BioenergeticsObjectives 3.1 to 3.4

Energy and Nutrient Flow

Definition of terms: Ecosystem: a self-contained community

of interacting organisms and their physical environment.

Habitat: the place where an organism lives.

Ecological Niche: the role of a species in a community including it’s position in the food chain and interactions with other species and the physical environment.

Energy Flow Food Chain: A diagram that shows flow of energy in

an ecosystem between named organisms at 2 or more trophic levels.

Trophic Level: the feeding level in a food chain.-Producer: autotrophic organism that uses either light energy or energy from simple chemical reactions to produce biological molecules.-Consumer: a heterotrophic organism that feeds on producers and/or consumers.

Food Web: A diagram that shows many interrelated food chains in an ecosystem.

Ecological Pyramids

Pyramids of Numbers Pyramids of Biomass Inverted Pyramids Pyramids of Energy

Ecological Deficiency Ecological Deficiency = energy available to a tropic level X

100 energy consumed by previous tropic level

This shows what percentage of the energy consumed by one trophic level is available to the next.

The Nitrogen CycleFacts about nitrogen: N2  is an unreactive molecule due to the

presence of a strong triple bond which also makes it not readily available to organisms

Nitrogen is an important component of biological molecules

Main processes in the Nitrogen Cycle:

 Amination: Autotrophs use nitrate ions to make amino acid. Nitrates(NO3)  in the soil are reduced to nitrites(NO2)which are then further reduced to ammonia(NH4). Ammonia then attaches itself to the products of the Calvin Cycle to form amino acids.

Ammonification: Decomposers break down excreted and egested materials in the soil as well break down the dead remains of plants and animals into ammonium compounds.

Nitrification: Conversion of ammonia to nitrates. Some bacteria use ammonia in their energy transfer reactions and oxidize it to nitrite ions. Other bacteria then use these nitrite ions (in similar reactions) and excrete nitrate ions

Denitrifiction: conversion of nitrite ions to atmospheric nitrogen. Usually carried out by bacteria which provide themselves with energy by reversing nitrogen fixation

Group Members