Majority of the nutrients that are essential for the growth and development of plants become available to the roots due to:
1. Microbial actions in the soil
2. Wet deposition from the atmosphere
3. Addition of fertilizers
4. Weathering and breakdown of rocks
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
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 incorrectly matched pair:
Mineral |
Function |
|
1. |
Nitrogen |
component of nucleic acids, proteins, hormones, coenzymes |
2. |
Magnesium |
component of chlorophyll; activates many enzymes |
3. |
Phosphorus |
component of nucleic acids, phospholipids, ATP, several coenzymes |
4. |
Sulfur |
component of DNA; activates some enzymes |
Essential micronutrients in plants:
I. are required in relatively small amounts.
II. are required for a plant to grow from a seed and complete its life cycle.
III. generally help in catalytic functions in the plant.
IV. are of small size and molecular weight.
1. Only I, II and III are correct
2. Only I, II and IV are correct
3. Only II, III and IV are correct
4. All are correct
Nitrogen fixation means:
1. releasing nitrogen from dead and decaying materials.
2. conversion of nitrite to nitrate.
3. conversion of nitrate to nitrite.
4. conversion of nitrogen gas into ammonia.
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.
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.
With respect to symbiotic relationships of plants, consider the following two statements:
I. Plants acquire most of their nitrogen in the form of N2 that they obtain from rhizobacteria.
II. The fungal hyphae of both ectomycorrhizae and arbuscular mycorrhizae absorb water and minerals, which they supply to their plant hosts.
1. Only I is true | 2. Only II is true |
3. Both I and II are true | 4. Both I and II are false |
A symptom common to the deficiency of Ca, Mg, Cu and K in plants is:
1. Chlorosis
2. Inhibition of cell division
3. Necrosis
4. Delay in flowering