Unit 1 - Cell Membranes

Question 1

Membranes are composed of a double layer of

Answer 1

phospholipid molecules with embedded protein molecules

Question 2

Membrane structure is often described as

Answer 2

fluid mosaic

Question 3

Membrane structures are fluid mosaic. Fluid because

Answer 3

the molecules are constantly moving

Question 4

Membrane structures are fluid mosaic. Mosaic because

Answer 4

the proteins sticking out of the phospholipid bilayer are likened to the pattern seen in a tile mosaic floor

Question 5

Only ______ molecules can pass through the phospholipid layer

Answer 5

fat soluble

Question 6

Most important cell molecules are

Answer 6

soluble in water

Question 7

Most cell molecules if they are small enough can only pass through the membrane via

Answer 7

pores in the embedded protein molecules

Question 8

Membranes are ________ permeable

Answer 8

Selectively

Question 9

All cells are enclosed by a plasma membrane which controls the molecules that

Answer 9

enter and leave a cell and so maintain a constant environment within a cell

Question 10

Water enters or leaves the cell by

Answer 10

osmosis

Question 11

Osmosis is the movement of water molecules from

Answer 11

a region of higher water concentration to a region of lower water concentration through a selectively permeable membrane

Question 12

The body must maintain a constant blood water concentration so that the body cells

Answer 12

neither shrink nor burst

Question 13

Blood cells would _____ if the plasma had a lower water concentration

Answer 13

SHRINK

Question 14

Blood cells would _____ if the plasma had a higher water concentration

Answer 14

BURST

Question 15

HYPERTONIC is when the plasma has a

Answer 15

lower water concentration

Question 16

HYPOTONIC is when the plasma has a

Answer 16

higher water concentration

Question 17

Diffusion is the movement of molecules from a

Answer 17

high concentration to a lower concentration

Question 18

Fat soluble molecules diffuse through

Answer 18

phospholipid bilayer

Question 19

Small molecules diffuse through

Answer 19

protein channels

Question 20

Oxygen and glucose diffuse into the cell because their use in

Answer 20

respiration produces a lower concentration

Question 21

CO2 released by respiration _____ out of the cell

Answer 21

diffuses

Question 22

Active transport is the movement of molecules from a

Answer 22

low concentration to a higher concentration against a concentration gradient

Question 23

The concentration of molecules in a cell can be maintained at a ______ or ______ concentration than in plasma

Answer 23

higher, lower

Question 24

Active transport is

Answer 24

selective

Question 25

Active transport requires energy in the form of ____ and __________

Answer 25

ATP and special carrier molecules in the membrane

Question 26

Active transport depends on

Answer 26

enzymes and ATP

Question 27

Active transports is affected by

Answer 27

temperature, oxygen, glucose availability and respiration inhibitors

Question 28

Active transport carriers are often called

Answer 28

'pumps'

Question 29

Some active transport carrier molecules have a dual role in that they

Answer 29

exchange one type of ion for another

Question 30

An example of an active transport carrier molecule is the

Answer 30

sodium/potassium pump

Question 31

Endocytosis is the process by which a cell

Answer 31

engulfs and takes in large particles

Question 32

There are two types of endocytosis:

Answer 32

Phagocytosis and Pinocytosis

Question 33

Phagocytosis means

Answer 33

cell eating

Question 34

Pinocytosis means

Answer 34

cell drinking

Question 35

Phagocytosis is the engulfing of large solid particles and then the contents of a vesicle are

Answer 35

digested

Question 36

Pinocytosis is the formation of

Answer 36

small liquid filled vesicles

Question 37

Exocytosis is the reverse of endocytosis and allows its contents to be

Answer 37

expelled from the cell

Question 38

Endocytosis allows the cell to acquire

Answer 38

hormones, lipids and protein

Question 39

Exocytosis allows the secretion of products such as

Answer 39

enzymes, glycoproteins and hormones