The world produces over 100 million tonnes of nitrogen-containing fertiliser annually. Farmers spread this artificial fertiliser over their soil.

Mark scheme

Marking points from the official mark scheme (May/June 2022). The mark or mark type is shown in brackets.

1. [5] any five from: ammonium ions / urea / nitrates + in fertiliser / into soil; bacteria + produce nitrates / nitrification; root hairs + take up / absorb ; active transport; transported in xylem ; produce amino acids / proteins; humans ingest / eat + proteins ;
2. [2] advantages replace nitrogen removed by crops ; needed for improved growth / more yield ; to feed increasing human population ;
3. [3] disadvantages production / transport is energy consuming ; promotes monoculture ; degrades soil structure ; reduces biodiversity of soil; leaches AW + into rivers / lakes; eutrophication / water pollution ; stimulates growth of plants / algal bloom ; decomposition / decay / bacteria feed on + algae /plants ; lack of oxygen + for water animals / named freshwater animal ;