Note AcademyNote Academy
Start

Biology · May / June 2021 · Paper 61 · Question 1

0610

As printed in the paper

The question as text

A student investigated the effect of the concentration of sugar solutions on osmosis in potato cells. Step 1 The student labelled four test-tubes A, B, C and D. Step 2 The volumes of 1 mol per dm3 sugar solution and distilled water shown in Table 1.1 were used to make solutions containing different concentrations of sugar in each test-tube.

Read automatically from the paper; the printed page above is exact.

Show the answer and mark scheme

  • 1(a)(i)[1]

    0.4 ;

  • 1(a)(ii)[3]

    table drawn with a minimum of two, columns / row, and a header line ; headers with units ;

    four correct lengths ±1 mm recorded ;

  • 1(a)(iii)[1]

    so that the results were comparable / so sugar concentration is the only variable that is changed / to ensure the surface area was the same / so surface area does not affect the rate of osmosis / AW ;

  • 1(a)(iv)[1]

    concentration of the sugar solution ;

  • 1(a)(v)[2]

    any two from:

    measure mass of cylinders (instead of length) ;

    more intermediate concentrations of sugar solution ;

    extend the range of concentrations used ;

    repeat at each concentration / replicate the investigation ;

    soak for longer than 20 minutes ;

    use warmer sugar solutions (to speed up diffusion) ;

    keep all at the same temperature ;

    dry cylinders before measuring ;

  • 1(a)(vi)[1]

    cut away from body / use wooden board or tile / cut on flat

    surface / keep blade away from body parts / dry before cutting ;

  • 1(b)[6]

    independent variable:

    1

    ref. to using at least 2 different temperatures ;

    method:

    2

    method of maintaining a temperature described ;

    3

    use of a tissue e.g. potato / leaves / root / stem, immersed in water / sugar / salt solution ;

    4

    method measuring dependent variable described, i.e.

    length / mass / volume / surface area of (cylinders / tissue / leaves) before and after (immersion) or measuring volume of immersion liquid before and after ;

    5 + 6 variables kept constant ;;

    max two from:

    same concentration (of solution) / same volume (of solution / water)
    same (initial) length / volume / mass / surface area, of potato or tissue
    same type / age /variety / AW, of (potato, tissue) / same potato / same plant
    same pH / use a buffer
    same immersion time

    7

    equilibration of temperature for tissue / solution ;

    8

    drying before reweighing (if mass measured) ;

    9

    at least two repeats (of each temperature) / total of three trials ; 10 AVP ;

  • 1(c)(i)[2]

    iodine solution ;

    blue-black ;

  • 1(c)(ii)[5]

    lines: clear, single, unbroken with no shading ;

    size: central cell has a minimum diameter of 56 mm ;

    detail one: double line (minimum) for entire cell wall ;

    detail two: minimum of five starch grains around perimeter of cell ; label: one starch grain labelled ;

  • 1(c)(iii)[3]

    (length of line AB) 10 ±1 (mm) ;

    0.013 (0.011–0.014) mm ;;

Practise this paper →

Make a free account to save your answers and see your weak topics and ask the AI why a wrong answer is wrong.