DP Biology (last assessment 2024)
Question 18N.3.SL.TZ0.13b
| Date | November 2018 | Marks available | [Maximum mark: 1] | Reference code | 18N.3.SL.TZ0.13b |
| Level | SL | Paper | 3 | Time zone | TZ0 |
| Command term | State | Question number | b | Adapted from | N/A |
b.
[Maximum mark: 1]
18N.3.SL.TZ0.13b
A biotic index allows water pollution to be monitored without the need for a large number of chemical tests. Aquatic invertebrates are assigned pollution tolerance levels and these are used to assess water quality. The amount of each invertebrate species in the water is measured and this is used to calculate the index. The tolerance level of three invertebrate species is shown.
(b)
State the name given to organisms whose presence or absence reflects an environmental condition.
[1]
Markscheme
indicator species ✔
