O-LevelBiologyPlant Nutrition5090/22 · May/June 2018 · Q411 Marks

The graph shows the effect on crop yield (amount harvested) of using fertilisers that contain nitrogen. [Figure: Graph showing crop yield in kg/hectare versus mass of fertiliser in kg/hectare]

(a)(i)Use the information in the graph to describe the effect on crop yield of using an increasing mass of fertiliser.[3]
(a)(ii)The nitrogen in the fertiliser is in the form of nitrates. Describe how the nitrogen in the fertiliser is absorbed by crop plants and used to give an increased yield.[3]
(a)(iii)Suggest and explain why a farmer may decide to use a mass of fertiliser per hectare which is less than that needed for a maximum crop yield.[3]
(b)Name one type of mineral ion, other than nitrate, that is required by a plant and state its importance to the plant. type of mineral ion ............................................................................................................................................................ importance to plant ............................................................................................................................................................[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 (May/June 2018). The mark or mark type is shown in brackets.

[3] 1 no fertiliser + yield is 200 (kg/hectare crop yield) ;
2 increased / more crop yield ;
3 reference to 150 (kg/hectare fertiliser) or 5600 (kg/hectare crop yield) ;
4 high fertiliser / above 150 + no increase in crop yield ;
[3] 1 root hair;
2 active transport / against concentration gradient / diffusion / down concentration gradient;
3 production AW of + amino acids / protein;
4 increased AW + growth ;
[3] 1 run-off / leaching AW ;
2 eutrophication or correct description of process ;
3 harm to animals ; A harm to named animal / 'aquatic life'
4 high cost / expensive;
5 possible economic return not beneficial over increased cost AW ;
[2] 1 (ion) magnesium ; phosphate ; sulfate ; calcium ; iron ; potassium ;
2 (importance) chlorophyll ; DNA / RNA / membranes ; amino acids / proteins ; cell walls ; chlorophyll ; enzymes ; note point 2 is to be awarded only if point 1 has been awarded credit note importance in point 2 must be correct for ion named in point 1

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