10 free IB Biology practice questions in the real exam format, covering the official content areas, with an explanation for every answer.
IB Biology Practice Test 4Tutor mode
Question 1 of 10
Form and function
Method. Cylinders of potato tissue were cut with a cork borer, blotted dry and weighed. Each cylinder was placed in 30 cm³ of sucrose solution (independent variable: 0.0 to 0.6 mol dm⁻³) for 24 hours. The cylinders were then blotted and reweighed, and the percentage change in mass (dependent variable) was calculated. Three cylinders were used at each concentration.
Percentage change in mass of potato cylinders
Sucrose concentration / mol dm⁻³
Mean change in mass / % (± SD, n = 3)
0.0
+18.2 ± 2.1
0.1
+10.4 ± 1.8
0.2
+3.1 ± 1.5
0.3
−4.0 ± 1.7
0.4
−10.6 ± 2.0
0.5
−15.8 ± 2.4
0.6
−18.9 ± 2.2
Error bars on the graph would show ± 1 standard deviation.
Using the data, estimate the sucrose concentration at which there would be no net change in the mass of the potato tissue.