A-LevelBiologyTransport in plants9700/22 · Oct/Nov 2019 · Q110 Marks

Fig. 1.1 is a photomicrograph of a transverse section through the stem of creeping buttercup, Ranunculus repens. [Figure 1.1]

(a)Draw one label line on Fig. 1.1 to indicate one precise location where phloem sieve tubes occur.[1]
(b)State the role of phloem sieve tubes.[2]
(c)(i)State the name of the tissue that forms the outer layer of the stem section of R. repens in Fig. 1.1.[1]
(c)(ii)State the piece of equipment that can be used in the light microscope to work out the correct proportions of the tissues.[1]
(d)Draw a diagram in the space provided to show the structure of a typical plant cell. Label your diagram with the name of any structures that are found only in plant cells. Do not label any structures that are also found in animal cells.[5]

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 (Oct/Nov 2019). The mark or mark type is shown in brackets.

[1] (a) label line to phloem in one vascular bundle;
[2] (b) transport / translocation, of, assimilates / photosynthates / sucrose / sugars / amino acids / other named nutrient; I food from, source / areas of synthesis, to, sink / areas of growth / areas of (high) activity / areas of storage ; A areas where they are needed for sink I 'where they used'
[1] (c)(i) epidermis / epidermal ; I upper / lower
[1] (c)(ii) eyepiece graticule ; I stage micrometre
[5] (d) drawing max 2: regular shaped cell and cell wall drawn in; central vacuole drawn ; labels: max 2 if animal structures also labelled max 1 for labels if incorrect non-cellular structure included e.g. vascular bundle / stoma large / permanent, vacuole ; A central vacuole A vacuole if clearly drawn as large tonoplast; R if drawn as double membrane (cellulose) cell wall; R chitin / murein plasmodesma(ta) ; chloroplast; A granum / thylakoid i.e. chloroplast not labelled but internal structures correct labelled A if drawn with a single or double membrane starch, grain / granule ; A amyloplast

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