3.3.1.1 Surface area to volume ratio and exchange Quiz: AQA Biology, Unit 3

The 20 questions

1. What is the surface area to volume ratio of a cube with side length 2 cm?

   • 12:1
   • 3:1
   • 6:1
   • 1:3

2. As an organism increases in size, what happens to its surface area to volume ratio?

   • It stays the same, because surface area and volume increase in proportion.
   • It decreases, so exchange surfaces must be supplemented by transport systems.
   • It doubles for each doubling of length, so exchange becomes easier.
   • It increases, so exchange across the body surface becomes more efficient.

3. Which adaptation of a large organism helps it compensate for a reduced surface area to volume ratio?

   • A larger number of cells per unit volume, so each cell has more surface area.
   • A circulatory system that carries substances between the exchange surfaces and the rest of the body.
   • A flatter body shape that increases the ratio as the organism grows larger.
   • A thinner body wall that increases the external surface area for diffusion.

4. A cube of side 1 cm and a cube of side 4 cm are compared. What is the ratio of their surface area to volume ratios?

   • The larger cube has a ratio 16 times greater than the smaller cube.
   • The smaller cube has a ratio 4 times greater than the larger cube.
   • The larger cube has a ratio 4 times greater than the smaller cube.
   • Both cubes have exactly the same ratio, because they have the same shape.

5. Which statement describes the relationship between surface area to volume ratio and metabolic rate?

   • Smaller organisms have a higher surface area to volume ratio and typically a higher metabolic rate per unit mass.
   • Larger organisms have a higher surface area to volume ratio and a higher metabolic rate per unit mass.
   • Smaller organisms have a lower surface area to volume ratio and therefore a lower metabolic rate.
   • Metabolic rate is unaffected by surface area to volume ratio in organisms of any size.

6. A cell is modelled as a cube of side 3 cm. What is its surface area to volume ratio?

   • 2:1
   • 1:2
   • 6:1
   • 9:1

7. A cylinder of radius 1 cm and height 4 cm is compared with a cube. Which factor determines whether diffusion is adequate for exchange?

   • The volume of the nucleus, since a larger nucleus always increases diffusion distance.
   • The colour of the cell membrane, since darker cells absorb more oxygen by diffusion.
   • The number of ribosomes in the cytoplasm, since ribosomes control the rate of diffusion.
   • The distance substances must diffuse, since larger distances make diffusion too slow.

8. An agar block containing indicator is placed in acid. Which factor would increase the rate of diffusion of the acid into the block?

   • A block with a smaller surface area to volume ratio, because less acid can enter the block.
   • A block with a larger surface area to volume ratio, because more acid can enter per unit volume.
   • A block with a thicker outer layer, because the acid must cross a greater distance quickly.
   • A block with fewer indicator molecules, because the acid is then able to diffuse faster.

9. A student measures the surface area and volume of a cube of side 5 cm. Which value is correct?

   • Surface area 30 cm^2 and volume 15 cm^3.
   • Surface area 25 cm^2 and volume 125 cm^3.
   • Surface area 150 cm^2 and volume 25 cm^3.
   • Surface area 150 cm^2 and volume 125 cm^3.

10. Why do large multicellular organisms need specialised exchange surfaces as well as mass transport?

    • Mass transport is only needed by plants, because animals can exchange by diffusion alone.
    • Diffusion is faster in large organisms, so specialised surfaces are not needed for exchange.
    • Large organisms have a higher surface area to volume ratio, so exchange is no longer limited.
    • Most cells are too far from the exchange surface for diffusion alone to maintain the tissue fluid composition.

11. A researcher finds that a small organism has a higher surface area to volume ratio than a large one. Which prediction is most reasonable?

    • The small organism will exchange substances more slowly per unit volume than the large organism.
    • The small organism will have the same exchange rate as the large one, because volume is the same.
    • The small organism will exchange substances more rapidly per unit volume than the large organism.
    • The small organism will have no exchange surface, because its ratio is too high.

12. A cell increases its length and width but keeps the same shape. What happens to its surface area to volume ratio?

    • It decreases, because volume increases faster than surface area as linear dimensions increase.
    • It increases, because surface area increases faster than volume as linear dimensions increase.
    • It doubles, because both surface area and volume are doubled in every case.
    • It stays the same, because the shape of the cell is unchanged by any scaling.

13. Which change most effectively increases the rate of exchange for a large organism?

    • Increasing the volume of the body without any change to the surface area.
    • Making the body shape flatter to reduce the surface area to volume ratio.
    • Reducing the number of cells, so each cell has less volume and more surface.
    • Developing a folded or branched exchange surface with a large surface area.

14. What is the surface area to volume ratio of a sphere of radius 1 cm?

    • 1:3
    • 4:1
    • 6:1
    • 3:1

15. What is the surface area to volume ratio of a cube with side length 10 cm?

    • 0.6:1
    • 0.06:1
    • 60:1
    • 6:1

16. An organism keeps the same shape but its length doubles. By what factor does its volume increase?

    • 2
    • 8
    • 4
    • 16

17. Which of these is an adaptation that increases the surface area to volume ratio of an organism?

    • Increasing body size, which reduces heat loss through the body wall.
    • A thicker body wall, which slows the rate of exchange with the environment.
    • A single large spherical body with no folds, which minimises the surface area.
    • A flattened body shape, as in a flatworm, which keeps every cell close to the surface.

18. A cube of side 2 cm is cut into eight cubes of side 1 cm. What is the total surface area of the eight small cubes?

    • 96 cm^2
    • 48 cm^2
    • 24 cm^2
    • 6 cm^2

19. A flat leaf and a sphere have the same volume. Which statement about their surface area to volume ratios is correct?

    • The sphere has a higher ratio, because a sphere has the largest surface area for its volume.
    • Both shapes have identical ratios, because they have identical volumes.
    • The sphere has a higher ratio, because a curved surface always gives more exchange area.
    • The flat leaf has a higher ratio, because a thin shape has a large area relative to its volume.

20. Which factor would most reduce the rate of diffusion in a large cell?

    • A higher density of channel proteins in the outer membrane of the cell.
    • A greater distance between the outer membrane and the centre of the cell.
    • A steeper concentration gradient across the outer membrane of the cell.
    • A larger surface area of the membrane available for diffusion.

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