Date | November 2017 | Marks available | 2 | Reference code | 17N.2.bp.04 |
Level | SL and HL | Paper | 2 | Time zone | |
Command term | Describe | Question number | 04 | Adapted from | N/A |
Question
State two causes of a negative change in sea level.
Briefly describe one landform associated with an advancing coast.
Using examples, explain two effects of the oceanic conveyor belt on different places.
“The loss of coral reefs has more serious effects than the loss of mangrove swamps.” Discuss this statement.
Markscheme
Sea level fall [1]
Uplift of land [1]
Accept other valid terminology.
Award [1] for a named landform and [1] for description.
Possibilities include:
- relict platform
- raised beaches
- sandbar
- spit
- saltmarsh
- tombolo.
For example: An abandoned cliff / stack [1] is a former marine cliff now above the high tide level [1].
Award [1] for each valid effect and a further [2] for development/exemplification.
The oceanic conveyor belt brings warm water [1] into high latitudes in the North Atlantic [1] causing temperatures, evaporation and rainfall to be higher in this region [1].
In other regions, such as Antarctica [1], the oceanic conveyor belt causes the uplift/mixing of colder water with surface water, leading to an increase in nutrients in the upper water [1], thereby supporting a rich marine life, and, potentially, fisheries [1].
Consequences of the loss of coral reefs include: erosion of coastlines, loss of fish habitats and biodiversity (they shelter more than 25 % of all known fish species), loss of economic productivity and livelihoods for people who depend on fishing and/or coral reef tourism/diving.
In addition to biodiversity loss, the removal of mangroves may reduce the amount of available food, fuel, building materials and medicine for local societies. Mangroves also act as natural filters, absorbing nutrients from farming and sewage disposal. The dense interlocking roads of mangroves help to stabilize shorelines and prevent erosion.
Good answers may provide a structured discussion of different types of effect/impact according to scale (local/global issues), or human and physical effects. Another approach might be to discuss the onshore context of mangroves and the offshore context of reefs, thus reaching a judgement on the severity of loss for local people (relatively more are affected by mangrove loss). Another approach might be to discuss how coral reefs and mangroves both protect coastlines by absorbing some wave energy, especially during storms such as hurricanes (tropical cyclones).
At band D, expect a description of some effects/impacts of coral and mangrove loss (do not expect balance).
At band E, expect either a more detailed explanation of some severe effects of coral and mangrove loss (do not expect balance) or a structured discussion of the statement.
At band F, expect both of these elements.
Marks should be allocated according to the markbands.