Chapter 8

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A cell placed in a high salt solution would swell because of osmosis.

F

Cell-surface markers face the inside of the cell.

F

Exocytosis is a process that uses vesicles to capture substances and bring them into a cell.

F

Osmosis is the diffusion of starch molecules through a selectively permeable membrane.

F

The cell membrane is made up of a double layer called the DNA bilayer.

F

The nonpolar tails of a phospholipid are attracted to water.

F

When the solute concentration outside a cell is equal to the solute concentration inside the cell, the cell's environment is hypotonic.

F

Refer to the illustration above. What happens when the structure labeled A binds to the structure labeled B?

Information is sent into the cell.

What change takes place in the cell membrane if a signal molecule causes a transport protein to open?

Permeability change

A concentration gradient exists when one area has a higher concentration of a substance than another area does.

T

Receptor proteins may cause the formation of a second messenger molecule inside the cell.

T

The movement down a concentration gradient is called diffusion.

T

Which of the following statements about an isotonic solution and a cell is correct?

The solution has the same solute concentration that the cytoplasm does.

Both active transport and facilitated diffusion involve

carrier proteins.

Proteins in the cell membrane that identify the cell are called

cell surface marker

Refer to the illustration above. The structure labeled C is a(n)

cell-surface marker.

Proteins that serve as tunnels for specific substances through the lipid bilayer are

channel proteins.

Molecules that are too large to be moved across a cell membrane can be removed from the cell by

exocytosis

Removing materials from a cell in vesicles is called

exocytosis

Sugar molecules cross the cell membrane by

facilitated diffusion.

How many potassium ions does the sodium-potassium pump move into a cell if it moves six sodium ions out of the cell?

four

Diffusion is the movement of a substance

from an area of high concentration to an area of lower concentration.

The sodium-potassium pump

is a carrier protein.

Refer to the illustration above. The structure labeled A is composed of

lipids

Phospholipids are molecules that have

one polar phosphate head and two non polar fatty acid tails

The diffusion of water into or out of a cell is called

osmosis

Ions move through ion channels by

passive transport

Osmosis is a type of

passive transport.

Which type of molecule forms the cell membrane?

phospholipid

The sodium-potassium pump usually pumps

potassium ions into the cell

Refer to the illustration above. The structure labeled B in the diagram is an example of a(n)

receptor protein.

Signal molecules bind to

receptor proteins

Which of the following transmit information into a cell by binding to signal molecules?

receptor proteins

The interior of the lipid bilayer of a cell membrane forms a nonpolar zone that

repels ions and most polar molecules

Unlike passive transport, active transport

requires energy

Which of the following descriptions of hormones is correct?

signal molecules distributed throughout the body

Which of the following is a form of active transport?

sodium-potassium pump

How does water pass through the cell membrane?

through channel proteins just for water

Refer to the illustration above. The structure labeled D is a(n)

transport protein

Refer to the illustration above. The process shown is called

diffusion

The dispersal of ink in a beaker of water is an example of

diffusion

Which of the following does not require energy?

diffusion

cell membrane : cell ::

door : house

Proteins and polysaccharides that are too large to move into a cell through diffusion or active transport move in by

endocytosis

As a result of diffusion, the concentration of many types of substances

eventually becomes balanced on both sides of a membrane.


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