Biology 9700 · AS & A Level · Movement into and out of cells

Movement into and out of cells — practice question

A red indicator solution was combined with agar, and the solid formed was then sliced into small cuboid blocks. The blocks were put into an acid that changes the indicator to yellow, while every other variable was kept the same. The dimensions of the three blocks used are shown. Block 1: $3\,\text{mm} \times 3\,\text{mm} \times 3\,\text{mm}$ Block 2: $8\,\text{mm} \times 8\,\text{mm} \times 8\,\text{mm}$ Block 3: $11\,\text{mm} \times 11\,\text{mm} \times 11\,\text{mm}$ Which row gives the correct surface area (SA) to volume (V) ratio for each block, together with the time needed for the block to turn yellow?

  • ABlock 1: SA:V = 0.5:1.0, time = 4 min; Block 2: SA:V = 1.33:1.0, time = 11 min; Block 3: SA:V = 1.83:1.0, time = 13 min
  • BBlock 1: SA:V = 0.5:1.0, time = 13 min; Block 2: SA:V = 1.33:1.0, time = 11 min; Block 3: SA:V = 1.83:1.0, time = 4 min
  • CBlock 1: SA:V = 2.0:1.0, time = 4 min; Block 2: SA:V = 0.75:1.0, time = 11 min; Block 3: SA:V = 0.55:1.0, time = 13 min
  • DBlock 1: SA:V = 2.0:1.0, time = 13 min; Block 2: SA:V = 0.75:1.0, time = 11 min; Block 3: SA:V = 0.55:1.0, time = 4 min

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