Cell BiologyAQA GCSE Biology (8461)

Transport in Cells

Work through the notes, try the practice questions, then take the quiz. The report tells you exactly what to revise next. (2026)

Practice progress

5 MCQs

0 of 5 attempted

Correct

Incorrect

Remaining

1
What does diffusion involve?
Answer & explanation
Correct: option B
Diffusion is passive movement DOWN the gradient (high to low). No energy needed.
2
Which change would INCREASE the rate of diffusion across a membrane?
Answer & explanation
Correct: option C
Steeper gradient = more particles moving down per second. Rate also increases with higher temperature, larger SA and thinner membrane (shorter distance).
3
A cube has sides of 3 cm. What is its surface area to volume ratio?
Answer & explanation
Correct: option B
SA = 6 × 3² = 54 cm². V = 3³ = 27 cm³. Ratio = 54/27 = 2:1.
4
Which adaptation of the alveoli reduces the diffusion DISTANCE?
Answer & explanation
Correct: option B
Thin walls = short diffusion distance. The other three relate to SA, gradient and ventilation respectively.
5
Why do larger organisms need specialised exchange surfaces?
Answer & explanation
Correct: option B
Big organisms have a low SA:V ratio — surface diffusion alone is too slow to meet their needs. Hence lungs, gills, gut villi etc.

Cell BiologyAQA GCSE Biology (8461)

Work through the notes, try the practice questions, then take the quiz. The report tells you exactly what to revise next. (2026)

5 MCQs

0 of 5 attempted

Correct

Incorrect

Remaining

1
What does diffusion involve?
Answer & explanation
Correct: option B
Diffusion is passive movement DOWN the gradient (high to low). No energy needed.
2
Which change would INCREASE the rate of diffusion across a membrane?
Answer & explanation
Correct: option C
Steeper gradient = more particles moving down per second. Rate also increases with higher temperature, larger SA and thinner membrane (shorter distance).
3
A cube has sides of 3 cm. What is its surface area to volume ratio?
Answer & explanation
Correct: option B
SA = 6 × 3² = 54 cm². V = 3³ = 27 cm³. Ratio = 54/27 = 2:1.
4
Which adaptation of the alveoli reduces the diffusion DISTANCE?
Answer & explanation
Correct: option B
Thin walls = short diffusion distance. The other three relate to SA, gradient and ventilation respectively.
5
Why do larger organisms need specialised exchange surfaces?
Answer & explanation
Correct: option B
Big organisms have a low SA:V ratio — surface diffusion alone is too slow to meet their needs. Hence lungs, gills, gut villi etc.