Barlinka is a variety of the common grapevine, Vitis vinifera. Barlinka grapes are used for making wine and are sold as fruit. There are economic and ecological benefits from using less water to irrigate grapevine plants, while still producing a high crop yield. The rate of flow of sap within xylem vessels from roots to leaves can be used as an estimate of the rate of transpiration. This also indicates water uptake.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2021). The mark or mark type is shown in brackets.

1. [2] cohesion ;
2. adhesion ;
3. [2] any two from:
4. 1 higher rate of transpiration during the day / lower rate of transpiration during the night / AW ; A flow of xylem sap for transpiration
5. 2 stomata are open during the day ; ora must be in context of transpiration
6. if mp1 and mp2 not gained, allow one mark for idea that results are related to pattern of, light / daylight / day, and, dark / night (use an ordinary tick)
7. 3 idea that all three vines were kept in the same conditions so a changed condition that affects transpiration will affect all three ; A all three have the same external factors acting that affect transpiration
8. 4 AVP ; e.g. (during daylight) stomata open, to obtain carbon dioxide / for photosynthesis idea that, increasing / decreasing, rate is related to degree of opening of stomata varying with light intensity
9. [2] allow (xylem sap) flow rate for rate of transpiration
10. any two from:
11. 1 the greater the (total) area of leaf, the higher the rate of transpiration ; ora A grapevine 1 has largest leaf area and highest rate of transpiration accept other comparisons R ref. to SA:V but allow ecf in mp2
12. 2 the greater the (total) area of leaf, the more stomata are present ; AW A more leaves means more stomata
13. 3 detail of any one grapevine ; e.g. grapevine 1 = highest transpiration rate and, highest number of / most, stomata grapevine 3 = lowest transpiration rate and, lowest number of / least, stomata allow use of comparative data to support mp (if detail includes ref. to (total) leaf area then check to see if mp2 can also be awarded)
14. 4 ref. to relationship between (total) internal surface area and (total) leaf area ; e.g. larger leaf surface area means internal surface area increased
15. 5 ref. to relationship between internal surface areas and rates of evaporation ;
16. 6 AVP ; higher rate of flow of xylem sap for largest leaf area as (overall) more water used in metabolism AW ora (greater area so) more leaves so more xylem vessels ora
17. [1] overcast / cloudy / rain / shade / AW ;
18. A lower wind speed / temperature
19. A higher humidity
20. R if described as stomata close (transpiration is still occurring)
21. [2] valid method e.g.
22. draw around / place, leaf on, squared paper / graph paper / grids ;
23. A square ruler
24. count number of (full) squares ; R multiply by two / do it on other side
25. method for part squares ; e.g. add up all part squares and divide by 2
26. match a larger part square with a smaller and count as one square
27. use graph paper with larger and smaller squares
28. or
29. photocopy leaves, cut out and weigh (cut out) ;
30. divide mass by mass of 1 cm³ of same paper ;
31. or
32. ref. to using an App ;
33. further detail ; e.g. place leaf, flat / on white surface ;
34. take photo of single leaf with smart phone / AW