Which of the following is a non–symbiotic nitrogen fixing bacteria?
1.  Rhizobium
2.  Mycorrhiza
3.  Azotobacter
4.  Nitrosomonas

Anabaena is associated with Azolla's:
1.  Stem
2.  Leaves
3.  Roots
4.  Flowers

Which of the following does not contain metal:
1.  Glycoproteins
2.  Ferritin
3.  Cytochromes
4.  Chromoproteins

Nitrogen-fixing bacteria converts:
1. $N_2$ $\to$ $N{H}_3$
2. $N{H}_4^{+}$ $\to$ $Nitrates$
3. $N{O}_2$ $\to$ $N{O}_3$
4. $N{O}_3$ $\to$ $N_2$

Insectivorous plants grow in the soil which is deficient in:
1.  Mg
2.  Ca
3.  P
4.  N

When the plants are grown in magnesium-deficient but urea-rich soil, the symptoms expressed are:

1. Yellowish leaves

2. Colourless petiole

3. Dark green leaves

4. Shoot apex die

Plants take zinc in the form of:

An aquatic fern that is used to increase the yield of paddy crops:

1. Azolla

2. Salvinia

3. Marsilea

4. Isoetes

What is the best pH of the soil for the cultivation of plants:
1.  3.4 – 5.4
2.  6.5 – 7.5
3.  4.5 – 8.5
4.  5.5 – 6.5

Enzyme first used for nitrogen fixation:
1.  Nitrogenase
2.  Nitroreductase
3.  Transferase
4.  Transaminase