Cell membranes and transport：練習題

A plant cell is placed in a solution with a higher water potential than the cell's contents. Which term describes the resulting state of the cell?

Which statement correctly describes the function of glycolipids and glycoproteins in the cell surface membrane?

The diagram represents a section of a cell surface membrane as described by the fluid mosaic model. Which statement correctly explains why the membrane is described as a 'mosaic'?

A plant cell is placed in a solution with a water potential higher (less negative) than that of its own cytoplasm. What is the expected outcome for the cell?

In the process of cell signaling, which membrane component typically acts as a receptor for a specific signaling molecule, such as a hormone?

State the name of the steroid molecule found within the hydrophobic core of the cell surface membrane that regulates the fluidity of the bilayer at temperatures such as \(37^\circ\text{C}\).

Calculate the surface area to volume ratio for a model of a cell represented by a cube with a side length of \(25\ \mu m\).

A plant cell is placed in a concentrated sucrose solution which has a lower water potential than the cell's cytoplasm.
(a) Define the term osmosis.
(b) Describe the net movement of water molecules in this scenario using the symbol \( \psi \).
(c) State the term used to describe the state of the plant cell when its protoplast has completely shrunk away from the cell wall.
(d) Explain why a plant cell does not burst when placed in pure water, whereas an animal cell would.

The efficiency of exchange in cells is limited by the surface area to volume ratio (\(SA:V\)). Consider two model cells represented by cubes.
(a) Calculate the \(SA:V\) ratio for a cube with a side length of \(5\text{ μm}\). Show your working.
(b) Calculate the \(SA:V\) ratio for a cube with a side length of \(10\text{ μm}\). Show your working.
(c) Using your answers and biological principles, explain why most metabolically active cells are small in size.