Movement into and out of cells：練習題

A plant cell is placed in a concentrated salt solution. After some time, a student observes that the cell membrane has pulled away from the cell wall, as shown in the diagram. Which term describes the state of this cell?

A plant cell with a water potential of \(-500 \text{ kPa}\) is placed in a solution with a water potential of \(-800 \text{ kPa}\). Which statement correctly describes the net movement of water and the resulting state of the cell?

Identify the specific cellular process that provides the necessary energy for active transport to move particles against a concentration gradient.

Define active transport and state the specific cellular process that provides the energy required for this movement.

Explain the importance of active transport in the roots of a plant, specifically referring to the movement of mineral ions and the role of respiration in this process.

A student investigates the movement of water into and out of plant cells using potato tissue. The diagram shows two potato cells, A and B, which have been immersed in different concentrations of sugar solution for two hours.
(a) Define the term osmosis with reference to water potential and the nature of the cell membrane.
(b) Cell A has become firm and swollen. Use the term turgid to explain the state of the cell and describe the net movement of water molecules that caused this.
(c) Cell B shows the cell membrane pulling away from the cell wall. Name this condition and explain why it occurs when a cell is placed in a solution with a lower water potential than its own cytoplasm.

Plant cells undergo various changes when placed in solutions of different water potentials.
(a) Define osmosis according to the net movement of water molecules through a partially permeable membrane.
(b) A plant cell is placed in a concentrated sugar solution. Describe the appearance of the cell using the term plasmolysis and explain why this occurs in terms of water potential.
(c) Explain the importance of water potential and osmosis in the uptake of water by root hair cells from the soil.