Sampling populations without choosing the answer
導入済み| English | 意味 |
|---|---|
| population/ˌpɒpjʊˈleɪʃn/ | 個体数 |
| quadrat/ˈkwɒdræt/ | 四角区画法 |
What would explain this observation?
- A field edge looks richer in plants than its centre. Choosing only the richest patches would build the desired result into the sampling method.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- A population 种群 consists of organisms of one species in a defined area. Random quadrats 样方 estimate density without deliberately selecting patches. A transect investigates change along an environmental gradient.
- quadrat: A defined area used for sampling; population: Organisms of one species in a defined area.
Which method investigates change from a path into woodland?
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
A transect samples at fixed distances along a line, so the change from open path into woodland is recorded systematically. Choosing only large plants or one convenient spot biases the sample and cannot show a gradient.
Match each technical term to its precise meaning.
難易度 2/5 · 140 コイン + 今日初回完了時に小ボーナス付与
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Estimate total abundance by multiplying mean density by area, with consistent units. This assumes sampled areas represent the habitat. Patchiness and too few samples widen uncertainty.
- Choose coordinates with random numbers before visiting the patches. Record quadrat area and counting rules. For a transect, use fixed distances and measure a relevant abiotic variable. Do not damage habitats or sample unsafe locations.
Which two habits make the investigation or model in this case more defensible?
難易度 2/5 · 140 コイン + 今日初回完了時に小ボーナス付与
Stating the conditions and assumptions lets others repeat the work exactly, and recording the supporting evidence lets them check the conclusion. Hiding disagreeing results removes the evidence that could challenge a wrong conclusion, and one measurement can never establish a wider claim.
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: five 0.25 square metre quadrats contain 3, 4, 6, 5 and 2 plants. Mean count = 20/5 = 4. Density = 4/0.25 = 16 plants per square metre. Estimated abundance in 100 square metres = 16 × 100 = 1,600 plants.
Mean count is 6 in a 0.5 square metre quadrat. Find density per square metre. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
Mean count is 6 in a 0.5 square metre quadrat. Find density per square metre.
難易度 2/5 · 140 コイン + 今日初回完了時に小ボーナス付与
The result is 12 . Known: mean count 6 plants per 0.5 square metre quadrat. Use density = mean count / quadrat area. Density = 6/0.5 = 12 plants per square metre. An abundance estimate scales this density up to the whole area.
Check the conclusion and its limits
- Quadrats suit organisms that do not move quickly. A food chain arrow shows the direction of energy transfer, not the direction a predator travels.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Sampling only the most crowded patches gives an unbiased population estimate. This claim is false: Choosing the most crowded patches overestimates density, because the samples are not representative of the whole area. Unbiased estimation needs random or systematic sampling decided before looking at the plants.
Sampling populations without choosing the answer: Estimate total abundance by multiplying mean density by area, with consistent units. This assumes sampled areas represent the habitat. Patchiness and too few samples widen uncertainty.
Sampling only the most crowded patches gives an unbiased population estimate.
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
Choosing the most crowded patches overestimates density, because the samples are not representative of the whole area. Unbiased estimation needs random or systematic sampling decided before looking at the plants.
A defined area used for sampling: write the technical term.
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
quadrat means A defined area used for sampling.