1.15 to 1.17 cell transport (diffusion, osmosis and active transport)

Question 1

What is simple diffusion?

Answer 1

The net movement of molecules from an area of high concentration to an area of low concentration down a concentration gradient

Question 2

What molecules enter and leave cells via simple diffusion through the cell membrane?

Answer 2

Small molecules e.g. oxygen, water, glucose, amino acids

Question 3

What factors affect the rate of diffusion? (3)

Answer 3

● Temperature
● Concentration gradient
● Surface area of cell membrane

Question 4

Define osmosis

Answer 4

The net movement of water molecules from an area of high water concentration to an area of low water concentration through a partially permeable membrane

Question 5

What is active transport?

Answer 5

The movement of molecules across a cell membrane from an area of low concentration to an area of high concentration, against the concentration gradient, using energy

Question 6

How is a percentage change in mass calculated?

Answer 6

% change = ((final mass - initial mass0 / initial mass) x 100

Question 7

which type of molecule is too large to diffuse through a cell membrane? (1)

Answer 7

glucose, proteins are too large to diffuse through a cell membrane

Question 8

in which of these scenarios is osmosis occurring?
A: water is moving from the mouth down into the stomach
B: sugar is being taken up into the blood from the gut
C: a plant is absorbing water from the soil
D: oxygen is entering the blood from the lungs (1)

Answer 8

C (osmosis involves the movement of WATER molecules across a partially permeable membrane)

Question 9

Dilute solution?

Answer 9

A solution that contains a relatively small amount of dissolved solute

Question 10

Concentrated solution?

Answer 10

A solution that contains a relatively large amount of dissolved solute

Question 11

Solute?

Answer 11

A dissolved substance in a solution such as glucose or salt

Question 12

Partially permeable membrane?

Answer 12

A membrane which allows some substances through but not others

Question 13

Turgidity?

Answer 13

When a plant cell is swollen due to the movement of water into the cell

Question 14

Flaccid?

Answer 14

When water moves out of the plant cell causing the cell to change shape and the vacuole to shrink

Question 15

Plasmolysis?

Answer 15

When water has completely moved out of plant tissue by osmosis and the vacuoles are empty

Question 16

Molarity?

Answer 16

The amount of substance in a certain volume of solution

Question 17

Cork borer?

Answer 17

A device used to make plant tissue cylinders of the same diameter

Question 18

Mass?

Answer 18

The measure of the amount of matter in an object measured in grams or kilograms

Question 19

Top pan balance?

Answer 19

A set of scientific measuring scales with an exposed pan

Question 20

Surface moisture?

Answer 20

The moisture covering the surface of the plant tissue that must be removed to ensure valid results

Question 21

Distilled water?

Answer 21

Water that has been evaporated and condensed and contains no dissolved solutes

Question 22

The concentration of solution….

Answer 22

The independent variable or factor that is changed in this experiment to investigate the effect of osmosis in plant tissue

Question 23

The mass or length of plant tissue….

Answer 23

The dependent variable or factor that is measured in this experiment to investigate the effect of osmosis in plant tissue (investigation of osmosis in potatoes)

Question 24

Temperature, time, plant tissue diameter, volume of solution …..

Answer 24

The variables that are controlled to ensure the experiment is a fair test

Question 25

Expected results

Answer 25

Plant material such as potato chips kept in dilute solutions will increase in mass or length, plant material kept in concentrated solutions will decrease in mass or length

Question 26

Passive process

Answer 26

Substances undergoing diffusion cross the membrane without any energy input from the cell

Question 27

Concentration gradient

Answer 27

The difference in concentration of a substance

Question 28

Factors affecting diffusion

Answer 28

Concentration gradient, temperature and surface area

Question 29

temperature in diffusion

Answer 29

Particles move more and diffuse quicker in warmer environments

Question 30

Surface area to volume ratio?

Answer 30

The amount of surface area in relation to how large something is

Question 31

Large surface area to volume ratio in diffusion

Answer 31

Leads to faster diffusion rates, as there is more room for particles to diffuse through a membrane

Question 32

Active process

Answer 32

A process that requires energy, such as active transport