Dichotomous Key A series of paired statements that describe physical traits used to identify and classify organism.

Groups of Living Things

Viruses Not actually a living thing because it is not capable of performing the majority of life functions. Examples include flu, cold, chicken pox, warts, polio, and small pox. The structure of a virus is a protein coat (capsid) that surrounds genetic information. The capsid is used to trick cells so the virus can attach and inject the genetic material.

Eubacteria Bacteria that are found in almost every condition except extremely harsh environments. Examples include strep throat, tetanus, tuberculosis, and E. coli Bacteria cells are prokaryotic (no nucleus or organelles). The majority of bacteria are going to be unicellular; however, some bacteria form cooperative groups called colonies. The cell wall contains peptidoglycan.

Archeabacteria Bacteria that are found in extremely harsh environments. These bacteria are thought to be the ancestors of eukaryotic organisms. Examples include bacteria that live in hot springs. Bacteria cells are prokaryotic (no nucleus or organelles). The majority of bacteria are going to be unicellular; however, some bacteria form cooperative groups called colonies. The cell wall does not contain peptidoglycan.

Protists This is a catch all category. If the cell is eukaryotic (has a nucleus) but the organism cannot be classified as a plant, fungus, or animal for any reason it is classified as a protist. Examples include ameba, euglena, paramecium, and diatoms. The cells are eukaryotic and most are unicellular. Some have cell walls. Some have cilia and flagella for movement.

Fungi Heterotrophic organisms that digest and absorb food from the structures they live on. Examples include mushrooms, yeast, ringworm, athletes foot, lichens, and mycorrhizza. The cells have a nucleus (eukaryotic) and a cell wall made of chitin. The bulk of the fungus is a chain of single cells called mycelium that cannot be seen by humans. The visible structure is called the fruiting body and is the reproductive structure of the fungus.

Green Algae Plants that are made up of individual cells that live in masses. They do not have specialized cells to perform different functions. A large mass of algae is called a bloom. Plants are autotrophic. Examples include volvox, and fresh water algae. The cells of algae are plant cells (eukaryotic) with a cell wall made of cellulose and chloroplasts to produce sugars. Some types of algae have cilia and flagella to allow them to move.

Bryophytes Plants that have specialized cells, but do not have vascular tissue to transport materials around the body, seeds, or flowers. Mosses are very cold tolerant making them the only plant that can live at the poles. Examples include mosses, liverworts, and hornworts. Plant cells are eukaryotic with cell walls made of cellulose and chloroplasts to make sugar.

Seedless Vascular Plants Plants that have vascular tissue (xylem and phloem) but they do not produce seeds or flowers. They reproduce by creating spores. Most are tolerant of low light conditions. Examples include ferns, club mosses, and horsetails. Plant cells are eukaryotic with cell walls made of cellulose and chloroplasts to make sugar.

Gymnosperms Plants that have vascular tissue to transport material and create seeds for reproduction but the seeds are not produced inside flowers, they are made on cones. Examples include conifers, cycads, ginkgoes, and gnetophytes. Plant cells are eukaryotic with cell walls made of cellulose and chloroplasts to make sugar.

Angiosperms Plants that have vascular tissue to transport materials and produce seeds inside of flowers. Examples include pecan trees, water lilies, grasses, carrots, broccoli, and roses. Plant cells are eukaryotic with cell walls made of cellulose and chloroplasts to make sugar.

Porifera Simplest animals. They do not have symmetry (asymmetrical). Some of the cells have cilia or flagella in order to push water through the animal because that is how they will eat, obtain oxygen, and remove waste. Examples include sponges. Animal cells are eukaryotic cells that lack a cell wall and chloroplasts.

Cnidarians Radially symmetrical animals that posses nematocysts which are stinging cells. Examples include jellyfish, sea anemones, and corals. Animal cells are eukaryotic cells that lack a cell wall and chloroplasts.

Platyhelminthes Animals that have three different layers of tissue, several organ systems, cephalization (organization of nervous tissue creating a head) and sensory organs including eye spots. Examples include flatworms such as planaria and tapeworms. Animal cells are eukaryotic cells that lack a cell wall and chloroplasts.

Nematodes Worms that are not segmented but they do posses a one way digestive tract. These worms also have a tough outer skin that must be molted in order to grow suggesting they are more related to arthropods than other worms. Examples include roundworms and hookworms such as heartworms in dogs. Animal cells are eukaryotic cells that lack a cell wall and chloroplasts.

Annelids Animals that have segmented bodies, a closed circulatory system (blood stays in blood vessels), and a one way digestive tract. Examples include leeches and earthworms. Animal cells are eukaryotic cells that lack a cell wall and chloroplasts.

Arthropods Most varied group of animals that have exoskeletons, segmented bodies, open circulatory systems, and jointed appendages. Many also posses wings. Examples include: Crustaceans such as crabs, lobster, and shrimp Chelicerae such as spiders, ticks, mites, scorpions, and horseshoe crabs. Uniramia such as centipedes millipedes, and insects. Animal cells are eukaryotic cells that lack a cell wall and chloroplasts.

Mollusks Animals that have soft bodies and a muscular foot. Some have external shells and some have internal shells that have modified. Examples include snails, slugs, clams, squid, octopi, and nautilus. Animal cells are eukaryotic cells that lack a cell wall and chloroplasts.

Echinoderms Animals that have spiny skin and a unique water vascular system to transport nutrients, get rid of waste, and exchange oxygen and carbon dioxide. Examples include starfish, sea cucumbers, brittle stars, sand dollars, and sea urchins. Animal cells are eukaryotic cells that lack a cell wall and chloroplasts.

Fish Animals that have scales, paired fins, a lateral line to detect water movement and gills. Examples include Jawless fish such as the lamprey and hagfish Cartilaginous fish such as sharks, skates, and rays. Boney fish such as perch and sea horses Animal cells are eukaryotic cells that lack a cell wall and chloroplasts.

Amphibians Animals that have thin moist skin so that they can move oxygen across it, no scales or claws, and live a double life. As juveniles they live in water with gills and no limbs. As adults they live mostly on land with lungs and strong appendages. Examples include frogs, salamanders, and toads. Animal cells are eukaryotic cells that lack a cell wall and chloroplasts.

Reptiles Animals that are exothermic, and have thick dry scaly skin, and claws. Examples include snakes, turtles, alligators, crocodiles, and lizards. Animal cells are eukaryotic cells that lack a cell wall and chloroplasts.

Birds Animals that are endothermic, have efficient body systems, are covered in feathers, and have modified front limbs called wings. Examples include birds of prey, song birds, and water fowl. Animal cells are eukaryotic cells that lack a cell wall and chloroplasts.

Mammals Animals that are endothermic, have efficient systems, have mammary glands to produce milk for young, and have hair. Examples include Monotremes such as a platypus and echidna Marsupials such as kangaroos, koalas, and opossums. Placental such as humans, bears, and dogs. Animal cells are eukaryotic cells that lack a cell wall and chloroplasts.