交換表面：小さなサイズと薄いバリアが重要である
導入済み| English | 意味 |
|---|---|
| surface-area-to-volume ratio/ˈsɜːfɪs ˈeərɪə tə ˈvɒljuːm ˈreɪʃɪəʊ/ | 表面積体積比 |
| exchange surface/eksˈtʃeɪndʒ ˈsɜːfɪs/ | 交換表面 |
What would explain this observation?
- A large animal cannot rely on diffusion through its outer surface to supply every cell quickly. Size changes the area available relative to the volume needing materials.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- A single-celled organism has a relatively large surface-area-to-volume ratio 表面积体积比, allowing enough transport across its surface. Larger multicellular organisms need specialized exchange surfaces 交换表面 and transport systems. Large area, thin membranes, efficient blood supply and ventilation improve exchange when relevant to the organ.
- surface-area-to-volume ratio: Surface area compared with the volume of the same object; exchange surface: A surface adapted for transfer of substances.
薄い肺胞壁が急速なガス交換を支持するのはなぜか
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拡散速度は距離とともに急激に低下するため、一細胞層の肺胞壁は短い経路で急速な交換を可能にする。壁は分子を遮断せず、染色体数は無関係である。
各専門用語を正確な意味と対応させよ。
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関連する物理量やプロセスを区別するために定義を使用せよ。
Choose evidence that can test it
- Villi give the small intestine a large absorbing area. Lungs have many alveoli with thin surfaces, a blood supply and ventilation. Fish gills provide a large exchange surface supplied with blood. Root hairs increase plant absorbing area, while leaves provide a large gas-exchange surface and short paths through their tissues.
- Compare cubes or labelled organ models using the same units. For a cube of side L, area=6L² and volume=L³. Link each organ feature to how it increases transfer or maintains a concentration difference; do not simply list “large area” without naming the structure.
この場合、調査やモデルをより妥当にする2つの習慣は何か。
難易度 2/5 · 140 コイン + 今日初回完了時に小ボーナス付与
条件や仮定を明記することで他者が正確に再現でき、根拠となる証拠を記録することで結論を検証できます。相反する結果を隠すと、誤った結論を疑う証拠を失いますし、単一の測定でより広い主張を成立させることはできません。
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: a cube of side 1 cm has area 6 cm², volume 1 cm³ and ratio 6:1. At side 2 cm, area=24 cm² and volume=8 cm³, giving 3:1. Length doubles, but area grows fourfold and volume eightfold. Less surface per unit volume helps explain the need for internal exchange systems.
A cube has side 3 cm. Calculate surface area divided by volume. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
一辺が3cmの立方体がある。表面積を体積で割った値を計算せよ。
難易度 2/5 · 140 コイン + 今日初回完了時に小ボーナス付与
結果は 2 /cm である。既知：立方体の辺 3 cm。表面積 = 6 × 3^2 = 54 cm^2；体積 = 3^3 = 27 cm^3。比率 = 54/27 = 2 /cm。大きい立方体ほど比率は小さく、これが大型生物が交換系を必要とする理由である。
Check the conclusion and its limits
- A bigger object has more total surface area but can have less surface per unit volume. Blood flow and ventilation maintain gradients rather than make molecules choose a direction. Plant roots and leaves do not use animal blood vessels.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Doubling a cube’s side doubles both its surface area and its volume. This claim is false: Area scales with the side squared and volume with the side cubed: doubling the side multiplies area by 4 and volume by 8. Equal scaling of both is impossible.
Exchange surfaces: small size and thin barriers matter: Villi give the small intestine a large absorbing area. Lungs have many alveoli with thin surfaces, a blood supply and ventilation. Fish gills provide a large exchange surface supplied with blood. Root hairs increase plant absorbing area, while leaves provide a large gas-exchange surface and short paths through their tissues.
立方体の辺長を倍にすると、表面積も体积も倍になる
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
面積は辺の二乗に比例し、体積は辺の三乗に比例する。辺を倍にすると面積は 4 倍、体積は 8 倍になる。両者を同じように増やすことはできない。
同じ物体の体積に対する表面積: 技術用語を記せ
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
表面積と体積の比とは、同じ物体の表面積をその体積で比較したものです。