Energy transfers: Nutrient cycles

From Mock A · Paper 2 (topics 5–8)

3.42 marks

Describe the roles of saprobionts and nitrifying bacteria in the nitrogen cycle.

From Mock B · Paper 2 (topics 5–8)

14.12 marks

Explain the role of mycorrhizae in nutrient uptake by plants.

From Mock B · Paper 2 (topics 5–8)

14.22 marks

Explain how leaching of fertiliser can lead to eutrophication.

From Mock C · Paper 2 (topics 5–8)

43 marks

Describe the roles of bacteria in the nitrogen cycle.

From Mock C · Paper 3 (all topics, practical skills and essay)

6.12 marks

Critical analysis (written for this paper): wheat plants were grown with and without mycorrhizal fungi at two levels of phosphate fertiliser for 8 weeks (n = 15 per group).

Group	Mean dry mass / g	Mean phosphate in leaves / mg g⁻¹
Low P, no fungi	2.1	1.2
Low P, with fungi	3.4	2.3
High P, no fungi	3.8	2.9
High P, with fungi	3.9	3.0

A fertiliser company claims that 'adding mycorrhizal fungi is as good as adding phosphate fertiliser'. Calculate the percentage increase in mean dry mass caused by fungi at low phosphate.

From Mock C · Paper 3 (all topics, practical skills and essay)

6.23 marks

Explain why fungi increase growth at low phosphate but not at high phosphate.

Score 0 / 14 · 0 of 6 marked

This paper is written by Plasmo in the style of the AQA A-Level Biology exam. It is not a past paper and is not produced or endorsed by the exam board.