Question 19M.3.HL.TZ1.14
| Date | May 2019 | Marks available | [Maximum mark: 5] | Reference code | 19M.3.HL.TZ1.14 |
| Level | HL | Paper | 3 | Time zone | TZ1 |
| Command term | Describe, State | Question number | 14 | Adapted from | N/A |
The graph shows how the world rock phosphate production and world population changed between 1900 and 2005.
[Source: Patrick D’ery and Bart Anderson]
Describe the relationship between rock phosphate production and world population.
[2]
a. as population increases so does phosphate production/positive correlation ✔
b. since 1985 phosphate production has not risen while population has continued to increase ✔
Many candidates were able to score 1 mark here for seeing the positive correlation. However, students continue to have problems determining when changes shown on graphs are significant. Although the final mark scheme allowed for credit to be given if a student wrote that the phosphate levels off/fluctuates/drops and rises while population has continued to increase, many candidates were still unable to draw correct conclusions about the final years shown on the graph.
Phosphate can be lost from agricultural land in several different ways. State one of these.
[1]
leaching/soil erosion, run-off/removed by the harvesting of agricultural crops ✔
Most students obtained the mark here, possibly because the mark scheme allowed for a variety of answers for the mark.
Describe how the changes in world rock phosphate production after 1985 may have affected world food supplies.
[2]
a. phosphorus is important as a fertilizer ✔
b. a drop in phosphate could lead to less agricultural output ✔
c. «this could mean» less food available for increasing population ✔
Students who struggled to read the graph correctly had problems with this question. Very few scored the full marks here, as only a small number of students clearly stated that rock phosphates were used as fertilisers to increase plant growth. Few students composed coherent answers that tied together fertiliser use, agricultural output and food.