BIOL 1404 - Sapli - CH5

What is an aquaporin? a) a protein network that blocks fluid movement b) a membrane protein that contains a channel for water movement c) a glycoprotein that identifies the cell d) a membrane protein that is linked to an enzyme

b) a membrane protein that contains a channel for water movement

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 phrases best describes the hydrophobic portion of a phospholipids? a) forms hydrogen bonds with water b) has few interactions with water c) has an affinity for low salt concentrations d) is repelled by lipids

b) has few interactions with water

Which example describes the use of symport transport across a membrane? a) the absorption of nucleic acids by the intestine during digestion b) the movement of sodium and glucose moving together into cells c) lipids being absorbed by the cells and potassium ions being forced out d) diffusion of both calcium ions and sodium ions into a cell

b) the movement of sodium and glucose moving together into cells

Select conditions that would cause diffusion to happen more slowly: -The solvent contains molecules similar in size and shape to the diffusing molecules. -The molecules are diffusing through a high density liquid. -The solution gets cooler. -The differences in concentration between two areas is small. -Very large molecules are diffusing instead of smaller, more compact molecules.

-The molecules are diffusing through a high density liquid. -The solution gets cooler. -The differences in concentration between two areas is small. -Very large molecules are diffusing instead of smaller, more compact molecules.

Which choice describes diffusion? a) The movement of a substance against its concentration gradient across a cell membrane from a region where it is less concentrated to a region where it is more concentrated b) The movement of a substance up its concentration gradient using ATP and transport proteins across a cell membrane. c) The movement of a substance down its concentration gradient from a region where it is less concentrated to an area where it is more concentrated d) The movement of a substance down a concentration gradient from an area of high concentration to an area of low concentration.

d) The movement of a substance down a concentration gradient from an area of high concentration to an area of low concentration.

Which example describes an antiport mechanism used during active transport in the cell? a) the absorption of carbohydrates by the intestine during digestion b) the transport of sodium and lactose out of the cells of certain bacteria c) amino acids and sodium ions being forced into the cell d) calcium ions going in and sodium ions going out

d) calcium ions going in and sodium ions going out

which of the phrases best describes the hydrophilic region of a phospholipids? a) repelled by water b) has an affinity for high salt concentrations c) floats in nonpolar compounds d) interacts with water

d) interacts with water

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 terms best describes facilitated diffusion? a) osmosis b) active transport c) ion pump d) passive transport

d) passive transport

which of these is a function of cholesterol in a cell's plasma membrane? a) replicating DNA b) helping in respiration c) helping in photosynthesis d) regulating membrane fluidity

d) regulating membrane fluidity