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

About 98 percent of the mass of every living organism is composed of just six elements

including carbon, hydrogen, nitrogen, oxygen and:

1. phosphorus and sulphur

2. sulphur and magnesium

3. magnesium and sodium

4. calcium and phosphorus

Which one of the following elements is not an essential micronutrient for plant growth?

1. Mn

2. Zn

3. Cu

4. Ca

A plant requires magnesium for

1. holding cells together

2. protein synthesis

3. chlorophyll synthesis

4. cell wall development

Farmers in a particular region were concerned that pre-mature yellowing of leaves of a pulse crop might cause a decrease in the yield. Which treatment could be most beneficial to obtain maximum seed yield?

1. Frequent irrigation of the crop

2. Treatment of the plants with cytokinins along with a small dose of nitrogenous fertilizer

3. Removal of all yellow leaves and spraying the remaining green leaves with 2, 4, 5 trichloro phenoxy acetic acid

4. Application of iron and magnesium to promote the synthesis of chlorophyll