All organisms of all populations in an ecosystem

the non-living / physical part of an ecosystem that can affect population size

Two examples of biotic factors that affect the population size of an organism

The study of inter-relationships between organisms & their environment This environment includes living (biotic) factors (e.g. competition & predation) & non-living (abiotic) factors (e.g. temperature & rainfall).

A line along which organisms can be sampled in ecological studies. Particularly useful in ecosystems such as sea shores and sand dunes where abiotic conditions and species vary across the area being studied.

competition between organisms of DIFFERENT species e.g. for food

The range and variety of genes, species and habitats within a particular ecosystem

a sampling area used for measuring the frequency or percentage cover of organisms (plants or slow moving organisms)

the category of living factors in the environment of an organism that affect population size

Competition between organisms of the SAME species e.g. for food or mates

When using a quadrat to estimate population size, we use a random number generator to avoid what?

Differences between organisms of the same species