4.1: The structure of the cell surface membrane

Question 1

All membranes around and within all cells (including the membranes around and within cell organelles) have the same what?

Answer 1

All membranes:
1. Around
2. Within
all cells (including the membranes around and within cell organelles) have the same basic structure

Question 2

All membranes around and within all cells (including the membranes around and within cell organelles) have the same basic structure and are known as what?

Answer 2

All membranes around and within all cells (including the membranes around and within cell organelles):

1. Have the same basic structure
2. Are known as plasma membranes

Question 3

All membranes around and within all cells (including the membranes around and within cell organelles) have the same basic structure and are known as plasma membranes.
The cell-surface membrane is the name specifically given to the plasma membrane that does what?

Answer 3

The cell-surface membrane is the name specifically given to the plasma membrane that:

1. Surrounds cells
2. Forms the boundary between the cell cytoplasm and the environment

Question 4

All membranes around and within all cells (including the membranes around and within cell organelles) have the same basic structure and are known as plasma membranes.
The cell-surface membrane is the name specifically given to the plasma membrane that surrounds cells and forms the boundary between the cell cytoplasm and the environment.
It allows what to be established inside and outside a cell?

Answer 4

The cell-surface membrane allows different conditions to be established:
1. Inside
2. Outside
a cell

Question 5

All membranes around and within all cells (including the membranes around and within cell organelles) have the same basic structure and are known as plasma membranes.
The cell-surface membrane is the name specifically given to the plasma membrane that surrounds cells and forms the boundary between the cell cytoplasm and the environment.
It allows different conditions to be established inside and outside a cell.
It controls the what in and out of the cell?

Answer 5

The cell-surface membrane controls the movement of substances:
1. In
2. Out
of the cell

Question 6

All membranes around and within all cells (including the membranes around and within cell organelles) have the same basic structure and are known as plasma membranes.
The cell-surface membrane is the name specifically given to the plasma membrane that surrounds cells and forms the boundary between the cell cytoplasm and the environment.
It allows different conditions to be established inside and outside a cell.
It controls the movement of substances in and out of the cell.
What are the molecules that form the structure of cell-surface membranes?

Answer 6

The molecules that form the structure of cell-surface membranes are:

1. Phospholipids
2. Proteins
3. Cholesterol
4. Glycolipids
5. Glycoproteins

Question 7

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Phospholipids form a what?

Answer 7

Phospholipids form a bilayer

Question 8

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Phospholipids form a bilayer.
Phospholipids are important components of cell-surface membranes for the following reasons:
1. The hydrophilic what of both phospholipid layers point to what?

Answer 8

The hydrophilic heads of both phospholipid layers point to the outside of the cell-surface membrane

Question 9

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Phospholipids form a bilayer.
Phospholipids are important components of cell-surface membranes for the following reasons:
1. The hydrophilic heads of both phospholipid layers point to the outside of the cell-surface membrane, what on both sides?

Answer 9

The hydrophilic heads of both phospholipid layers point to the outside of the cell-surface membrane, attracted by water on both sides

Question 10

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Phospholipids form a bilayer.
Phospholipids are important components of cell-surface membranes for the following reasons:
1. The hydrophilic heads of both phospholipid layers point to the outside of the cell-surface membrane, attracted by water on both sides.
2. The hydrophobic what of both phospholipid layers point into what?

Answer 10

The hydrophobic tails of both phospholipid layers point into the centre of the cell membrane

Question 11

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Phospholipids form a bilayer.
Phospholipids are important components of cell-surface membranes for the following reasons:
1. The hydrophilic heads of both phospholipid layers point to the outside of the cell-surface membrane, attracted by water on both sides.
2. The hydrophobic tails of both phospholipid layers point into the centre of the cell membrane, what on both sides?

Answer 11

The hydrophobic tails of both phospholipid layers point into the centre of the cell membrane, repelled by the water on both sides

Question 12

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Phospholipids form a bilayer.
Phospholipids are important components of cell-surface membranes for the following reasons:
1. The hydrophilic heads of both phospholipid layers point to the outside of the cell-surface membrane, attracted by water on both sides.
2. The hydrophobic tails of both phospholipid layers point into the centre of the cell membrane, repelled by the water on both sides.
What moves through the membrane?

Answer 12

Lipid-soluble material moves through the membrane

Question 13

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Phospholipids form a bilayer.
Phospholipids are important components of cell-surface membranes for the following reasons:
1. The hydrophilic heads of both phospholipid layers point to the outside of the cell-surface membrane, attracted by water on both sides.
2. The hydrophobic tails of both phospholipid layers point into the centre of the cell membrane, repelled by the water on both sides.
Lipid-soluble material moves through the membrane via what?

Answer 13

Lipid-soluble material moves through the membrane via the phospholipid bilayer

Question 14

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Phospholipids form a bilayer.
Phospholipids are important components of cell-surface membranes for the following reasons:
1. The hydrophilic heads of both phospholipid layers point to the outside of the cell-surface membrane, attracted by water on both sides.
2. The hydrophobic tails of both phospholipid layers point into the centre of the cell membrane, repelled by the water on both sides.
Lipid-soluble material moves through the membrane via the phospholipid bilayer.
The functions of phospholipids in the membrane are to:
1. Allow what?

Answer 14

The functions of phospholipids in the membrane are to allow lipid-soluble substances to:
1. Enter
2. Leave
the cell

Question 15

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Phospholipids form a bilayer.
Phospholipids are important components of cell-surface membranes for the following reasons:
1. The hydrophilic heads of both phospholipid layers point to the outside of the cell-surface membrane, attracted by water on both sides.
2. The hydrophobic tails of both phospholipid layers point into the centre of the cell membrane, repelled by the water on both sides.
Lipid-soluble material moves through the membrane via the phospholipid bilayer.
The functions of phospholipids in the membrane are to:
1. Allow lipid-soluble substances to enter and leave the cell.
2. Prevent what?

Answer 15

The functions of phospholipids in the membrane are to prevent water-soluble substances:
1. Entering
2. Leaving
the cell

Question 16

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Phospholipids form a bilayer.
Phospholipids are important components of cell-surface membranes for the following reasons:
1. The hydrophilic heads of both phospholipid layers point to the outside of the cell-surface membrane, attracted by water on both sides.
2. The hydrophobic tails of both phospholipid layers point into the centre of the cell membrane, repelled by the water on both sides.
Lipid-soluble material moves through the membrane via the phospholipid bilayer.
The functions of phospholipids in the membrane are to:
1. Allow lipid-soluble substances to enter and leave the cell.
2. Prevent water-soluble substances entering and leaving the cell.
3. Make the membrane what?

Answer 16

The functions of phospholipids in the membrane are to make the membrane:

1. Flexible
2. Self-sealing

Question 17

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Proteins are what throughout the cell surface membrane?

Answer 17

Proteins are interspersed throughout the cell surface membrane

Question 18

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Proteins are interspersed throughout the cell surface membrane.
Proteins are embedded in the phospholipid bilayer in 2 main ways:
1. Some proteins occur where?

Answer 18

Some proteins occur in the surface of the phospholipid bilayer

Question 19

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Proteins are interspersed throughout the cell surface membrane.
Proteins are embedded in the phospholipid bilayer in 2 main ways:
1. Some proteins occur in the surface of the phospholipid bilayer and never do what?

Answer 19

Some proteins:

1. Occur in the surface of the phospholipid bilayer
2. Never extend completely across it

Question 20

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Proteins are interspersed throughout the cell surface membrane.
Proteins are embedded in the phospholipid bilayer in 2 main ways:
1. Some proteins occur in the surface of the phospholipid bilayer and never extend completely across it.
They act either to do what or, in conjunction with glycolipids, as what?

Answer 20

They act either:
1. To give mechanical support to the membrane
Or,
2. In conjunction with glycolipids, as cell receptors

Question 21

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Proteins are interspersed throughout the cell surface membrane.
Proteins are embedded in the phospholipid bilayer in 2 main ways:
1. Some proteins occur in the surface of the phospholipid bilayer and never extend completely across it.
They act either to give mechanical support to the membrane or, in conjunction with glycolipids, as cell receptors for what?

Answer 21

They act either:
1. To give mechanical support to the membrane
Or,
2. In conjunction with glycolipids, as cell receptors for molecules such as hormones

Question 22

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Proteins are interspersed throughout the cell surface membrane.
Proteins are embedded in the phospholipid bilayer in 2 main ways:
1. Some proteins occur in the surface of the phospholipid bilayer and never extend completely across it.
They act either to give mechanical support to the membrane or, in conjunction with glycolipids, as cell receptors for molecules such as hormones.
2. Other proteins completely do what?

Answer 22

Other proteins completely span the phospholipid bilayer

Question 23

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Proteins are interspersed throughout the cell surface membrane.
Proteins are embedded in the phospholipid bilayer in 2 main ways:
1. Some proteins occur in the surface of the phospholipid bilayer and never extend completely across it.
They act either to give mechanical support to the membrane or, in conjunction with glycolipids, as cell receptors for molecules such as hormones.
2. Other proteins completely span the phospholipid bilayer from what?

Answer 23

Other proteins completely span the phospholipid bilayer from:
1. One side
to
2. The other

Question 24

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Proteins are interspersed throughout the cell surface membrane.
Proteins are embedded in the phospholipid bilayer in 2 main ways:
1. Some proteins occur in the surface of the phospholipid bilayer and never extend completely across it.
They act either to give mechanical support to the membrane or, in conjunction with glycolipids, as cell receptors for molecules such as hormones.
2. Other proteins completely span the phospholipid bilayer from one side to the other.
Some proteins are protein channels.
What do protein channels do?

Answer 24

Protein channels form water-filled tubes to allow water-soluble ions to diffuse across the membrane

Question 25

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Proteins are interspersed throughout the cell surface membrane.
Proteins are embedded in the phospholipid bilayer in 2 main ways:
1. Some proteins occur in the surface of the phospholipid bilayer and never extend completely across it.
They act either to give mechanical support to the membrane or, in conjunction with glycolipids, as cell receptors for molecules such as hormones.
2. Other proteins completely span the phospholipid bilayer from one side to the other.
Some proteins are protein channels.
Protein channels form water-filled tubes to allow water-soluble ions to diffuse across the membrane.
Other proteins are what?

Answer 25

Other proteins are carrier proteins

Question 26

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Proteins are interspersed throughout the cell surface membrane.
Proteins are embedded in the phospholipid bilayer in 2 main ways:
1. Some proteins occur in the surface of the phospholipid bilayer and never extend completely across it.
They act either to give mechanical support to the membrane or, in conjunction with glycolipids, as cell receptors for molecules such as hormones.
2. Other proteins completely span the phospholipid bilayer from one side to the other.
Some proteins are protein channels.
Protein channels form water-filled tubes to allow water-soluble ions to diffuse across the membrane.
Other proteins are carrier proteins that do what?

Answer 26

Other proteins are carrier proteins that:

1. Bind to ions or molecules like glucose and amino acids
2. Then change shape in order to move these molecules across the membrane

Question 27

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Proteins are interspersed throughout the cell surface membrane.
Proteins are embedded in the phospholipid bilayer in 2 main ways:
1. Some proteins occur in the surface of the phospholipid bilayer and never extend completely across it.
They act either to give mechanical support to the membrane or, in conjunction with glycolipids, as cell receptors for molecules such as hormones.
2. Other proteins completely span the phospholipid bilayer from one side to the other.
Some proteins are protein channels.
Protein channels form water-filled tubes to allow water-soluble ions to diffuse across the membrane.
Other proteins are carrier proteins that bind to ions or molecules like glucose and amino acids and then change shape in order to move these molecules across the membrane.
The functions of the proteins in the membrane are to:
1. Provide what?

Answer 27

The functions of the proteins in the membrane are to provide structural support

Question 28

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Proteins are interspersed throughout the cell surface membrane.
Proteins are embedded in the phospholipid bilayer in 2 main ways:
1. Some proteins occur in the surface of the phospholipid bilayer and never extend completely across it.
They act either to give mechanical support to the membrane or, in conjunction with glycolipids, as cell receptors for molecules such as hormones.
2. Other proteins completely span the phospholipid bilayer from one side to the other.
Some proteins are protein channels.
Protein channels form water-filled tubes to allow water-soluble ions to diffuse across the membrane.
Other proteins are carrier proteins that bind to ions or molecules like glucose and amino acids and then change shape in order to move these molecules across the membrane.
The functions of the proteins in the membrane are to:
1. Provide structural support.
2. Act as channels, doing what?

Answer 28

The functions of the proteins in the membrane are to act as channels, transporting water-soluble substances across the membrane

Question 29

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Proteins are interspersed throughout the cell surface membrane.
Proteins are embedded in the phospholipid bilayer in 2 main ways:
1. Some proteins occur in the surface of the phospholipid bilayer and never extend completely across it.
They act either to give mechanical support to the membrane or, in conjunction with glycolipids, as cell receptors for molecules such as hormones.
2. Other proteins completely span the phospholipid bilayer from one side to the other.
Some proteins are protein channels.
Protein channels form water-filled tubes to allow water-soluble ions to diffuse across the membrane.
Other proteins are carrier proteins that bind to ions or molecules like glucose and amino acids and then change shape in order to move these molecules across the membrane.
The functions of the proteins in the membrane are to:
1. Provide structural support.
2. Act as channels, transporting water-soluble substances across the membrane.
3. Allow what through carrier proteins?

Answer 29

The functions of the proteins in the membrane are to allow active transport across the membrane through carrier proteins

Question 30

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Proteins are interspersed throughout the cell surface membrane.
Proteins are embedded in the phospholipid bilayer in 2 main ways:
1. Some proteins occur in the surface of the phospholipid bilayer and never extend completely across it.
They act either to give mechanical support to the membrane or, in conjunction with glycolipids, as cell receptors for molecules such as hormones.
2. Other proteins completely span the phospholipid bilayer from one side to the other.
Some proteins are protein channels.
Protein channels form water-filled tubes to allow water-soluble ions to diffuse across the membrane.
Other proteins are carrier proteins that bind to ions or molecules like glucose and amino acids and then change shape in order to move these molecules across the membrane.
The functions of the proteins in the membrane are to:
1. Provide structural support.
2. Act as channels, transporting water-soluble substances across the membrane.
3. Allow active transport across the membrane through carrier proteins.
4. Form what?

Answer 30

The functions of the proteins in the membrane are to form cell-surface receptors

Question 31

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Proteins are interspersed throughout the cell surface membrane.
Proteins are embedded in the phospholipid bilayer in 2 main ways:
1. Some proteins occur in the surface of the phospholipid bilayer and never extend completely across it.
They act either to give mechanical support to the membrane or, in conjunction with glycolipids, as cell receptors for molecules such as hormones.
2. Other proteins completely span the phospholipid bilayer from one side to the other.
Some proteins are protein channels.
Protein channels form water-filled tubes to allow water-soluble ions to diffuse across the membrane.
Other proteins are carrier proteins that bind to ions or molecules like glucose and amino acids and then change shape in order to move these molecules across the membrane.
The functions of the proteins in the membrane are to:
1. Provide structural support.
2. Act as channels, transporting water-soluble substances across the membrane.
3. Allow active transport across the membrane through carrier proteins.
4. Form cell-surface receptors for doing what?

Answer 31

The functions of the proteins in the membrane are to form cell-surface receptors for identifying cells

Question 32

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Proteins are interspersed throughout the cell surface membrane.
Proteins are embedded in the phospholipid bilayer in 2 main ways:
1. Some proteins occur in the surface of the phospholipid bilayer and never extend completely across it.
They act either to give mechanical support to the membrane or, in conjunction with glycolipids, as cell receptors for molecules such as hormones.
2. Other proteins completely span the phospholipid bilayer from one side to the other.
Some proteins are protein channels.
Protein channels form water-filled tubes to allow water-soluble ions to diffuse across the membrane.
Other proteins are carrier proteins that bind to ions or molecules like glucose and amino acids and then change shape in order to move these molecules across the membrane.
The functions of the proteins in the membrane are to:
1. Provide structural support.
2. Act as channels, transporting water-soluble substances across the membrane.
3. Allow active transport across the membrane through carrier proteins.
4. Form cell-surface receptors for identifying cells.
5. Help cells do what?

Answer 32

The functions of the proteins in the membrane are to help cells adhere together

Question 33

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Proteins are interspersed throughout the cell surface membrane.
Proteins are embedded in the phospholipid bilayer in 2 main ways:
1. Some proteins occur in the surface of the phospholipid bilayer and never extend completely across it.
They act either to give mechanical support to the membrane or, in conjunction with glycolipids, as cell receptors for molecules such as hormones.
2. Other proteins completely span the phospholipid bilayer from one side to the other.
Some proteins are protein channels.
Protein channels form water-filled tubes to allow water-soluble ions to diffuse across the membrane.
Other proteins are carrier proteins that bind to ions or molecules like glucose and amino acids and then change shape in order to move these molecules across the membrane.
The functions of the proteins in the membrane are to:
1. Provide structural support.
2. Act as channels, transporting water-soluble substances across the membrane.
3. Allow active transport across the membrane through carrier proteins.
4. Form cell-surface receptors for identifying cells.
5. Help cells adhere together.
6. Act as what?

Answer 33

The functions of the proteins in the membrane are to act as receptors

Question 34

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Proteins are interspersed throughout the cell surface membrane.
Proteins are embedded in the phospholipid bilayer in 2 main ways:
1. Some proteins occur in the surface of the phospholipid bilayer and never extend completely across it.
They act either to give mechanical support to the membrane or, in conjunction with glycolipids, as cell receptors for molecules such as hormones.
2. Other proteins completely span the phospholipid bilayer from one side to the other.
Some proteins are protein channels.
Protein channels form water-filled tubes to allow water-soluble ions to diffuse across the membrane.
Other proteins are carrier proteins that bind to ions or molecules like glucose and amino acids and then change shape in order to move these molecules across the membrane.
The functions of the proteins in the membrane are to:
1. Provide structural support.
2. Act as channels, transporting water-soluble substances across the membrane.
3. Allow active transport across the membrane through carrier proteins.
4. Form cell-surface receptors for identifying cells.
5. Help cells adhere together.
6. Act as receptors, for example for what?

Answer 34

The functions of the proteins in the membrane are to act as receptors, for example for hormones

Question 35

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Cholesterol molecules occur where?

Answer 35

Cholesterol molecules occur within the phospholipid bilayer of the cell-surface membrane

Question 36

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Cholesterol molecules occur within the phospholipid bilayer of the cell-surface membrane.
They do what?

Answer 36

The cholesterol molecules add strength to the membranes

Question 37

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Cholesterol molecules occur within the phospholipid bilayer of the cell-surface membrane.
They add strength to the membranes.
Cholesterol molecules are very what?

Answer 37

Cholesterol molecules are very hydrophobic

Question 38

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Cholesterol molecules occur within the phospholipid bilayer of the cell-surface membrane.
They add strength to the membranes.
Cholesterol molecules are very hydrophobic and therefore play an important role in preventing what?

Answer 38

Cholesterol molecules are very hydrophobic and therefore play an important role in preventing the loss of:
1. Water
2. Dissolved ions
from the cell

Question 39

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Cholesterol molecules occur within the phospholipid bilayer of the cell-surface membrane.
They add strength to the membranes.
Cholesterol molecules are very hydrophobic and therefore play an important role in preventing the loss of water and dissolved ions from the cell.
The cholesterol molecules also pull together what?

Answer 39

The cholesterol molecules also pull together the fatty acid tails of the phospholipid molecules

Question 40

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Cholesterol molecules occur within the phospholipid bilayer of the cell-surface membrane.
They add strength to the membranes.
Cholesterol molecules are very hydrophobic and therefore play an important role in preventing the loss of water and dissolved ions from the cell.
The cholesterol molecules also pull together the fatty acid tails of the phospholipid molecules, doing what?

Answer 40

The cholesterol molecules also pull together the fatty acid tails of the phospholipid molecules:
1. Limiting their movement and that of other molecules
,but
2. Without making the membrane as a whole too rigid

Question 41

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Cholesterol molecules occur within the phospholipid bilayer of the cell-surface membrane.
They add strength to the membranes.
Cholesterol molecules are very hydrophobic and therefore play an important role in preventing the loss of water and dissolved ions from the cell.
The cholesterol molecules also pull together the fatty acid tails of the phospholipid molecules, limiting their movement and that of other molecules, but without making the membrane as a whole too rigid.
The functions of cholesterol in the membrane are to:
1. Reduce what?

Answer 41

The functions of cholesterol in the membrane are to reduce lateral movement of other molecules

Question 42

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Cholesterol molecules occur within the phospholipid bilayer of the cell-surface membrane.
They add strength to the membranes.
Cholesterol molecules are very hydrophobic and therefore play an important role in preventing the loss of water and dissolved ions from the cell.
The cholesterol molecules also pull together the fatty acid tails of the phospholipid molecules, limiting their movement and that of other molecules, but without making the membrane as a whole too rigid.
The functions of cholesterol in the membrane are to:
1. Reduce lateral movement of other molecules, including what?

Answer 42

The functions of cholesterol in the membrane are to reduce lateral movement of other molecules, including phospholipids

Question 43

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Cholesterol molecules occur within the phospholipid bilayer of the cell-surface membrane.
They add strength to the membranes.
Cholesterol molecules are very hydrophobic and therefore play an important role in preventing the loss of water and dissolved ions from the cell.
The cholesterol molecules also pull together the fatty acid tails of the phospholipid molecules, limiting their movement and that of other molecules, but without making the membrane as a whole too rigid.
The functions of cholesterol in the membrane are to:
1. Reduce lateral movement of other molecules, including phospholipids.
2. Make the membrane what?

Answer 43

The functions of cholesterol in the membrane are to make the membrane less fluid at high temperatures

Question 44

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Cholesterol molecules occur within the phospholipid bilayer of the cell-surface membrane.
They add strength to the membranes.
Cholesterol molecules are very hydrophobic and therefore play an important role in preventing the loss of water and dissolved ions from the cell.
The cholesterol molecules also pull together the fatty acid tails of the phospholipid molecules, limiting their movement and that of other molecules, but without making the membrane as a whole too rigid.
The functions of cholesterol in the membrane are to:
1. Reduce lateral movement of other molecules, including phospholipids.
2. Make the membrane less fluid at high temperatures.
3. Prevent what from the cell?

Answer 44

The functions of cholesterol in the membrane are to prevent leakage of:
1. Water
2. Dissolved ions
from the cell

Question 45

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Glycolipids are made up of what?

Answer 45

Glycolipids are made up of a:
1. Carbohydrate
covalently bonded with
2. Lipid

Question 46

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Glycolipids are made up of a carbohydrate covalently bonded with a lipid.
What does the carbohydrate portion of the glycolipids do?

Answer 46

The carbohydrate portion of the glycolipids extends from the:
1. Phospholipid bilayer
into
2. Watery environment outside the cell

Question 47

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Glycolipids are made up of a carbohydrate covalently bonded with a lipid.
The carbohydrate portion of the glycolipids extends from the phospholipid bilayer into the watery environment outside the cell, where it acts as a what?

Answer 47

The carbohydrate portion of the glycolipids extends from the:
1. Phospholipid bilayer
into
2. Watery environment outside the cell
,where it acts as a cell-surface receptor

Question 48

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Glycolipids are made up of a carbohydrate covalently bonded with a lipid.
The carbohydrate portion of the glycolipids extends from the phospholipid bilayer into the watery environment outside the cell, where it acts as a cell-surface receptor for what?

Answer 48

The carbohydrate portion of the glycolipids extends from the:
1. Phospholipid bilayer
into
2. Watery environment outside the cell
,where it acts as a cell-surface receptor for specific chemicals

Question 49

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Glycolipids are made up of a carbohydrate covalently bonded with a lipid.
The carbohydrate portion of the glycolipids extends from the phospholipid bilayer into the watery environment outside the cell, where it acts as a cell-surface receptor for specific chemicals.
Example

Answer 49

For example, the human ABO blood system operates as a result of glycolipids on the cell-surface membrane

Question 50

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Glycolipids are made up of a carbohydrate covalently bonded with a lipid.
The carbohydrate portion of the glycolipids extends from the phospholipid bilayer into the watery environment outside the cell, where it acts as a cell-surface receptor for specific chemicals.
The functions of glycolipids in the membrane are to:
1. Act as what?

Answer 50

The functions of glycolipids in the membrane are to act as recognition sites

Question 51

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Glycolipids are made up of a carbohydrate covalently bonded with a lipid.
The carbohydrate portion of the glycolipids extends from the phospholipid bilayer into the watery environment outside the cell, where it acts as a cell-surface receptor for specific chemicals.
The functions of glycolipids in the membrane are to:
1. Act as recognition sites.
2. Help maintain what?

Answer 51

The functions of glycolipids in the membrane are to help maintain the stability of the membrane

Question 52

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Glycolipids are made up of a carbohydrate covalently bonded with a lipid.
The carbohydrate portion of the glycolipids extends from the phospholipid bilayer into the watery environment outside the cell, where it acts as a cell-surface receptor for specific chemicals.
The functions of glycolipids in the membrane are to:
1. Act as recognition sites.
2. Help maintain the stability of the membrane.
3. Help cells to do what?

Answer 52

The functions of glycolipids in the membrane are to:

1. Help cells to attach to one another
2. So form tissues

Question 53

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Carbohydrate chains are attached to many what?

Answer 53

Carbohydrate chains are attached to many extrinsic proteins

Question 54

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Carbohydrate chains are attached to many extrinsic proteins where?

Answer 54

Carbohydrate chains are attached to many extrinsic proteins on the outer surface of the cell membrane

Question 55

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Carbohydrate chains are attached to many extrinsic proteins on the outer surface of the cell membrane.
These glycoproteins also act as what?

Answer 55

These glycoproteins also act as cell-surface receptors

Question 56

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Carbohydrate chains are attached to many extrinsic proteins on the outer surface of the cell membrane.
These glycoproteins also act as cell-surface receptors, more specifically for what?

Answer 56

These glycoproteins also act as cell-surface receptors, more specifically for:

1. Hormones
2. Neurotransmitters

Question 57

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Carbohydrate chains are attached to many extrinsic proteins on the outer surface of the cell membrane.
These glycoproteins also act as cell-surface receptors, more specifically for hormones and neurotransmitters.
The functions of glycoproteins in the membrane are to:
1. Act as what?

Answer 57

The functions of glycoproteins in the membrane are to act as recognition sites

Question 58

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Carbohydrate chains are attached to many extrinsic proteins on the outer surface of the cell membrane.
These glycoproteins also act as cell-surface receptors, more specifically for hormones and neurotransmitters.
The functions of glycoproteins in the membrane are to:
1. Act as recognition sites.
2. Help cells to do what?

Answer 58

The functions of glycoproteins in the membrane are to help cells to:

1. Attach to one another
2. So form tissues

Question 59

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Carbohydrate chains are attached to many extrinsic proteins on the outer surface of the cell membrane.
These glycoproteins also act as cell-surface receptors, more specifically for hormones and neurotransmitters.
The functions of glycoproteins in the membrane are to:
1. Act as recognition sites.
2. Help cells to attach to one another and so form tissues.
3. Allow cells to do what?

Answer 59

The functions of glycoproteins in the membrane are to allow cells to recognise one another

Question 60

The molecules that form the structure of cell-surface membranes are phospholipids, proteins, cholesterol, glycolipids and glycoproteins.
Carbohydrate chains are attached to many extrinsic proteins on the outer surface of the cell membrane.
These glycoproteins also act as cell-surface receptors, more specifically for hormones and neurotransmitters.
The functions of glycoproteins in the membrane are to:
1. Act as recognition sites.
2. Help cells to attach to one another and so form tissues.
3. Allow cells to recognise one another.
Example

Answer 60

For example, lymphocytes can recognise an organism’s own cells

Question 61

The functions of membranes within cells are to:

1. Control the entry and exit of materials in what organelles?

Answer 61

The functions of membranes within cells are to control the:
1. Entry
2. Exit
of materials in discrete organelles

Question 62

The functions of membranes within cells are to:

1. Control the entry and exit of materials in discrete organelles, such as what?

Answer 62

The functions of membranes within cells are to control the entry and exit of materials in discrete organelles, such as:

1. Mitochondria
2. Chloroplasts

Question 63

The functions of membranes within cells are to:

1. Control the entry and exit of materials in discrete organelles, such as mitochondria and chloroplasts.
2. Separate what?

Answer 63

The functions of membranes within cells are to separate organelles from the cytoplasm

Question 64

The functions of membranes within cells are to:

1. Control the entry and exit of materials in discrete organelles, such as mitochondria and chloroplasts.
2. Separate organelles from the cytoplasm, so that what?

Answer 64

The functions of membranes within cells are to separate organelles from the cytoplasm, so that specific metabolic reactions can take place within them

Question 65

The functions of membranes within cells are to:

1. Control the entry and exit of materials in discrete organelles, such as mitochondria and chloroplasts.
2. Separate organelles from the cytoplasm, so that specific metabolic reactions can take place within them.
3. Provide a what system?

Answer 65

The functions of membranes within cells are to provide an internal transport system

Question 66

The functions of membranes within cells are to:

1. Control the entry and exit of materials in discrete organelles, such as mitochondria and chloroplasts.
2. Separate organelles from the cytoplasm, so that specific metabolic reactions can take place within them.
3. Provide an internal transport system, for example what?

Answer 66

The functions of membranes within cells are to provide an internal transport system, for example endoplasmic reticulum

Question 67

The functions of membranes within cells are to:

1. Control the entry and exit of materials in discrete organelles, such as mitochondria and chloroplasts.
2. Separate organelles from the cytoplasm, so that specific metabolic reactions can take place within them.
3. Provide an internal transport system, for example endoplasmic reticulum.
4. Isolate what?

Answer 67

The functions of membranes within cells are to isolate enzymes that might damage the cell

Question 68

The functions of membranes within cells are to:

1. Control the entry and exit of materials in discrete organelles, such as mitochondria and chloroplasts.
2. Separate organelles from the cytoplasm, so that specific metabolic reactions can take place within them.
3. Provide an internal transport system, for example endoplasmic reticulum.
4. Isolate enzymes that might damage the cell, for example what?

Answer 68

The functions of membranes within cells are to isolate enzymes that might damage the cell, for example lysosomes

Question 69

The functions of membranes within cells are to:

1. Control the entry and exit of materials in discrete organelles, such as mitochondria and chloroplasts.
2. Separate organelles from the cytoplasm, so that specific metabolic reactions can take place within them.
3. Provide an internal transport system, for example endoplasmic reticulum.
4. Isolate enzymes that might damage the cell, for example lysosomes.
5. Provide what on which reactions can occur?

Answer 69

The functions of membranes within cells are to provide surfaces on which reactions can occur

Question 70

The functions of membranes within cells are to:
1. Control the entry and exit of materials in discrete organelles, such as mitochondria and chloroplasts.
2. Separate organelles from the cytoplasm, so that specific metabolic reactions can take place within them.
3. Provide an internal transport system, for example endoplasmic reticulum.
4. Isolate enzymes that might damage the cell, for example lysosomes.
5. Provide surfaces on which reactions can occur.
Example

Answer 70

For example, protein synthesis using ribosomes on rough endoplasmic reticulum

Question 71

Permeability of the cell-surface membrane:
The cell-surface membrane controls the movement of substances into and out of the cell.
In general, most molecules do not freely do what?

Answer 71

In general, most molecules do not freely diffuse across the cell-surface membrane

Question 72

Permeability of the cell-surface membrane:
The cell-surface membrane controls the movement of substances into and out of the cell.
In general, most molecules do not freely diffuse across the cell-surface membrane, because many are:
1. Not soluble in what?

Answer 72

In general, most molecules do not freely diffuse across the cell-surface membrane, because many are not soluble in lipids

Question 73

Permeability of the cell-surface membrane:
The cell-surface membrane controls the movement of substances into and out of the cell.
In general, most molecules do not freely diffuse across the cell-surface membrane, because many are:
1. Not soluble in lipids and therefore cannot do what?

Answer 73

In general, most molecules do not freely diffuse across the cell-surface membrane, because many:

1. Are not soluble in lipids
2. Therefore cannot pass through the phospholipid bilayer

Question 74

Permeability of the cell-surface membrane:
The cell-surface membrane controls the movement of substances into and out of the cell.
In general, most molecules do not freely diffuse across the cell-surface membrane, because many are:
1. Not soluble in lipids and therefore cannot pass through the phospholipid bilayer.
2. Too large to pass through what?

Answer 74

In general, most molecules do not freely diffuse across the cell-surface membrane, because many are too large to pass through the channels in the membrane

Question 75

Permeability of the cell-surface membrane:
The cell-surface membrane controls the movement of substances into and out of the cell.
In general, most molecules do not freely diffuse across the cell-surface membrane, because many are:
1. Not soluble in lipids and therefore cannot pass through the phospholipid bilayer.
2. Too large to pass through the channels in the membrane.
3. Of the same what as what?

Answer 75

In general, most molecules do not freely diffuse across the cell-surface membrane, because many are of the same charge as the charge on the protein channels

Question 76

Permeability of the cell-surface membrane:
The cell-surface membrane controls the movement of substances into and out of the cell.
In general, most molecules do not freely diffuse across the cell-surface membrane, because many are:
1. Not soluble in lipids and therefore cannot pass through the phospholipid bilayer.
2. Too large to pass through the channels in the membrane.
3. Of the same charge as the charge on the protein channels and so even if they are small enough to pass through, they are what?

Answer 76

In general, most molecules do not freely diffuse across the cell-surface membrane, because many are:

1. Of the same charge as the charge on the protein channels
2. So even if they are small enough to pass through, they are repelled

Question 77

Permeability of the cell-surface membrane:
The cell-surface membrane controls the movement of substances into and out of the cell.
In general, most molecules do not freely diffuse across the cell-surface membrane, because many are:
1. Not soluble in lipids and therefore cannot pass through the phospholipid bilayer.
2. Too large to pass through the channels in the membrane.
3. Of the same charge as the charge on the protein channels and so even if they are small enough to pass through, they are repelled.
4. Electrically what (in other words what)?

Answer 77

In general, most molecules do not freely diffuse across the cell-surface membrane, because many are electrically charged (in other words polar)

Question 78

Permeability of the cell-surface membrane:
The cell-surface membrane controls the movement of substances into and out of the cell.
In general, most molecules do not freely diffuse across the cell-surface membrane, because many are:
1. Not soluble in lipids and therefore cannot pass through the phospholipid bilayer.
2. Too large to pass through the channels in the membrane.
3. Of the same charge as the charge on the protein channels and so even if they are small enough to pass through, they are repelled.
4. Electrically charged (in other words polar) and therefore have difficulty passing through what?

Answer 78

In general, most molecules do not freely diffuse across the cell-surface membrane, because many are electrically charged (in other words polar) and therefore have difficulty passing through the non-polar hydrophobic tails in the phospholipid bilayer

Question 79

The fluid-mosaic model of the cell-surface membrane:

What is known as the fluid-mosaic model?

Answer 79

The way in which all the various molecules are combined into the structure of the cell-surface membrane is known as the fluid-mosaic model

Question 80

The fluid-mosaic model of the cell-surface membrane.

It is fluid, because what?

Answer 80

It is fluid, because the individual phospholipid molecules can move relative to one another

Question 81

The fluid-mosaic model of the cell-surface membrane.
It is fluid, because the individual phospholipid molecules can move relative to one another.
This gives the membrane a what structure?

Answer 81

This gives the membrane a flexible structure

Question 82

The fluid-mosaic model of the cell-surface membrane.
It is fluid, because the individual phospholipid molecules can move relative to one another.
This gives the membrane a flexible structure that is constantly what?

Answer 82

This gives the membrane a flexible structure that is constantly changing in shape

Question 83

The fluid-mosaic model of the cell-surface membrane.
It is fluid, because the individual phospholipid molecules can move relative to one another.
This gives the membrane a flexible structure that is constantly changing in shape.
It is mosaic, because what?

Answer 83

It is mosaic, because the proteins that are embedded in the phospholipid bilayer vary in:
1. Shape
2. Size
3. Pattern
in the same way as the stones or tiles of a mosaic

Question 84

Organelles such as what are surrounded by how many plasma membranes?

Answer 84

Organelles such as:
1. Mitochondria
2. Chloroplasts
are surrounded by 2 plasma membranes

Question 85

Organelles such as mitochondria and chloroplasts are surrounded by 2 plasma membranes.
The term cell-surface membrane is reserved only for what?

Answer 85

The term cell-surface membrane is reserved only for the plasma membrane around the cell

Question 86

When representing a phospholipid, it is important to be accurate.
It has what?

Answer 86

A phospholipid has:

1. A single phosphate head
2. 2 fatty acid tails

Question 87

All plasma membranes found around and inside cells have the same what structure?

Answer 87

All plasma membranes found:
1. Around
2. Inside
cells have the same phospholipid bilayer structure

Question 88

All plasma membranes found around and inside cells have the same phospholipid bilayer structure.
What gives plasma membranes their different properties are what?

Answer 88

What gives plasma membranes their different properties are the different substances they contain

Question 89

All plasma membranes found around and inside cells have the same phospholipid bilayer structure.
What gives plasma membranes their different properties are the different substances they contain, especially what?

Answer 89

What gives plasma membranes their different properties are the different substances they contain, especially proteins

Question 90

The fluid mosaic model of the plasma membrane:
The proteins can move freely through the phospholipid bilayer.
The ease with which they do this is dependent on what?

Answer 90

The ease with which they do this is dependent on the number of phospholipids with unsaturated fatty acids