Question 19N.3.HL.TZ0.1
| Date | November 2019 | Marks available | [Maximum mark: 5] | Reference code | 19N.3.HL.TZ0.1 |
| Level | HL | Paper | 3 | Time zone | TZ0 |
| Command term | Compare and contrast, State, Suggest | Question number | 1 | Adapted from | N/A |
Scientists have constructed systems to reproduce the conditions of natural wetlands. The mesocosms below were used to study nutrient removal from water flowing through.
[Source: © 2013. Silviya Lavrova and Bogdana Koumanova (October 2nd 2013). Nutrients and Organic Matter Removal in a
Vertical-Flow Constructed Wetland, Applied Bioremediation – Active and Passive Approaches, Yogesh B. Patil and
Prakash Rao, IntechOpen, DOI: 10.5772/56245. Available from: https://www.intechopen.com/books/applied-bioremediationactive-
and-passive-approaches/nutrients-and-organic-matter-removal-in-a-vertical-flow-constructed-wetland]
Compare and contrast the design of both mesocosms (vertical flow and horizontal flow).
[2]
Similarities [1 max]
a. both have similar design «input and output» ✔
b. both open systems ✔
Differences [1 max]
c. vertical flow/«figure» A has pump but horizontal flow/«figure» B does not/flows naturally ✔ Do not accept references to rate of flow or pressure as they are unknown.
d. horizontal flow/«figure» B has a larger «surface» area
OR
horizontal flow/«figure» B has more plants ✔ Accept vice versa.
e. vertical flow/«figure» A has a pre-treatment «with sedimentation tank» before treatment but not horizontal flow/«figure» B ✔ Accept vice versa.
Suggest with a reason which system best reproduces the conditions of the natural environment.
[1]
a. horizontal flow/«figure» B because it is larger
OR
horizontal flow/«figure» B contains more/several plants ✔
b. horizontal flow/«figure» B because it works by natural flow
OR
horizontal flow/«figure» B because it works without a pump ✔ Do not accept river instead of flow.
State two variables other than temperature and light that should be controlled in this experiment, in order to discover which system is more effective at removing nutrients from water.
[2]
a. type/number of plants ✔
b. type of soil/substrate ✔
c. pH level ✔
d. initial concentration of nutrients ✔
e. timespan of experiment ✔
f. volume of water/influent
OR
flow rate ✔ Do not accept amount instead of volume.
If more than two variables written, mark only the first two.