Aboral - the side of an echinoderm that is opposite the mouth. In sea stars (starfish), the mouth is on the underside of the animal and the aboral surface is the top surface.

Aerobic - Requires oxygen

Alcohol - Organic molecules that contain one or more hydroxyl (OH) groups

Amoeboid cells are cells that resemble an amoeba. They do not have a cell wall and are therefore flexible. They move by extending portions of the cell (pseudopods) and creeping on the substrate.

Anaerobic - Does not require oxygen

Appendage - an external structure such as an arm, leg, antenna, or branch.

Aquatic - lives in water. Aquatic organisms live in water environments, either freshwater or marine.

Autotrophs are organisms that make their own organic food. The energy to synthesize organic food usually comes from the sun (photosynthesis) or high-energy chemicals (chemosynthesis).

Budding 1) Budding is a form of mitosis in which a small cell pinches off from a larger one. 2) In animals, budding refers to a form of asexual reproduction in which a smaller individual breaks off of a larger, parent individual.

Calcareous - contains calcium. The exoskeletons of crustaceans are impregnated with calcium to harden them.

Carapace - a hard, protective covering on the dorsal surface of animals.

Carnivore - an animal that feeds on other animals.

Cloaca - A common exit in an animal body for both the digestive and excretory system. The reproductive system may also exit via the cloaca.

Colony - A colony is a loose association of independent cells in which there may be some cells specialized for reproduction.

Conjugation - Conjutation is a mecnanism that allows sexual reproduction between two cells. Conjugating cells form a connection between the two so that DNA can be transferred from one to the other. Conjugation is common in prokaryotes, protists, and fungi.

Dimers - Molecules that have two components.  For example, tubulin dimers are composed of two molecules of the protein tubulin.

Diploid refers to cells that have a nucleus (or nuclei) that contains two complete sets of chromosomes.

Dormancy is a period of inactivity. During dormancy, the metabolic rate (rate of chemical reactions within the cells) is low, so little water, oxygen, and food is needed. The ability to become dormant allows some organisms to survive environmental extremes when food and/or water are scarce. Plant seeds are dormant before they germinate. Hibernation in animals is a form of dormancy.

Endemic refers to species that are found only in one area. For example, species endemic to Lake Baikal are found only in Lake Baikal and nowhere else.

Filament - An arrangement of cells to produce a hairlike strand. Each cell in the filament is joined end to end.

Food chain refers to a path of energy flow in a community. Initially, solar energy is captured by photosynthetic organisms. Some of this energy may be then be passed to other organisms (primary consumers) that eat photosynthetic organisms. Energy may pass from these consumers to other organisms (secondary consumers or carnivores) if they are eaten by them. The chain of energy flow from photosynthetic organism to primary consumer to secondary consumer, etc. is a food chain.

Filament - A filament is a hair-like strand of cells joined end to end.

Gametes - Gametes are sex cells.  They are haploid (N). Sperm and eggs are gametes.

Ganglion - Nerves are composed of cells called neurons that contain long extensions (called dendrites and axons). The bulk of the cell is called the cell body and contains the nucleus and other organelles. A ganglion is a concentration of cell bodies from a number of neurons.

Gastrovascular cavity - a digestive cavity in cnidarians and flatworms that has one opening that functions as a mouth and as an anus. These animals do not have a circulatory system, so the cavity also functions to distribute nutrients to the many cells that line the cavity.

Gene - A unit of heredity information. The information in genes is stored as DNA (deoxyribonucleic acid). Chromosomes are long strands of DNA and contain many genes. The information is stored as sequences of bases (A, T, G, and C). The information contained in the code of A, T, G, and C enables cells to assemble amino acids together in the correct sequence to produce specific kinds of proteins.

Glycolipid - A lipid with a carbohydrate chain attached

Glycoprotein - A protein with a carbohydrate chain attached

Gonads - ovaries or testies. The gonads produce sperm or eggs.

Gut - digestive tract of animals. This includes all of the structures from the mouth to the anus.

Haploid refers to cells that have a nucleus (or nuclei) that contains one set of chromosomes.

Herbaceous - nonwoody plants or parts of plants. Herbaceous plants are plants that do not contain woody material.

Herbivore - An animal that eats plants. Herbivory is the process of animals eating plants.

Hermaphroditic - an organism that possesses both male and female sex organs.

Heterotrophs are organisms that consume organic food. They do not synthesize their own.

Hydrogen ion - A hydrogen ion is a proton.  Ions are atoms that have gained or lost electrons.  A hydrogen atom normally has one electron and one proton

Invertebrate is a general term used for animals that do not have a backbone. Animals with a backbone are vertebrates.

Isogametes are gametes that are the same size. Isogamous species do not produce sperm (small gametes) or eggs (large gametes). 

Larva (pl. larvae) - Larvae refers to immature individuals of animal species in which the body form of the immature individuals (the larvae) is very different than the body form of the adult. Because larvae and adults have different forms, they often eat different food and may live in different habitats. Larvae are transformed into adults by a developmental process called metamorphosis.

Marine refers to the ocean. Marine organisms are ocean-dwelling organisms.

Multicellular organisms have more than one cell.

Multinucleate - Cells that contain more than one nucleus are multinucleus. Large cells are often multinulceate due to the limited amount of volume that a single nucleus can service.

Mutation - A mutation is a change in the genetic code.  It is a change in the sequence of nucleotides that make up DNA.  Most mutations are harmful because they result in the production of proteins that are less functional or nonfunctional.

Mutualistic - A mutualistic relationship is a close relationship between two species in which both species benefit by the relationship. For example, a close relationship often develops between plants and certain kinds of fungi in the soil. In this particular relationship (called a mycorrhiza), the fungus absorbs nutrients for the plant and in return, the plant provides the fungus with the products of photosynthesis (sugars).

Nerve - Nerve cells that conduct information are called neurons. These cells have long, threadlike structures called axons and dendrites that conduct information to and from other cells. A nerve is a bundle of axons or dendrites.

Neuron - A neuron is a cell that conducts information. A nerve is composed of neurons.

Organelle - Structures within cells are organelles. Examples are chloroplasts, golgi apparatus, lysosomes, mitochondria, nucleus, nucleolus, ribosomes, rough and smooth endoplasmic reticulum, vacuoles, vesicles

Organic - Organic molecules are molecules that contain carbon and hydrogen. Inorganic molecules do not contain carbon.

Parasites form close associations with other species. The parasite benefits from this relationship but the other species is harmed.

Pellicle - A thin outer covering of some kinds of protists.

Phagocytosis - A process in which a cell engulfs a particle or particles. For example, single-celled organisms feed by engulfing (phagocytizing) their food items. Cells of the human immune system destroy bacteria or other foreign particles by phagocytizing them. The vacuole that contains the phagocytized items typically fuses with a vacuole containing hydrolytic (digestive) enzymes.

Pharynx - The area in the back of the mouth of vertebrates. Food entering the esophagus and air entering the trachea pass through this area. In flatworms, the pharynx is a tube that protrudes from the ventral surface and is used to take in food.

Photosynthetic organisms are able to synthesize their own food. These organisms use light energy to produce sugar from carbon dioxide and water. Click here to go to the photosynthesis notes. Example: Plants are photosynthetic.

Phytoplankton are small photosynthetic organisms that float in water.

Pigment - Pigments are molecules that appear colored. Photosynthetic pigments absorb light energy for use during photosynthesis.

Plankton are small organisms that float in aquatic (water) environments. Phytoplankton are photosynthetic plankton. Phytoplankton are the base of most food chains in aquatic ecosystems.

Polymer - A large molecule composed of many smaller units (monomers) bonded together

Population - A population is an interbreeding group of organisms (the same species) that occupies a particular area.

Predator - An organism that kills and feeds on other organisms. Predation refers to killing and feeding upon other organisms.

Primary host - Many species of parasites have complex life cycles that involve two different host species. For example, the primary host of schistosomiasis is a human and the secondary host is a snail. The infection alternates hosts by passing from human to snail to human, etc.

Pseudopod - A temporary extension of a cell used for movement or to surround and engulf a particle

Saprotroph - Saprotrophic organisms are decomposers. They play a critical role in recycling (releasing) nutrients that are tied up in the bodies of dead organisms.

Scavenger - an animal that feeds on dead organic matter.

Secondary host - Many species of parasites have complex life cycles that involve two different host species. For example, the primary host of schistosomiasis is a human and the secondary host is a snail. The infection alternates hosts by passing from human to snail to human, etc.

Sessile - Organisms that don't move. They are attached to the substrate.

Sexual Reproduction is reproduction that involves the fusion of gametes from two different parents. As a consequence of combining genes from two different parents, sexual reproduction promotes genetic variation in populations.

Silica - A mineral that contains silicon and oxygen. It is a major component of quartz and glass.

Solute - A molecule or ion dissolved in a liquid

Solvent - a liquid that can contain dissolved molecules or ions

Sporangium - a structure that produces spores

Spores are reproductive cells that are capable of growing into an individual organism. They may be resistant to environmental extremes and thus allow overwinter survival or survival during dry periods. They may also be a mechanism to allow dispersal of the species. For example, windborne spores may be carried for many miles before they are deposited.

Substrate - An atom, molecule, or ion that will react in a chemical reaction.  As a result of the reaction, the substrate will be converted to product.

Symbiosis - Symbiosis refers to a close relationship between two or more different species.

Tentacles - Long, growths that project from the head or mouth area of some invertebrate species such as cnidarians and mollusks, and annelids.

Terrestrial - organisms that live on land

Tissue - A tissue is an aggregation of cells functioning together in a specialized activity. For example, muscle tissue is composed of cells that function by contracting.

Transcription factors are proteins in eukaryotic cells that bind to DNA and act to promote or inhibit transcription.

Trochophore larvae - A ciliated larval form of some mollusks and annelids.

Vertebrates are animals with a backbone. Phylum: Chordata     Subphylum: Vertebrata

Whorl - Whorl refers to several leaves attached in a ring or circular arrangement around a stem.

Zygote - A fertilized egg. A zygote is produced when two gametes fuse such as when an egg is fertilized by a sperm.