Glossary O-Z

  • O

    Open Circulatory System - a system of blood flow that has no true heart and no blood vessels

    Order - the taxonomic category below the class and above the family

    Osculum - an opening in a sponge's body through which water exits

    Ostia - one of the small openings in a sponge's body through which water enters

    Ovary - in the female reproductive system of animals, an organ that produces eggs; in flowering plants, the lower part of a pistil that produces eggs in ovules


    Pancreas - the organ that lies behind the stomach and that produces and secretes insulin, glucagon, and digestive enzymes

    Parasite - an organism that feeds on an organism of another species (the host) and that usually harms the host; the host never benefits from the presence of the parasite

    Pathogenic Bacteria - a microorganism, or other substance that causes disease; an infectious agent

    Peripheral Nervous System - all of the parts of the nervous system except for the brain and the spinal cord (the central nervous system); includes the cranial nerves and nerves of the neck, chest, lower back, and pelvis

    Petal - one of the usually brightly colored, leaf-shaped parts that make up one of the rings of a flower

    Phenotype - an organism's appearance or other detectable characteristic that results from the organism's genotype and the environment

    Phloem - the tissue that conducts food (sugars, amino acids, and mineral nutrients) in vascular plants

    Photosynthesis - the process by which plants, algae, and some bacteria use sunlight, carbon dioxide, and water to produce carbohydrates and oxygen

    Phylum - the taxonomic group below kingdom and above class

    Pistil - the female reproductive part of a flower that produces seeds and consists of an ovary, style, and stigma

    Pollen - the tiny granules that contain the male gametophyte of seed plants

    Pollination - the transfer of pollen from the male reproductive structures (the anthers) to the tip of a female reproductive structure (the pistil) of a flower in angiosperms or to the ovule in gymnosperms

    Polyp - a form of a cnidarian that has a cylindrical, hollow body and that is usually attached to a rock or to another object

    Precocial Bird - active and able to move freely from birth or hatching and requiring little parental care

    Preening- to trim or dress (feathers, fur, etc.) with the beak or tongue

    Prokaryote - an organism that consists of a single cell that does not have a nucleus or cell organelles; an example is a bacterium

    Protein – a critical chemical of life that builds cells

    Protozoa -a single-celled protist that can be aquatic or parasitic, that has organelles enclosed by a membrane, and that can move independently; examples include amebas and paramecia

    Pseudopod - a retractable, temporary cytoplasmic extension that functions in food ingestion and movement in certain ameboid cells

    Pulmonary circulation - the flow of blood from the right ventricle of the heart to the lungs and back to the left atrium of the heart through the network of pulmonary arteries, capillaries, and veins

    Pulmonary respiration - exchange of gases between the lungs and the air           

    Punnett Square - graphic used to predict the results of a genetic cross      


    Qualitative Data – any information that uses words to describe your data (shape, color, smell, etc.)

    Quantitative Data – any information that is expressed in numbers or measured  (height, weight, length, etc.)


    Radial Nerve – a nerve that runs from the nerve ring to the tip of each arm in sea stars, controlling the arm

    Radial Symmetry - a body plan in which the parts of an animal's body are organized in a circle around a central axis

    Receptor - a specialized sensory nerve that responds to specific types of stimuli

    Receptor Site - a site on the outside of cell where proteins can be transferred into the cell

    Recessive - describes a trait or an allele that is expressed only when two recessive alleles for the same characteristic are inherited

    Reflex - an involuntary and almost immediate movement in response to a stimulus

    Respiration - the process by which cells produce energy from carbohydrates; atmospheric oxygen combines with glucose to form water and carbon dioxide

    Rhizoid - a rootlike structure in nonvascular plants, such as mosses or liverworts, that holds the plants in place and aids in absorption

    Rhizome - a horizontal, underground stem that provides a mechanism for asexual reproduction

    Ribosome - makes protein inside of a cell for repairing


    Sac Fungi – the largest group of fungi containing yeasts, mildews and truffles.

    Segment - annelid worms are exterior structure that move independently

    Sepal - in a flower, one of the outermost rings of  modified leaves that protect the flower bud

    Sexual Reproduction - process of two organisms making offspring that looks different from parent organisms

    Scales - outer layer of a fish acting as protection

    Skeletal Muscle - a voluntary muscle that is attached to the bones and that moves parts of the body

    Slime Mold – a type of colorful protist that lives on decaying plants and feeds on bacteria and other microorganisms

    Small Intestine - the region of the digestive tube between the stomach and the colon (large intestine) where food's acidity is neutralized and most of the nutrients are absorbed

    Smooth Muscle - the elongated muscle that is not under voluntary control and that is found in the digestive tract, blood vessels, glands, and hair follicles, but not in the heart

    Sponge - an aquatic invertebrate of the phylum Porifera that attaches to stones or plants and that has a porous structure and a tough, elastic skeleton

    Spore - reproductive cell or multicellular structure that is resistant to environmental conditions and that can develop into an adult without fusion with another cell

    Species - a group of organisms that are closely related and can mate to produce fertile offspring; also the level of classification below genus

    Spontaneous Generation – the theory of how life began that says that living things come from nonliving things

    Stamen - the male reproductive structure of a flower that produces pollen and consists of an anther at the tip of a filament

    Stigma - the expanded apex of a pistil, supported by the style; the part of the pistil that receives the pollen

    Stimulus - anything that causes a reaction or change in an organism or any part of an organism

    Stoma - one of many openings in a leaf or a stem of a  plant that enable gas exchange to occur (plural, stomata )

    Stomach - the saclike, expandable digestive organ that is located between the esophagus and the small intestine and that breaks down food into a liquid by the action of muscles, enzymes, and acids

    Stress - a physical or mental response to an unusual environmental condition

    Style - in plants, the slender, upper part of the pistil

    Swim Bladder - the region of a fish that collects air for the buoyancy

    Systemic circulation - the movement of blood from the heart to all parts of the body and back to the heart


    Taxonomy - the science of describing, naming, and classifying organisms

    Temperate-A virus that will attach itself to a cell and reproduce when the cell goes through mitosis (HIV is an example)

    Tendon - a tough connective tissue that attaches a muscle to a bone or to another body part

    Theory - an explanation for some phenomenon that is based on observation, experimentation, and reasoning

    Thorax - in higher vertebrates, the part of the body between the neck and the abdomen; in other animals, the body region behind the head; in arthropods, the mid-body region

    Threadlike Fungus – shapeless, fuzzy molds that decompose rotting material

    Trachea - the tube that connects the pharynx to the lungs

    Trait - a genetically determined characteristic   

    Transpiration - the process by which plants release water vapor into the air through stomata

    Tympanic membrane - the eardrum


    Urinary Bladder - a hollow, muscular organ that stores urine



    Vacuole - Stores food, waste and water

    Vascular plant - a plant that has a vascular system composed of xylem and phloem, specialized tissues that conduct materials from one part of the plant to another


    Veins - a vessel that carries blood to the heart


    Vertebrate - an animal that has a backbone; includes mammals, birds, reptiles, amphibians, and fish

    Virulent - a violent virus that will reproduce quickly and create symptoms quickly

    Virus - a non living thing that can interfere with human cells

    Volume - a measure of the size of a body or region in three-dimensional space


    Vomerine teeth - two rough pads in the roof of the mouth.



    Water Vascular System - a system of canals filled with a watery fluid that circulates throughout the body of an echinoderm



    Xylem - the type of tissue in vascular plants that provides support and conducts water and nutrients from the roots