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

1. Azolla

2. Salvinia

3. Marsilea

4. Isoetes

The major role of minor elements inside living organisms is to act as:
1. Co-factors of enzymes
2. Building blocks of important amino acids
3. Constituent of hormones
4. Binder of cell structure

Which element is located at the center of the porphyrin ring in chlorophyll?

Which one of the following mineral elements plays an important role in biological nitrogen fixation:
1. Copper
2. Manganese
3. Zinc
4. Molybdenum

Plants deficient in the element zinc show its effect on the biosynthesis of which plant growth hormone:

In which one of the following nitrogen is not a constituent:

1. Idioblast

2. Bacteriochlorophyll

3. Invertase

4. Pepsin

Boron in green plants assists in:
1. Activation of enzymes
2. Acting of enzyme cofactor
3. Photosynthesis
4. Sugar transport

Grey spots of oat are caused by deficiency of:

1. Cu

2. Zn

3. Mn

4. Fe

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