Q. No.When nitrates are scarce in the soil where legumes are growing:
I. The plants secrete Nod factors that attract Rhizobia to their root hairs.
II. In turn the bacteria secrete flavonoids that stimulate the infection process in the plant.
1. Both I and II are correct
2. Only I is correct
3. Only II is correct
4. Both I and II are incorrect
I. The plants secrete Nod factors that attract Rhizobia to their root hairs.
II. In turn the bacteria secrete flavonoids that stimulate the infection process in the plant.
1. Both I and II are correct
2. Only I is correct
3. Only II is correct
4. Both I and II are incorrect
The uptake of which of the following by a plant contributes maximum to its dry weight:
1. water and minerals through root hairs.
2. water and minerals through mycorrhizae.
3. carbon dioxide by leaves through stoma.
4. sugars in the root hairs.
All the following regarding bacteroid form of Rhizobium are true except:
1. It is a differentiated symbiotic form of nitrogen fixing Rhizobium
2. It is non-motile and non-reproductive
3. It has a more freely permeable membrane than free living Rhizobium
4. It is larger in size than the free living Rhizobium and spherical in shape
What percentage of the dry weight of a plant is made up of organic molecules?
1. 10%
2. 23%
3. 72%
4. 96%
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 |
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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:
| 1. carbon and nitrogen | 2. oxygen and hydrogen |
| 3. nitrogen and oxygen | 4. oxygen and carbon |
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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
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