細胞的物質運輸：練習題

A student placed a plant cell in a solution with a much higher solute concentration than the cell sap. After 30 minutes, the cell membrane had pulled away from the cell wall.
Which term correctly describes the state of this cell and the process that caused it?

A scientist observes a plant cell where the permanent vacuole has shrunk, and the cell membrane has completely detached from the cellulose cell wall. Which statement best explains the state of this cell in terms of water potential?

The small intestine is adapted for the efficient absorption of soluble food molecules. Which of the following describes a specific adaptation and its correct reason for increasing the rate of exchange?

In a large multicellular organism, the surface area to volume ratio is relatively small compared to a single-celled organism. How does the human respiratory system adapt its surface for gas exchange to overcome this limitation?

Substances move across cell membranes through various mechanisms.

Which statement correctly distinguishes active transport from diffusion?

In multicellular organisms, active transport is essential for moving substances against a concentration gradient. Compare this process to diffusion in terms of the energy requirement and the direction of particle movement relative to the concentration gradient.

The small intestine is highly adapted for the absorption of nutrients. Explain how the presence of a rich capillary network and a thin exchange surface (one cell thick) specifically enhances the effectiveness of solute exchange.

In a clinical study, human cells are placed in a hypertonic solution. Describe the net movement of water molecules and identify the specific term used to describe the resulting state of the cell membrane in plant cells.

Substances move in and out of cells via various transport mechanisms. Consider a root hair cell in a plant and a cell lining the small intestine in a human.

a) Explain how the structure of a root hair cell is adapted to increase the rate of water absorption by osmosis.
b) In some cases, plants must absorb mineral ions from the soil where the concentration of ions is very low. Name the process used and explain why this process requires energy from respiration.
c) Describe two features of the small intestine that increase the efficiency of exchange for dissolved food molecules.