Ecology and Populations

Ecology The scientific study of interactions between organisms and the environment. Biosphere: all the inhabitable parts of Earth. Species: a group of organisms that is closely related enough to breed and produce fertile offspring.

Populations and Communities A population is a group of the same species that live in the same area. A community is all of the different species living in the same area. An ecosystem is all the living and non-living things in an area. A biome is a collection of all the related ecosystems in the world.

Energy Flow Autotrophs (producers): make their own energy from sunlight. Heterotrophs (consumers): obtain energy from eating other organisms. Trophic levels are the steps in a food chain or food web.

Food Webs and Food Chains A food web shows all of the possible feeding relationships in a community. A food chain is a single path from autotroph to higher order consumer.

Genes in Populations v. Individuals Populations evolve just as species do. Genotype: the genetic composition of an individual. Gene Pool: the genetic composition of a population. All the possible alleles for all the genes in a population. Evolution: a change in a populations gene pool.

Hardy-Weinberg Principle Allele frequencies within gene pools remain constant from one generation to the next, in sexually reproducing populations, if certain conditions are met.

Conditions for Hardy-Weinberg No mutations. No net movement into or out of the population. Mating is random. No natural selection. Population is large.

Cycles of Matter There are four major cycles of matter in the biosphere. They are the Water Cycle, the Carbon Cycle, the Nitrogen Cycle and the Phosphorous Cycle.

Water Cycle

Nitrogen Cycle

Carbon Cycle

Phosphorous Cycle