Basic Ecology Concepts

Population density is defined as the number of individuals of a species per unit area. It measures how crowded a population is within a specific space.

Population size changes due to births, deaths, immigration, and emigration. 'Lost members' is not a standard scientific term used to describe these demographic processes.

Direct observation, sampling, and mark-and-recapture are all standard scientific methods for estimating population size. A 'guesstimate' is an informal term and not a scientific method.

An ecosystem consists of the community of living organisms (biotic) interacting with the non-living (abiotic) components of their environment.

A community is defined as all the different populations of organisms that live together in a particular area. A biome is a much larger regional ecosystem.

A population is defined as all members of the same species living in a specific area at the same time.

The biological species concept defines a species as a group of organisms that can interbreed and produce fertile offspring.

Abiotic factors are the non-living parts of an ecosystem, such as water, air, sunlight, and soil. Option A provides the most comprehensive list of these factors.

Biotic factors include all living or once-living components of an ecosystem. This includes organisms, their remains, and products like waste or organic matter.

A habitat is the specific environment where an organism lives, providing the necessary resources like food, water, and shelter for survival and reproduction.

The hierarchy of biological organization in ecology is: organism, population, community, ecosystem. Option B correctly follows this progression from smallest to largest.