Population — Science definition
Defined in 3 courses:
- All the individuals of one species in a defined area at a defined time; both the boundary and the date are part of the definition. (Life Science & Scientific Inquiry)
- All the members of a single species living and interbreeding in the same area at the same time. (Life Science: Biology)
- A group of individuals of the same species living in the same area, whose size changes with births, deaths, immigration, and emigration. (Physics & Environmental Science)
Where it is taught
- Habitats, Resources & Population Change — Ecosystems, Matter & Energy, Life Science & Scientific Inquiry, Grade 7
- Populations & Communities — Ecosystems & Conservation Decisions, Life Science: Biology, Grade 10
- Population Ecology — Ecology, Populations & Biodiversity, Physics & Environmental Science, Grade 12
In use
The lichen that had taken centuries to accumulate was gone, a severe winter finished what overgrazing had started, and the population collapsed almost completely.
Habitats, Resources & Population Change
A population is all the members of one species living together in the same place — every gray wolf in a valley, every cattail in a marsh.
Populations & Communities
A population is a group of one species in one place, and its size is bookkeeping: it rises with births and immigration and falls with deaths and emigration.
Population Ecology
Questions using population
Problem 1
Answer and explanation
The modeled population ends at 55, a net increase of five. The same net change could result from other combinations of births, deaths, and movement. Before-after counts alone do not identify the mechanism; pathway observations, boundaries, and detection methods are needed. This model does not establish a permanent habitat capacity.
Gains: 12+5=17.
Losses: 8+4=12.
End: 50+17−12=55.
Response criteria
- Explain the relevant biological process accurately.
- Use the supplied evidence and show calculation steps with units where needed.
- Connect a labeled model or mechanism with the claim.
- State an assumption, evidence limitation, or useful next observation.
Problem 2
Answer and explanation
No. More effort can detect more individuals. Use comparable survey effort and methods before interpreting the difference as true growth.
Response criteria
- Explain the relevant biological process accurately.
- Use the supplied evidence and show calculation steps with units where needed.
- Connect a labeled model or mechanism with the claim.
- State an assumption, evidence limitation, or useful next observation.
Problem 3
Answer and explanation
43 individuals
40+10−7=43.
Problem 4
- the carrying capacity
- twice the carrying capacity
- an ever-increasing value
- zero
Answer and explanation
the carrying capacity
Logistic growth flattens out at the carrying capacity (K), where birth and death rates roughly balance.
Taught alongside
- community
- biotic factor
- abiotic factor
- carrying capacity
- exponential growth
- logistic growth
- limiting factor
- symbiosis
- carrying capacity (K)
- survivorship curve