Reading Practice Test 11: Body and Planet

Read the text below and answer questions 1-13.

The Placebo Effect in Modern Medicine

For much of medical history, the placebo effect — the measurable improvement patients experience after receiving a treatment with no active therapeutic ingredient — was treated mainly as a nuisance: something to be controlled for in clinical trials rather than a phenomenon worth studying in its own right. Neuroscientist Priya Mehta has spent much of her career arguing that this dismissal has obscured a genuinely useful biological mechanism.

Mehta's brain-imaging studies have shown that placebo treatments for pain trigger measurable activity in the same neural pathways activated by actual painkilling drugs, including the release of the body's own natural pain-relieving compounds. In other words, the relief patients report is not merely imagined or reported out of politeness toward a physician — it corresponds to real, observable changes in brain chemistry, even though no pharmacologically active substance was administered.

One of Mehta's more surprising findings concerns what has become known as open-label placebo treatment, in which patients are told explicitly that they are receiving a placebo with no active ingredient, rather than being deceived into believing it is real medication. Conventional wisdom held that the placebo effect depended entirely on the patient's belief that they were receiving genuine treatment, so an effect should disappear once the deception was removed. Instead, several of Mehta's trials found that patients told honestly that they were taking a placebo still experienced meaningful symptom improvement for certain conditions, particularly for chronic pain and fatigue, suggesting the ritual and expectation of treatment itself carries some therapeutic value independent of active deception.

The size of the placebo response also appears to vary considerably depending on the form treatment takes. Mehta's research indicates that placebo injections tend to produce stronger reported effects than placebo pills, and that the colour, size, and branding of a placebo pill can measurably influence how effective patients perceive it to be — larger pills and certain colours are consistently associated with stronger placebo responses across multiple studies, an effect Mehta attributes to learned cultural associations between appearance and perceived potency.

None of this means placebo treatment should replace active medication where effective treatments exist, and Mehta is careful to stress this point in her public communication. Her research instead points toward a more targeted implication: that clinicians could potentially harness expectation and ritual as a genuine supplementary tool alongside active treatment, rather than dismissing the placebo response as an inconvenient statistical artifact to be subtracted out of trial results.

Read the text below and answer questions 14-26.

Microplastics and the Food Chain

Plastic pollution is most visible in its largest forms — bottles, bags, and fishing nets accumulating in rivers and oceans — but environmental chemist Tobias Lindqvist argues that the far greater long-term concern may be invisible to the naked eye: microplastics, fragments smaller than five millimetres, formed as larger plastic items break down under sunlight, wave action, and general weathering over years or decades.

Lindqvist's research has focused on tracing how these fragments move through food chains. Microplastics are readily ingested by small marine organisms such as plankton and filter-feeding shellfish, often because the fragments are similar in size to the organisms' normal food sources and are consumed indiscriminately. From there, the particles can accumulate up the food chain as predators consume large numbers of contaminated prey, a process Lindqvist has documented at each trophic level from plankton through small fish to larger predatory species.

A particular concern in Lindqvist's work involves the chemical additives used in plastic manufacturing, including compounds added to make plastics more flexible or fire-resistant. Unlike the solid plastic fragment itself, which may pass through an organism's digestive system without being absorbed, some of these additives can leach out and be absorbed into tissue, and evidence suggests certain additives may accumulate in fatty tissue over an organism's lifetime rather than being fully excreted, raising the possibility of increasing concentration in longer-lived predatory species.

Human exposure to microplastics occurs through multiple pathways beyond eating contaminated seafood, including drinking water, table salt, and even airborne dust settling on food during preparation, though Lindqvist is notably cautious about overstating current evidence regarding human health effects specifically. Research on ingested microplastics' health impact in humans remains at an early stage, he notes, and it would be premature to draw firm conclusions about specific disease risks based on current evidence, even as the ecological accumulation patterns in wildlife are increasingly well documented.

Addressing the problem at its source is complicated by how deeply plastic is embedded in modern packaging and manufacturing, meaning Lindqvist sees no realistic prospect of eliminating new microplastic formation quickly. He points instead to a combination of approaches showing incremental promise: improved wastewater filtration capable of capturing smaller particles before they reach waterways, reduced reliance on single-use plastic in the first place, and continued monitoring to track whether concentrations in wildlife and water supplies are increasing or beginning to stabilise over time.