4. Cell membranes and transport
A section of Biology, 9700
Listing 10 of 418 questions
Agar cubes can be used to demonstrate the effect on diffusion of changing the surface area to volume ratio. Three different agar cubes made using a coloured indicator solution were placed into a dilute acid that diffused into the cubes. As the acid diffused into the agar cubes, the colour of the indicator solution changed. The cubes had volumes of 1 cm3, 2 cm3 and 3 cm3 and were left in the dilute acid for 10 minutes. All other variables were kept the same. After 10 minutes, the agar cubes were removed from the dilute acid and cut in half. The cut surfaces were observed and the results were recorded as diagrams. All diagrams were drawn to the same scale. The results for the 2 cm3 cube are shown...
9700_m24_qp_12
MCQ
2024
Paper 1, Variant 2
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Visking tubing can be used to investigate the properties of cell membranes. A student carried out an experiment to investigate osmosis using Visking tubing. An outline of the investigation is shown in . measuring rule (cm / mm) top of the knot in Visking tubing 15 cm3 of sucrose solution (0.9 mol dm–3) meniscus sucrose solution Visking tubing • Six pieces of Visking tubing were filled with 10 cm3 of different concentrations of sucrose solution: 0.0, 0.4, 0.8, 1.2, 1.6 and 2.0 mol dm–3. • The height of the meniscus of each solution in the Visking tubing was measured. • The pieces of Visking tubing were put into test-tubes containing 15 cm3 of 0.9 mol dm–3 sucrose solution. • After 20 minutes, the pieces of Visking tubing were removed from the test-tubes and the height of the meniscus in each was measured. The results are shown in Table 3.1. Table 3.1 concentration of sucrose solution inside Visking tubing / mol dm–3 difference in height of meniscus after 20 minutes / mm 0.0 –12 0.4 – 4 0.8 –2 1.2 +1 1.6 +6 2.0 +11 The Visking tubing used by the student was not permeable to sucrose. Explain the results shown in Table 3.1. When red blood cells are placed in water they are destroyed by bursting. The student also investigated how red blood cells are affected by immersion in solutions of sodium chloride of different concentration. Blood samples of the same volume were added to solutions of sodium chloride in separate test-tubes. After 10 minutes, the student took 0.1 cm3 of the blood samples from the test-tubes and estimated the percentage of red blood cells that had burst in each blood sample. shows the student’s results. 00.00 0.05 0.10 0.15 0.20 0.25 percentage of red blood cells destroyed by bursting concentration of sodium chloride solution / mol dm–3
9700_s21_qp_21
THEORY
2021
Paper 2, Variant 1
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An experiment was carried out to investigate the effect of concentration of sucrose solution on cells in a plant tissue. A sample of plant tissue was cut into seven cylinders of equal length and diameter. The mass of each cylinder was recorded. Each of the seven cylinders was put into a different sucrose solution concentration. bung test-tube sucrose solution plant tissue cylinder After two hours, the cylinders were removed, blotted dry and reweighed. The percentage change in mass of each cylinder was recorded. The graph shows the results of this investigation. –5 –10 –15 –20 0.7 0.6 0.5 0.4 0.3 0.2 0.1 percentage change in mass of plant tissue cylinder concentration of sucrose solution / mol dm–3 Which row explains the results if plant tissue cells were put in a sucrose solution of 0.45 mol dm–3?
9700_s23_qp_12
MCQ
2023
Paper 1, Variant 2
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Questions Discovered
418