Both Rhizobium and Frankia:
1. are symbionts with legumes
2. are symbionts with actinorrhizal plants
3. initiate the formation of root nodules in the symbiont plant
4. are filamentous bacteria

Subtopic:  Nodule formation |
 65%

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Phytoremediation is:
1. concentrating minerals in rhizosphere.
2. minimizing soil erosion in arid lands.
3. nitrogen fixation by symbiotic bacteria in root nodules.
4. removal of heavy metals from polluted sites.

Subtopic:  Mineral Deficiency & Toxicity |

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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

Subtopic:  Nodule formation |

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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.

Subtopic:  Introduction | Criteria for Essentiality of Elements |

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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

Subtopic:  Nodule formation |

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What percentage of the dry weight of a plant is made up of organic molecules?
1. 10%
2. 23%
3. 72%
4. 96%

Subtopic:  Introduction |

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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
Subtopic:  Nodule formation |
 60%
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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

Subtopic:  Hydroponics & Aeroponics |
 69%

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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
Subtopic:  Introduction |
 55%
From NCERT

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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

Subtopic:  Nodule formation |

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