B1-Diffusion And Osmosis

Question 1

Diffusion

Answer 1

The movement of particles from an area of high concentration to an area of low concentration, down a concentration gradient. This typically continues until an equilibrium is reached and the particles are evenly distributed.

Question 2

What are the factors that affect diffusion?

Answer 2

Concentration gradient, temperature and surface area

Question 3

Concentration gradient?

Answer 3

If there is a steep concentration gradient (the difference in concentration is greatest) diffusion will be faster because many particles will move randomly to an area of low concentration to any other direction. For example from the lungs to red blood cells to get around the body.

Question 4

Temperature

Answer 4

When there is a higher temperature particles move more which means they move randomly into an area of low concentration quicker because there is more kinetic energy from the energy used to create the temperature. For example when you breath in your nose because it has a greater distance to travel so when you breath in it has more time to warm up.

Question 5

Surface area

Answer 5

When the surface area of the exchanged surface is greater in folds as more of the substance can move at a given time for example folds in the cell membrane form microvilli like in root hair cells improves the rate of diffusion.

Question 6

Water potential is

Answer 6

The ability for water to move freely (solutes prevent it moving freely more solutes=less water potential)

Question 7

Osmosis is

Answer 7

The diffusion of water from a more dilute solution to a more concentrated solution, across a partially permeable membrane.

Question 8

Compare dilute and concentration solutions

Answer 8

Dilute solutions have a:
Higher water potential than concentrated solutions
A higher water concentration compared to concentrated solutions
But a lower solute concentration than a concentrated solution

Question 9

What do solutes do

Answer 9

Prevent water from moving freely like salt etc.

Question 10

Isotonic

Answer 10

the concentration of solutes in the solution outside the cell is the same as the internal concentration

Question 11

Hypertonic

Answer 11

the concentration of solutes in the solution outside the cell is higher than the internal concentration

Question 12

Hypotonic

Answer 12

the concentration of solutes in the solution outside the cell is lower than the internal concentration

Question 13

Tugor pressure

Answer 13

makes the cells hard and rigid which keeps the leaves and stems of the plant rigid and firm it occurs when water moves into the plant in osmosis and presses the cytoplasm against the cell wall until no more water can physically enter the cell.

Question 14

Plasmolysis

Answer 14

is when more water is lost by osmosis the vacuole and cytoplasm shrink so the cell membrane eventually pulls away from the cell wall and plasmolysed cells die quickly unless the osmotic balance is restored.

Question 15

Required practical 2 sugar on salt on plant tissue -plan

Answer 15

• Take a potato and using a cork borer take three samples of potato roughly from the centre but never too near where the other three have been taken and always taken straight down (samples)
• Cut of curved surface and potato skin and then make sure they are 3cm length wide (all of them)
• Note down the mass of the potato chip and length
• Get three test tubes with measured 10ml of distilled water etc and pour ALL of it in making sure there was no liquids etc in the test tube before and the measuring cylnder
• Leave them for 24hrs
• pour out liquid out get potato chip
• Wipe excessive liquid off quickly on paper towel
• measure length and mass with ruler and scales
• draw graph and work out percentage change

Question 16

Required practical 2 sugar on salt on plant tissue- control variables

Answer 16

The volume of ml of solution
The diameter and length of the potato chip
Dry chips before measuring
Time

Question 17

Concentration

Answer 17

measurement of how much solute is dissolved in a given
volume of solvent. If a solution contains a lot of dissolved solute, we say it is concentrated. If it contains little solute, it is dilute.

Question 18

Required practical 2 dependent variable

Answer 18

Percentage change which is the change in mass divided by initial mass

Question 19

concentration of solution surrounding the cell affects the

movement of water how

Answer 19

The concentration of glucose at a concentration solution moves from a dilute solution to it with an overall net movement into the concentration solution. The water moves into the potato chips.

Question 20

You can also investigate the effect of other variables on osmosis in plant tissues think of another variable and why it would effect and write a method

Answer 20

The size of concentration of the actual potato chip the bigger the potato chip the bigger it gets when it is left in water as the concentration solution is more concentrated and will absorb more water. Get three different shaped potato chips from the same potato using a cork borer to make sure they are the same diameter but different length leave in 20ml of water for 24hrs wipe of excess and weigh them making sure to weigh them before as well and calculate the percentage change in the different size of potato.