Cell Membrane Transport: AP Biology flashcards

Question 1

What does it mean that a plasma membrane is selectively permeable?

Accepted Answer

It lets some substances pass through but not others.

Question 2

Which way do substances move in passive transport?

Accepted Answer

From an area of higher concentration to an area of lower concentration.

Question 3

Does passive transport require the cell to use its own energy?

Accepted Answer

No.

Question 4

What is diffusion?

Accepted Answer

The passive movement of a substance from a region of high concentration to a region of low concentration.

Question 5

Why is diffusion called a passive process?

Accepted Answer

It uses no cellular energy.

Question 6

What is dynamic equilibrium in diffusion?

Accepted Answer

A state with no concentration gradient, so molecules still move but there is no net movement.

Question 7

How does a steeper concentration gradient affect the rate of diffusion?

Accepted Answer

It makes diffusion faster.

Question 8

How does higher temperature affect the rate of diffusion?

Accepted Answer

It increases the rate.

Question 9

How does greater molecular mass affect the rate of diffusion?

Accepted Answer

Heavier molecules diffuse more slowly.

Question 10

How does a thicker membrane affect the rate of diffusion?

Accepted Answer

It reduces the rate.

Question 11

How does a greater distance to travel affect the rate of diffusion?

Accepted Answer

It slows diffusion.

Question 12

Which kind of molecules slip most easily through the hydrophobic core of the membrane?

Accepted Answer

Small nonpolar, lipid-soluble molecules.

Question 13

Why can ions such as sodium and potassium not easily cross the lipid core of the membrane?

Accepted Answer

They carry a charge.

Question 14

What is facilitated transport (facilitated diffusion)?

Accepted Answer

Diffusion of materials across the membrane with the help of membrane proteins.

Question 15

Does facilitated diffusion need cellular energy?

Accepted Answer

No.

Question 16

What are the two kinds of transport proteins in facilitated diffusion?

Accepted Answer

Channel proteins and carrier proteins.

Question 17

What is a channel protein?

Accepted Answer

A transmembrane protein with a hydrophilic pore that lets a specific substance pass through the membrane.

Question 18

What is a gated channel protein?

Accepted Answer

A channel that opens and closes to control passage.

Question 19

What do aquaporins do?

Accepted Answer

They are channel proteins that let water cross the membrane at a very high rate.

Question 20

How does a carrier protein move a substance across the membrane?

Accepted Answer

It binds the substance and changes shape.

Question 21

What does it mean when carrier proteins are saturated?

Accepted Answer

All of them are bound to their ligands, so the transport rate is at its maximum.

Question 22

What is osmosis?

Accepted Answer

The movement of water across a semipermeable membrane down its concentration gradient.

Question 23

What is tonicity?

Accepted Answer

How an extracellular solution changes a cell's volume by affecting osmosis.

Question 24

What does osmolarity describe?

Accepted Answer

The total solute concentration of a solution.

Question 25

What is a hypotonic solution compared with the cell?

Accepted Answer

One with lower osmolarity than the cell's cytoplasm.

Question 26

What happens to an animal cell in a hypotonic solution?

Accepted Answer

Water enters and the cell swells.

Question 27

What is a hypertonic solution compared with the cell?

Accepted Answer

One with higher osmolarity than the cell's cytoplasm.

Question 28

What happens to an animal cell in a hypertonic solution?

Accepted Answer

Water leaves and the cell shrinks.

Question 29

What happens to the size of a cell in an isotonic solution?

Accepted Answer

It does not change, because there is no net water movement.

Question 30

What is the term for a red blood cell bursting in a hypotonic solution?

Accepted Answer

Lysis.

Question 31

What is the term for a red blood cell shrinking in a hypertonic solution?

Accepted Answer

Crenation.

Question 32

What does active transport require that passive transport does not?

Accepted Answer

Cellular energy, usually from ATP.

Question 33

Which way does active transport move a substance relative to its gradient?

Accepted Answer

Against the gradient.

Question 34

What is an electrochemical gradient?

Accepted Answer

The combined concentration gradient and electrical charge difference acting on an ion.

Question 35

Is the inside of a living cell electrically negative or positive relative to the outside?

Accepted Answer

Negative.

Question 36

What is primary active transport?

Accepted Answer

Transport that moves ions across a membrane and depends directly on ATP.

Question 37

What is secondary active transport?

Accepted Answer

Transport driven by an electrochemical gradient set up by primary active transport, not directly by ATP.

Question 38

What is a uniporter?

Accepted Answer

A carrier protein that moves one specific ion or molecule.

Question 39

What is a symporter?

Accepted Answer

A carrier protein that moves two different substances in the same direction.

Question 40

What is an antiporter?

Accepted Answer

A carrier protein that moves two different substances in opposite directions.

Question 41

What does the sodium-potassium pump (Na+-K+ ATPase) do with sodium?

Accepted Answer

It moves Na+ out of the cell.

Question 42

What does the sodium-potassium pump do with potassium?

Accepted Answer

It moves K+ into the cell.

Question 43

What is the ratio of Na+ out to K+ in for the sodium-potassium pump?

Accepted Answer

Three Na+ out for every two K+ in.

Cell Membrane Transport: AP Biology flashcards

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Cell Membrane Transport: AP Biology flashcards

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How this deck was checked

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