With regard to the Biological Nitrogen Fixation by Rhizobium in association with soyabean, which one of the following statement/statements does not hold true?
1. Nitrogenase may require oxygen for its functioning .
2. Nitrogenase is MO-Fe protein.
3. Leg-hemoglobin is a pink coloured pigment.
4. Nitrogenase helps to convert gas into two molecules of ammonia.
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 |
Identify the correct statement regarding biological nitrogen fixation:
1. The plant contributes the nitrogenase enzyme.
2. The process does not require much energy.
3. Leghemoglobin keeps concentration low within the nodule.
4. The bacteria of the nodule are autotrophic.
In plants with nitrogen fixing bacteria (such as alfalfa or soybeans), the presence of oxygen will poison the bacterium. Which of the following acts as a natural defense against oxygen toxicity by scavenging free oxygen in these systems?
1. Hemoglobin | 2. Myoglobin |
3. Leghemoglobin | 4. Methemoglobin |
For biological fixation of one molecule of nitrogen into two molecules of ammonia, the number of ATP molecules needed is:
1. 4 | 2. 8 |
3. 12 | 4. 16 |
1. Only I | 2. Only II |
3. Both I and II | 4. Neither I nor II |
Leghemoglobin in a root nodule:
1. regulates the supply of oxygen to Rhizobium.
2. promotes ion uptake by root hairs.
3. retards the activity of nitrogenase.
4. supplies the legume with fixed nitrogen.
In plants, ammonia reacts with alpha ketoglutaric acid to form glutamic acid in a process called as:
1. Deamination | 2. Reductive amination |
3. Transamination | 4. Aminoacylation |
Identify the incorrect statement regarding the development of root nodules in soyabean:
1. Rhizobium bacteria contact a susceptible root hair, divide near it
2. Successful infection of the root hair causes it to curl
3. Infected thread carries the bacteria to the inner cortex, the bacteria get modified into rod-shaped bacteroids and cause inner cortical and pericycle cells to divide which leads to nodule formation
4. A mature nodule is complete without any vascular tissues continuous with those of the root.
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