Organisms in environment

• Population

  Total number of all organisms of the same species in a geographical area
• Community

  Group of 2 or more populations of different species in the same geographical area
• Habitat

  Natural environment of a living organism
• ecosystem

  A community of living organisms and the non living parts of their environment
• Biotic factors

  Living parts of the environment
• Abiotic factors

  Non living parts of the environment
• Biodiversity

  Measure of the variety of all the different species of organisms on earth Or within a particular ecosystem
• Measures:

  • number of different species present (species richness)
  • relative abundance of each species ( evenness of numbers)
• Trophic level

  A stage in a feeding relationship which represents an organism in a food chain or a group of organisms in a food chain
• Organisms in the first trophic level make food by photosynthesis ( producer) + how they get energy
• Pyramid of biomass is always pyramid shaped
• The amount of energy at each trophic level decreases as it moves through an ecosystem. As little as 10 percent of the energy at any trophic level is transferred to the next level; the rest is lost largely through metabolic processes as heat
• Producers always have a large biomass than the rest because producers consist of plants and they can get energy from doing photosynthesis which allows them to build up a large amount of biomass
• To show the flow of energy through ecosystems, food chains are sometimes drawn as energy pyramids. Each step of the pyramid represents a different trophic level, starting with primary producers at the bottom. The width of each step represents the rate of energy flow through each trophic level.