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the study of the structure of an organism


the study of the functions of an organism

convergent evolution

occurs because natural selection leads to a similar adaptations when diverse organisms face a similar environmental challenge

surface-to-volume ratio

one of the physical constraints on the size of single-celled organisms


groups of cells that have a common structure and function

epithelial tissue

occurs insheets of tightly packed cells, covers the body, lines the organs, and acts as a protective barrier

connective tissue

mainly supports and binds other tissues

nervous tissue

senses stimuli and transmits signals from one part of the body to the other neurons, glands, muscles, and the brain

muscle tissue

composed oflong cells called muscle fibers, contract when they arestimulated by a nerve impulse


organized groups of tissues

metabolic rate

the amount of energe it uses in a unit of time


warmed by the heat generated by their metabolism


do not produce enough heat by metabolism to influence their body temperature

basal metabolic rate

its metabolic rate when it iss at rest, is experiencingnostress, and has an empty stomach


the state of internal balance in the face of external changes


detects a change

control center

processes information


makes an appropriate response

negative feedback system

a change in the variable being monitored triggers a change in the control center that prevents further change in the variable or brings the variable back within desirable parameters

positive feedback system

a change in some variable triggers mechanisms that amplify rather than reverse the change


refers to how animals maintain their internal temperature


the transfer of heat between molecules of objects thatare in direct contact with one another


the transfer of heat through the movement of air or a liquid past a surface


the emission of electromagnetic waves by all objects that are warmer than absolute zero


the removal of heat from the surface of a liquid, as molecules leave the surface as gas

adjustment of the rate of heat exchange

between the animal and its environment - through insulating hair, feathers, and fat - is accomplished through vasodilation

suspension feeders

animals that sift small food particles from water

substrate feeders

live in or on their food source, eating their way through food

fluid feeders

pull nutrient-rich fluid from a living host

bulk feeders

eat relatively large pieces of food

caloric imbalance

can result in undernourished animals that have diets deficient in calories, or overnourished animals that consume more calories than they need


calcium and phosphorus, are simple inorganic nutrients that are also required in the diet in small amounts

enzymatic hydrolysis

the reaction by which macromolecules are broken up, involves addition of water

intracellular digestion

within a cell enclosed by a protective membrane, sponges digest their food this way

extracellular digestion

carried out by most animals, in this type of digestion, food is broken down outside of cells

salivary amylase

hydrolyzes starch and glycogen into smaller polysaccharides and the disaccharide maltose


a junction that opens to the esophagus and the trachea


covers the trachea, diverts the food down the esophagus


rhymthic waves of contraction by smooth muscle in the walls of the esophagus

stroke volume

amount of blood pumped by the left ventricle during each contraction

atrioventricular valve

between each atrium and ventricle prevents the backflow of blood intop the atria

semilunar valves

one located at the entrance to the pulmonary artery and the second at the entrance to the aorta that prevent backflow of blood

sinoatrial node

the pacemaker of the heart

lymphatic system

responsible for returning lost fluid and proteins to the blood in the form of lymph


mostly water, contains ions, electrolytes, and plasma proteins


the respiratory pigment found in almost all vertebrates

B Lymphocytes

proliferate in the bone marrow

T Lymphocytes

the lymphocytes mature in the thymus


foreign molecules that elicit a response by lymphocytes


proteins secreted by B cells during an immune response

MHC molecules

responsible for stimulating the rejection of tissue grafts and organ transplants

antidiuretic hormone

an important hormone in the regulation of water balance

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