| Assertion (A): | The large holes in Swiss cheese are formed due to the release of carbon dioxide by Propionibacterium sharmanii during fermentation. |
| Reason (R): | Propionibacterium sharmanii ferments lactose into lactic acid, which produces large quantities of carbon dioxide. |
| 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. | Both (A) and (R) are False. |
| Assertion (A): | Alcoholic fermentation by yeast is used in the production of bread |
| Reason (R): | Alcoholic fermentation by yeast produces ethanol. |
| 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. |
| 1. | They inhibit the enzyme responsible for blood clot formation. |
| 2. | They block the metabolic pathway leading to cholesterol biosynthesis. |
| 3. | They destroy pathogenic microbes in the bloodstream. |
| 4. | They enhance the immune response to suppress cholesterol accumulation. |
| I: | Biochemical oxygen demand (BOD) is often used as an indicator of the degree of organic pollution of water. |
| II: | An increase in BOD is used as a gauge of the effectiveness of wastewater treatment plants. |
| 1. | Only I is correct | 2. | Only II is correct |
| 3. | Both I and II are correct | 4. | Both I and II are incorrect |
| 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. |
| 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. |
| 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. |
| Assertion (A): | The sewage water is treated till the Biological Oxygen Demand (BOD) is reduced. |
| Reason (R): | BOD indicates the rate of uptake of oxygen by microorganisms in a sample of water. |
| 1. | Both (A) and (R) are True and (R) explains (A). |
| 2. | Both (A) and (R) are True but (R) does not explain (A). |
| 3. | (A) is True but (R) is False. |
| 4. | (A) is False but (R) is True. |