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Question #46745
The Question
Lysosomes contain hydrolytic enzymes that are optimally active at an acidic pH. In highly invasive metastatic cancer cells, lysosomal proteases (such as cathepsins) are often secreted into the extracellular matrix (ECM) to degrade it and facilitate tissue invasion. Which of the following physiological adaptations at the plasma membrane of these cancer cells is essential to ensure the optimal activity of these secreted enzymes?
Options
- A.
Overexpression of H+-ATPases on the plasma membrane to acidify the extracellular microenvironment.
- B.
Increased active transport of H+ ions into the cytoplasm to maintain an alkaline extracellular matrix.
- C.
Secretion of bicarbonate ions to buffer the extracellular fluid and activate the acid hydrolases.
- D.
Downregulation of membrane proton pumps to prevent the denaturation of secreted lysosomal enzymes.
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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
Metastasis|Plasma_Membrane_Fluidity|Proton_Pump
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize that lysosomes are strictly intracellular organelles with an internal acidic pH.
The application requires understanding that if an enzyme's intrinsic property requires low pH (acid hydrolase), its functional environment must be acidified regardless of location.
The trap lies in assuming extracellular spaces must always be buffered to neutral pH, failing to recognize the pathological adaptation of cancer cells to create an acidic microenvironment via proton efflux.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Cell – The Unit of Life - Class 11 |
| Concept | Lysosomal pH Homeostasis |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |