Diffusion And Osmosis Biology Chapter 2

Front 1

What is the concentration gradient?

Back 1

The concentration gradient is the difference in concentration between two regions.

Front 2

What factors affect the rate of diffusion?

Back 2

Temperature, surface area, steeper concentration gradient.

Front 3

The steeper the concentration gradient, the faster the rate of diffusion is for that substance.

Back 3

Learn by heart.

Front 4

What is dynamic equilibrium?

Back 4

When the particles are evenly spread , there is no net change in the system.

This is dynamic equilibrium.

Front 5

Give a substance that don't form ions when they dissolve.

Back 5

Sugar do not form ions when they dissolve.

Front 6

What is a permeable membrane?

Back 6

A permeable membrane allows both the solvent and the solutes (the dissolved substances) to pass through it.

Front 7

Give 2 substances that can pass through the cell membrane.

Back 7

Substances such can pass through the cell membrane:

1) Oxygen

2) Carbon dioxide.

Front 8

Give 1 substance that cannot pass through the cell membrane.

Back 8

Proteins cannot pass through the cell membrane.

Front 9

Give 1 example of diffusion in animal cell.

Back 9

The cells of the lungs exchange oxygen and carbon dioxide through diffusion.

Front 10

Give 1 example of diffusion in plant cells.

Back 10

Plant cells such as root hair cells take in oxygen and remove carbon dioxide through diffusion.

Front 11

Give an experiment on how to demonstrate osmosis.

Back 11

1) Tie a piece of cellophane paper tightly over the mouth of a thistle funnel.

2) Fill the funnel with 5% sucrose solution and mark the level of the solution.

3) Lower the funnel into a beaker of water such as the liquid levels inside and outside the funnel are the same.

4) Set up a second experiment in a similar way but with distilled water inside the funnel instead of sucrose solution.

Front 12

What does the term 'water potential' mean?

Back 12

Water potential is a measure of the tendency of water to move from one place to another.

Front 13

Which one has a higher water potential: a dilute solution or a concentrated solution?

Back 13

A dilute solution contains more water molecules per unit volume than a concentrated solution , so it has a higher water potential than a concentrated solution.

Front 14

What is osmosis?

Back 14

Osmosis is the movement of water molecules from a solution of higher water potential to a solution of lower water potential, through a partially permeable membrane.

Front 15

What are hypotonic solutions?

Back 15

A hypotonic solution is one with higher water potential than another.(only apply to animal cells)

Front 16

What are isotonic solutions ?

Back 16

isotonic solutions are two solutions that have equal concentrations.(only apply to animal cells)

Front 17

What are hypertonic solution?

Back 17

A hypotonic solution is one with lower water potential than another.(only apply to animal cells)

Front 18

Explain what happens to a plant cell in a solution of high water potential.

Back 18

1) The cell sap has lower water potential than outside solution.

2) water enters the cell by osmosis. As water enters the cell, the vacuole increases in size and pushes the cell contents against the cell wall.

3) The cell wall is strong and relatively inelastic. It prevents over-expansion of the cell by exerting an opposing pressure as water enters the cell.This prevents the entry of more water.

4) when the plant cell expands, it becomes swollen and turgid. The cell doesn't burst because it is protected by the cell wall.

Front 19

What is turgor?

Back 19

The turgidity of the cell with water is called turgor.

Front 20

What is turgor pressure?

Back 20

The pressure exerted by the water on the cell wall is called turgor pressure.

Front 21

What is the advantage of turgor pressure in plant cells?

Back 21

Turgor pressure helps to keep the plant cells firm.

Front 22

Explain what happens to an animal cell in a solution of high water potential.

Back 22

1) The cytoplasm has lower water potential than outside solution,so water enters by osmosis.

2) Since,the animal cells doesn't have a cell wall, the cell expands and bursts.

Front 23

What happens to cells in a solution of same water potential.

Back 23

Cells immersed in a solution of the same water potential as their cytoplasm, will not change their size or shape.

Front 24

Explain what happens to a plant cell in a solution of low water potential.

Back 24

1) Cell sap has higher water potential than outside solution.

2) Water leaves the cell by osmosis.As the cell loses water,the vacuole decreases in size and the cytoplasm shrinks away from the cell wall.

3)The cell is plasmolysed.

Front 25

What is plasmolysis?

Back 25

The shrinkage of the cytoplasm and cell membrane from the cell wall is known as plasmolysis.

Front 26

Draw and label a plant cell in a solution of higher water potential and in a solution of lower water potential.

Back 26

Front 27

Explain what happens to an animal cell in a solution of low water potential.

Back 27

1) The cytoplasm has a higher water potential than outside solution, water leaves by osmosis.

2) The cell shrinks and little spikes appear on the cell.

3) The animal cell becomes dehydrated and eventually dies .

Front 28

What is crenation?

Back 28

Crenation is the process by which the animal cell shrinks and little spikes appear on the cell membrane.

Front 29

Draw and label an animal cell in a solution of higher water potential and in a solution of lower water potential.

Back 29

Front 30

What is reverse osmosis?

Back 30

Reverse osmosis (RO) is a water purification process that uses a partially permeable membrane to separate ions, unwanted molecules and larger particles from drinking water.

Front 31

What happens when there is a high rate of evaporation of water from the plant cells?

Back 31

When there is a high rate of evaporation of water from the plant cells, they lose their turgidity and the plant wilts.

Front 32

What causes the opening and closing of the stomata ?

Back 32

Changes in turgor of the guard cells causes the opening and closing of the stomata.

Front 33

Why certain plant parts move?

Back 33

The movement of certain plant parts are due to changes in turgor.

Front 34

Why is it not advisable to add too much fertiliser around the roots of plants?

Back 34

It is not advisable to add too much fertiliser around the roots of plants because the soil solution will become very concentrated and water will move out of the root by osmosis.

The cells will be killed if they remain plasmolysed for too long.

Front 35

What is "soil solution" ?

Back 35

Soil solution is a thin film of water that surrounds individual soil particles.

Front 36

What does the soil solution contains?

Back 36

The soil solution usually contains dissolved mineral salts and ions.

Front 37

Why do cells move materials across their cell membranes?

Back 37

cells move materials across their cell membranes to stay alive.

Front 38

What will happen if cells cannot move materials quickly enough?

Back 38

If cells cannot move materials quickly enough, they will die.

Front 39

The greater the area of cell membrane per unit volume, the faster the rate of diffusion of a substance for a given concentration gradient.

Back 39

Learn by heart.

Front 40

What happens when cells grow in size?

Back 40

When cells grow in size, their metabolism usually slows down.

Front 41

When does cells stop growing?

Back 41

Cells stop growing when they reach a maximum size.

Front 42

Why cells responsible for the absorption of substances are modified?

Back 42

Cells responsible for the absorption of substances are modified to increase their surface area to volume ratio.

Front 43

Give 3 examples of cells that are modified to increase the surface area to volume ratio.

Back 43

3 examples of cells that are modified to increase the surface area to volume ratio:

1) The long, narrow protrusions of root hair cells

2) microvilli in epithelial cells in the small intestine

3) the flattened biconcave shape of red blood cells.

Front 44

What is the relationship between surface area to volume ratio and absorption?

Back 44

The larger the surface area to volume ratio of a cell, the faster is the rate of absorption.

Front 45

What is Active transport?

Back 45

Active transport is the process in which energy is used to move the particles of a substance against a concentration gradient, that is from a region of lower concentration to a region of lower concentration.

Front 46

Where is the part of the energy produced in Respiration used?

Back 46

Part of the energy produced in Respiration is used in active transport.

Front 47

Give 2 examples of active transport.

Back 47

1) Absorption of dissolved mineral salts by the root hairs

2) Absorption of glucose and amino acids by cells in the small intestine of humans.

Front 48

Does active transport occurs in non-living things and why?

Back 48

Active transport occurs only in living cells because living cells respire.