Nitrogen-fixation in root nodules of Alnus is brought about by:

1.	Bradyrhizobium	2.	Clostridium
3.	Frankia	4.	Azorhizobium

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

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?

Sulphur is an important nutrient for optimum growth and productivity in:

1. pulse crops

2. cereals

3. fibre crops

4. oilseed crops

Which of the following is a symbiotic nitrogen fixer?
1. Glomus
2. Azotobacter
3. Frankia
4. Azolla

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

The free-living, anaerobic nitrogen-fixer is:

1. Beijerinckia

2. Rhodospirillum

3. Rhizobium

4. Azotobacter