Biology Cell Membrane Quiz

Biology Quiz: Cell Membrane
1. Which two molecules are the principal components of membranes?
a. Glycogen and Proteins
2. The diagram below shows a channel protein in the membrane. Whichwould be composed of polar amino acids?
Answer: A
3. Answer: A
4. Outline the process of endocytosis.
* Endocytosis is an active process in which the cell encloses a particle in amembrane-bound vesicle. Part of the membrane pinches off to form a membrane around the material, and brings it into the cell.
5.
a. Distinguish between osmosis and diffusion.
b. Diffusion isthe movement of molecules from an area of high concentration to an area of low concentration; osmosis is the diffusion of water across a partially permeable membrane.
c. Explain how the propertiesof phospholipids help to maintain the structure of the cell surface membrane.
* The phosphate head is hydrophilic and the two hydrocarbon tails are hydrophobic. In water, phospholipids form doublelayers with the hydrophilic heads in contact with water on both sides and the hydrophobic tails away from the center. The attraction between the heads and the surrounding water makes membranes stable.d. State the composition and the function of the plant cell wall.
A plant cell wall consists of cellulose microfibrils running through a matrix of other complex polysaccharides. Cell wallsallow plant cells to become full of water without bursting, and to develop a turgor pressure which helps support the plant.
e. Draw a labeled diagram of the fluid mosaic model of the plasma membrane.6. A study was carried out to determine the relationship between the diameter of a molecule and its movement through a membrane. The graph shows the results of the study.

a. From theinformation in the graph alone, describe the relationship between the diameter of a molecule and its movement through a membrane.
* As the diameter of the molecule increases the permeability /...