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Bio 112 Exam 3
terms for exam 3
| Question | Answer |
|---|---|
| signal transduction | The process by which a stimulus (a hormone, a neurotransmitter, or sensory information) outside a cell is amplified and converted into a response by the cell. Usually involves a specific sequence of molecular events, or signal transduction pathway |
| phosphorylation cascades | a series of enzyme-catalyzed phosphorylation reactions commonly used in signal transduction pathways to amplify and convey a signal inward from the plasma membrane. |
| hormone | any numerous different signaling molecules that circulate throughout the body in blood or other body fluids |
| second messengers | a nonprotein signaling molecule produced or activated inside a cell in response to stimulation at the cell surface. commonly used to relay the message of a hormone or other extracellular signaling molecule |
| coleoptile | a modified leaf that covers and protects the stems and leaves of young grasses |
| auxin | indoleacetic acid, a plant hormone that stimulates phototropism and some other responses |
| photoreversibility | a change in conformation that occurs in certain plant pigments when they are exposed to their preferred wavelengths of light and that triggers responses by the plant. |
| phytochromes | a specialized plant photoreceptor that exists in two shapes depending on the ratio of red to far-red light and is involved in the timing certain physiological processes, such as flowering, steam elongation, and germination. |
| gravitropism | the growth or movement of a plant in a particular direction in response to gravity. |
| root cap | a small group of cells that covers and protects the tip of a plant root. senses gravity and determines the direction of root growth |
| amyloplasts | dense, starch-storing organelles that settle to the bottom of plant cells and that may be used as gravity detectors |
| statoliths | a tiny stone or dense particle found in specialized gravity-sensing organs in some animals such as lobsters |
| thigmotropism | growth or movement of an organism in response to contact with a solid object |
| membrane potential | a difference in electric charge across a cell membrane; a form of potential energy |
| apical dominance | inhibition of lateral bud growth by the apical meristem at the tip of a plant branch |
| abscission | in plants, the normal (often seasonal) shedding of leaves, fruits, or flowers |
| cytokinins | a class of plant hormones that stimulate cell division and retard aging |
| gibberellins | a class of hormones found in plants and fungi that stimulate growth. gibberellic acid is one of the major gibberellins. |
| abscisic Acid (ABA) | a plant hormone that inhibits cell elongation and stimulates leaf shedding and dormancy |
| stomata | pores or openings. in plants, a microscopic pore on the surface of a leaf or stem through which gas exchange occurs. |
| guard cells | one of two specialized, crescent-shaped cells forming the border of a plant stoma. guard cells can change shape to open or close the stoma |
| brassinosteroids | a family of steroid hormones found in plants |
| senescence | the process of aging |
| ethylene | a gaseous plant hormone that induces fruits to ripen, flowers to fade, and leaves to drop. |
| pathogens | any entity capable of causing disease, such as a microbe, virus, or prion |
| virulence | the ability of a pathogen or parasite to cause disease and death. |
| HR response | a specific sequence in DNA to which a steroid hormone-receptor complex can bind and affect gene transcription |
| resistance genes (r genes) | genes in plants encoding proteins involved in sensing the presence of pathogens and mounting a defensive response |
| avirulence genes (avr genes) | genes in pathogens encoding proteins that trigger a defense response in plants. |
| gene for gene hypothesis | the hypothesis that there is a one-to-one correspondence between the resistance loci of plants and the avirulence loci of pathogenic fungi; particularly, the R genes produce receptors and avr genes produce molecules that bind to those receptors |
| systemic acquired resistance (SAR) | a slow, widespread response of plants to a localized infection that protects healthy tissue from invasion by pathogens. |
| proteinase inhibitors | defense compounds, produced by pants, that induce illness in herbivores by inhibiting digestive enzymes |
| parasitoid | an organism that has a parasitic larval stage and a free-living adult stage. most parasitoids are insects that lay eggs in the bodies of other insects. |
| pheromones | a chemical signal, released by one individual into the external environment, that can trigger responses in a different individual |
| sporophyte | in organisms undergoing alternation of generations, the multicellular diploid form that arises from two fused gametes and produces haploid spores |
| gametophyte | in organisms undergoing alternation of generations, the multicellular haploid form that arises from a single haploid spore and produces gametes. female: embryo sac; male: pollen grain |
| alternation of generations | a life cycle involving alternation of a multicellular haploid stage (gametophyte) with a multicellular diploid stage (sporophyte). occurs in most plants and some protists. |
| spore | (1) in bacteria, a dormant form that generally is resistant to extreme conditions. (2) in eukaryotes, a single cell produced by mitosis or meiosis (not by fusion of gametes) that is capable of developing into an adult organism. |
| sporangia | spore-producing structures found in seed plants, some protists, and some fungi |
| rhizomes | modified stems that runs horizontally underground and produce new plants at the nodes (asexual reproduction) |
| corms | a rounded, thick underground stem that can produce new plants via asexual reproduction |
| plantlets | a small plant, particularly one that forms on a parent plant via asexual reproduction and drops, becoming an independent individual. |
| photoperiodism | any response by an organism to the relative lengths of day and night |
| sepals | one of the protective leaflike organs enclosing a flower bud and alter supporting the blooming flower. |
| petals | one of the leaflike organs arranged around the reproductive organs of a flower |
| calyx | all of the sepals of a flower |
| nectary | a nectar-producing structure in a flower. |
| nectar | the sugary fluid produced by flowers to attract and reward pollinating animals |
| stamens | the male reproductive structure of a flower. consists of an anther, in which pollen grains are produced, and a filament, which supports the anther. |
| filament | any thin, threadlike structure, particularly (1) the threadlike extensions of a fish's gills or (2) the slender stalk that bears the anthers in a flower |
| anthers | the pollen producing structure at the end of a stamen in flowering plants |
| carpel | the female reproductive organ in a flower. consists of the stigma, to which pollen grains adhere; the style, through which pollen grains move; and the ovary, which house the ovule. |
| stigma | the moist tip at the end of a flower carpel to which pollen grains adhere |
| style | the slender stalk of a flower carpel connecting the stigma and the ovary |
| ovary | the egg-producing organ of a female animal, or the seed-producing structure int he female part of a flower |
| ovules | in flowering plants, the structure inside an ovary that contains the female gametophyte and eventually becomes a seed |
| perfect flowers | a flower that contains both male parts and female parts |
| imperfect flowers | a flower that contains male parts OR female parts |
| monoecious | describing an angiosperm species that has both male and female reproductive structures on each plant |
| dioecious | describing an angiosperm species that has male and female reproductive structures on separate plants |
| gydnodioecious | WAAAHHHHHHHHHHHHH |
| megaspore | in seed plants, a haploid (n) spore that is produced in a megasporangium by meiosis of a diploid (2n) parents cell produces four haploid (n) reproductive cells (gametes); results in halving of the chromosome number. |
| embryo sac | a young developing organism; the stage after fertilization and zygote formation. |
| polar nuclei | in flowering plants, the nuclei in the female gametophyte that fuse with one sperm nucleus to produce the endosperm. most species have two |
| micropyle | the tiny pore in a plant ovule through which the pollen tube reaches the embryo sac. |
| microspore | in seed plants, a haploid (n) spore that is produced in a microsporangium by meiosis of a diploid (2n) microsporocyte; develops into a male gametophyte. |
| pollen grain | in seed plants, a male gametophyte enclosed within a protective coat. |
| pollination | the process by which pollen reaches the carpel of a flower or reaches the ovule directly |
| fertilization | fusion of the nuclei of two haploid gametes to form a zygote with a diploid nucleus |
| selfing | property of a molecule or cell such that immune system cells do not attack it, due to certain molecular similarities to other body cells. |
| heterospory | in seed plants, the production of two distinct types of spore-producing structures and thus two distinct types of spores: microspores, which become the male gametophyte, and megaspores, which become the female gametophyte |
| crosspollination | pollination of a flower by pollen from another individual, rather than by self-fertilization |
| outcrossing | reproduction by fusion of the gametes of different individuals, rather than self-fertilization. |
| mutualism | a symbiotic relationship between two organisms that benefits both |
| coevolution | a pattern of evolution in which two interacting species reciprocally influence each other's adaptations over time |
| germination | the process by which a seed becomes a young plant |
| pollination | the process by which pollen reaches the carpel of a flower or reaches the ovule directly |
| cleistogamous flowers | non-opening, self-pollinating flowers (peas, beans, peanuts) |
| pollen tube | in flowering plants, a structure that grows out of a pollen grain after it reaches the stigma, extends down the style, and through which two sperm cells are delivered to the ovule. |
| double fertilization | an unusual form of reproduction seen in flowering plants, in which one sperm nucleus fuses with an egg to form a zygote and the other sperm nucleus fuses with two polar nuclei to form the triploid endosperm |
| endosperm | a triploid (3n) tissue in the seed of a flowering plant that serves as food for the plant embryo. functionally analogous to the yolk in some animal eggs. |
| seed coat | a protective layer around a seed that encases both the embryo and the endosperm |
| embryogenesis | the process by which a single-celled zygote becomes a multicellular embryo |
| cotyledon | the first leaf, or seed leaf, of a plant embryo. used for storing and digesting nutrients and/or for early photosynthesis |
| hypocotyl | the stem of a very young plant; the region between the cotyledon and the redicle |
| radicle | the root of a plant embryo |
| epicotyl | in some embryonic plants, a portion of the embryonic stem that extends above the cotyledons |
| simple fruits | a fruit that develops from a single flower that has a single carpel or several fused carpels |
| aggregate fruits | a fruit that develops from a single flower that has many separate carpels. |
| multiple fruits | a fruit that develops from many separate flowers and thus many carpels. |
| pericarp | the part of a fruit, formed from the ovary wall, that surrounds the seeds and protects them. corresponds to the flesh of most edible fruits and the hard shells of most nuts. |
| scarify | to scrape, rasp, cut, or otherwise damage the coat of a seed. necessary in some species to trigger germination. |
| trade-offs | in evolutionary biology, an inescapable compromise between two traits that cannot be optimized simultaneously |
| acclimatization | gradual physiological adjustment of an organism to new environmental conditions that occur naturally or as part of a laboratory experiment. |
| adaptation | any heritable trait that increases the fitness of an individual with that trait, compared with individuals without that trait, in a particular environment. |
| tissue | a group of similar cells that function as a unit, such as muscle tissue or epithelial tissue |
| connective tissue | an animal tissue consisting of scattered cells in a liquid, jellylike, or solid extracellular matrix. includes bone, cartilage, tendons, ligaments, and blood. |
| loose connective tissue | a type of connective tissue consisting of fibrous proteins in a soft matrix. often functions as a padding for organs. |
| adipose tissue | a type of connective tissue whose cells store fats |
| dense connective tissue | a type of connective tissue, distinguished by having an extracellular matrix dominated by collagen fibers |
| supporting connective tissue | a type of connective tissue, distinguished by having a firm extracellular matrix. |
| fluid connective tissue | a type of connective tissue, distinguished by having a liquid extracellular matrix. |
| nervous tissue | an animal tissue consisting of nerve cells (neurons) and various supporting cells |
| neuron | a cell that is specialized for the transmission of nerve impulses. typically has dendrites, a cell body, and a long axon that forms synapses with other neurons. |
| axons | a long projection of a neuron that can propagate an action potential and transmit it to another neuron |
| dendrites | short extensions from a neuron's cell body that receives signals from other neurons. |
| muscle tissue | an animal tissue consisting of bundles of long, thin contractile cells (muscle fibers) |
| skeletal tissue | the muscle tissue attached to the bones of the vertebrate skeleton. consists of long, unbranched muscle fibers with a characteristic striped appearance; controlled voluntarily. |
| cardiac tissue | the muscle tissue of the vertebrate heart. consists of long branched fibers that are electrically connected and that initiate their own contractions; not under voluntary control. |
| smooth muscle | the unstriated muscle tissue that lines the intestine, blood vessels, and some other organs. consists of tapered, unbranched cells that can sustain long contractions. not voluntarily controlled. |
| voluntary muscle | muscle tissue that can respond to conscious thought |
| involuntary muscle | muscle that cannot respond to conscious thought |
| epithelial tissue | an animal tissue consisting of sheet-like layers of tightly packed cells that lines an organ, a duct, or a body surface. |
| organ | a group of tissues organized into a functional and structural unit |
| gland | an organ whose primary function is to secrete some substance, either into the blood or into some other space such as the gut or skin |
| basolateral | toward the bottom and sides. in animals, the side of an epithelial layer that faces other body tissues and not the environment |
| basal lamina | a thick, collagen-rich extracellular matrix that underlies most epithelial tissues |
| metabolic rate | the total energy use by all the cells of an individual. for aerobic organisms, often measured as the amount of oxygen consumed per hour |
| sensor | any cell, organ, or structure with which an animal can sense some aspect of the external or internal environment. usually functions, along with an integrator and effector, as part of a homeostatic system |
| integrator | a component of an animal's nervous system that functions as part of a homeostatic system by evaluating sensory information and triggering appropriate responses. |
| effector | any cell, organ, or structure with which an animal can respond to external or internal stimuli. usually functions, along with a sensor and integrator, as part of a homeostatic system. |
| negative feedback | a self-lining, corrective response in which a deviation in some variable triggers responses aimed at returning the variable to normal |
| convection | transfer of heat by movement of large volumes of a gas or liquid |
| radiation | transfer of heat between two bodies that are not in direct physical contact. |
| conduction | direct transfer of heat between two objects that are in physical contact |
| evaporation | the energy-absorbing phase change from a liquid state to a gaseous state. many organisms evaporate water as a means of heat loss |
| thermoregulation | regulation of body temperature |
| endotherm | an animal whose primary source of body heat is internally generated heat |
| ectotherm | an animal that does not use internally generated heat to regulate its body temperature |
| homeotherm | an animal that has a constant or relatively constant body temperature |
| heterotherm | an animal whose body temperature varies markedly with environmental conditions |
| torpor | an energy-conserving physiological state, marked by a decrease in metabolic rate, body temperature, and activity, that lasts for a short period. occurs in some small mammals when the ambient temperature drops significantly. |
| hibernation | an enery-conserving physiological state, marked by a decrease in metabolic rate, body temperature, and activity, that lasts for a prolonged period. occurs in some animals in response to winter cold and scarcity of food. |
| hypothalamus | a part of the brain that functions in maintaining the body's internal physiological state by regulating the autonomic nervous system, endocrine system, body temperature, water balance, and appetite |
| heat shock proteins | proteins that facilitate refolding of proteins that have been denatured by heat or other agents. |
| countercurrent exchanger | in animals, any anatomical arrangement that allows the maximum transfer of heat or a soluble substance from one fluid to another. two two fluids must be flowing in opposite directions and have a heat or concentration gradient between them. |
| nutrient | a substance that an organism requires for normal growth, maintenance, or reproduction. |
| vitamin | an organic micronutrient that usually functions as a coenzyme |
| suspension feeder | any organism that obtains food by filtering small particles or small organisms out of water or air |
| deposit feeder | an animal that eats its way through a food-containing substrate |
| fluid feeder | an animal that feeds by sucking or mopping up liquids such as nectar, plant sap, or blood |
| mass feeder | an animal that takes chunks of food into its mouth |
| digestion | the physical and chemical breakdown of food into molecules that can be absorbed into the body of an animal |
| absorption | in animals, the uptake of ions and small molecules derived from food across the lining of the intestine and into the bloodstream |
| incomplete digestive tract | a digestive tract with just one opening |
| complete digestive tract | a digestive tract with two openings, usually called a mouth and an anus |
| amylase | any enzyme that can break down starch by catalyzing hydrolysis of the glycosidic linkages between the glucose residues. |
| lipase | any enzyme that can break down fat molecules into fatty acids and monoglycerides |
| salivary gland | vertebrae glands that secrete saliva into the mouth |
| mucus | a slimy mixture of glycoproteins and water that is secreted in many animal organs for lubrication |
| esophagus | the muscular tube that connects the mouth to the stomach. |
| peristalsis | rhythmic waves of muscular contraction that push food along the digestive tract. |
| reflex | an involuntary response to environmental stimulation. may involve the brain. |
| crop | a storage organ in the digestive systems of certain vertebrates. |
| stomach | a tough, muscular pouch in the vertebrate digestive tract between the esophagus and small intestine. physically breaks up food and begins digestion of proteins |
| sphincter | a muscular valve that can close off a tube, as in a blood vessel or a part of the digestive tract. |
| pepsin | a protein-digesting enzyme present in the stomach. |
| pepsinogen | the precursor of the digestive enzyme pepsin. is secreted from cells in the stomach lining and converted to pepsin by the acidic environment of the stomach lumen. |
| parietal cells | cells in the stomach lining that secrete hydrochloric acid. |
| mucous cell | a type of cell found in the epithelial layer of the stomach; responsible for secreting mucus into the stomach. |
| carbonic anhydrase | an enzyme that catalyzes the formation of carbonic acid from carbon dioxide and water |
| ulcer | a hole in an epithelial layer that damages the underlying basement membrane and tissues |
| ruminant | a group of hoofed mammals that have a four-chambered stomach specialized for digestion of plant cellulose |
| symbiosis | any close and prolonged physical relationship between individuals of two different species |
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kim.kamps
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