Structure and Functions in Living Organisms - Transport (Paper 2)

Question 1

how is water absorbed by root hair cells?

Answer 1

• high concentration of water molecules outside the cell in the soil and low concentration in the cell
• strong concentration gradient, so water molecules travel by osmosis into the cell
• root hair cells have a high surface area to volume ratio

Question 2

what is transpiration?

Answer 2

loss of water vapour by evaporation from the surface of a plant

Question 3

how does temperature affect transpiration rate?

Answer 3

• as temperature increases rate of transpiration increases
• increase in temperature will cause water molecules to gain kinetic energy, increasing rate

Question 4

how does humidity affect transpiration rate?

Answer 4

• as humidity increases, rate of transpiration decreases
• this is because the concentration gradient is weaker

Question 5

how does wind affect transpiration rate?

Answer 5

• as wind increases, rate of transpiration increases
• this is because greater wind removes water vapours surrounding the plant, meaning concentration gradient is stronger

Question 6

how does light intensity affect transpiration rate?

Answer 6

• as light intensity increases rate of transpiration increases
• this is because an increase in light intensity will stimulate more stomata to open

Question 7

how would you investigate the factors that affect transpiration?

Answer 7

• cut shoot underwater to prevent air from entering and place through hole throught stopper on potometer
• fill potometer with water
• use vaseline to seal apparatus
• trap air bubble in capillary tube
• measure and record the starting distance of the air bubble
• change environmental factor
• allow shoot to adapt for a set time period
• measure and record final distance of air bubble

Question 8

how are platelets involved in blood clotting?

Answer 8

• when skin is wounded, clotting factors are released by damaged cells and platelets
• clotting factors cause platelets to become sticky and for a plug
• clotting also triggers formation of fibrin which forms a mesh around the wound

Question 9

how does vaccination protect against pathogens?

Answer 9

• vaccine contains weakened form of pathogen
• this triggers an immune response
• memory cells are created