Kingdom Monera
Bacteria are referred to as monerans. Monerans consist of bacteria and blue-green algae which is also called cyanobacteria. They are microscopic, which means they can't be seen with the naked eye, as they are unicellular. They are just about everywhere. Bacterial cells are smaller than plant and animal cells. A typical bacterial cell wall is surrounded by a cell membrane and a cell wall, and there is a liquid material called cytoplasm that fills the cell. Bacterial cells are prokaryotes, which means they do not contain a nucleus or other internal structures common in plant and animal cells. Most bacteria are quite harmless, like the ones that are used in making food (e.g. acidophilus bacteria is used in making yogurt), but some bacteria do cause harm, like the streptococcus bacteria that can give humans a strep throat. Monerans play a very important role in decomposing once living things. They are used in waste water treatment plants to help digest and eliminate waste products. Bacteria are believed to have existed on Earth for at least 3.5 billion years, and are thought to be the first living things to inhabit the planet. There is a wide variety of bacteria. Scientists often classify bacteria based on their shapes. Their three main shapes are cocci (spherical shape), bacilli (rod shape), and spirilla (spiral shape). Scientists are not in complete agreement on how to classify monerans, but another system of classification separates monerans not two distinct kingdoms: eubacteria and archaebacteria. Eubacteria are everywhere around us (e.g. if you have an infected cut, eubacteria are likely responsible for the infection). The organisms within the eubacteria kingdom are diverse, so scientists made a wide variety of characteristics to classify them (e.g. aerobic (e.g. salmonella) or anaerobic, autotrophic (e.g. cyanobacteria) or heterotrophic (e.g. Escherichia coli), etc.). Archaebacteria are the extreme monerans of the bacterial world (many live in extreme or hostile environments). Archaebacteria tend to be chemosynthetic, meaning they produce energy from chemicals in their environment. Archaebacteria are classified based on where they live and how they obtain their energy.
Kingdom Protista
Protists, like monerans, are microscopic. Some examples are amoeba, paramecium, kelp, and diatom. Protists vary widely in shape, size, and form, and can be unicellular or multicellular. Protists are eukaryotic, meaning they have a nucleus and other structures in their cells, which are not found in prokaryotic cells. Protists are divided into numerous different phyla and the classification of these organisms changes periodically. There are three different kinds of protists: animal-like protists, fungus-like protists, and plant-like protists. Animal-like protists are also referred to as protozoans. Protozoans need to eat other things for their energy. Protozoans are often grouped by how they move: ciliates move by tiny hairs called cilia, which move back and forth, rapidly propelling the the organisms through water, classic ciliates are paramecium, ciliates posess one or more nuclei, and a food vacuole which is used to digest food; flagellates move by waving a whip-like flagella back and forth; sarcodines (e.g. amoebas) move by a pseudopod (false foot), have no definite shape, and feed by engulfing its prey. Amoebas have a nucleus and a food vacuole and reproduce by binary fission. Fungus-like protists are heterotrophs, meaning they need to eat other living things or once living things. Fungus-like protists can attack potato plants, corns, cabbages, and grapes. One type of fungus-like protists is slime mold. At some stage in their lives, slime molds form a moist, shapeless ooze that forms on once living things, such as dead trees. Slime molds reproduce via small structures called spores, which give rise to cells. Plant-like protists are autotrophs, producing their own food from the sun's light energy. An important by-product of this process is oxygen. It is thought that plant-like protists produce about 70% of Earth's oxygen supplies. There are a wide variety of plant-like protists, ranging from unicellular organisms to large, multicellular algae. Plant-like protists are often referred to as algae. There are a few different kinds of plant-like protists: euglena, diatom, dinoflagellate, green algae, red algae, and brown algae. Euglena has a whip-like flagellum with which it propels itself, and has the ability to make food from the sun's energy in the absence of light (they become heterotrophic). Diatom is microscopic and has a glass-like shell. It lives in water. Many possess beautiful geometric shapes. When it dies, it collects in the bottom of the ocean and forms a coarse, powdery diatomaceous earth, that serves as an excellent polishing agent. Dinoflagellate can be autotrophic or heterotrophic. It is unicellular algae. It is found mostly in oceans. The action of flagella causes the cell to twirl or roll in the water. Some can cause a very serious problem referred to as red tide. Some of the dinoflagellates responsible for the red tide possess a powerful toxin which can be very harmful to humans who eat shellfish contaminated by toxic dinoflagellates. Green algae (e.g. sea lettuce), red algae (e.g. Irish moss, which is found along the intertidal zone, this algae contains a substance called carrageenan, which is used to thicken ice-cream and other products), brown algae (e.g. kelp, giant kelp can reach over 100m) are broadly categorized based on the dominant pigment they contain. They are common in both freshwater and saltwater, in unicellular and multicellular forms.