Unit 3

Question 1

It is the internal balance

Answer 1

Homeostasis

Question 2

It provides protection and support for the cell

Answer 2

Cell membrane

Question 3

It contains almost proteins called

Answer 3

Membrane proteins

Question 4

2 layers of
phospholipids

Answer 4

Lipid Bilayer

Question 5

Phosphate head is ____________ and Fatty acid tail is ____________

Answer 5

Polar, Non-Polar

Question 6

Allows some molecules in and keeps other molecules out.

Answer 6

Selectively permeable

Question 7

proposed that the membrane is a mosaic of proteins dispersed within the bilayer, with only the hydrophilic regions exposed to water.

Answer 7

S.J. Singer and G. Nicolson

Question 8

Phospholipids in the plasma membrane can not move within the bilayer. TRUE OR FALSE?

Answer 8

FALSE

Question 9

Some of the lipids, and most proteins, drift laterally. TRUE OR FALSE?

Answer 9

FALSE

Question 10

Rarely does a molecule flip-flop transversely across the membrane. TRUE OR FALSE?

Answer 10

TRUE

Question 11

70% of Cell membrane
proteins part and parcel of membrane structure

Answer 11

Integral proteins

Question 12

What are the membrane proteins?

Answer 12

Integral, Pumps, Channel, Carrier, Enzyme, Receptor, and Peripheral

Question 13

They transfer substances against
Concentration

Answer 13

Pumps

Question 14

Opened and closed by gates

Answer 14

Channel proteins

Question 15

Involved in transport of substances

Answer 15

Carrier proteins

Question 16

Takes place in membrane reaction

Answer 16

Enzyme proteins

Question 17

They bear appropriate sites
for recognition of Specific Ligands

Answer 17

Receptor proteins

Question 18

are bound to the surface of
the membrane

Answer 18

Peripheral proteins

Question 19

Membrane carbohydrates may be covalently bonded to lipids forming _____________

Answer 19

Glycolipids

Question 20

Membrane carbohydrates may be covalently
bonded to proteins forming ___________

Answer 20

Glycoproteins

Question 21

Permeability of Lipid bilayer

Answer 21

Hydrophobic (nonpolar) and polar molecules

Question 22

allow passage of hydrophilic substances across the membrane

Answer 22

Transport proteins

Question 23

Channel proteins are also called _________

Answer 23

Aquaporins

Question 24

bind to molecules and change shape to shuttle them across the membrane

Answer 24

Carrier proteins

Question 25

is the tendency for molecules to spread out evenly into the available space.

Answer 25

Diffusion

Question 26

What are the passive processes of transport mechanism?

Answer 26

Simple diffusion Facilitated diffusion Osmosis Bulk flow filtration

Question 26

What are the active processes of Transport Mechanism?

Answer 26

Primary and secondary transport

Question 27

the region along which the density of a chemical substance increases or decreases

Answer 27

Concentration gradient

Question 28

The diffusion of a substance across a biological membrane is ___________ because no energy is expended by the cell to make it happen.

Answer 28

Passive transport

Question 29

Factors that influences Diffusion Rates

Answer 29

 Distance  Molecular Size  Temperature  Steepness of Concentration Gradient  Membrane of Surface Area

Question 30

can enter cells easily because they diffuse through the lipid portion of the membrane

Answer 30

Lipophilic substances

Question 31

Membrane channels are transmembrane proteins

Answer 31

Channel-Mediated Diffusion

Question 32

is the diffusion of water across a selectively permeable membrane

Answer 32

Osmosis

Question 33

is the ability of a surrounding solution to cause a cell to gain or lose water

Answer 33

Tonicity

Question 34

Solute concentration is the same as that inside the cell; no net water movement across the plasma membrane

Answer 34

Isotonic solution

Question 35

Solute concentration is greater than that inside the cell; cell loses water

Answer 35

Hypertonic solution

Question 36

Solute concentration is less than that inside the cell; cell gains water

Answer 36

Hypotonic solution

Question 37

A plant cell in a hypotonic solution swells until the wall opposes uptake; the cell is now

Answer 37

Turgid (firm)

Question 38

If a plant cell and its surroundings are isotonic, there is no net movement of water into the cell; the cell becomes ____________, and the plant may wilt

Answer 38

Flacid (limp)

Question 39

In a hypertonic environment, plant cells lose water; eventually, the membrane pulls away from the wall, a usually lethal

Answer 39

Plasmolysis

Question 40

transport proteins speed the passive movement of molecules across the plasma membrane

Answer 40

Facilitated diffusion

Question 41

- moves substances against their concentration gradients - allows cells to maintain concentration gradients that differ from their surroundings

Answer 41

Active transport

Question 42

is one type of active transport system.

Answer 42

Sodium-potassium pump

Question 43

is the voltage difference across a membrane

Answer 43

Membrane potential

Question 44

is created by differences in the distribution of positive and negative ions across a membrane

Answer 44

Voltage

Question 45

Two combined forces, collectively called the _____________, drive the diffusion of ions across a membrane

Answer 45

Electrochemical gradient

Question 46

is a transport protein that generates voltage across a membrane

Answer 46

Electrogenic pump

Question 47

The main electrogenic pump of plants, fungi, and bacteria is a

Answer 47

Proton pump

Question 48

occurs when active transport of a solute indirectly drives transport of other solutes.

Answer 48

Cotransport

Question 49

transport vesicles migrate to the membrane, fuse with it, and release their contents

Answer 49

Exocytosis

Question 50

the cell takes in macromolecules by forming vesicles from the plasma membrane

Answer 50

Endocytosis

Question 51

Three types of endocytosis

Answer 51

Phagocytosis (cellular eating) Pinocytosis (cellular drinking) Receptor-mediated endocytosis