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Question #45908
The Question
An E. coli culture is inoculated into a sealed secondary sewage treatment bioreactor containing a high initial concentration of organic waste, including abundant glucose and lactose. The microbes exhibit 'resource-starvation sensing' mechanisms that dictate their metabolic and transcriptional priorities. Which of the following statements regarding the physiological and environmental shifts in this system is INCORRECT?
Options
- A.
The initial abundance of glucose induces catabolite repression, preventing RNA polymerase from efficiently binding to the lac promoter even if lactose is present.
- B.
The exponential growth of aerobic microbes and their rapid oxidation of the sugars will cause the Biochemical Oxygen Demand (BOD) of the medium to rise continuously until the organic matter is exhausted.
- C.
The exhaustion of dissolved oxygen (DO) and glucose both act as 'resource-starvation' signals, forcing a metabolic shift from highly efficient primary pathways to less efficient secondary pathways.
- D.
Full-scale transcription of the lac operon requires a dual condition: the exhaustion of the preferred carbon source (glucose) and the binding of allolactose to the repressor protein.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Glucose|cAMP|BOD|Decomposers
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students frequently confuse the 'rate of microbial activity' with the 'value of BOD'.
A common misconception is that active, multiplying microbes cause BOD to increase.
In reality, BOD represents the unconsumed organic matter; as microbes break down sugars, BOD decreases.
This question synthesizes this environmental concept with the molecular genetics of the Lac Operon, testing the parallel logic of 'resource-starvation' adaptations across two different NCERT domains.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Molecular Basis of Inheritance - Class 12 |
| Concept | Lac Operon Inducibility |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |