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121 Cards in this Set
- Front
- Back
Amnion |
The innermost of four extraembryonic membranes; encloses a fluid-filled sac in which the embryo is suspended |
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Chorion |
The outermost of four extraembryonic membranes; contributes to the formation of the mammalian placenta |
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Allantois |
One of four extraembryonic membranes; serves as a repository for the embryo's nitrogenous waste |
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Yolk |
Nutrients stored in an egg |
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Polyspermy |
An egg that has been fertilized by more than one sperm |
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Zygote |
The diploid product of the union of haploid gametes in conception; a fertilized egg |
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Totipotency |
Describing a cell that can give rise to all parts of an organism |
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Blastula |
The hollow ball of cells marking the end stage of cleavage during early embryonic development |
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Archenteron |
The endoderm-lined cavity, formed during the gastrulation process, that develops into the digestive tract of an animal |
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Deuterostomes |
Organisms in which the first opening is the anus |
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Protostomes |
Organisms in which the first opening is the mouth |
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Cleavage |
The succession of rapid cell divisions without growth during early embryonic development that converts the zygote into a ball of cells |
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Blastopore |
The opening of the archentron in the gastrula that develops into the mouth in protosomes and the anus in deuterostomes |
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Neurulation |
Formation in the early embryo of the neural plate and neural folds, followed by its closure with development of the neural tube |
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Notochord |
A long, flexible rod that runs along the dorsal axis of the body in the future position of the vertebral column |
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Induction |
The ability of one group of embryonic cells to influence the development of another |
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Meristem |
Plant tissue that remains embryonic as long as the plant lives, allowing for indeterminate growth |
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Primary growth |
Growth produced by apical mersistems, which lengthen stems and roots |
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Secondary growth |
Growth produced by lateral meristems, which thickens the roots and shoots of woody plants |
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Apical meristem |
Embryonic plant tissue in the tips of roots and in the buds of shoots that supplies cells for the plant to grow in length |
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Lateral meristem |
A meristem that thickens the roots and shoots of woody plants. The vascular cambium and cork cambium are examples of this |
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Cork cambium |
A cylinder of meristematic tissue in woody plants that replaces the epidermis with thicker, tougher cork cells |
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Leaf primordia |
Fingerlike projections along the flanks of a shoot apical meristem, from which leaves arise |
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Vascular cambium |
A cylinder of meristematic tissue in woody plants that adds layers of secondary vascular tissue called secondary xylem (wood) and secondary phloem |
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Periderm |
The protective coat that replaces the epidermis in plants during secondary growth, formed of the cork and cork cambium |
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Heartwood |
Older layers of secondary xylem, closer to the center of a stem or root, that no longer transport xylem sap |
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Sapwood |
Outer layers of secondary xylem that still transport xylem sap |
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Osmoconformer |
An animal that does not actively adjust its internal "osmolarity" because it is isotonic with its environment |
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Osmolarity |
Solute concentration expressed as molarity |
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Euryhaline |
Referring to organisms that can tolerate substantial changes in external osmolarity |
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Stenohaline |
Referring to organisms that cannot tolerate substantial changes in external osmolarity |
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Secretion |
In the vertebrate kidney, the discharge of wastes from the blood into the filtrate from the nephron tubules |
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Excretion |
The disposal of nitrogen-containing waste products of metabolism |
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Coelom |
A body cavity completely lined with mesoderm |
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Metanephridium |
In annelid worms, a type of excretory tubule with internal openings called nephrostomes that collect body fluids and external openings called nephridiopores |
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Hemolymph |
In invertebrates with an open circulatory system, the body fluid that bathes tissues |
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Nephrons |
The tubular excretory unit of the vertebrate kidney |
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Glomerulus |
A ball of capillaries surrounded by a Bowman's capsule in the nephron and serving as the site of filtration in the vertebrae kidney |
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Bowman's capsule |
A cup-shaped receptacle in the vertebrate kidney that is the initial, expanded segment of the nephron where filtrate enters from the blood |
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Proximal tubule |
In the vertebrate kidney, the portion of a nephron immediately downstream from Bowman's capsule that conveys and helps refine filtrate |
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Loop of henle |
The long hairpin turn, with a descending and ascending lion, of the renal tubule in the vertebrate kidney; functions in water and salt reabsorption |
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Distal tubule |
In the vertebrate kidney, the portion of a nephron that helps refine filtrate and empties it into a collecting duct |
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Collecting duct |
The location in the kidney where filtrate rom renal tubules is collected; the filtrate is now called urine |
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Antidiuretic hormone (ADH) |
A hormone produced in the hypothalamus and released from the posterior pituitary, It promotes water retention by the kidneys as part of an elaborate feedback scheme that helps regulate the osmopolarity of the blood |
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Saprophyte |
A plant, fungus, or microorganism that lives on dead or decaying organic matter |
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Parasitic |
An organism that absorbs nutrients from the body fluids of living hosts |
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Soil depletion |
Removal of nutrients, biological diversity, or structural quality of soil due to improper extractive practices |
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Root hairs |
A tiny extension of a root epidermal cell, growing just behind the root tip and increasing surface area for absorption of water and minerals |
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Nitrogen cycle |
The series of processes by which nitrogen and its compounds are interconverted in the environment and in living organisms, including nitrogen fixation and decomposition |
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Nitrogen-fixing bacteria |
Microorganisms that restock nitrogenous materials in the soil by converting nitrogen to ammonia |
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Legumes |
A leguminous plant, especially one grown as a crop |
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Mycorrhizae |
Mutualistic associations of plant roots and fungi |
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Ingestion |
A heterotrophic mode of nutrition in which other organisms or detritus are eaten whole or in pieces |
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Digestion |
The process of breaking down food into molecules small enough for the body to absorb |
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Absorption |
The uptake of small nutrient molecules by an organism's own body; the third main stage of food processing, following digestion |
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Elimination |
The passing of undigested material out of the digestive compartment |
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Peristalsis |
Rhythmic waves of contraction of smooth muscle that push food along the digestive tract |
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Amylase |
An enzyme, found chiefly in saliva and pancreatic guild, that converts starch and glycogen into simple sugars |
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Epiglottis |
A cartilaginous flap that blocks the top of the windpipe, the glottis, during swallowing, which prevents the entry of food or fluid into the respiratory system |
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Chyme |
The pulpy acidic fluid that passes from the stomach to the small intestine, consisting of gastric juices and partially digested food |
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Pepsin |
An enzyme present in gastric juice that begins the hydrolysis of proteins |
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Trypsin |
A digestive enzyme that breaks down proteins in the small intestine. |
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Bile |
A mixture of substances that is produced in the liver, stored in the gallbladder, and acts as a detergent to aid in the digestion and absorption of fats |
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Emulsify |
Make into or become an emulsion: a fine dispersion of minute droplets of one liquid in another in which it is not soluble or miscible |
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Gall bladder |
An organ that stores bile and releases it as needed into the small intestine |
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Duodenum |
The first section of the small intestine, where acid chyme from the stomach mixes with digestive juices from the pancreas, liver, gall bladder, and gland cells of the intestinal wall |
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Jejunum |
The part of the small intestine between the duodenum and ileum |
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Ileum |
The third portion of the small intestine, between the jejunum and the cecum |
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Villi |
Fingerlike projections of the inner surface of the small intestine |
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Microvilli |
File, fingerlike projections of the epithelial cells in the lumen of the small intestine that increase its surface area |
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Lumen |
The inner open space or cavity of a tubular organ,as of a blood vessel or intestine |
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Gastrin |
A hormone that stimulates secretion of gastric juice, and is secreted into the bloodstream by the stomach wall in response to the presence of food |
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Insulin |
A hormone secreted by pancreatic beta cells that lowers blood glucose levels. It promotes the uptake of glucose by most body cells and the synthesis and storage of glycogen in the liver and also stimulates protein and fat synthesis |
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Glycogen |
An extensively branched glucose storage polysaccharide found in the liver and muscle of animals; the animal equivalent of starch |
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Cecum |
A blind out pocket of a hollow organ such as an intestine |
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Mastication |
The process by which food is crushed and ground by teeth |
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Pressure potential |
A component of water potential that consists of the physical pressure on a solution, which can be positive, zero, or negative |
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Solute potential |
A component of water that is proportional to the number of dissolved solute molecules in a solution and measures the effect of solutes on the direction of water movement; also called osmotic potential, can be zero or negative |
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Hypertonic |
In comparing two solutions, referring to the one with a greater solute concentration |
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Symplastic |
In plants, the continuum of cytoplasm connected by plasmodesmata between cells |
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Apoplastic |
In plants, the continuum of cell walls plus the extracellular spaces |
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Endodermis |
The innermost layer of the cortex in plant roots; a cylinder one cell thick that forms the boundary between the cortex and the vascular cylinder |
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Transpiration |
The evaporative loss of water from a plant |
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Mesophyll |
The ground tissue of a leaf, sandwiched between the upper and lower epidermis and specialized for photosynthesis |
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Stomate |
A microscopic core surrounded by guard cells in the epidermis of leaves and stems that allows gas exchange between the environment and the interior of the plant |
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Transpirational pull |
The upward movement of water in the sap column that allows for the evaporation of water from leaves |
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Guttation |
The exudation of water droplets caused by root pressure in certain plants |
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Guard cells |
The two cells that flank the stomatal pore and regulate the opening and closing of the pore |
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Xerophytes |
A plant adapted to an arid climate |
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Open circulatory system |
A circulatory system in which fluid called hemolymph bathes the tissues and organs directly and there is no distinction between the circulating fluid and the interstitial fluid |
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Septum |
One of the cross-walls that divide a fungal hypha into cells. Usually have pores large enough to allow ribosomes, mitochondria and even nuclei to flow from cell to cell |
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Erythrocytes |
A red blood cell; contains hemoglobin, which functions in transporting oxygen in the circulatory system |
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Leukocytes |
A white blood cell; typically functions in immunity, such as phagocytosis or antibody production |
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Platelets |
A small enucleated blood cell important in blood clotting; derived from large cells in the bone marrow |
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Plasma |
The liquid matrix of blood in which the cells are suspended |
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Pulmonary circuit |
The branch of the circulatory system that supplies the lungs |
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Systemic circuit |
The branch of the circulatory system that supplies all body organs and then returns oxygen-poor blood to the right atrium via the veins |
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Arteries |
A vessel that carries blood away from the heart to organs throughout the body |
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Capillaries |
A microscopic blood vessel that penetrates the tissues and consists of a single layer of endothelial cells that allows exchange between the blood and interstitial fluid |
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Veins |
A vessel that returns blood to the heart; a vascular bundle in a leaf |
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Interstitial fluid |
The internal environment of vertebrates, consisting of the fluid filling the spaces between cells |
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Plaque |
A small, distinct, typically raised patch or region resulting from local damage or deposition of material |
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Cholesterol |
A steroid that forms an essential component of animal cell membranes and acts as a precursor molecule for the synthesis of other biologically important steroids |
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Trachea |
The windpipe; that portion of the respiratory tube that has c-shaped cartilaginous rings and passes from the larynx to two bronchi |
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Bronchi |
A pair of breathing tubes that branch from the trachea into the lungs |
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Alveoli |
One of the dead-end multi lobed air sacs that constitute the gas exchange surface of the lungs |
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Diaphragm |
A sheet of muscle that forms the bottom wall of the thoracic cavity in mammals; active in ventilating the lungs |
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Innate immunity |
The kind of defense that is mediated by phagocytic cells, antimicrobial proteins, the inflammatory response, and natural killer (NK) cells. It is present before exposure to pathogens and is effective from the time of birth |
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Pathogens |
A disease-causing agent |
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Humoral immune response |
The branch of acquired immunity that involves the activation of B cells and that leads to the production of antibodies, which defend against bacteria and viruses in body fluids |
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Cell-mediated response |
The branch of acquired immunity that involves the activation of cytotoxic T cells, which defend against infected cells, cancer cells, and transplanted cells |
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Antibodies |
A protein secreted by plasma cells (differentiated B cells) that binds to a particular antigen and marks in for elimination; also called immunoglobin. All have the same Y-shaped structure and in their monomer form consist of two identical heavy chains and two identical light chains joined by disulfide bridges |
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Antigens |
A macromolecule that elicits an immune response by lymphocytes |
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Plasma cells |
The antibody-secreting effector cell of humoral immunity; arises from antigen-stimulated B cells |
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Memory cells |
One of a clone of long-lived lymphocytes, formed during the primary immune response, that remains in a lymphoid organ until activated by exposure to the same antigen that triggered its formation. They mount the secondary immune response |
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Antigen presentation |
The process by which an MHC molecule binds to a fragment of an intracellular protein antigen and carries it to the cell surface, where it is displayed and be recognized by a T cell |
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Antibiotics |
A medicine that inhibits the growth of or destroys microorganisms |
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Stimulus |
A thing or event that evokes a specific functional reaction in an organ or tissue |
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Response |
A physical reaction to a specific stimulus or stimulation |
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Phototropism |
Growth of a plant shoot toward or away from light |
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Circadian rhythms |
A physiological cycle of about 24 hours that is present in all eukaryotic organisms and that persists even in the absence of external clues |