4.3: Osmosis

Question 1

Osmosis

Answer 1

Osmosis is the passage of water from a region where it has a higher water potential to a region where it has a lower water potential through a selectively permeable membrane

Question 2

A solute

Answer 2

A solute is any substance that is dissolved in a solvent

Question 3

Water potential is measured in units of what?

Answer 3

Water potential is measured in units of pressure

Question 4

Water potential is measured in units of pressure, usually what?

Answer 4

Water potential is measured in units of pressure, usually kiloPascals (kPa)

Question 5

Water potential is measured in units of pressure, usually kiloPascals (kPa).
Water potential is the pressure created by water molecules.
Under standard conditions of temperature and pressure (25 degrees Celsius and 100 kPa), pure water is said to have a water potential of what?

Answer 5

Under standard conditions of:
1. Temperature
2. Pressure
(25 degrees Celsius and 100 kPa), pure water is said to have a water potential of 0

Question 6

Water potential is measured in units of pressure, usually kiloPascals (kPa).
Water potential is the pressure created by water molecules.
Under standard conditions of temperature and pressure (25 degrees Celsius and 100 kPa), pure water is said to have a water potential of 0.
The addition of a solute to pure water will do what?

Answer 6

The addition of a solute to pure water will lower its water potential

Question 7

Water potential is measured in units of pressure, usually kiloPascals (kPa).
Water potential is the pressure created by water molecules.
Under standard conditions of temperature and pressure (25 degrees Celsius and 100 kPa), pure water is said to have a water potential of 0.
The addition of a solute to pure water will lower its water potential.
The water potential of a solution must always be what?

Answer 7

The water potential of a solution must always be less than 0, a negative value

Question 8

Water potential is measured in units of pressure, usually kiloPascals (kPa).
Water potential is the pressure created by water molecules.
Under standard conditions of temperature and pressure (25 degrees Celsius and 100 kPa), pure water is said to have a water potential of 0.
The addition of a solute to pure water will lower its water potential.
The water potential of a solution must always be less than 0, a negative value.
The more solute that is added (the more concentrated a solution), the what its water potential?

Answer 8

The more solute that is added (the more concentrated a solution), the lower (more negative) its water potential

Question 9

Water potential is measured in units of pressure, usually kiloPascals (kPa).
Water potential is the pressure created by water molecules.
Under standard conditions of temperature and pressure (25 degrees Celsius and 100 kPa), pure water is said to have a water potential of 0.
The addition of a solute to pure water will lower its water potential.
The water potential of a solution must always be less than 0, a negative value.
The more solute that is added (the more concentrated a solution), the lower (more negative) its water potential.
Water will move by osmosis from a region of higher (less what) water potential to one of lower (more what) water potential?

Answer 9

Water will move by osmosis from a region of:
1. Higher (less negative) water potential
to
2. One of lower (more negative) water potential

Question 10

One way of finding the water potential of cells or tissues is to place them in a series of solutions of different water potentials.
Where this is no net gain or loss of water from the cells or tissues, the water potential inside the cells or tissues must be what?

Answer 10

Where this is no net gain or loss of water from the cells or tissues, the water potential inside the:
1. Cells
Or,
2. Tissues
must be the same as that of the external solution

Question 11

While diffusion can be the movement of any molecule, osmosis is the movement of what only?

Answer 11

While diffusion can be the movement of any molecule, osmosis is the movement of water molecules only

Question 12

All water potential values are what?

Answer 12

All water potential values are negative

Question 13

All water potential values are negative.

What is the highest water potential?

Answer 13

The highest water potential is 0

Question 14

All water potential values are negative.
The highest water potential is 0.
Therefore, the lower the water potential, the more what it becomes?

Answer 14

Therefore, the lower the water potential, the more negative it becomes

Question 15

Animals cells, such as red blood cells, contain a variety of what dissolved in their watery cytoplasm?

Answer 15

Animals cells, such as red blood cells, contain a variety of solutes dissolved in their watery cytoplasm

Question 16

Animals cells, such as red blood cells, contain a variety of solutes dissolved in their watery cytoplasm.
If a red blood cell is placed in pure water, it will do what?

Answer 16

If a red blood cell is placed in pure water, it will absorb water by osmosis

Question 17

Animals cells, such as red blood cells, contain a variety of solutes dissolved in their watery cytoplasm.
If a red blood cell is placed in pure water, it will absorb water by osmosis, because it has what?

Answer 17

If a red blood cell is placed in pure water, it will absorb water by osmosis, because it has a lower water potential

Question 18

Animals cells, such as red blood cells, contain a variety of solutes dissolved in their watery cytoplasm.
If a red blood cell is placed in pure water, it will absorb water by osmosis, because it has a lower water potential.
Cell surface membranes are very what (how much)?

Answer 18

Cell surface membranes are very thin (7 nm)

Question 19

Animals cells, such as red blood cells, contain a variety of solutes dissolved in their watery cytoplasm.
If a red blood cell is placed in pure water, it will absorb water by osmosis, because it has a lower water potential.
Cell surface membranes are very thin (7 nm) and, although they are flexible, they cannot do what?

Answer 19

Cell surface membranes are very thin (7 nm) and, although they are flexible, they cannot stretch to any great extent

Question 20

Animals cells, such as red blood cells, contain a variety of solutes dissolved in their watery cytoplasm.
If a red blood cell is placed in pure water, it will absorb water by osmosis, because it has a lower water potential.
Cell surface membranes are very thin (7 nm) and, although they are flexible, they cannot stretch to any great extent.
The cell-surface membrane will therefore do what?

Answer 20

The cell-surface membrane will therefore break

Question 21

Animals cells, such as red blood cells, contain a variety of solutes dissolved in their watery cytoplasm.
If a red blood cell is placed in pure water, it will absorb water by osmosis, because it has a lower water potential.
Cell surface membranes are very thin (7 nm) and, although they are flexible, they cannot stretch to any great extent.
The cell-surface membrane will therefore break, doing what?

Answer 21

The cell-surface membrane will therefore break:

1. Bursting the cell
2. Releasing its contents

Question 22

Animals cells, such as red blood cells, contain a variety of solutes dissolved in their watery cytoplasm.
If a red blood cell is placed in pure water, it will absorb water by osmosis, because it has a lower water potential.
Cell surface membranes are very thin (7 nm) and, although they are flexible, they cannot stretch to any great extent.
The cell-surface membrane will therefore break, bursting the cell and releasing its contents.
In red blood cells, this is called what?

Answer 22

In red blood cells, this is called haemolysis

Question 23

Animals cells, such as red blood cells, contain a variety of solutes dissolved in their watery cytoplasm.
If a red blood cell is placed in pure water, it will absorb water by osmosis, because it has a lower water potential.
Cell surface membranes are very thin (7 nm) and, although they are flexible, they cannot stretch to any great extent.
The cell-surface membrane will therefore break, bursting the cell and releasing its contents.
In red blood cells, this is called haemolysis.
To prevent this happening, animal cells normally do what?

Answer 23

To prevent this happening, animal cells normally live in a liquid that has the same water potential as the cells

Question 24

Animals cells, such as red blood cells, contain a variety of solutes dissolved in their watery cytoplasm.
If a red blood cell is placed in pure water, it will absorb water by osmosis, because it has a lower water potential.
Cell surface membranes are very thin (7 nm) and, although they are flexible, they cannot stretch to any great extent.
The cell-surface membrane will therefore break, bursting the cell and releasing its contents.
In red blood cells, this is called haemolysis.
To prevent this happening, animal cells normally live in a liquid that has the same water potential as the cells.
With red blood cells, what is the liquid?

Answer 24

With red blood cells, the liquid is the blood plasma

Question 25

Animals cells, such as red blood cells, contain a variety of solutes dissolved in their watery cytoplasm.
If a red blood cell is placed in pure water, it will absorb water by osmosis, because it has a lower water potential.
Cell surface membranes are very thin (7 nm) and, although they are flexible, they cannot stretch to any great extent.
The cell-surface membrane will therefore break, bursting the cell and releasing its contents.
In red blood cells, this is called haemolysis.
To prevent this happening, animal cells normally live in a liquid that has the same water potential as the cells.
With red blood cells, the liquid is the blood plasma.
If a red blood cell is placed in a solution with a water potential lower than its own, what happens?

Answer 25

If a red blood cell is placed in a solution with a water potential lower than its own:

1. Water leaves by osmosis
2. The cell shrinks and becomes shrivelled

Question 26

Water molecules do what across the membrane at the same time?

Answer 26

Water molecules move in both directions across the membrane at the same time

Question 27

Plant cell walls are fully permeable to what?

Answer 27

Plant cell walls are fully permeable to all molecules

Question 28

Cytoplasm is fluid (cytosol) and contains organelles.
It is surrounded by the plasma membrane.
The vacuole contains watery cell sap (a solution of salts and other dissolved substances).
The vacuole is separated from the cytoplasm by what?

Answer 28

The vacuole is separated from the cytoplasm by a semi-permeable membrane (a tonoplast)

Question 29

Hypertonic

Answer 29

Hypertonic is when there is more solute concentration

Question 30

Hypotonic

Answer 30

Hypotonic is when there is less solute concentration

Question 31

Isotonic

Answer 31

Isotonic is when there is the same solute concentration

Question 32

Hypertonic is when there is more solute concentration.

There is less what, because there is more solute present?

Answer 32

There is less free water, because there is more solute present

Question 33

Hypertonic is when there is more solute concentration.

There is less free water, because there is more solute present, so there is a what water potential?

Answer 33

There is less free water, because there is more solute present, so there is a lower water potential

Question 34

Hypotonic is when there is less solute concentration.

There is lower solute present, which means more what?

Answer 34

There is lower solute present, which means more free water

Question 35

Hypotonic is when there is less solute concentration.

There is lower solute present, which means more free water, so there is a what water potential?

Answer 35

There is lower solute present, which means more free water, so there is a higher water potential

Question 36

Isotonic is when there is the same solute concentration.

There is the same amount of free water and there is the same what?

Answer 36

1. There is the same amount of free water

2. There is the same water potential

Question 37

Isotonic is when there is the same solute concentration.

There is the same amount of free water and there is the same water potential, so there is no what?

Answer 37

1. There is the same amount of free water
2. There is the same water potential
   ,so there is no net movement of water

Question 38

Turgor pressure in young and soft parts of a plant provides what?

Answer 38

Turgor pressure in:
1. Young
2. Soft
parts of a plant provides support

Question 39

Turgor pressure in young and soft parts of a plant provides support.
What does reduced turgor pressure result in?

Answer 39

Reduced turgor pressure results in the plant wilting

Question 40

Turgor (pressure)

Answer 40

Turgor (pressure) is a force exerted outward on a plant cell wall by the water contained in the cell

Question 41

Turgor (pressure) is a force exerted outward on a plant cell wall by the water contained in the cell.
The force gives the plant what and may help to keep it what?

Answer 41

The force:

1. Gives the plant rigidity
2. May help to keep it erect