Which one of the following is the wrong statement?

1. Anabaena and Nostoc are capable of fixing nitrogen in a free-living state also

2. Root nodule-forming nitrogen fixers live as aerobes under free-living conditions

3. Phosphorus is a constituent of cell membranes, certain nucleic acids, and all proteins

4. Nitrosomonas and Nitrobacter are chemoautotrophs

A nitrogen fixing microbe associated with Azolla in rice fields is

1. Spirulina

2. Anabaena

3. Frankia

4. Tolypothrix

The function of leghaemoglobin in the root nodules of legumes is 

(1) oxygen removal

(2) nodule differentiation

(3) expression of nif gene

(4) inhibition of nitrogenase activity

Nitrifying bacteria

1. convert free nitrogen to nitrogen compounds

2. convert proteins into ammonia

3. reduce nitrates to free nitrogen

4. oxidize ammonia to nitrates

An organism used as a biofertilizer for raising soyabean crop is

1. Azospirillum

2. Rhizobium

3. Nostoc

4. Azotobacter

An element playing important role in nitrogen fixation is

1. molybdenum

2. copper

3. manganese

4. zinc

Which one of the following is not a micronutrient?

1. Molybdenum

2. Magnesium

3. Zinc

4. Boron

The free-living, anaerobic nitrogen-fixer is

1. Beijerinckia

2. Rhodospirillum

3. Rhizobium

4. Azotobacter

The common nitrogen-fixer in paddy fields is

1. Rhizobium

2. Azospirillum

3. Oscillatoria

4. Frankia

Which of the following is a symbiotic nitrogen fixer?

1. Glomus

2. Azotobacter

3. Frankia

4. Azolla