AP Biology Glossary

  1. abiotic components
    The nonliving players in an ecosystem, such as climate and nutrients.
  2. abscisic acid
    Plant hormone that inhibits cell growth, prevents premature germination, and stimulates closing of the stomata.
  3. achondroplasia
    Autosomal dominant form of dwarfism seen in one out of 10,000 people.
  4. active transport
    The movement of a particle across a selectively permeable membrane against its concentration gradient. This movement requires the input of energy, which is why it is termed "active" transport.
  5. adaptation
    A trait that, if altered, affects the fitness of the organism. Adaptations are the result of natural selection and can include not only physical traits such as eyes and fingernails but also the intangible traits of organisms, such as lifespan.
  6. adaptive radiation
    A rapid series of speciation events that occur when one or more ancestral species invates a new environment.
  7. adrenocorticotropic hormone (ACTH)
    A hormone that stimulates the secretion of adrenal cortical hormones, which work to maintain electrolytic homeostasis in the body.
  8. aerobic respiration
    Energy-producing reactions in animals that involve three stages: glycolysis, the Krebs cycle, and oxidative phosphorylation. Requires oxygen.
  9. age structure
    Statistic that compares the relative number of individuals in the population from each age group.
  10. agnostic behavior
    Behavior that results from a conflict of interest between individuals; often involves intimidation and submission.
  11. alcohol
    Organic compound that contains a gydroxyl (-OH) hunctional group.
  12. alcohol fermentation
    Occurs in fungi, yeast, and bacteria. Pyuvate is converted in two steps to ethanol. regenerating two molecules of NAD+.
  13. aldehyde
    Carbonyl group in which one R is a hydrogen and the other is a carbon chain. Hydrophilic and polar.
  14. aldesterone
    Released from the adrenal gland, this hormone acts on the distal tubules to cause the reabsorption of move Na+ and water. This increases blood volume and pressure.
  15. allantois
    Transports waste products in mammals to the placenta. Later it is incorporated into the umbilical cord.
  16. allele
    A variant of a gene for a particular character.
  17. allopatric speciation
    Interbreeding ceases because some sort of barrier separates a single population into two (an area with no food, a mountain, etc.). The two populations evolve independently, and if they change enough, then even if the barrier is removed, they cannot interpreed.
  18. alternation of generations
    Plant life cycle, so named because during the cycle, pplants sometimes exist as a diploid organism and at other times as a haploid organism.
  19. altruistic behavior
    Behavior pattern that reduces the overall fitness of one organism while increasing the fitness of another.
  20. Alveoli
    Functional unit of the lung where gas exchange occurs.
  21. amines
    Compounds containing amino groups.
  22. amino acid
    A compound with a carbon center surrounded by an amino group, a carboxyl group, a hydrogen, and a R group that provides an amino acid's unique chemical characteristics.
  23. aminoacyl tRNA synthetase
    Enzyme that makes sure that each tRNA molecule picks up the appropriate amino acid for its anticodon.
  24. amino group
    A functional group that contains -NH2 and that acts as a base; an example is an amino acid.
  25. amnion
    Structure formed from epiblast that encloses the fluid-filled cavity that helps cushion the developing embryo.
  26. amylase
    Enzyme that breaks down the starches in the human diet to simpler sugars such as maltose, which are fully digested further down in the intestines.
  27. anaerobic respiration
    Energy-producing reactions, known as fermentation, that do not involve oxygen. It begins with glycolysis and concludes with the formation of NAD+.
  28. anemia
    Illness in which a lack of iron causes red blood cells to have a dimished capoacity for delivering oxygen.
  29. aneuploidy
    The condition of having an abnormal number of chromosomes.
  30. angiosperm
    Flowering plant divided into monocots and dicots (monocotyledons and dicotyledons).
  31. anion
    Ion with a negative charge that contains more electrons than protons.
  32. anterior pituitary gland
    Structure that produces six hormones: TSH, STH (or HGH), CTH, LH, FSH, and prolactin.
  33. anther
    Pollen-producing portion of a plant
  34. antheridia
    Male gametangia in bryophytes and ferms designed to product flagellated sperm that swim to meet up with the eggs produced by the female gametangia.
  35. anticodon
    Region present at a tRNA attachment site; a three-nucleotide sequence that is perfectly complementary to a particular codon.
  36. antidiuretic hormond (ADH)
    A hormone produced in the brain and stured in the pituitary gland; it increases the permeability of the collecting duct to water, leading to more concentrated urine content.
  37. antigen
    A molecule that is foreign to our bodies and causes our immune system to respond.
  38. apical meristem
    Region at the tips of roots and shoots where plant growth is concentrated and many actively dividing cells can be found.
  39. apoplast pathway
    Movement of water and nutrients through the nonliving portion of cells.
  40. aposematic coloration
    Warning coloration adopted by animals that possess a chemical defense mechanism.
  41. archaebacteria
    One of two major prokaryotic evolutionary branches. These organisms thed to live in extreme environments and include halophiles, methanogens, and thermaacidophiles.
  42. archegonium
    Female gametangia in bryophytes, ferns, and gymnosperms.
  43. archezoa
    Eukaryotic organism that allegedly most closely resembles prokaryotes.
  44. arteries
    Structures that carry blood away from the heart.
  45. artificial selection
    When humans become the agents of natural selection (breeding of dogs).
  46. ascospores
    Haploid meiotic products produced by certain fungi
  47. A site
    Region on protein synthesis machinery that holds the tRNA carrying the next amino acid.
  48. associative learning
    Process by which animals take one stimulus and associate it with another.
  49. atom
    The smallest form of an element that still displays its unique properties.
  50. ATP synthase
    Enzyme that uses the flow of hydrogens to drive the phosphorylation of an adenosine diphosphate molecule to produce adenosine triphosphate.
  51. auditory communication
    Communication that involve the use of sound in the conveying of a message.
  52. autonomic nervous system (ANS)
    A subdivision of the perepheral nervous system (PNS) that controls the involuntary activities of the body: smooth muscle, cardiac muscle, and glands. The ANS is divided into the sympathetic and parasynpathetic divisions.
  53. autosomal chromosome
    Ont that is not directly involved in determining gender.
  54. autotroph
    An organism that is self-nourishing. It obtains carbon and energy without ingesting other organisms.
  55. auxin
    Plant hormone that leads to elongation of stems and plays a role in phototropism and gravitropism.
  56. axon
    A longer extension that leaves a neuron and carries the impulse away from the cell body toward target cells.
  57. balanced polymorphism
    When there are two or more phenotypic variants maintained in a population.
  58. bare-rock succession
    The attachment of lichen to rocks, followed by the step-by-step arrival of replacement species.
  59. Barr bodies
    Inactivated genes on X chromosomes.
  60. Batesian mimicry
    An animal that is harmless copies the appearance of an animal that is dangerous as a defense mechanism to make predators think twice about attacking.
  61. behavioral ecology
    Science that studies that studeis the inter action between animals and their environments from an evolutionary perspective.
  62. bile
    Substance that contains bile salts, phospholipids, cholesterol, and bile pigments such as bilirubin, is stored in the gallbladder, and is dumped into the small intestine on the arrival of the food.
  63. bile salts
    Help to mechanically digest fat by emulsifying it into small droplets contained in water.
  64. binary fission
    Mechanism by which prokaryotic cells divide. The cell elongates and pinches into two new daughter cells.
  65. binomial system of classification
    System created by Linnaeus in which each species is given a two-word name: Genus + species (e.g., Homo sapiens).
  66. biogeochemical cycles
    Cycles that represent the movement of elements, such as nitrogen and carbon, from organisms to the environment and back in a continuous cycle.
  67. biomass pyramid
    Biomass represents the cululative weight of all the member at a given trophic level.
  68. biome
    The various geographic regions of the earth that serve as hosts for ecosystems.
  69. biosphere
    The entire life-containing area of a planet--all ecosystems and communities.
  70. biotic components
    Living organisms of an ecosystem.
  71. biotic potential
    The maximum growth rate for a population given unlimited resources, unlimited space, and lack of competition or predators.
  72. birth rate
    Offspring produced per a specific time period.
  73. bivalves
    Mollusks with hinged shells such as oysters and clams.
  74. blastula
    As a morula undergoes its next round of cell divisions, fluid fills its center to create this hollow-looking structure.
  75. "blending" hypothesis
    Theory that the genes contributed by the two parents mix as if they are paint colors and the exact genetic makeup of each parent can never be recovered; the genes are as inseparable as blended paint.
  76. bottleneck
    A dramatic reduction in population size that increases the likelihood of genetic drift.
  77. bronchi
    Tunnels that branch off the trachea that elad into the individual lungs and divide into smaller branches called bronchioles.
  78. bronchioles
    Tiny lung tunnels that branch repeatedly until they conclude as tiny air pockets containing alveoli
  79. brush border
    Large number of microvilli that increase the surface area of the small intestine to improve absorption efficiency.
  80. bryophytes
    The first land plants to evolve from teh chlorophytes. Members of this group include mosses. liverworts, and hornworts.
  81. bundle sheath cells
    Cells that are tightly wrapped around the veins of a leaf. They are the site for the Calvin cycle in C4 plants.
  82. C4 photosynthesis
    Photosynthetic process that alters the way in which carbon is fixed to better deal with the lack of CO2 that comes from the closing of the stomata in hot, dry regions.
  83. Calvin cycle
    A name of the light-independent (dark) reactions of photosynthesis.
  84. CAM (crassulacean acid metabolism) photosynthesis
    Plants close their stomata during the day, collecting CO2 at night, and store the CO2 in the form of acids until it is needed during the day for photosynthesis.
  85. capsid
    A protein shell that surrounds genetic material.
  86. carbohydrate
    Organic compund used by the cells of the human body in energy-producing reactions and as a structural material. The three main types of carbohydrates are monosaccharides, disaccharides, and polysaccharides.
  87. carbon cycle
    The movement of carbon from the atmosphere to living organisms and back to the environment in a continuous cycle.
  88. carbon fixation
    The attachment of the carbon from CO2 to a molecule that is able to enter the Canvin cycle, assisted by rubisco.
  89. carbonyl group
    A functional group that is hydrophilic and polar. It has a central carbon connected to R groups on either side. If both Rs are carbon chains, it is a ketone. If one R is a gydrogen and the other is a carbon chain, it is an aldehyde.
  90. carboxyl group
    An acidic functional group (COOH). This functional group shows up along with amino groups in amino acids.
  91. cardiac muscle
    Involuntary muscle of the heart that is striated in appearance and contains multiple nuclei.
  92. carnivore
    A consumer that obtains energy and nutritients through consumption of other animals.
  93. carotenoid
    A photosynthetic pigment.
  94. carrying capacity
    The maximim number of individuals a population can sustain in a given environment.
  95. casparian strip
    Obstacle that blocks the passage of water through the endodermis of plants
  96. catalase
    Enzyme that assists in the conversion of hydrogen peroxide to water and oxygen. Found in peroxisomes.
  97. catalysts
    Molecules that speed up reactions by lowering the activation energy of a reaction.
  98. cation
    Ion with a positive charge that contains more protons than electrons.
  99. cell body
    The main body of the neuron.
  100. cell cycle
    A cycle that consists of four stages: G1, S, G2, and M. G1 and G2 are growth stages, S is the part of the cell cycle in which the DNA is duplicated, and the M phase stands for mitosis--the cell division phase.
  101. cell-mediated immunity
    This type of immunity involves direct cellular response to invasion as opposed to antibody-based defense.
  102. cell plate
    Plant cell structure constructed in the Golgi apparatus composed of vesicles that fuse together anong the middle of the cell, completing the separation process.
  103. cellular slime molds
    Protists with a unique eating strategy. When plenty of food is available, they eat alone. When food is scarce, they clump together and form a unit.
  104. cellulose
    Polysaccharide composed of flucose used by plants to form cell walls.
  105. cell wall
    Wall that functions to shape and protect cells. Present in plant but not animal cells.
  106. central nervous system (CNS)
    The CNS is made up of the brain and the spinal cord. The CNS controls skeletal muscles and voluntary movement.
  107. cephalization
    The concentration of sensory machinery in the anterior end of a bilateral organism.
  108. cerebellum
    Portion of the brain that controls functions such as speech, hearing, sight, and motor control. Divided into two hemispheres and four lobes per hemisphere.
  109. cerebrum
    Portion of the brain that controls functions such as speech, hearing, sight, and motor control. Divided into two hemispheres and four lobes per hemisphere.
  110. cervix
    The uterus connects to the vaginal opening via this narrowed region.
  111. character
    A heritable feature, such as flower color, that varies amond individuals.
  112. checkpoints
    Stop points throughout the cell cycle where the cell verifies that there are enough nutrients and raw materials to progress to the next stage of the cycle.
  113. chemical communication
    Mammals and insects communicate through the use of chemical signals called pheromones.
  114. chemiosmosis
    The coupling of the movement of electrons down the electron transport chain with the formation of ATP using the driving force provided by a proton gradient. Seen in both photosynthesis and respiration.
  115. chemautotrophs
    Autotrophs that produce energy through oxidation of inorganic substances.
  116. chitin
    Polysaccharide that is an important part of the exoskeletons of arthropods such as insects, spiders, and shellfish.
  117. chloraphyll
    A photosynthetic pigment.
  118. chlorophytes
    Green algae that are probably the common ancestors of land plants.
  119. chloroplast
    The site of photosynthesis and energy production in plant cells and algae.
  120. choanoflagellate
    Accepted to be the common ancestor of the animal kingdom.
  121. choice
    Refers to the selection of mates by one sex (in mammals, it is usually females who exercise choice over males).
  122. choice chamber
    Chamber used in scientific experiments to study kinesis.
  123. cholesterol
    Steroid that is an important structural component of cell membranes and serves as a precurson molecule for steroid sex hormones.
  124. chorion
    Formed from the trophoblast, it is the outer membrane of the embryo and the site of implantation onto the endometrium. It contributes to formation of the placenta in mammals.
  125. chromatin
    The raw material that gives rise to the chromosomes (genetic material is uncoiled).
  126. chromosomal translocations
    Condition in which a piece of one chromosome is attached to another, non-homologous chromosome.
  127. chromosome duplication
    Error in chromosomal replication that results in the repetition of a genetic segment.
  128. chromosome inversion
    Condition in shich a chromosome separates and reattaches in the opposite direction.
  129. chronic myelogenous leukemia
    A cancer affecting white blood cell precurson cells. In this disease, a portion of chromosome 22 has been swapped with a pice of chromosome 9.
  130. chymotrypsin
    Enzyme that cuts protein bonds in the small intestine.
  131. cilia
    Structures that beat in rhythmical waves to carry foreign particles and mucus away from the lungs.
  132. circadian rhythm
    A physiologic cycle that occurs in time increments that are roughly equivalent to the length of a day.
  133. class I histocompatability antigens
    The surface of all the cells of the human body, except for red blood cells, have these antigens, which are slightly different for each individual. The immune system accepts any cell that has the identical match for this antigen as friendly. Anything with a different major histocompatibility complex is foreign.
  134. class II histocompatibility antigens
    Antigens found on the surface of the immune cells of the body. These antigens play a role in the interaction between the cells of the immune system.
  135. classical conditioning
    Type of associative learning that Ivan Pavlov demonstrated with his experiments involving salivation in dogs.
  136. cleavage divisions
    Delevloping embryo divides; cytoplasm is distributed unevenly to the daughter cells while the genetic information is distributed equally.
  137. cleavage furrow
    Groove formed, in animal cells, between the two daughter cells; this groove pinches together to complete the separation of the two cells after mitosis.
  138. climax community
    Final stable stage at the completion of a succession cycle.
  139. clumped dispersion
    Scenario in which individuals live in packs that are space out from each other.
  140. codominance
    Both alleles express themselves fully in a heterozygous organism.
  141. codon
    A triplet of nucleotides that codes for a particular amino acid.
  142. coefficient of relatedness
    Statistic that represents the average proportion of genes that two individuals have in common.
  143. coelom
    Fluid-filled body cavity found between the body wall and the gut that has a lining and is derived from teh mesoderm.
  144. coelomates
    Animals that contain a true coelum.
  145. coencytic fungi
    Fungi that do not contain septae.
  146. coevolution
    The mutual evolution between two species, which is exemplified by predator-prey relationships.
  147. coleoptile
    Protective structure found around a grass seedling.
  148. collenchyma cells
    Live plant cells that provide flexible and mechanical support.
  149. commensalism
    One organism benefits from the relationship while the other is unaffected.
  150. community
    A collection of populations of species in a given geographic area.
  151. competent
    Describes a cell that is ready to accept foreign DNA from the environment.
  152. competition
    Both involved are harmed by this kind of interaction. The two major forms of competition are intraspecific and interspecific competition.
  153. competitive inhibition
    Condition in which an inhibitor molecule resembling the substrate binds to the active site and physically blocks the substrate from attaching.
  154. complement
    A protein that coats cells that need to be cleared, stimulating phagocytes to ingest them.
  155. compounds
    Elements are combined to form entities called compoinds.
  156. condution
    Process by which heat moves from a place of hight temperature to a place of lower temperature.
  157. conifers
    Gymnosperm plants whose reproductive structure is a cone.
  158. conjugation
    The transfer of DNA between two bacterial cells connected by appendates called sex pili.
  159. conservative DNA replication
    The original double helix of DNA does not change at all; it is as if the DNA is placed on a copy machine and an exact duplicate is made. DNA from the aprent appears in only one of the two daughter cells.
  160. convection
    Heat transfer caused by airflow.
  161. convergent characters
    Characters are convergent if they look the same in two species, even though the species do not share a common ancestor.
  162. convergent evolution
    Two unrelated species evolve in a way that makes them more similar. They both respond the same way to some environmental challenge, bringing them closer together.
  163. cork cambium
    Area that produces a thick cover for stems and roots. It produces tissue that replaces dried-up epidermis lost during secondary growth.
  164. cork cells
    Cells produced by the cork cambium that die and form a protective barrier against infection and physical damage.
  165. corpus callosum
    Bridge that connects the two hemispheres of the brain.
  166. cortex
    Outer region of the kidney or adrenal gland.
  167. cotyledon
    Structure that provides nutrients for a developing angiosperm plant.
  168. cri-du-chat syndrome
    This syndrome occurs with a deletion in chromosome 5 that leads to mental retardation, unusual facial features, and a small head. Most die in infance or early childhood.
  169. crossover
    Also referred to as "crossing over." When the homologous pairs match up during prophase I of meiosis, complementary pieces from the two homologous chromosomes wrap around each other and are exchanged between the chromosomes. This is one of the mechanisms that allows offspring to differ from their parents.
  170. cryptic coloration
    Those being hunted adopt a coloring scheme that allows them to blend in to the colors of the environment.
  171. cuticle
    Waxy covering that protects terrestrial plants against water loss.
  172. cutin
    Waxy coat that protects plants.
  173. cyclic light reactions
    Pathway that produces only ATP and uses only photosystem I.
  174. cyclin
    Protein that accumulates during interphase; vital to cell cycle control.
  175. cystic figrosis (CF)
    A recessive disorder that is the most common lethal genetic disease in the United States. A defective version of a gene on chromosome 7 results in the excessive secreation of a thick mucus, which accumulates in the lungs and digestive tract. Left untreated, children with CF die at a very young age.
  176. cytokinesis
    The physical separation of the newly formed daughter cells during meiosis and mitosis. Occurs immediately after telophase.
  177. cytokinin
    Plant hormone that promotes cell division and leaf enlargement, and slows down the aging of leaves.
  178. cytoskeleton
    Provides support, shape, and mobility to cells.
  179. death rate
    Number of deaths per time period.
  180. deceptive markings
    Patterns that can cause a predator to think twice before attaching. For example, some insects may have colored designs on their wings that resemble large eyes, making individuals look more imposing than they are.
  181. dehydration reaction
    A reaction in which two compounds merge, releasing H2O as a product.
  182. deletion
    A piece of the chromosome is lost in the developmental process.
  183. demographers
    Scientists whgo study the theory and statistics behind population growth and decline.
  184. dendrite
    One of many short, branched processes of a neuron that help send the nerve impulses toward the cell body.
  185. denitrification
    The process by which bacteria use nitrates and release N2 as a product.
  186. density-dependent inhibition
    When a certain density of cells is reached, cell growth will slow or stop. This is because there are not enough raw materials for the growth and survival of more cells.
  187. density-dependent limiting factors
    Factors related to population size that come into play as population size approaches or passes the carrying capacity. Examples of density-dependent limiting factors include food, waste, and disease.
  188. density-independent limiting factors
    Factors that limit population growth that have nothing to do with the population size, such as natural disasters and weather.
  189. depolarization
    The electric potential becomes less negative inside the cell, allowing an action potential to occur.
  190. desert
    The driest land biome on earth, which experiences a wide range of temperatures from day to night and exists on nearly every continent.
  191. detritivore
    Also know as decomposer. A consumer that obtains its energy through the consumption of dead animals and plants.
  192. dicot
    (Dicotyledon) An angiosperm plant that has two cotyledons.
  193. diffusion
    The movement of molecules down their concentration gradients without the use of energy. It is a passive process during which molecules move from a region of higher concentration to a region of lower concentration.
  194. dihybrid cross
    The crossing of two different characters (BbRr x Bb Rr). A dihybrid cross between heterozygous gametes gives a 9 : 3 : 3 : 1 phenotype ration in the offspring.
  195. diploid (2n)
    An organism that has two copies of each type of chromosome. In humans, this refers to the pairs of homologous chromosomes.
  196. diplomonads
    A phylum that is associated with the archezoan eukaryotes.
  197. directional selection
    Occurs when members of a population at one end of a spectrum are selected against and/or those at the other end are selected for.
  198. disaccharide
    A sugar consisting of two monosaccharides bound together. Common disaccharides include sucrose, maltose, and lactose.
  199. dispersive DNA replication
    A theory othat suggests that every daughter strandcontains some parental DNA, but it is dispersed among pieces of DNA not of parental origin.
  200. disruptive selection
    Selection is disruptive when individuals at the two extremes of a spectrum of variation do better than the more common forms in the middle.
  201. distribution
    Describes the way populations are dispersed over a geographic area.
  202. divergent evolution
    Two related species evolve in a way that makes them less similar, sometimes causing speciation.
  203. division
    The classification category that replaces the phylum in plant classification.
  204. DNA methylation
    The addition of CH3 groups to the bases of DNA, rendering DNA inactive.
  205. DNA polymerase
    The main enzyme in DNA replication that attaches to primer proteins and adds nucleotides to the growing DNA chain in a 5'-to-3' direction.
  206. DNA replication
    The process by which DNA is copied. This process occurs during the S phase of the cell cycle to ensure that every cell prodeced during mitosis or meiosis receives the proper amount of DNA.
  207. dominance hierarchy
    A ranking of pwer amoug the members of a group of individuals.
  208. double helix
    The shape of DNA--two strands help together by hydrogen bonds.
  209. Down syndrome
    A classic aneuploid syndrome affecting one of every 700 children born in the United States. It most ofteninvolves a trisomy of chromosome 21, and leads to mental retardation, heart defects, short stature, and characteristic facial features.
  210. Duchenne muscular dystrophy
    Sex-linked disorder caused by the absence of an essential muscle protein that leads to progressive weakening of the muscles combined with a loss of muscle coordination.
  211. ecosystem
    All the individuals of a community and the environment in which it exists.
  212. ectoderm
    Outer germ layer that gives rise to the nervous system, skin, hair, and nails.
  213. ectothermic animal
    Animal whose basic metabolic rates increase in response to increase in temperature.
  214. Edwards syndrome
    The presence of trisomy 18, which occurs in one out of every 10,000 live births and affects almost every organ of the body.
  215. electron transport chain (ETC)
    The chain of molecules, located in the mitochondria, that passes electrons along during the process of chemiosmosis to regenerate NAD+ to form ATP. Each time an electron passes to another member of the chain, the energy of the system drops.
  216. element
    The simplest form of matter.
  217. embryology
    The study of embryonic development.
  218. emigration rate
    Rate at which individuals relocate out of a given population.
  219. endergonic reaction
    A reaction that requires input of energy to occur. A + B + energy => C.
  220. endocytosis
    Process by which substances are brought into cells by enclosure into a membrane-created visticle that surrounds the substance and escorts it into the cell.
  221. endoderm
    Inner germ layer that gives rise to the inner lining of the gut, digestive system, liver, thyroid, lungs, and bladder.
  222. endodermis
    Cells that line the innermost layer of the cortex in plants that give rise to the casparian strip.
  223. endometrium
    Inner wall of the uterus to which the embryo attaches.
  224. endopeptidases
    Enzymes that initiate the digestion of proteins by hydrolyzind all the polypeptides into small amino acid groups.
  225. endosymboitic theory
    Proposes that groups of prokaryotes associated in simbiotic relationships to form eukaryotes (mitochondria and chloroplasts).
  226. endothermic animal
    Animal whose body temperature is relatively unaffected by external temperature
  227. enhancer
    DNA region, also known as a "regulator," that is located thousands of bases away from the promoter that influences transcription by inter acting with specific transcription factors.
  228. enzymes
    Catalytic proteins that re picky, interacting only with particular substrates. However, the enzymes can be reused and react with more than one copy of their substrate of choice and have a major effect on a reaction.
  229. epiblast
    Develops into three germ layers of the enbryo: the endoderm, the mesoderm, and the ectoderm.
  230. epidermis (plants)
    The protective outer coating of plants.
  231. epididymis
    The coiled region that extends from the testes. This is where the sperm completes its maturation and waits until it is called on to do its duty.
  232. episomes
    Plasmids that can be incorporated into a bacterial chromosome.
  233. epistasis
    A gene at one locus alters the phenotypic expression of a gene at another locus. A dihybrid cross involving epistatic genes produces a 9:4:3 phenotype ratio.
  234. esophageal sphincter
    Valvelike trapdoor between the esophagus and the stomach.
  235. esophagus
    Structure that connects the throat to the stomach.
  236. estrogen
    Hormone make (secreted) in ovaries that stimulates development of sex characteristics in women and indces the release of luteinizing hormone (LH) before LH surge.
  237. ethology
    The study of animal behavior.
  238. ethylene
    Plant hormone that initiates the ripening of fruit and the dropping of leaves and flowers from trees.
  239. eubacteria
    One of two major prokaryotic evolutionary branches. Categorized according to their mode of nutritional acquisition, mechanism of movement, shape, and other characteristics.
  240. eukaryotic cell
    Complex cell that contains a nucleus, which functions as the control center of the cell, directing DNA replication, transcription, and cell growth. Organisms can be unicellular or multicellular and contain many different membrane-bound organelles.
  241. evaporation
    Process by which a liquid changes into a vapor form. Functions in thermoregulation for humans when water elaves our bodies in the form of water vapor--sweat.
  242. evolution
    Descent with modification. Evolution happens to populations, not individuals, and describes change in allele frequencies in populations with time.
  243. excision repair
    Repain mechanism for DNA replication in which a section of DNA containing an error is cut out and the gap is filled by DNA polymerase.
  244. exergonic reaction
    A reaction that gives off energy as a product. A + B => energy + C.
  245. exocytosis
    Process by which substances are exported out of the cell. A vesticule escorts the substance to the plasma membrane, fuses with the membrane and ejects its contents out of the cell.
  246. exons
    Coding regions produced during transcription that re glued back together to produce the mRNA that is translated into a protein.
  247. exopeptidases
    Enzymes that complete the digestion of proteins by hydrolyzing all the amino acids of the fragments remaining.
  248. exponential growth
    A population grows at a rate that creates a J-shaped curve.
  249. extreme halophiles
    Archaebacteria that live in environments with high salt concentrations.
  250. F1
    The first generation of offspring, or the first "filial" generation in a genetic cross.
  251. F2
    The second generation of offspring, or the second "filial" generation in a genetic cross.
  252. facilitated diffusion
    The diffusion of particles across a selectively permeable membrane with the assistance of transport proteins that are specific in what they will carry and have a binding site designed for molecules of interest. This process requires no energy.
  253. facultative anaerobe
    Organisms that can survive in oxygen-rich or oxygen-free environments.
  254. fats
    Libids, made by combining glycerol and fatty acids, used as long-term energy stores in cells. They can be saturated or unsaturated.
  255. fatty acid
    Long carbon chain that contains a carboxyl group on one end that combines with glycerol molecules to form lipids.
  256. fermentation
    Anaerobic respiration pathway that occurs in absense of oxygen. Produces less ATP than aerobic respiration.
  257. ferredoxin
    Modecule that donates the electrons to NADP+ to produce NADPH during light reactions of photosynthesis.
  258. fibrous root system
    Root system found in monocots that provides the plant with a very strong anchor without going very deep into the soil.
  259. filtration
    Capillaries allow small particles through the pores of their endothelial linings, but large molecules such as proteins, platelets, and blood cells tend to remain in the vessel.
  260. fixed-action pattern
    An innate behavior that seems to be a programmed response to some stimulus.
  261. florigen
    Hormone thought to assist in the blooming of flowers.
  262. fluid mosaic model
    Model that states that the membrane is made of a pospholipid bilayer with proteins of various lengths and sizes, interspersed with cholesterol.
  263. fluke
    Parasitic flatworm that alternates between sexual and asexual reproductive cycles.
  264. follicle-stimulating hormone (FSH)
    A gonadotropin that stimulates activities of the testes and ovaries. In females, it induces the development of the ovarian follicle, leading to the production and secretion of estrogen.
  265. food chain
    A hierarchical list of who snacks on who. For example, bugs are eaten by spiders, who are eaten by birds, who are eaten by cats.
  266. food web
    Can be regarded as overlapping food chains that show all the various dietary relationships in an environment.
  267. foraging
    The behavior of actively searching and eating a particular food resource.
  268. fossil record
    The physical manifestation of species that have gone extince (e.g., bones and imprints).
  269. F-plasmid
    Plasmid that contains the genes necessary for the prodection of a sex pillus.
  270. frameshift mutations
    Delection or addition of DNA nucleotides that does not add or remove a multiple of three nucleotides. Usually produces a non-functional protein unless it occurs late in protein production.
  271. frequency-dependent selection
    Alleles are selected for or against depending on their relative frequency in a population.
  272. functional groups
    The groups responsible for the chemical properties of organic compounds.
  273. G1 phase
    The first growth phase of the cell cycle that produces all the necessary raw materials for DNA synthesis.
  274. G2 phase
    Second growth phase of the cycle that produces all the necessary raw materials for mitosis.
  275. gametangia
    Protective covering that provides a safe haven for the fertilization of the gametes and the development of the zygote in bryophytes, ferns, and some gymnosperms.
  276. gametes
    Sex cells produced during meiosis in the human life cycle.
  277. gametophyte
    A haploid multicellular organism.
  278. gastrulation
    Cells separate into three primary layers called germ layers, which eventually give rise to the different tissues of an adult.
  279. gene flow
    The change in frequencies of alleles as genes from one population are incorporated into another.
  280. generalized transduction
    Transduction caused by the accidental placement of host DNA into a phage instead of viral DNA during viral reproduction. The host DNA may find its way into another cell where crossover could occur.
  281. generation time
    Time needed for individuals to reach reproductive maturity.
  282. genetic code
    Code that translated codons found on mRNA strands into amino acids.
  283. genetic drive
    A change in allele frequencies that is due to chance events.
  284. genotype
    An organism's genetic makeup for a given trait. A simple example of this could involve eye color, where B represents the allele for brown and b represents the allele for blue. The possible genotypes include homozygous brown (BB), heterozygous brown (Bb), and homozygous blue (bb).
  285. genus
    Taxonomic group to which a species belongs.
  286. gibberellin
    Plant hormone that assists in stem elongation and induces growth in dormant seeds, buds, and flowers.
  287. glomerular capillaries
    The early portion of the nephron where the filtration process begins.
  288. glucagon
    Hormone that stimulates conversion of glycogen into glucose.
  289. glycerol
    Three-carbon molecule that combines with fatty acids to produce a variety of lipids.
  290. glycolysis
    Occurs in the cytoslasm of cells and is the beginning pathway for both aerobic and anaerobic resporation. During glycolysis, a glucose molecule is broken down through a series of reactions into two molecules of ATP, NADH, and pyruvate.
  291. glycoprotein
    Protein that has been modified by the addition of a sugar.
  292. Golgi apparatus
    Organelle that modifies proteins, lipids, and other macromolecules by the addition of sugars and other molecules to form glycoproteins. The products are then sent to other parts of the cell.
  293. G-proteins
    Proteins vital to signal cascade pathways. Directly activate molecules such as adenyl cyclase to assist in a reaction.
  294. gradualism
    The theory that evolutionary change is a steady, slow process.
  295. grana
    Flattened channels and disks arranged in stacks found in the thylakoid membrane.
  296. gravitropism
    A plant's growth response to gravitational force. Auxin and gibberellins are involved in this response.
  297. gross productivity
    The difference over time between the dissolved oxygen concentrations of the light and dark bottles calculated in primary productivity experiments.
  298. growth factors
    Assist in the growth of structures.
  299. guard cells
    Cells within the epidermis of plants that control the opening and closing of the stomata.
  300. gymnosperm
    First major seed plant to evolve. Heterosporous plant that usually transports its sperm through the use of pollen. Conifers are the major gymnosperm to know.
  301. habituation
    Loss of responsiveness to unimportant stimuli that do not provide appropriate feedback.
Card Set
AP Biology Glossary
Glossary from study guide