BIO 156: Chp. 5, Lesson 4

Phagocytosis

"Cell eating," type of receptor-mediated endocytosis in which a cell engulfs a large solid particle such as another cell

Osmotic pressure

Amount of turgor that prevents osmosis into cytoplasm or other hypertonic fluid

Name the five factors that influence diffusion

Concentration Temperature Charge Molecular Size Pressure

Hypertonic

Describes a fluid that has a high overall solute concentration relative to another fluid

Hypotonic

Describes a fluid that has a low overall solute concentration relative to another fluid

Isotonic

Describes two fluids with identical solute concentrations

Osmosis

Diffusion of water across a selectively permeable membrane; occurs in response to a difference in solute concentration between the fluids on either side of the membrane

Pinocytosis

Endocytic pathway by which fluid and materials in bulk are brought into the cell

Active transport

Energy-requiring mechanism in which a transport protein pumps a solute across a cell membrane against the solute's concentration gradient

Receptor protein

Membrane protein that triggers a change in cell activity in response to a stimulus such as binding a hormone

Passive transport

Membrane-crossing mechanism that requires no energy input

Fluid mosaic

Model of a cell membrane as a two-dimensional fluid of mixed composition

Facilitated diffusion

Passive transport mechanism in which a solute follows its concentration gradient across a membrane by moving through a transport protein

Adhesion protein

Plasma membrane protein that helps cells stick together in animal tissues. Some types form adhering junctions and tight junctions.

Turgor

Pressure that a fluid exerts against a structure that contains it

Exocytosis

Process by which a cell expels a vesicle's contents to extracellular fluid

Endocytosis

Process by which a cell takes in a small amount of extracellular fluid (and its contents) by the ballooning inward of the plasma membrane

Transport protein

Protein that moves specific ions or molecules across a membrane

Diffusion

Spontaneous spreading of molecules or atoms through a fluid or gas

Which of the following processes could result in the net movement of a substance into a cell, if the substance is more concentrated in the cell than the surroundings? a. Active transport b. Diffusion c. Facilitated diffusion d. Osmosis e. None of these choices are correct

a. Active transport

Relaying a message from a membrane receptor to a molecule that performs a specific function within a cell is called which of the following? a. Signal transduction b. Competition c. Selective permeability d. Inhibition e. Self-recognition

a. Signal transduction

In lab, you use a special balloon that is permeable to water but not sucrose to make an "artificial cell." The balloon is filled with a solution of 20% sucrose and 80% water and is immersed in a beaker containing a solution of 40% sucrose and 60% water. Which of the following will occur? a. Water will leave the balloon. b. Sucrose will leave the balloon. c. Water will enter the balloon. d. Sucrose will enter the balloon. e. None of these choices will occur.

a. Water will leave the balloon

Which one of the following substances would have the most trouble crossing a biological membrane by diffusing through the lipid bilayer? a. O2 b. Na+ c. CO2 d. A small, nonpolar molecule such as butane (C4H10)

b. Na+

Facilitated diffusion across a biological membrane requires which of the following? Where does facilitated diffusion move a substance? a. Energy and transport proteins; down its concentration gradient. b. Transport proteins; down its concentration gradient. c. Transport proteins; against its concentration gradient. d. Energy; down its concentration gradient. e. Energy and transport proteins; against its concentration gradient.

b. Transport proteins; down its concentration gradient.

The cholesterol associated with cell membranes does which of the following? a. It is attached to membrane proteins and extends into the watery environment surrounding the cell. b. It makes the cell membrane fluid at room temperature. c. It helps to stabilize the cell membrane at body temperature. d. It is an abnormality resulting from a diet high in cholesterol. e. None of these choices are correct.

c. It helps to stabilize the cell membrane at body temperature.

Certain cells that line the stomach synthesize a digestive enzyme and secrete it into the stomach. This enzyme is a protein. Which of the following processes could be responsible for its secretion? a. Endocytosis b. Diffusion c. Passive transport d. Exocytosis e. Pinocytosis

d. Exocytosis

In lab, you use a special balloon that is permeable to water but not sucrose to make an "artificial cell." The balloon is filled with a solution of 20% sucrose and 80% water and is immersed in a beaker containing a solution of 40% sucrose and 60% water. The solution in the balloon is in which way relative to the solution in the beaker? a. Isotonic b. Hypertonic c. Hydrophilic d. Hypotonic e. Hydrophobic

d. Hypotonic

You are adrift in the Atlantic Ocean, and, being thirsty, drink the surrounding seawater. As a result, what will happen? a. You quench your thirst. b. Your cells become turgid. c. Your cells lyse, due to the excessive intake of salt. d. You dehydrate yourself. e. None of these choices are correct.

d. You dehydrate yourself

Which of the following is not a true statement about diffusion? a. Diffusion is a result of the kinetic energy of atoms and molecules. b. Diffusion requires no input of energy into the system. c. Diffusion proceeds until equilibrium is reached. d. Diffusion is driven by entropy. e. Diffusion occurs when particles spread from areas where they are less concentrated to areas where they are more concentrated.

e. Diffusion occurs when particles spread from areas where they are less concentrated to areas where they are more concentrated.

Which one of the following is not a function of the plasma membrane? a. The plasma membrane forms a selective barrier around the cell. b. The plasma membrane has receptors for chemical messages. c. The plasma membrane is involved in self-recognition. d. The plasma membrane plays a role in signal transduction e. The plasma membrane is the control center of the cell.

e. The plasma membrane is the control center of the cell.