O-LevelBiologyTransport in Plants5090/21 · May/June 2014 · Q412 Marks

Fig. 4.1 shows a type of plant cell. [Figure 4.1]

(a)(i)Name the type of cell shown in Fig. 4.1.[1]
(a)(ii)Describe how water is taken up from the soil into the cytoplasm of the cell shown in Fig. 4.1.[3]
(b)(i)Using Fig. 4.2, describe the effect of increasing oxygen concentration in the soil on the rate of ion uptake.[2]
(b)(ii)Suggest how most ions are taken up during section X and section Y on Fig. 4.2. Give an explanation for your answers. process during section X process during section Y explanation[5]
(b)(iii)Suggest a reason for the shape of the graph during section Z on Fig. 4.2.[1]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (May/June 2014). The mark or mark type is shown in brackets.

[1] root + hair/epidermis ;
[3] osmosis/diffusion ;
high water conc. to low(er) water conc. / down water potential gradient/hypotonic to hypertonic ;
through/across partially permeable (AW) ;
membrane;
[2] (at Y) (initial) increase in O2 concentration leads to increase in uptake ;
(at X or Z) (further) increase in O2 concentration leads to no increase in uptake;
[5] process during section X: diffusion ;
process during section Y: active transport/active uptake;
explanation: (during) X/diffusion + passive/not energy-requiring ;
(during) Y/active transport + requires energy ;
(energy for active transport from) respiration ;
respiration requires oxygen ;
[1] rate of (ion) uptake dependent on another/other factor(s)/named factor e.g. temperature/ref. other limiting factor;

On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.