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Q. No.If oxygen availability to activated sludge flocs in a sewage treatment plant is reduced:
1.
the rate of degradation of organic matter slows down
2.
the center of flocs becomes anoxic, causing death of bacteria and eventually breakage of flocs.
3.
the flocs would increase in size as anaerobic bacteria would grow around flocs.
4.
Protozoa would grow in large numbers.
Subtopic: Â Microbes in Sewage Treatment |
Level 3: 35%-60%
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How many of the given pairs are correctly matched?
1. 0
2. 1
3. 2
4. 3
| I: | Lady birds: Aphids |
| II: | Dragon fly: Mosquito |
| III: | Trichoderma: Fungicide |
2. 1
3. 2
4. 3
Subtopic: Â Microbes in Biocontrol Agent |
 51%
Level 3: 35%-60%
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Which of the following microbes, capable of fixing atmospheric nitrogen, is an important biofertilizer in paddy fields?
1. Rhizobium
2. Frankia
3. Azotobacter
4. Anabaena
Subtopic: Â Microbes as Biofertilizer |
 59%
Level 3: 35%-60%
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Which of the following is used to estimate the biochemical oxygen demand and hence the polluting potential of a sample of water?
| 1. | total organic matter | 2. | biodegradable organic matter |
| 3. | oxygen evolution | 4. | oxygen consumption |
Subtopic: Â Microbes in Sewage Treatment |
 59%
Level 3: 35%-60%
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All the following are benefits of mycorrhizal association to vascular plants except:
1. Increasing its tolerance to drought
2. Enhancing its resistance to root pathogens
3. Enhancing its phosphorus uptake capacity
4. Biological nitrogen fixation
1. Increasing its tolerance to drought
2. Enhancing its resistance to root pathogens
3. Enhancing its phosphorus uptake capacity
4. Biological nitrogen fixation
Subtopic: Â Microbes as Biofertilizer |
 65%
Level 2: 60%+
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How many of the given statements are true?
1. 1
2. 2
3. 3
4. 4
| I: | BOD refers to the amount of oxygen that would be consumed if all the organic matter in one litre of water were oxidised by bacteria. |
| II: | The sewage water is treated until BOD reduces to zero. |
| III: | The BOD test measures the rate of uptake of oxygen by micro-organisms in a sample of water and thus, indirectly, BOD is a measure of the organic matter present in the water. |
| IV: | The greater the BOD of waste water, greater is its polluting potential. |
2. 2
3. 3
4. 4
Subtopic: Â Microbes in Sewage Treatment |
 54%
Level 3: 35%-60%
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Consider the given two statements:
Choose the correct option.
| Assertion (A): | Secondary treatment of sewage water involves the use of aerobic bacteria. |
| Reason (R): | Aerobic bacteria break down organic matter into inorganic substances like \(\text{CO}_2\) and \(\text{H}_2 \text{O}\). |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | (A) is False but (R) is True. |
Subtopic: Â Microbes in Sewage Treatment |
 54%
Level 3: 35%-60%
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The primary objective of anaerobic sludge digestion in sewage treatment is:
1. removal of nutrients from the polluted water
2. methane production
3. disinfection
4. promotion of growth of algae and cyanobacteria
1. removal of nutrients from the polluted water
2. methane production
3. disinfection
4. promotion of growth of algae and cyanobacteria
Subtopic: Â Microbes in Sewage Treatment |
 56%
Level 3: 35%-60%
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Mycorrhizal symbiotic fungi in plant roots primarily help in:
| 1. | Nitrogen fixation | 2. | Phosphate absorption |
| 3. | Photosynthesis | 4. | Bicontrol |
Subtopic: Â Microbes as Biofertilizer |
 57%
Level 3: 35%-60%
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Considering biocontrol agents in agriculture, which of the following pairs is correctly matched with its target pest?
1. Only A
2. Only B
3. Both A and B
4. Neither A nor B
| A: | Bacillus thuringiensis - Nematodes |
| B: | Trichoderma - Root fungi |
2. Only B
3. Both A and B
4. Neither A nor B
Subtopic: Â Microbes in Biocontrol Agent |
 54%
Level 3: 35%-60%
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