英検2級の生物多様性・外来種長文｜native・invasive・habitat・eDNAを読む独自4長文40問【全訳】

英検2級の生物多様性・環境語彙7語

試験形式：英検協会の2級一次試験では、長文内容一致は8問、題材はEメール・説明文です。環境や自然も主な話題に含まれます。本記事の40問は実戦前の補強演習であり、本番の問題数ではありません。英検協会公式・2級の試験内容

独自長文1｜在来植物と花粉を運ぶ昆虫｜native species・habitat

For years, the grassy area behind Maple School was cut every week. Last spring, the science club persuaded the school to leave three small sections unmowed during the flowering season. Students then planted forty native wildflowers in each section. Native species are plants or animals that occur naturally in a particular region, although this does not mean that every native species grows well in every location.

The club monitored pollinating insects for twenty minutes every Friday morning. During the first four weeks, students recorded an average of twelve insect visits per observation in the planted sections. In a nearby mowed section of similar size, they recorded an average of five. These were visits, not necessarily twelve different insects. One insect might visit more than once.

The students were pleased, but their teacher pointed out that the planted sections also received more sunlight. The team therefore could not conclude that native flowers alone caused the difference. Next year, they plan to compare plots with similar sunlight and repeat observations on additional days. They will also check whether the plants survive the winter before recommending a larger project.

本文根拠を選ぶ独自10問

独自長文2｜湖の外来植物と除去計画｜non-native・invasive・monitor

Silver Lake is home to several kinds of water plants. Two years ago, volunteers noticed a non-native plant growing near the northern shore. A non-native species has been introduced to an area from somewhere else. It is not automatically invasive. The lake committee uses the term invasive only when evidence shows that the introduced species spreads and causes, or is likely to cause, harm.

A survey this summer showed that the introduced plant had covered about eighteen percent of the shallow northern area, up from six percent the previous year. In the same period, volunteers found fewer spaces where native plants could grow. However, they had not measured all possible causes of that change, including water depth and seasonal temperature.

The committee approved a limited removal trial in two marked areas. Volunteers will remove the target plant by hand under professional supervision, while a third area will be monitored without removal. They will not use chemical treatments during this trial. Removing every introduced plant across the entire lake is not the plan.

After three months, staff will compare plant coverage and check whether native species have recovered. They also plan to inspect equipment to avoid carrying plant fragments to other lakes. The results will guide whether to continue or change the project.

本文根拠を選ぶ独自10問

独自長文3｜川のDNA調査｜detect・confirm・sample・evidence

Researchers wanted to learn whether a rare fish might still live in Brook River. Instead of catching fish, they collected water samples at six locations. Their method examined environmental DNA, or eDNA: small traces of genetic material that organisms leave in the environment. This technique can help researchers detect signs of a species without observing the animal directly.

Samples from two locations showed possible genetic traces of the rare fish. The other four did not. The researchers carefully described these as detections in water samples, not as confirmed sightings of living fish. Genetic material can sometimes move downstream, and samples can be affected by contamination or limitations of the test.

To reduce error, the team collected additional water samples on a second day, used clean equipment, and included control samples. The results again suggested the species might be present near one location. However, the team did not estimate the number of fish from the number of positive samples. Two positive locations do not necessarily mean two fish.

The scientists recommended continued monitoring and, if appropriate, a separate visual survey. They also asked the town not to advertise guaranteed fish sightings to visitors. Protecting the river habitat is useful even while questions about the species remain unresolved.

本文根拠を選ぶ独自10問

独自長文4｜都市公園の緑の回廊｜restore・connect・biodiversity

Greenfield City has three parks separated by wide roads and car parks. A local group proposed planting native flowers along a walking path between two of the parks. It called this a pollinator corridor because the planted areas might give insects additional places to find food as they move through the city. The project was not intended to create a complete forest between the parks.

The city provided funding for eighty plants and four information signs. The volunteers planted the flowers in April and recorded insect visits at the start and end of summer. Their initial counts averaged nine visits per observation. At the end of summer, the average was fifteen. The group was careful not to describe the increase as the number of new species; visits and species are different measures.

Maintenance turned out to be important. Twenty plants failed during an unusually dry month, and several signs were damaged. The group replaced some plants with locally suitable native varieties and asked residents to join watering shifts. Because these changes occurred during the trial, the volunteers could not isolate the effect of the original planting design.

The council will review the project’s costs in winter. It has not approved extending the corridor to the third park. Before expansion, the volunteers want to compare the path with an unplanted area and monitor which insects use the flowers.

本文根拠を選ぶ独自10問

40問正答一覧

長文1：1C／2A／3D／4B／5B／6D／7A／8C／9D／10B

長文2：11A／12C／13B／14C／15D／16A／17C／18A／19B／20D

長文3：21D／22C／23A／24B／25A／26D／27B／28C／29B／30A

長文4：31C／32D／33A／34B／35D／36C／37C／38D／39B／40A

3つの読み違いを防ぐ

① 外来＝侵略的ではない。non-nativeは他地域から来たこと、invasiveは生態系等へ害を与える性質や可能性があることを表します。② 訪問回数＝個体数ではない。昆虫1匹が複数回訪れる可能性があります。③ 検出＝目撃ではない。eDNAは種の手がかりとなりますが、単独で個体数や直接の目撃を保証しません。

7日間の復習手順

初日は4長文を解き、翌日に数値（40株・12回・5回・18％・6％・2地点など）を本文の対象ごとに表へ分けます。3日目はmay・might・not necessarily・cannot concludeを探して、言い過ぎた選択肢を修正します。7日目に誤答を解き直し、原文で正答根拠を確認してください。

よくある質問

non-nativeとinvasiveは同じですか？

同じではありません。外来種であることだけで、侵略的であると断定できません。本文に拡散や被害の証拠があるかを確認します。

昆虫が12回訪れたら12種類の昆虫が来たのですか？

いいえ。同じ個体が複数回来た可能性があり、訪問回数と個体数・種類数は別です。

環境DNAが検出されたら魚の匹数がわかりますか？

通常、検出数だけでは匹数を確定できません。検査方法・試料の条件・追加調査などが必要です。

この教材は英検協会の過去問ですか？

いいえ。慶英会が作成したオリジナル問題です。

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長文読解や英文要約が難しい場合は、慶英会の最大1か月無料体験・学習相談をご利用ください。

参照情報

公益財団法人日本英語検定協会・2級の試験内容。教材の英文・数値・設問・解答・和訳は慶英会オリジナルです。