Quiz 2

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

If glucose in your breakfast foods was radioactively labeled with C14, where inside the cell would you be able to find highest level of radioactivity? A. Cytoplasm B. Endoplasmic reticulum C. Peroxisomes D. Nucleus

A. Cytoplasm

Glucose from your breakfast travels in blood to different tissues. It entered the neurons in the brain through: A. GLUT 3 B. SGLT 1 C. Passive diffusion D. Glucose pump

A. GLUT 3

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

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

An amphipathic molecule is A. part water-soluble and part water-insoluble. B. hydrophobic. C. water-insoluble. D. water-soluble. E. hydrophilic.

A. part water-soluble and part water-insoluble.

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. amphipathic; bipolar D. small; charged E. large; charged

A. small; uncharged

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

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. No Chainge

B. Decreases

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

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

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 molecule 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.

Coupled transport of glucose and Na+ into the intestinal epithelial cell is an example of A. facilitated diffusion. B. symport. C. endocytosis. D. transcytosis. E. antiport.

B. symport.

What couples the movement of an ion or molecule down the concentration gradient in order to move another molecule against the concentration gradient? A. Symporter B. Antiporter C. Both of the above D. none of the above

C. Both of the above

If GLUT 3 uniporter proteins were blocked by a toxin what would be a possible outcome: A. GLUT 3 allows glucose to pass to and from the liver cells, glucose from glycogen break down would not be able to escape the liver B. GLUT 3 allows glucose to pass to and from the muscle cells, this would result in inability of the muscle to contract C. GLUT 3 allows glucose to pass to and from neurons in the brain, glucose would not be able to enter the brain resulting in neuronal cell death D. GLUT 3 allows for glucose to pass to and from the fat cells, glucose would not be able to be stored in the form of glycerol in fat cells

C. GLUT 3 allows glucose to pass to and from neurons in the brain, glucose would not be able to enter the brain resulting in neuronal cell death

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

C. transport in the energetically favorable direction

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

D. Alcohol

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

D. action of the Na+-K+ pump.