bio 151 chapter 5 Pearson mastering

Which of the following molecules is most likely to passively diffuse across the plasma membrane? -Carbon dioxide -Glucose -Sodium ion -DNA -Hemoglobin

Carbon dioxide

Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the plasma membrane would cholesterol most likely be found?

In the interior of the membrane

Testosterone, a lipid-soluble signaling molecule, crosses the membranes of cells throughout the body but affects only target cells because

intracellular receptors for testosterone are present only in target cells

Nitric oxide is unusual among animal signal molecules in that it

is a gas

Receptors for signal molecules

may be found embedded in the plasma membrane or found within the cytoplasm or nucleus

Early work on signal transduction and glycogen metabolism by Sutherland indicated that

the signal molecule did not interact directly with the cytosolic enzyme but required an intact plasma membrane before the enzyme could be activated

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because

they amplify the original signal manyfold

Which of the following statements concerning carbohydrates associated with the plasma membrane is correct? -Membrane carbohydrates have a primary role in cell-cell recognition. -Carbohydrates are only found associated with the membranes of prokaryotic cells. -The carbohydrate composition of most eukaryotic plasma membranes is quite similar. -Carbohydrates on the plasma membrane are typically short chains of between two and five monosaccharides. -Carbohydrates associated with the plasma membrane are located on both surfaces of the membrane.

Membrane carbohydrates have a primary role in cell-cell recognition.

Steroid hormones enter a cell by simple diffusion. In doing so, these steroids -move up a concentration gradient and are nonpolar -move up a concentration and are polar -move down a concentration gradient and are polar -move through a channel and down a gradient and are nonpolar -None of the listed responses is correct.

None of the listed responses is correct.

Which of the following would tend to increase membrane fluidity? -A greater proportion of phospholipids with unsaturated hydrocarbon tails -A greater proportion of phospholipids with saturated hydrocarbon tails -A lower temperature -A relatively high protein content in the membrane -A greater proportion large glycolipids relative to lipids having smaller molecular masses

A greater proportion of phospholipids with unsaturated hydrocarbon tails

The concentration of solutes in a particular cell is about 2%, but the cell contains almost no sucrose or urea. Sucrose cannot pass through the membrane of this cell, but water and urea can. Osmosis would cause this cell to shrink the most when immersed in which of the following solutions?

A hypertonic sucrose solution

-Which of the following would be least likely to pass through a plasma membrane without the help of a transport protein? -A large polar molecule -A large nonpolar molecule -Dissolved gases such as oxygen or carbon dioxide -A small nonpolar molecule -All of the listed substances would pass easily through the membrane.

A large polar molecule

In what way do the membranes of eukaryotic cells vary?

Certain proteins are unique to the membrane of each cell type.

Which of the following processes and organelle(s) account for the replacement of lipids and proteins lost from the plasma membrane? -Exocytosis and smooth and rough ER -Endocytosis and Golgi -Active transport and the rough endoplasmic reticulum -Receptor-mediated endocytosis and smooth ER and Golgi -Flip-flop of phospholipids from one side of the plasma membrane to the other and the Golgi

Exocytosis and smooth and rough ER

-Which of these statements describes some aspect of facilitated diffusion? -Facilitated diffusion of solutes may occur through transport proteins in the membrane. -Facilitated diffusion is another name for osmosis. -Facilitated diffusion of solutes occurs through phospholipid pores in the membrane. -Facilitated diffusion requires energy to drive a concentration gradient. -There is only one kind of protein pore for facilitated diffusion.

Facilitated diffusion of solutes may occur through transport proteins in the membrane.

Which of the following processes includes all the others? -Passive transport -Osmosis -Diffusion of a solute across a membrane -Facilitated diffusion -Transport of an ion down its electrochemical gradient

Passive transport

Which of the following statements about passive transport is correct? -Passive transport involves movement of solute in both directions across a membrane, but with a net movement of solute down its concentration gradient. -Passive transport operates independently of diffusion -Passive transport operates independently of the concentrations of the moving solute.-In passive transport, solute movement stops when the solute concentration is the same on both sides of a membrane. -Passive transport does not occur in the human body.

Passive transport involves movement of solute in both directions across a membrane, but with a net movement of solute down its concentration gradient.

Which of the following pairs correctly matches a membrane transport process to its primary function? -Pinocytosis; the uptake of water and small solutes into the cell by formation of vesicles at the plasma membrane -Phagocytosis; secretion of large particles from the cell by fusion of vesicles with the plasma membrane -Exocytosis; the movement of water and solutes out of the cell by vesicle fusion with the plasma membrane -Osmosis; passive diffusion of water and small solutes across a membrane -Receptor-mediated endocytosis; engulfing a particle by extending pseudopodia around it and packaging it within a membranous sac called a food vacuole

Pinocytosis; the uptake of water and small solutes into the cell by formation of vesicles at the plasma membrane

Which of the following enables a cell to concentrate and take in a specific kind of molecule? -Receptor-mediated endocytosis -Passive transport -Facilitated diffusion -Osmosis -Channel proteins

Receptor-mediated endocytosis

The plasma membrane is referred to as a "fluid mosaic" structure. Which of the following statements about that model is true? -The fluid aspect of the membrane is due to the lateral and rotational movement of phospholipids, and embedded proteins account for the mosaic aspect. -The fluid aspect of the membrane is due to the behavior of phospholipids, and the mosaic aspect is due to the presence of carbohydrates. -The fluid aspect of the membrane describes its structure at normal temperatures, and the mosaic aspect describes the behavior of the membrane as the temperature is lowered. -The mosaic aspect of the membrane is due to the glycosylation of inner leaflet phospholipids. -Only phospholipids are capable of moving in the membrane.

The fluid aspect of the membrane is due to the lateral and rotational movement of phospholipids, and embedded proteins account for the mosaic aspect.

Which of the following correctly describes a general property of all electrogenic pumps? -They create a voltage difference across a membrane. -They pump sodium out of the cell and potassium into the cell. -They can pump a large variety of solutes across a membrane against their concentration gradients. -They create a cell interior that is positively charged relative to the outside of the cell. -They create a high concentration of protons within a cell.

They create a voltage difference across a membrane.

The general name for an enzyme that transfers phosphate groups from ATP to a protein is

protein kinase

The molecule cAMP directly activates

protein kinase A

Second messengers tend to be water-soluble and small. This accounts for their ability to

rapidly move throughout the cell by diffusion

What event would activate a G protein?

replacement of GDP with GTP