Question 19M.3.HL.TZ2.18
| Date | May 2019 | Marks available | [Maximum mark: 6] | Reference code | 19M.3.HL.TZ2.18 |
| Level | HL | Paper | 3 | Time zone | TZ2 |
| Command term | Discuss | Question number | 18 | Adapted from | N/A |
Commercial fertilizers are often applied to agricultural land. Discuss the use of fertilizers on crops and their effect on other ecosystems.
[6]
a. adding fertilizer increases nitrogen/phosphate in soil/nutrient cycles ✔
b. adding fertilizer increases crop yield ✔
c. commercial fertilizers may not stay in ground as long as organic fertilizers/manure ✔
d. commercial fertilizers release compounds more rapidly than organic fertilizers/manure ✔
e. nutrients run off/leached from land into water/groundwater/lakes/streams ✔
f. «high concentrations of nitrogen/phosphate in water» causes eutrophication ✔
g. «high concentrations of nitrogen/phosphate» causes algae to multiply rapidly
OR
leads to algal blooms ✔
h. algae die and decomposed by bacteria ✔
i. «decomposers» require oxygen from water
OR
increased biochemical oxygen demand/BOD ✔
j. if oxygen levels drop too low fish/aquatic organisms die ✔
A fair number provided a complete and logical discussion including both the usage and the impact of fertilizers. Too many nevertheless discussed other issues, such as decrease of phosphorous availability (which addressed a question of a previous paper), or confused fertilizers with pesticides, sometimes also mentioning biomagnification.
