4.3 explain how quadrats can be used to sample the distribution of organisms in their habitats.

A sample square is taken at random. The number of a population in that square is taken. This is repeated in different areas and compared to show where populations are dense and not.

4.2 explain how quadrats can be used to estimate the population size of an organism in two different areas

A square of around a meter takes a sample from a area and the populations are counted. This can be repeated many times before being multiplyed out as if it were the complete area of the land. Two different samples can be put in two separate areas and the sampling done for both will estimate population for both areas.

4.1 understand the terms population, community, habitat and ecosystem

Population

Number of individuals in a particular species.

Community

Populations of different species interacting.

Habitat

The area where a population lives.

Ecosystem

A community in a particular habitat made up of different populations interacting with in the habitat.