Which of the following bacteria reduce nitrate in soil into nitrogen?

1. Nitrobacter

2. Thiobacillus

3. Nitrococcus

4. Nitrosomonas

The common nitrogen-fixer in paddy fields is

(1) Frankia

(2) Rhizobium

(3) Azospirillum

(4) Oscillatoria

A free living aerobic soil bacterium capable of
fixing nitrogen is
1. Azotobacter

2. Clostridium

3. Rhizobium

4. Streptococcus

During biological nitrogen fixation, the cells of which of the following regions take part in the formation of nodules in roots for bacteroides?
1. Epidermis
2. Cortex
3. Endodermis
4. Vascular bundle

Thiobacillus is a group of bacteria helpful in carrying out:

1. Denitrification

2. Nitrogen fixation

3. Chemoautotrophic fixation

4. Nitrification

Azotobacter and Bacillus polymyxa are

1. Decomposers

2. Nonsymbiotic nitrogen fixer

3. Symbiotic nitrogen fixer

4. Pathogenic bacteria

Which of the following is a flowering plant with nodules containing filamentous nitrogen-fixing microorganism?

1. Casuarina equisetifolia

2. Crotolaria juncea

3. Cycas revoluta

4. Cicer arietinum

Manganese is required in:
1. nucleic acid synthesis
2. plant cell wall formation
3. photolysis of water during photosynthesis
4. chlorophyll synthesis