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Cell interior that is surrounded by a wall made of carbohydrates and proteins and a membrane that is made largely of phospholipids

Transport Proteins

Special proteins that are embedded in the cell membrane

Selectively Permeable

Membranes that regulate the exchange of materials in a very specific way


Proteins that are embedded in membranes that have sugars attached to them


Sugars that are attached to the heads of membrane lipids


The movement of molecules from an area of higher concentration to an area of lower concentration

Concentration Gradient

Is existent when there is a difference in concentration of molecules across a distance


A special form of diffusion; the movement of water across a selectively permeable membrane


The outward pressure of a cell against its cell wall

Passive Transport

Involves diffusion without any input of energy

Active Transport

Moves substances against their concentration gradients and thus requires energy

Facilitated Diffusion

The transport in which molecules move down their concentration gradient with the help of transport proteins in the membrane


The process by which very large molecules are moved into a cell by a special active transport mechanism that requires energy


The process by which very large molecules are moved out of a cell by a special active transport mechanism that requires energy


Air sacs in a lung


The waxy outer layer covering the surfaces of most land-dwelling plants, animals, and fungi


The opening between two guard cells in the epidermis of a plant leaf through which gases are exchanged with the air


The loss of water to the atmosphere by a plant through the stomates in its leaves


The tendency for an organism to maintain a relatively stable internal environment by regulating its metabolism and adjusting to its environment


A toxic nitrogen compound (NH3) excrete by some aquatic organisms; thought to have been present in Earth's early atmosphere


The functional unit of a kidney consisting of a glomerulus, its associated capsule, and tubule surrounded by capillaries


An organ that regulates water and salt levels, filters water and wastes from the blood, and excretes the end products

Urinary System

A vertebrate organ system that regulates levels of water and dissolved substances in the body, excreting wastes as urine


The solution of wastes excreted from the kidney


A muscular tube that carries urine from the kidney to the urinary bladder

Urinary Bladder

An organ that stores urine before it is discharges from the body through the urethra


The tube through which urine travels from the bladder to the outside of the body

Glomerular Capsule

The cup of a nephron, which filters blood; also called Bowman's capsule


A ball of capillaries surrounded by a glomerular capsule in the nephron; the site of filtration in the kidneys


A hormone secreted by the adrenal gland, helps regulate sodium and potassium concentrations and water balance

Feedback Regulation

The regulation of the activity of an enzyme by one of its products


A hormone released from the posterior lobe of the pituitary (an endocrine gland in the brain); enhances conservation of water by the kidneys


Fluid from plasma passes into nephron, occurs in the glomerulus


Molecules are reabsorbed into the capillaries, occur in the tubule of the nephron


Molecules from blood are secreted unto nephron tubules, occurs as the filtrate moves through the tubule

Cell Membranes

Surrounds the cytoplasm, composed of two thin layers of phospholipids and proteins

Nitrogenous Waste

Excreted as urea, shows important evolutionary patterns


A characteristic that improves an organism's chance of surviving to reproduce


What nitrogenous wastes are excreted as

Uric Acid

Formed by in the body by the metabolism of protein and is excreted in the urine

Ion Balance

The correct balance of ions within cells

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