due to presence of gelatinous sheath, and compactness of protein molecules in protoplasm.

Correct Option: D

Some of the blue green algae can tolerate extremes of temperature due to presence of gelatinous sheath, and compactness of protein molecules in protoplasm.

Escherichia coli, lives as a symbiont in human intestine.

Correct Option: A

Escherichia coli, lives as a symbiont in human intestine.