Chapter 5: Structure and function of plasma membranes

28. Exocytosis is a type of cellular transport that allows materials to move across the plasma membrane of a cell. Which of the statements describe properties of exocytosis?

- Exocytosis secretes materials from the cell through the fusion of a vesicle with the plasma membrane. - Exocytosis is the primary method of transporting large molecules out of the cell.

27. Select the statements that accurately describe endocytosis.

- The cell membrane engulfs a particle in the cytoplasm and forms a vesicle around it. - The cell expends energy to transport materials into the cytosol.

25. One way that cells engulf material from the environment is by ingesting solutes in the aqueous environment and enclosing them in intracellular vesicles. What is the name of this method of ingestion?

- pinocytosis

12. Which statements describe examples of facilitated diffusion?

-An erythrocyte low on glucose replenishes its supply using a membrane protein to transport glucose down its concentration gradient. -A neuron allows potassium ions to leave the cell down their concentration gradient using a membrane channel. -An inner ear hair cell allows chloride ions to flow down their concentration gradient after a molecule binds to a membrane receptor.

29. Exocytosis is one of the processes living organisms use to move molecules. Choose all the examples of exocytosis.

-Pancreatic cells release digestive enzymes into the small intestine. -A single-celled eukaryotic organism excretes digestive waste into the surrounding water. -A nerve cell releases peptides used as messengers into the extracellular space.

2. What does the fluid mosaic model describe about the structure of plasma membranes?

-Phospholipids in the membrane are not covalently bonded to each other. -A membrane has proteins and other components embedded among the phospholipids.

22. Select the descriptions that apply to the sodium-potassium pump.

-Select the descriptions that apply to the sodium-potassium pump. -The pump is an active mechanism for transporting ions through the plasma membrane.

21. Which of the following are properties of protein-facilitated active transport?

-Substances move from an area of lower concentration to an area of higher concentration. -The cell spends energy to move substances through a protein across the plasma membrane.

17. A selectively permeable membrane divides a container in half. One half of the container, Side A, is filled with a starch solution, while the other half, Side B, is filled with an iodine tincture. Starch is a large macromolecule that forms a milky white solution when dissolved. An iodine tincture contains very small iodide ions and is a brown solution. Iodide ions turn dark blue when they react with starch molecules. After several hours, Side A is dark blue, while Side B is brown. Which statement describes the diffusion of solutes through the membrane?

-The iodide ions diffused through the membrane, but the starch molecules were excluded.

13. Which choice describes diffusion?

-The movement of a substance from a region where it is more concentrated to a region where it is less concentrated down its concentration gradient.

10. The plasma membrane is an outer boundary that separates the interior of a cell from its external environment and is found in all cells. The molecules that make up the plasma membrane have a unique quality that helps to ensure the integrity of the cell. Considering the structure of the plasma membrane, which of the following choices best explains why human cells do not dissolve in water?

-The plasma membrane is composed of phospholipids, which have hydrophobic regions.

19. The sodium-potassium pump, also known as the Na /K ATPase, is shown in this animation. The movement of ions through this membrane protein is an example of _________.

-active transport

5. Cell membranes are composed of phospholipids that have head and tail regions. The phospholipid tail is hydrophobic and spontaneously orients to the inside of the membrane. Which of the following phrases best describes the hydrophobic portion of a phospholipid

-has few interactions with water

3. Label the parts of a cell membrane with the term that describes each part.

-hydrophobic -hydrophilic -cholesterol -Glycoprotein -integral protein -peripheral protein

11.Facilitated diffusion is a protein-facilitated movement of solutes across a membrane from an area of higher concentration to an area of lower concentration. Which of the following best describes facilitated diffusion?

-passive transport

8. Which of the following is a function of cholesterol in a cell's plasma membrane?

-regulating membrane fluidity

18. Select the statement that describes an electrochemical gradient.

-sum of the differences in charge and chemical concentration of ions across a membrane

14. Plasma membranes are selectively permeable (semipermeable), meaning that

-the membrane regulates what enters and leaves the cell.

4. Which of the following describes the fluid mosaic model? A. all the liquid and solid components within a cell\'s interior, excluding the nucleus B. a phospholipid bilayer with various molecules embedded within and floating between the layers C. the gel-like extracellular mix of proteins, polysaccharides, and other substances within tissues D. an explanation of how proteins embedded within the plasma membrane aid in cell functioning

B. a phospholipid bilayer with various molecules embedded within and floating between the layers

1. Which of the following molecules are the main structural components of the plasma membrane? A. Carbohydrates B. Nucleic Acid C. Lipids D. Proteins

C. Lipids D. Protein