O-LevelBiologyEcology & Environment5090/22 · Oct/Nov 2023 · Q28 Marks

Fig. 2.1 shows a reindeer. [Figure 2.1] Reindeer live in areas of the Arctic where there are no trees. In some months of the year reindeer eat mostly grasses, ferns and mosses. Reindeer are eaten by wolves and brown bears. In other months of the year reindeer eat an alternative source of food. This alternative source of food contains a carbohydrate called lichenan. Reindeer are the only animals that are able to digest lichenan.

(a)Construct a food web to show the flow of energy between organisms in this ecosystem.[4]
(b)(i)List the chemical elements that make up a molecule of lichenan.[1]
(b)(ii)State one advantage to reindeer of eating food that contains lichenan.[1]
(b)(iii)Use your knowledge of how cell function is controlled to suggest why other animals are not able to digest lichenan.[2]

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 2023). The mark or mark type is shown in brackets.

[4] all six organisms in a diagram ; producer/s and consumer/s linked by lines to reindeer ; correct arrow/s from (grasses ferns and mosses) to reindeer ; correct separate arrows from reindeer to wolves and bears ;
[1] carbon / C + hydrogen / H + oxygen / O;
[1] energy ; converted into + glycogen / fat / protein ;
[2] no enzyme AW ; no gene / no allele ;

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.