Chapter 5 Post Test

Facilitated diffusion requires __________.

a membrane transport protein and a concentration gradient

Many metabolic poisons work by inhibiting ATP production. Which type of transport would be most affected?

active transport

The concentration of sodium ions is lower in the cytoplasm of a heart muscle cell than it is in the extracellular fluid. By what mechanism does the cell maintain this difference?

active transport

Due to a high percentage of unsaturated fatty acids in their membranes, certain microorganisms __________.

are able to withstand low temperatures because their membranes do not solidify as rapidly

Which of the following associations is NOT correct?

desmosomes-allow inflexible attachments among cells

Which of the following transport processes require(s) energy?

endocytosis

Membrane fluidity within a phospholipid bilayer is based upon __________.

interactions among nonpolar (hydrophobic) lipid tails

The point at which a substance is evenly dispersed within a fluid __________.

is referred to as "dynamic equilibrium" and happens when net diffusion is zero

Choose the substance that will diffuse most rapidly across the plasma membrane.

oxygen

Which type of cell would you expect to burst when placed in a hypotonic solution?

red blood cell

Each substance needs a different type of transport to get into a cell. Pick the answer choice that accurately matches the type of transport needed to convey each of the following substances into a cell. oxygen, water, sodium ions, potassium ions, bacteria (Note that sodium ions are more concentrated outside cells than inside, and potassium ions are more concentrated inside cells than outside.)

simple diffusion, osmosis, facilitated diffusion, active transport, endocytosis

Which of the following types of molecules must pass through membranes via the pores formed by membrane proteins?

small charged ions such as Na+ and Ca++

Substances are able to cross the lipid bilayer of a cell at different rates that are unique for each substance. Which of the following characteristics would favor the simple diffusion of a substance across a cell membrane?

small molecule size

In osmosis, water diffuses from the side of the membrane with a higher concentration of water to the side with a lower concentration of water. What determines the concentration of water in a solution?

the number of molecules other than water dissolved in the solution

The fluid mosaic model describes membranes as fluid because __________.

the phospholipids and proteins move from place to place within the bilayer

When a drop of food coloring is placed in a glass of water, the spreading out of the molecules of food dye is caused by __________.

the random movement of molecules

A chloride ion is in a cell that has no channel proteins in its membrane. Will the chloride be able to get out of the cell?

No, there is no channel through which to diffuse.

Imagine that you are studying cell structure in various organisms in your biology lab. Your instructor gives you a microscope slide showing two types of cells that have been suspended in pure water. One type of cell swells up until it bursts. The other cell maintains its shape throughout the experiment. Suggest an explanation for these observations. Assume that both cells were alive at the start of the experiment and that the concentration of water inside both types of cells is similar.

The cell that remained intact had a contractile vacuole for pumping out the excess water that entered the cell via osmosis.

If there is a high concentration of oxygen on one side of a biological membrane, what will happen?

The oxygen will diffuse across the membrane until the concentration of oxygen on each side is the same.

A cell is placed in a hypotonic solution. What will happen?

Water will move into the cell.