Glossary A-N

  • A

    Abdomen - the distinct, usually elongated posterior region of an arthropod's body

    Abiotic – the non-living things in an environment

    Adaptation - the process of becoming adapted to an environment; an anatomical, physiological, or behavioral change that improves a population's ability to survive

    Alleles - one of the alternative forms of a gene that governs a characteristic, such as hair color

    Algae - organisms that convert the sun's energy into food through photosynthesis but that do not have roots, stems, or leaves (singular, alga )

    Altricial Bird - helpless at birth or hatching and requiring parental care for a period of time

    Alveoli - any of the tiny air cells of the lungs where oxygen and carbon dioxide are exchanged; singular is alveolus

    Amino Acid - a critical chemical that creates proteins

    Angiosperm - a flowering plant that produces seeds within a fruit

    Annelid - A worm that is made up of rings or segments.

    Antennae - a feeler on the head of an invertebrate, such as an arthropod, a crustacean, or an insect, that senses touch, taste, or smell

    Antibiotic - a substance that can inhibit the growth of or kill some microorganisms

    Antibody- proteins created to fight off antigens

    Antigens - foreign bacteria in your body

    Archaebacteria - classification kingdom made up of bacteria that live in extreme environments; differentiated from other prokaryotes by various important chemical differences

    Arteries - a blood vessel that carries blood away from the heart to the body's organs

    Asexual Reproduction - how organisms will make offspring by themselves and will look identical to the parent organism

    Asymmetry - irregular in shape; without symmetry

    Atom – the smallest part of an element


    Bacteria - extremely small, single-celled organisms that usually have a cell wall and reproduce by cell division (singular, bacterium )

    Bilateral symmetry - a condition in which two equal halves of a body mirror each other

    Binary Fission - a form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size

    Biogenesis – the theory of how life began that says that living things come from other living things

    Biotic – the living things in an environment

    Bioremediation - the biological treatment of hazardous waste by natural or genetically engineered microorganisms

    Blood - the fluid that carries oxygen and nutrients to the body and that is made up of platelets, white blood cells, red blood cells, and plasma

    Bronchi - the two tubes that connect the lungs with the trachea; singular is bronchus

    Brooding - to warm, protect, or cover (young) with the wings or body.


    Capillaries - a tiny blood vessel that allows an exchange between blood and cells in tissue

    Capsid - hard outer covering of a bacteria cell

    Carbohydrates – a critical chemical of life that is an energy source

    Cardiac Muscle - the type of involuntary muscle found in the heart

    Cartilage - a flexible and strong connective tissue

    Cell - the basic unit of life

    Cell Wall - A part of a plant cell that gives shape and structure

    Cell Membrane - A part  of a cell that allows certain proteins to pass through into and out the cell

    Central Nervous System - the brain and the spinal cord; its main function is to control the flow of information in the body

    Cephalothorax - in arachnids and some crustaceans, the body part made up of the head and the thorax

    Characteristic – a feature that has different forms in a population

    Chelicerae – the claw-like mouthparts on arachnids such as spiders, scorpions and ticks

    Chloroplasts - A part of a plant cell that carries out photosynthesis.

    Cilia - a hairlike structure arranged in tightly packed rows that projects from the surface of some cells; single is cilium

    Class - a taxonomic category containing orders with common characteristics

    Classification - the division of organisms into groups, or classes, based on specific characteristics

    Closed Circulatory System - a system that contains blood with a true heart and blood vessels

    Club Fungi – a type of fungus that reproduces sexually, many of which have “gills” underneath; includes mushrooms, puffballs and bracket fungi

    Cnidarians - An organism that contains a stinging cell to capture prey

    Coelom - a body cavity that contains the internal organs

    Collar Cells - any of the flagellate cells that line the cavities of a sponge; also called a choanocyte

    Complete Metamorphosis - the transformation from larva to adult in insects

    Compound Eye - an eye composed of many light detectors separated by pigment cells

    Conjugation - in prokaryotes, algae, and fungi, a type of sexual reproduction in which two cells join temporarily to recombine nuclear material

    Connective Tissue - a tissue that has a lot of intracellular substance and that connects and supports other tissues

    Contour Feather - one of the feathers that form the surface plumage of a bird, including those of the wings and tail

    Crop - A part of the digestive system of a worm that stores soil

    Cutaneous respiration - exchange of gases between the skin and the air/water

    Cyanobacteria – a bacterium that can carry out photosynthesis, such as a blue-green alga

    Cytoplasm - Fluid substance that allows  all cell organelles to function


    Denticles - specialized scales on the skin of a fish (small teeth)

    Dermis - the layer of skin below the epidermis

    Dichotomous Key - an aid that is used to identify unknown organisms and that consists of the answers to a series of questions, of which each involves alternate choices

    Dicot - an angiosperm that has to cotyledons and flower parts in groups of four or five.

    Dominant - describes the allele that is fully expressed when carried by only one of a pair of homologous chromosomes

    Down Feather - soft fine feathers used for insulation


    Echinoderm - a radially symmetrical marine invertebrate that has an endoskeleton, such as a starfish, a sea urchin, or a sea cucumber

    Ectotherm - an organism that cannot create its own heat (cold blooded)

    Element – a substance that is made up of only 1 type of atom'

    Endoplasmic reticulum - A cell part that transports materials in a cell

    Endoskeleton - an internal skeleton made of bone and cartilage

    Endotherm - an organism that can create its own heat (warm blooded)

    Endospore - a thick-walled protective spore that forms inside a bacterial cell and resists harsh conditions

    Epidermis - the outer surface layer of cells of a plant or animal

    Epithelial tissue - a tissue composed of cells that form a barrier between an organism and its external environment

    Esophagus - a long, straight tube that connects the pharynx to the stomach

    Eubacteria - a classification kingdom that contains all prokaryotes except archaebacteria

    Eukaryotic - an organism made up of cells that have a nucleus enclosed by a membrane, multiple chromosomes, and a mitotic cycle; eukaryotes include animals, plants, and fungi but not bacteria or cyanobacteria

    Eustachian tube - a channel that connects the middle ear to the mouth cavity

    Exoskeleton - a hard, external, supporting structure that develops from the ectoderm


    Family - the taxonomic category below the order and above the genus

    Fins - specialized parts of the body that allow the fish to swim or to keep water travelling over the gills

    Flagella - a long, hairlike structure that grows out of a cell and enables the cell to move

    Fungus - an organism whose cells have nuclei, rigid cell walls, and no chlorophyll and that belongs to the kingdom Fungi



    Gallbladder - sac-shaped organ that stores bile produced by the liver

    Ganglia - a mass of nerve cells

    Genes - a segment of DNA that is located in a chromosome and that codes for a specific hereditary trait

    Genotype - the entire genetic makeup of an organism; also the combination of genes for one or more specific traits

    Genus - the level of classification that comes after family and that contains similar species

    Gills - specialized organs to remove oxygen from the water

    Gizzard - A part of the digestive system that grinds up food for digestion

    Gram - measurement for mass in the metric system

    Gut - the digestive tract

    Gymnosperm - a woody vascular seed plant whose seeds are not enclosed by an ovary or fruit


    Heredity - the passing of genetic traits from parent to offspring

    Heterotroph - an organism that obtains organic food molecules by eating other organisms or their by products and that cannot synthesize organic compounds from inorganic materials

    Homeostasis - the maintenance of a constant internal state in a changing environment

    Host- the cell that a bacteria feeds off of

    Hyphae - a nonreproductive filament of a fungus

    Hypothesis - a theory or explanation that is based on observations and that can be tested


    Impulse - an electrical message that passes along a neuron

    Incomplete Metamorphosis - a change from egg to nymph to adult with little change in appearance

    Inquiry – a seeking request for truth, information, or knowledge

    Interferon - proteins that interfere with the reproduction of viruses

    Invertebrate - an animal that does not have a backbone


    Joint - a place where two or more bones meet


    Kidney - one of the organs that filter water and wastes from the blood, excrete products as urine, and regulate the concentration of certain substances in the blood

    Kingdom - the highest taxonomic category, which contains a group of similar phyla


    Large Intestine - the broader and shorter portion of the intestine, where water is removed from the mostly digested food to turn the waste into semisolid feces, or stool

    Lateral Line - region of a fish that senses vibrations in the water

    Law - a summary of many experimental results and observations; a law tells how things work

    Lichen - a mass of fungal and algal cells that grow together in a symbiotic relationship and that are usually found on rocks or trees

    Ligament - a type of tissue that holds together the bones in a joint

    Lipids – a critical chemical of life that are made up of fats and oils

    Liter - measurement for volume in the metric system

    Liver - the largest organ in the body; it produces bile, stores and filters blood, and converts sugars into glycogen

    Lysosome - A cell part that breaks down food


    Mandibles - a type of mouthpart found in some arthropods and used to pierce and suck food; the lower part of the jaw

    Mass - a measure of the amount of matter in an object; a fundamental property of an object that is not affected by the forces that act on the object, such as the gravitational force

    Medusa - a free-swimming, jellyfish-like, and often umbrella-shaped sexual stage in the life cycle of a cnidarian; also a jellyfish or a hydra

    Metabolism – the process of the chemical activities of life including digestion, ingestion, respiration and excretion

    Meter - the basic unit of length in the SI (abbreviation, m)

    Metric System - system of measurement using meters, grams, liters

    Microtubules - part of an animal cell that provides shape and stucture


    Mitosis - in eukaryotic cells, a process of cell division that forms two new nuclei, each of which has the same number of chromosomes

    Mitochondria - the energy producer of the cell making ATP

    Mold - in biology, a fungus that looks like wool or cotton

    Monocot- a plant that produces a plant with only one cotyledon

    Mucous glands – a gland that secretes a slippery substance called mucous


    Muscle tissue - the tissue made of cells that can contract and relax to produce movement

    Mycellium - the mass of fungal filaments, or hyphae, that forms the body of a fungus


    Nematocyst - in cnidarians, a stinging cell that is used to inject a toxin into prey

    Nephron - the functional unit of the kidney

    Nerve - a collection of nerve fibers through which impulses travel between the central nervous system and other parts of the body

    Nerve Cord – a pack of nerves on a single path; simpler than a spinal cord but serves the same purpose


    Nerve Ring – a circle of nerve fibers around the mouth of an echinoderm


    Nervous tissue - the tissue of the nervous system, which consists of neurons, their supporting cells, and connective tissue

    Neuron - a nerve cell that is specialized to receive and conduct electrical impulses

    Nictitating membrane - a third eyelid found under the lower eyelid of many vertebrates, including birds, reptiles, and amphibians

    Nonvascular plant - the three groups of plants (liverworts, hornworts, and mosses) that lack specialized conducting tissues and true roots, stems, and leaves

    Nucleic Acid – a critical chemical of life that builds proteins

    Nucleus - The part of a cell that controls all cell activities

    Nuclear membrane - part of a cell that protects the nucleus