Compared to other cell types, cells with a very high demand for resource are likely to

Question

BlackTom AI · Accepted Answer

High-resource-demand cells increase membrane transport capacity by expressing many channels and transporters.

1. Relevant knowledge points and concepts
- Rate of substance exchange is limited by membrane permeability and number/type of transport proteins (channels, carriers, pumps).
- Surface area-to-volume ratio and specialization (microvilli) affect uptake.
- Transport mechanisms: simple diffusion (for small nonpolar gases), facilitated diffusion (channels/carriers for ions, sugars, amino acids), and active transport (ATP-driven pumps) to concentrate substances against gradients.
- Examples: intestinal epithelial cells, kidney proximal tubule cells, and enterocytes express numerous transporters; neurons and muscle fibers have many ion channels and glucose transporters.

2. Step-by-step reasoning
- A cell with very high resource demand (nutrients, ions, metabolites) must increase net flux across its membrane to meet metabolic needs.
- Flux = permeability × surface area × concentration gradient; permeability is largely determined by the number and specificity of membrane transport proteins.
- To increase flux without relying solely on greater gradients, the cell upregulates transport proteins and often increases membrane surface area (microvilli).
- Some uptake requires active transport to accumulate nutrients against gradients, so cells also express ATP-dependent pumps when needed.

3. Intermediate steps (conceptual)
- Identify limiting step: membrane transit of specific molecules.
- Increase transporter density → greater facilitated diffusion/active transport capacity → higher uptake rate.
- Complementary changes (more mitochondria, more glycolytic enzymes) support energy needs for active transport.

4. Why the correct answer is correct
- Producing many different membrane channels and transporters directly increases specific uptake rates and allows selective, regulated import/export to satisfy high demand. This is the common biological solution seen in absorptive and highly active cells.

5. Why the other options are incorrect
- Performing structural/protective roles: these specialize in support, not high resource uptake.
- Reduced reliance on active transport: high-demand cells often increase, not reduce, active transport when necessary.
- Actively transporting gases: O2 and CO2 mainly cross membranes by diffusion; active transport of gases is not a primary mechanism.

6. Conclusion
Therefore, the best choice is "produce many different membrane channels and transporters," which matches the provided answer.

Compared to other cell types, cells with a very high demand for resource are likely to单项选择题

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