Organisms and their environment

explain in terms of energy loss why food chains usually have fewer than five trophic levels

energy is lost between trophic levels via respiration

advantages of using a pyramid of biomass rather than a pyramid of numbers to represent a food chain

accounts for organism size; always pyramid-shaped; gives accurate representation of available food/energy at each level

advantages of using a pyramid of energy

most accurate representation; shows actual energy transfer over time

Nitrogen fixation in root nodules

nitrogen-fixing bacteria in root nodules convert nitrogen gas into ammonia; plants use fixed nitrogen to build amino acids

decomposition to nitrate ions

decomposers (bacteria/fungi) break down dead protein into amino acids; deamination releases ammonia; nitrifying bacteria convert ammonia to nitrites then nitrates

desc. the role of Nitrifying bacteria

converts ammonia/ammonium ions into nitrites and then nitrates; makes nitrates available for plant absorption to synthesize proteins

Describe a population

group of organisms of one species living in the same area at the same time

Describe a community

all of the populations of different species living in an ecosystem

Describe an ecosystem

unit containing a community of organisms and their environment interacting together