SAT Reading - Khan Diagnostic Quiz level 1 - reading 7

Questions 1-5 are based on the following

This passage is excerpted from Marcus Eriksen’s "Plastic Pollution in the World’s Oceans: More Than 5 Trillion Plastic Pieces Weighing Over 250,000 Tons Afloat at Sea," ©2014.

Plastic pollution is globally distributed across all oceans

due to its properties of buoyancy and durability, and the

absorption of toxicants by plastic while traveling through the
environment has led some researchers to claim that synthetic
5 polymers in the ocean should be regarded as hazardous

waste. Through photo degradation and other weathering

processes, plastics fragment and disperse in the ocean,

converging in the subtropical gyres.* Accumulation of plastic

pollution also occurs in closed bays, gulfs and seas
10 surrounded by densely populated coastlines and watersheds.
Despite oceanographic model predictions of where debris

might converge, estimates of regional and global abundance

and weight of floating plastics have been limited to

microplastics less than 5 mm. Using extensive published and
15 new data, particularly from the Southern Hemisphere

subtropical gyres and marine areas adjacent to populated

regions corrected for wind-driven vertical mixing, we

populated an oceanographic model of debris distribution to

estimate global distribution and count and weight densities of
20 plastic pollution in all sampled size classes.
Plastics of all sizes were found in all ocean regions,

converging in accumulation zones in the subtropical gyres,

including southern hemisphere gyres where coastal

population density is much lower than in the northern
25 hemisphere. While this shows that plastic pollution has

spread throughout all the world's oceans, the comparison of

size classes and weight relationships suggests that during

fragmentation plastics are lost from the sea surface.
The observations that there is much less microplastic at the
30 sea surface than might be expected suggests that removal

processes are at play. These include UV degradation,

biodegradation, ingestion by organisms, decreased buoyancy

due to fouling organisms, entrainment in settling detritus, and

beaching. Fragmentation rates of already brittle microplastics
35 may be very high, rapidly breaking small microplastics

further down into ever smaller particles, making them

unavailable for our nets (0.33 mm mesh opening). Many

recent studies also demonstrate that many more organisms

ingest small plastic particles than previously thought, either
40 directly or indirectly, i.e. via their prey organisms. Beginning

of reading passage footnotes.

*In oceanography, a “gyre” refers to a large system of rotating ocean currents.

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Question 1 According to the passage, ocean plastics are found in greatest quantities in