| Date | May 2016 | Marks available | 2 | Reference code | 16M.3.HL.TZ0.17 |
| Level | Higher level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | Suggest | Question number | 17 | Adapted from | N/A |
Question
The Laysan Albatross (Phoebastria immutabilis) sometimes ingests plastic. A bolus is a pellet made of material that the albatross cannot digest, so brings it back up from its stomach to its mouth and then ejects the indigestible matter. Graph A indicates the mass of indigestible natural material, such as bones and octopus beaks, in the bolus of birds at two different locations. Graph B indicates the mass of plastic in the bolus at both locations.
Suggest one reason for the Laysan Albatross ingesting indigestible plastic.
Suggest a reason for the difference in ingested plastic in the diets of the Laysan Albatross in the two locations.
Outline the origin of microplastic debris in the marine environment.
Using microplastics as an example, outline the concept of biomagnification.
Markscheme
«Coloured object» mistaken for food
OR
skimming of ocean surface for food leads to plastic intake
Ocean currents concentrate plastic debris
Kure receives more debris than Oahu
More plastic available/more exposure to human populations/waste in the environment of Kure
«Macro» plastics blown/carried/washed from land sources into the ocean
Degraded over time
To form microplastic fragments
Substances already containing microplastics «eg: washing/cleansing products» get into water
Microplastic ingested by organisms at lower trophic levels
Accumulates in the tissues/guts of organisms
Becomes concentrated in the organs/tissues of organisms as moves through the food chain/at higher trophic levels
Examiners report
Most understood that plastic was being mistaken for food so were able awarded the mark.
Most were only able to score one mark for suggesting that perhaps Kure had more exposure to human populations and waste than Oahu (which is not in fact the real situation). Most candidates did not see the role of ocean movement and currents in distribution of floating plastics in waters around the two locations where the albatrosses feed.
Most answers about sources of microplastic debris were vague. However, many were able to get a mark for indication that plastics were carried from land sources to the ocean. A few knew that some washing products contain microplastics.
This question on biomagnification was surprisingly poorly answered, a few even writing about magnification using a microscope. Vague answers were given and few properly outlined the concept of biomagnification or seemed to know that substances accumulate in the tissues or gut of organisms.
