Biology 1009 - Lab - Rebecca Teed

Classification Study Sheet: Some Basic Distinctions

All living things use energy, and store it in the form of chemical bonds. Where does it come from?
Heterotrophic organisms use energy previously stored by other organisms (taking it from their corpses, living bodies or waste products.
Autotrophic organisms obtain energy from non-living sources. Photoautotrophs use light-fixing pigments to convert sunlight into stored chemical energy for themselves. Chemautotrophs oxidize iron, sulfides, nitrate, or ammonia. These reactions release energy, which the chemautotroph fixes and uses for itself. Note that organisms which use biologically-produced chemicals (like rnethane) for energy are considered heterotrophs.
Every kingdom except Plantae contains heterotrophs (all of the Animalia and Fungi are obligate heterotrophs). Carnivorous plants are not heterotrophs; they exploit their prey for nitrogen, not for energy. Some Protista, some Monera, and all Plantae are photoautotrophs (certain Protista are facultative photoautotrophs, all the other organisms mentioned are obligate photoautotrophs). Only certain Monera are chemoautotrophs.

Prokaryotic organisms do not have internal membranes with which to wall off their nuclei, nor do they have organelles that would ordinarily be bounded by membranes, such as mitochondria or chloroplasts. All Monera are prokaryotes and all prokaryotes are Monera. Some prokaryotes are capable of aerobic respiration and some are not.
Eukarotic organisms (the other four kingdoms) are more complex, their cytoplasm and nuclei partitioned by the nuclear membrane. Most have mitochondria (where oxidation of sugar takes place), and some (Plantae and certain Protista) also have chloroplasts (which fix light into sugar) as well. These organelles not only have membranes between them and the cytoplasm, they also contain some of their own DNA. It is thought that mitochondria were originally symbiotic bacteria which performed aerobic respiration for the host and that chloroplasts were symbiotic Cyanobacteria enabling the host to photosynthesize. Their DNA is graduaily being incorporated into the hosts' nuclei (it is partway there already in animals and plants).

Unicellular organisms (all Monera except certain Cyanobacteria and many or all Protista (depending on whether algae are Protista)) consist of only one cell which performs all their necessary functions. Colonial organisms are made up of many cells, but these are capable of splitting up and functioning as unicellular organisms (but may not be able to reproduce separately). Colonial organisms include a few Moneran species (such as stromatolite-forming Cyanobacteria), some Protista, and some Plantae (depending on where various kinds of algae are classified), some Fungi (slime molds), and some Animalia. The cells of multicellular organisms cannot survive separately.

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