Previous Year Questions

Question :

Directions : Read the following passage carefully and answer the questions that follow.

Strong evidence supports two main hypotheses about plastic ingestion and its effects on sea turtles, based on necropsy data. First, sea turtles with plastic listed as the cause of death were found to have more plastic debris in their gastrointestinal tracts compared to turtles that died from other causes. Deaths appeared to be grouped by the amount of plastic present, showing a clear link between debris concentration and cause of death. Second, analysis showed that the chance of death increased as the number of plastic items in the digestive tract increased. This pattern was confirmed using data from a national stranding database. As expected, turtles with unknown causes or non-plastic-related causes had less plastic, while those with plastic-related deaths had the most. The results allow prediction of the chance of death for any turtle by using measurements such as curved carapace length (CCL), age class, and number of plastic items found in the gut. For example, a juvenile turtle with a CCL of 43.5 cm, the average size in the data, faces a 50% chance of dying if it has ingested 17 plastic items. Ingestion of 226 plastic items results in a 100% likelihood of death. Some turtles died after eating only one plastic item. In these cases, death was caused either by gut blockage or perforation. The estimated risk of death from a single item is approximately 22%.

Sea turtle anatomy increases the risk of plastic accumulation and death. The gastrointestinal tract is long and coiled, and turtles cannot vomit. These traits make it more likely that plastic will build up. The kind of plastic also affects how it moves through the gut. Items vary in size, shape, and density. These features can slow movement and increase the chance of obstruction. For instance, soft plastics can stick together and form a single large blockage, even when swallowed separately. Some items have been shown to stay in the digestive system for long periods, such as four months for small soft latex pieces or six months for large flat plastic sheets. Different plastic types cause different levels of harm. Sharp or long objects, like fishing lines or metal hooks, can fold the gut and pierce tissue. In contrast, small hard pieces of plastic might pass through quickly without causing much damage. Exposure to different types and amounts of plastic depends on the feeding location. Turtles feeding near shore or in ocean zones where floating trash gathers may swallow larger and more dangerous debris. Debris distribution patterns also vary, with plastic fragments found to be widely spread across coastal zones and open waters, increasing the chance of ingestion across various habitats. Life stage also influences ingestion patterns. Among the turtles examined, 54% of post-hatchlings and 23% of juveniles had plastic in their guts. These young turtles feed near the ocean surface or along coastlines, where debris is more concentrated. In contrast, only 15% of sub-adults and 16% of adults had ingested plastic. Younger turtles are more exposed to floating trash because of their feeding habits and locations.

The shape and appearance of plastic may also influence ingestion. Research suggests that some turtles may mistake plastic for food, especially thin, soft plastics that resemble jellyfish or other prey. This behaviour is more common in younger turtles, but does not rule out accidental ingestion. Studies of turtles caught in fisheries show that even healthy-looking pelagic juveniles often carry significant amounts of plastic. In longline fisheries that operate in ocean convergence zones, all sampled pelagic juveniles had between 24 and 39 pieces of plastic in their guts. Despite these high amounts, these turtles died from drowning, not plastic ingestion. However, the calculated risk of death from the amount of plastic found in these turtles was between 69% and 90%, according to the mortality model. This difference highlights a possible bias in the data. Most turtles studied came from coastal regions, having washed ashore already dead or dying. These coastal samples represent a mix of death causes. In contrast, turtles from longline fishing are recovered only if they die in the fishing gear. This makes the pelagic turtle data less complete. Turtles that die from plastic ingestion may never be recovered. This suggests that the current mortality model is best used for coastal turtles. For offshore turtles, the model may overestimate the risk of death from plastic ingestion. Plastic pollution poses a major threat not only to sea turtles but also to many marine species. Currently, nearly 700 species are known to interact with human-made debris. As global plastic production increases, so does the number of affected species. Animals such as seabirds, fish, marine mammals, and invertebrates, including corals, are also known to ingest or get entangled in plastic waste. Some organisms become ____X____ in fishing lines, packaging bands, or netting, which can lead to injury, drowning, or death.

According to the passage, which of the findings is related to predicting sea turtle mortality from plastic ingestion?