⚡ Show all reasoning — the AI marks against the AQA mark scheme. Partial credit for correct biology even if wording differs.
1 markActive transport definitionAQA 8461 style
Which of the following best describes active transport?
A Movement of water from low to high water potential
B Movement of substances from high to low concentration, requiring no energy
C Movement of substances from low to high concentration, requiring energy from respiration
D Movement of substances from low to high concentration through a semi-permeable membrane, requiring no energy
4 marksRoot hair cellsAQA 8461 P1 style
Explain why mineral ions are absorbed by root hair cells by active transport rather than diffusion. (3 marks)
Hint: Start by comparing concentrations. Then explain why diffusion wouldn't work. Then explain what active transport provides that diffusion doesn't.
+40 XP
1 markEnergy requirementAQA 8461 style
A student reduces the oxygen supply to root hair cells. What effect would this have on the uptake of mineral ions and why?
A Uptake would increase because less energy is used for other processes
B Uptake would decrease because less aerobic respiration means less energy for active transport
C Uptake would be unaffected because mineral ions move by diffusion
D Uptake would increase because anaerobic respiration replaces aerobic
4 marksGut absorption questionAQA 8461 style
After a large meal, glucose is absorbed from the small intestine into the blood. Initially, absorption is by diffusion. Later, when glucose concentration in the intestine falls below that in the blood, absorption continues by active transport. Explain why active transport is needed at this stage. (4 marks)
Hint: Compare the concentrations. Explain why diffusion fails. Explain what active transport achieves. Mention energy.
+40 XP
1 markComparison questionAQA 8461 style
How does active transport differ from diffusion?
A Active transport only moves water molecules
B Active transport requires energy and moves substances against the concentration gradient
C Diffusion requires energy but active transport does not