unit 3

Question 1

Cell membrane

Answer 1

an extremely pliable structure composed primarily of back-to-back phospholipids (a “bilayer”).

Question 2

Hydrophilic molecule

Answer 2

attracted to water

Question 3

Hydrophobic molecule

Answer 3

repels and is repelled by water

Question 4

Amphipathic molecule

Answer 4

contains both hydrophobic and hydrophilic molecules

Question 5

Intracellular fluid

Answer 5

fluid interior of the cell

Question 6

Extracellular fluid

Answer 6

fluid environment outside of the cell

Question 7

Interstitial fluid

Answer 7

extracellular fluid not contained within blood vessels

Question 8

Phospholipid structure/molecule

Answer 8

1 hydrophilic head and 2 hydrophobic tails

Question 9

Receptor

Answer 9

a type of recognition protein that can selectively bind a specific molecule
outside the cell, and this binding induces a chemical reaction within the cell

Question 10

Ligand

Answer 10

the specific molecule that binds
to and activates a receptor

Question 11

Glycoprotein

Answer 11

a protein that has carbohydrate molecules attached,
which extend into the extracellular matrix

Question 12

Glycocalyx

Answer 12

a fuzzy-appearing coating around the cell formed from glycoproteins and other carbohydrates attached to
the cell membrane

Question 13

Peripheral proteins

Answer 13

found on the inner or outer surface of the lipid bilayer but can also be attached to the
internal or external surface of an integral protein

Question 14

Selective permeability

Answer 14

allows only substances meeting certain criteria to pass through it unaided

Question 15

Passive transport

Answer 15

the movement of substances across the membrane without the expenditure of cellular energy

Question 16

Active transport

Answer 16

the movement of substances across the membrane using energy from adenosine triphosphate (ATP)

Question 17

Concentration gradient

Answer 17

the difference in concentration of a substance across a space

Question 18

Diffusion

Answer 18

the movement of particles from an area of higher concentration to an area of lower concentration

Question 19

Facilitated diffusion

Answer 19

the diffusion process used for those substances that cannot cross the lipid bilayer due to their size, charge, and/or polarity