Rhizobium:

1.	lives as aerobe under free-living conditions with an operational nitrogenase that does not fix nitrogen
2.	lives as anaerobe under free-living conditions with a non operational nitrogenase
3.	lives as aerobe during nitrogen-fixing conditions with an operational nitrogenase
4.	lives as anaerobe during nitrogen-fixing conditions with an operational nitrogenase

It is vital to bubble air into the solute in hydroponic culture to:
1. evenly distribute the dissolved nutrients
2. provide oxygen to the root cells
3. inhibit the growth of fungi
4. inhibit the growth of anaerobic bacteria

More than 90% of the dry weight of plants is due to:

In the symbiotic relationship, rhizobia supply ammonia to the plant and in return receive:
1. Simple sugars
2. Fatty acids
3. Organic acids like malate and succinate
4. Amino acids

Plant growth and development mainly depend on:
1. nitrogen; phosphorus; oxygen
2. potassium; carbon; calcium
3. oxygen; carbon; hydrogen
4. phosphorus; nitrogen; potassium

If the leaves of whole plant show chlorosis, the mineral nutrient most likely to be deficient would be:
1. boron
2. manganese
3. nitrogen
4. calcium

Identify the incorrectly matched pair:

The formation and stability of plant cell walls mainly requires:

To regenerate phospophenolpyruvate, C4 and CAM plants require:
1. Boron
2. Manganese
3. Magnesium
4. Sodium

Micronutrients in plants generally act:
1. as cofactors in enzymatic reactions.
2. to enhance regulatory functions.
3. to prevent chlorosis.
4. in the formation of cell walls.