B1b - cell transport fact test

Question 1

what is the definition of diffusion

Answer 1

the net movement of particles from an area of highER concentration to an area of lowER concentration down a concentration gradient

Question 2

what increases the rate of diffusion

Answer 2

• increase in concentration gradient
• increase in temperature
• increase in surface area

Question 3

what dissolved substances move in and out of cells by diffusion

Answer 3

• glucose
• urea
• oxygen
• carbon dioxide

Question 4

what is the definition of osmosis

Answer 4

the movement of water from a dilute concentration to a more concentrated solution through a partially permeable membrane

Question 5

when is the solution isotonic to the cell

Answer 5

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

Question 6

when is the solution hypertonic to the cell

Answer 6

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

Question 7

what is the definition of active transport

Answer 7

the movement of substances from a dilute concentration to a more concentrated solution (against a concentration gradient). this requires energy from respiration

Question 8

what does active transport allow

Answer 8

• allows mineral ions to be absorbed into plant root hairs from very dilute solution in the soil
• allows mineral ions to be absorbed from lower concentrations in the small intestine into the blood which has a higher sugar concentration
• sugar molecules are used in respiration

Question 9

how are exchange surfaces adapted for exchanging materials

Answer 9

• thin so a short distance to diffuse
• large surface area so lots of substances can diffuse at once
• maintain concentration gradient (e.g by having a good blood supply) so substances diffuse in the right direction
• often moist but this isn’t usually accepted by mark schemes