Topic 4: Cell Membranes and Walls

Question 1

____ ____ are asymmetric.

Answer 1

plasma membranes

Question 2

Integral proteins act as ____ or ____ that work in one direction

Answer 2

channels or pumps

Question 3

____ and ____ molecules can pass through easier than the ____ or ___ molecules

Answer 3

Small and uncharged; large or charged

Question 4

Why can ions not pass through the membrane easily?

Answer 4

the charge

Question 5

Why can simple sugars and amino acids not pass through the membrane easily?

Answer 5

their large size

Question 6

Define concentration gradient

Answer 6

difference in concentration of a single substance

Question 7

What does it mean to go down a concentration gradient?

Answer 7

going from high to low concentration

Question 8

Define passive transport

Answer 8

naturally occurring phenomenon and does not require the cell the expend energy to accomplish the movement

Question 9

What does it mean to go up a concentration gradient?

Answer 9

going from low to high concentration

Question 10

Define diffusion

Answer 10

passive process of transport used by living organisms

Question 11

Define solvent

Answer 11

fluid within which other molecules are dissolved

Question 12

Define solutes

Answer 12

the molecules dissolved

Question 13

Define solution

Answer 13

combined form of solutes and solvent

Question 14

Diffusion requires no additional energy other than _____ energy already present in the molecule

Answer 14

thermodynamic

Question 15

How does the extent of the concentration gradient effect the rate of diffusion?

Answer 15

the greater the difference in concentration, the more rapid the rate of diffusion

Question 16

How does the mass of molecules effect the rate of diffusion?

Answer 16

the more massive the molecules the slower the rate of diffusion

Question 17

How does temperature effect the rate of diffusion?

Answer 17

the higher the temperature the faster the rate of diffusion

Question 18

How does solute density effect the rate of diffusion?

Answer 18

the more dense a solute, the slower the rate of diffusion

Question 19

What are the required conditions for passive transport to take place?

Answer 19

1. concentration gradient
2. permeability of the molecule to the membrane

Question 20

What kind of molecules can pass through via simple diffusion?

Answer 20

Nonpolar neutral molecules like oxygen and carbon dioxide

Question 21

Define facilitated diffusion

Answer 21

material moves across the plasma membrane with the assistance of transmembrane proteins

Question 22

What kind of molecules pass through via facilitated diffusion?

Answer 22

Polar molecules and ions

Question 23

What are the two steps of facilitated transport?

Answer 23

1. material is attached to protein/glycoprotein receptors on exterior
2. passed to specific integral/transport proteins that facilitate passage

Question 24

Define uniporter

Answer 24

allows transport down a concentration gradient of a single molecule

Question 25

What are the two cotransporters?

Answer 25

symporter and antiporter

Question 26

Define symporter

Answer 26

uses concentration gradient of one molecule to move another at the same time in the same direction

Question 27

Define antiporter

Answer 27

uses concentration gradient of one molecule to move another at the same time in the opposite direction

Question 28

What is active transport?

Answer 28

Form of facilitated transport that uses a pump, protein transporter, and cellular energy

Question 29

Define osmosis

Answer 29

the net diffusion of water through a semipermeable membrane according to the availability of water on either side of the membrane

Question 30

Since the concentration of water is not usually known, how is it known where water will move?

Answer 30

difference in solute concentration

Question 31

Water moves from ____ solute to ____ solute.

Answer 31

less; more

Question 32

What is homeostasis and how is it maintained?

Answer 32

State of stability that provides optimal conditions needed to sustain life; to maintain water will continue to move back and forth but there is not net movement

Question 33

Define osmolarity

Answer 33

total amount of solutes dissolved within a specific volume of solution

Question 34

Define tonicity

Answer 34

describes how the solutes in a solution influence the movement of water into or out of the cell

Question 35

How does water move in a hypotonic solution?

Answer 35

water will enter the cell

Question 36

How does water move in

Question 37

How does water move in a hypertonic cell?

Answer 37

Water moves out of the cell

Question 38

Define endocytosis

Answer 38

type of active transport that moves particles, such as large molecules, part of cells, and even whole cells, into a cell

Question 39

Define exocytosis

Answer 39

purpose to expel material from the cell into the extracellular fluid