Habitat, niche and interactions

A niche is the role of a species in an ecosystem, including how it uses resources and interacts with other species.

True. It includes role, resource use and interactions, not just location.

Resources are things organisms need to survive, such as food, water, light, space or shelter.

Niche overlap is when two species use the same resources in the same way and place/time.

Habitat is where a species lives; niche is how it lives (its role and resource use).

True. Habitat is the place or physical environment where a species lives.

If resources are limited, both species demand the same resource, reducing growth, survival or reproduction for at least one.

Food type and feeding method; activity time; abiotic tolerances; interactions (predator, competitor, pollinator).

Competition (often caused by niche overlap).

State feeding role, key interactions, and the abiotic conditions needed for survival.

One species may be outcompeted and decline locally, reducing biodiversity.

By resource partitioning: using different food types, locations, or activity times (different niches).

Their niches overlap, so competition is likely unless resources are abundant or they separate by time/place.

More available niches allow species to specialise and coexist with less direct competition.

More niches usually allow more species to coexist, increasing biodiversity.

Births, deaths, immigration and emigration.

Predation is an interaction where a predator hunts, kills and eats a prey organism.

Carrying capacity is the maximum population size an environment can support sustainably over time.

Because counting every individual is usually impossible; sampling estimates population size from a representative subset.

The maximum population size the environment can support sustainably over time.

Competition is the demand by two or more organisms for the same limited resource.

Quadrats are used to sample non-mobile organisms (mainly plants) to estimate density, frequency or percentage cover.

The prey population peaks first; the predator peak usually lags behind.

A limiting factor is an environmental factor that restricts population growth, size or distribution.

Prey peaks first; predator peaks later due to time lag.

Liebig’s Law of the minimum.

Negative feedback is a process that reduces change and returns a population towards balance (for example predators increase when prey increase).

A transect is used to show how species or abundance change across an environmental gradient (for example shore to land).

Population growth is limited by the factor in shortest supply, even if other resources are abundant.

Mutualism benefits both species; parasitism benefits the parasite while harming the host.

Non-mobile organisms, mainly plants (and very slow animals).

A time lag is a delay between a change in one population and the response of another population.

Density-dependent: competition, disease, predation. Density-independent: drought, flood, fire, storm.

N = (n1 × n2) / m, where n1 is marked first, n2 is caught second, and m is recaptured marked.

Pathogens spread faster when population density is high because individuals contact each other more often.

N = (n1 × n2) / m.

Identify the lowest bar and state it is the limiting factor because it caps population size.

Describe the pattern (rise, fall, oscillation, time lag) before explaining the cause.

Name the interaction and state who benefits and who is harmed (or how resources are affected).

The population is closed (no immigration/emigration) and marks are not lost and do not affect survival or capture.