2D Movement of substances

Question 1

Define the term diffusion

Answer 1

The movement of substances from a high to a low concentration
(down the concentration gradient)

Question 2

Define the term osmosis

Answer 2

The movement of water from a high to a low concentration through a partially-permeable membrane
(down the concentration gradient)

Question 3

Define the term active transport

Answer 3

The movement of substances from a low to a high concentration
(against the concentration gradient)

Question 4

What are the similarities between diffusion and active transport

Answer 4

They both involve the movement of substances

Question 5

What are the differences between diffusion and active transport

Answer 5

Particles move down the concentration gradient in diffusion, but against in active transport

Active transport requires energy, diffusion does not

Question 6

Give 2 examples of diffusion taking place in organisms

Answer 6

Diffusion of oxygen from the alveoli into the capillaries

Diffusion of carbon dioxide from the air into the leaf through the stomata

Question 7

Give 2 examples of osmosis taking place in organisms

Answer 7

Movement of water from the soil into the root hair cell

Movement of water from the blood into the nephrons of the kidney

Question 8

Give 2 examples of active transport taking place in organisms

Answer 8

Movement of mineral ions (e.g. nitrates) from the soil into the root hair cells

Movement of amino acids and glucose from the lumen of the small intestine into the capillaries in the villi

Question 9

List 4 factors that affect the rate of diffusion

Answer 9

Higher temperature = faster rate
Larger surface area to volume ratio = faster rate
Shorter diffusion distance = faster rate
Larger concentration gradient = faster rate

Question 10

What does concentration gradient mean

Answer 10

The difference in concentration between two areas

Question 11

Describe how animal cells respond when put in solutions with very high and very low water concentration

Answer 11

In high water concentration → cell bursts

In low water concentration → cell crenates (shrivels))

Question 12

Describe how plant cells respond when put in solutions with very high and very low water concentration

Answer 12

In high water concentrations → become turgid (don’t burst due to strong cell walls)

In low water concentrations → becomes plasmolysed

Question 13

Explain how the concentration of a potato chip can be determined

Answer 13

Weigh potato chips and place in different salt/sugar solutions i.e. 0M, 0.2M…
Reweigh chips and calculate % change in mass
Plot results
The x intercept shows you the concentration of the chip because that is where there is no change in mass

Question 14

Explain why it is better to calculate the % change in mass of potato chip rather than simply the change in mass

Answer 14

All the potato chips have different starting masses

% change makes it easier to compare between chips