Cell Physiology Test 1 Q2 Practice Questions

Phosphotylcholine is the only major phospholipid in the plasma membrane A. true B. false

-false phosphotylcholine is not the only major phospholipid

All cells in the body have a gradient of Na+ and K+ established by the pumps. Bacterial toxins damage our cells by "punching" holes in the membranes. What happens? A. K+ escapes from the cell B. K+ will flow into the cell C. Gradient across the membrane is getting larger

A. K+ escapes from the cell

Molecules that traverse a membrane against their concentration gradient do so by _______ transport. A. active B. passive C. carrier-mediated D. channel-mediated E. All of the above

A. active

ATP serves to transfer energy from energy-producing to energy-requiring reactions. A. true B. false

A. true

The Vatican Archives maintain a vault where century's worth of old documents are stored in very high N2 levels to prevent oxidation of the papyrus. When you do research in the vault how does this affect the amount of O2 in your body? A. increases B. decreases C. stays the same

B. decreases

Chemotherapy drugs that are engineered as hydrophobic molecules will A. Bind to cell surface receptors and kill the cancer cell B. Diffuse through the membrane until equilibrium is reached C. Go through uniporter until toxic concentration is achieved D. Be pumped out of the cell against the gradient

B. diffuse through the membrane until equilibrium is reached

Facilitated diffusion is a lipid-mediated process. A. true B.false

B. false -it is not a lipid-mediated process

Channels form pores through which molecules of appropriate size and charge can cross a membrane. By contrast, carrier proteins A. Actively transport molecules B. Selectively bind the molecule to be transported, change configuration, and release it on the other side C. Require ATP D. Transport a molecules against its concentration gradient E. All of the above

B. selectively bind the molecule to be transported, change configuration, and release it on the other side

Molecules that diffuse passively across the plasma membrane most rapidly are A. hydrophobic. B. small and hydrophobic. C. small and hydrophilic. D. small. E. charged

B. small and hydrophobic

Active transport differs from facilitated diffusion in that A. active transport requires a protein component, whereas facilitated diffusion occurs by simple diffusion through the plasma membrane. B. active transport involves a conformational change in the transport molecule. C. active transport involves the transport of molecules up their concentration gradient. D. ions are not transported via active transport, only by facilitated diffusion.

C. active transport involves the transport of molecules up their concentration gradient

Active transport is transport A. In an energetically unfavorable direction driven only by the flow of another molecule across a membrane. B. In an energetically unfavorable direction always driven by hydrolysis of ATP. C.In an energetically unfavorable direction always coupled to another reaction or source of energy. D. Of all molecules simultaneously, against their concentration gradients, across the membrane. E. In an energetically favorable direction coupled to the hydrolysis of ATP.

C. in an energetically unfavorable direction always coupled to another reaction or source of energy.

About 50% of the mass of most biological membranes consists of lipids and about 50% consists of proteins. Therefore... A. The membranes contain fewer molecules of lipid than of protein. B. Only a few membrane proteins are exposed at the cell surface. C. The membranes contain more molecules of lipid than of protein D. The membranes contain equal numbers of lipid and protein molecules.

C. the membranes contain more molecules of lipid than of protein

Passive transport across a membrane refers to A. Transport into the interior of a cell. B. Simple diffusion across membranes, without the help of proteins such as channels or carriers. C. Transport in the energetically favorable direction. D. Transport out of a cell.

C. transport in the energetically favorable direction

If a suspension of cells is frozen and fractured, the most likely path of the fracture plane will be A. Between the cell surface and the outside solution B. Between the membrane and the cytoplasm of the cells C. Through the middle of the cytoplasm D. Between the two leaflets of the cell membranes E. None of the above

D. between the two leaflets of the cell membranes

Transport across biological membranes is speeded by what class of biological molecules? A. Nucleic acids B. Carbohydrates C. Lipids D. Proteins

D. proteins

The most abundant molecules in cells are A. Lipids B. Proteins C. Carbohydrates D. Water E. Minerals

D. water

The Na+ and K+ ion gradients across the plasma membrane are produced primarily by the A. ratio of these ions in the blood. B. flow of these ions through voltage-gated channels. C. permeability of these ions across the lipid bilayer. D. passive flow of these ions through channels. E. action of the Na+-K+ pump.

E. action of the Na+-K+ pump

The unique properties of different membranes are primarily a function of their A. cholesterol molecules. B. glycolipids. C. triglycerides. D. phospholipids. E. proteins.

E. proteins

Passive transport molecules A. Carry small molecules across membranes. B. Are peripheral proteins C. Can transport against a concentration gradient D. Use the energy of ATP to transport molecules E. None of the above

A. carry small molecules across membranes

Which of the following has the fastest rate of transport? A. Channel-mediated diffusion B. Facilitated diffusion C. Active transport D. Facilitated diffusion and active transport are equally fast. E. All of the above are equally fast.

A. channel-mediated diffusion

The plasma membrane barrier to passive diffusion is primarily a function of the membrane's A.Phospholipids B. Cholesterol C. Proteins D. Glycoproteins E. All of the above

A. phospholipids

Lipid bilayers are permeable only to molecules that are ____ and _____ A. Small; uncharged B. Large; uncharged C. Small; charged D. Large; charged E. Amphipathic; bipolar

A. small; uncharged

The sugar groups of glycolipids and glycoproteins are found on the outer surface of the plasma membrane. A. true B. false

A. true they are found on the outer surface

The major ATPase maintaining the plasma membrane potential is the Na+-K+ pump. A. true B. false

A.true

Which of the following substances does not require transport proteins to cross into the blood from the intestines? A. Glucose B. ATP C. Leucine D. Alcohol

D. alcohol

A feature common to most transmembrane proteins is A. An amino acid sequence rich in acidic residues B. A structure consisting almost exclusively of β-sheets. C. A phosphorylated exterior domain D. An α-helical region of about 20-25 hydrophobic amino acids.

D. an α-helical region of about 20-25 hydrophobic amino acids

Coupled transport of glucose and Na+ into the intestinal epithelial cell is an example of A. Antiport B. Transcytosis C. Endocytosis D. Facilitated diffusion E. Symport

E. symport