Mastering Biology Lab 4

In active transport,

molecules move across the plasma membrane against their concentration gradient.

A molecule moves down its concentration gradient using a transport protein in the plasma membrane. This is an example of

Facilitated diffusion

Water crosses the plasma membrane

through facilitated diffusion or diffusion

The sodium-potassium pump uses energy from ATP to move sodium ions out of the cell, and potassium ions into the cell. This is an example of

Active transport

The plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. This describes the process of

Endocytosis

Frequently, transplanted organs are rejected by the recipient's body. how is this reaction related to plasma membranes?

Each person has a unique set of carbohydrate chains attached to his or her plasma membranes.

The lipids in a cell membrane are arranged.

so that the nonpolar parts of two lipids point toward each other

The fluid mosaic model describes the plasma membrane as consisting of

diverse proteins embedded in a phospholipid bilayer

Most of the functions of a cell membrane, including transport and enzymatic function, are performed by

proteins

When considering the formation of membranes, they......

form spontaneously in aqueous environments

The plasma membrane is selectively permeable. Which of the following can pass freely through the membrane with no assistance?

Oxygen and carbon dioxide

Which of the following substances would have the most trouble crossing a biological membrane by diffusing through the lipid bilayer?

Na+

Diffusion does not require the cell to expend ATP. therefore, diffusion is considered a type of

passive transport

The ideal osmotic environment for an animal cell is a environtment

Isotonic

An animal cell placed in an solution will gain water, swell, and possibly burst

hypotonic

There is a net diffusion of water out of animal cell when it is placed in an .... solution

Hypertonic

The ideal osmotic environment for a plant cell is a ...... environment

hypotonic

a plant cell placed in a ..... solution will lose water and plasmolyze

hypertonic

a plant cell surrounded by a ..... solution will be flaccid (limp)

isotonic

Osmosis is often viewed incorrectly as a process driven directly by differences in solute concentration across a selectively permeable membrane. What really drives osmosis?

the difference in water concentration across a selectively permeable membrane

In the lab, you use a special balloon that is permeable to water but not sucrose to make an "artificial cell" the balloon is filled with a solution of 20% sucrose and 80% water and is immersed in a beaker containing a solution of 40% sucrose and 60% water

Water will leave the balloon

Green olives may be preserved in brine, which is a 20-30% salt solution. How does this method prevent contamination by microorganism?

Bacteria can't survive in a hypertonic solution because they lose water.

If placed in tap water, an animal cell will undergo lysis, whereas a plant cell will not. What accounts for this difference?

the relative inelasticity and strength of the plant cell wall

Exocytosis

A vesicle inside the cell fuses with the plasma membrane and releases its content outside the cell

Facilitated Diffusion

A form of passive transport. Molecules move across the plasma membrane using a transport protein.

Endocytosis

The plasma forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell.

Diffusion

A form of passive transport. Molecules move across the plasma membrane by crossing the lipid bilayer.

Active Transport

Requires energy from the cell. Molecules move against their concentration gradient.

What name is given to the process by which water crosses a selectively permeable membrane?

osmosis