SAT Subject Biology Glossary from Barron
Barron 's SAT Subject Biology Glossary
Abiotic Factors: Nonliving factors in an ecosystem
Abscisic acid (ABA): Plant hormone that inhibits growth
Accessory pigments: (Also Antennae) Molecules that assist in photosynthesis by capturing and passing on photons of light to chlorophyll a and expanding the range of light that can be used to produce sugar. Examples are chlorophyll b and the caretenoids.
Acoelomate: An animal that has no true coelom; ex: flatworms
Actin: Protein that makes up the thin myofilaments in skeletal muscle
Active Transport: movement of particles against a gradient, from low concentration to high concentration. This always requires the expenditure of energy
Adventitious roots: roots that rise above the ground; examples are aerial roots and prop roots
Agonistic behavior: aggressive behavior
Alcohol fermentation: The process by which certain cells convert pyruvic acid or pyruvate from glycolysis into ethyl alcohol and carbon dioxide in the absence of oxygen
Allantois: Extra embryonic membrane in a bird's egg. Exchanges respiratory gases to and from the embryo
Alleles: Alternate forms of a gene. For example, there are two of these for height in pea plants: tall and dwarf.
Alveoli: Microscopic air sacs in the lung where diffusion of the respiratory gases, oxygen and carbon dioxide occurs
Amnion: Membrane that encloses the embryo in protective amniotic fluid
Amylase: Enzyme that digests starch
Analogous structures: Structures, such as a bat's wing and a fly's wing, that have the same function but not the same underlying structure (not evidence of a common origin).
Aneuploidy: any abnormal condition of the chromosomes
Angiosperms: Anthophyta or flowering plants
Anion: a negative ion
Antennae: (Also accessory pigments) Molecules that assist in photosynthesis by capturing and passing on photons of light to chlorophyll a and expanding the range of light that can be used to produce sugar. Examples are chlorophyll b and the caretenoids.
Anther: Male part of flower where sperm (pollen) is produced by meiosis. Sits atop the filament
Antheridia: structures located on the tips of a gametophyte plant and produce sperm
Antibodies: Immunoglobins. Part of the third line of defense, the specific immune response. Each molecule is a Y shaped molecule consisting of four polypeptide chains
Anticodon: The three nucleotide sequence associated with tRNA
Antigens: anything that triggers an antibody response
Apoptosis: programmed cell death
Archaeopteryx: intermediate fossil that shows both reptile and bird characteristics
Archegonia: structures located on the tips of a gametophyte plant and that produces eggs.
Associative learning: one type of learning in which one stimulus becomes linked to another through experience.
ATP: special high energy molecule that stores energy for immediate use in the cell
ATP synthase: structure in the membranes of mitochondria and chloroplasts where ATP is formed
Autonomic nervous system: part of the nervous system that controls automatic functions, such as heart and breathing rate
Autosomes: chromosomes other than the sex chromosomes. Humans have 44 in each cell
Auxins: growth hormones in plants that are responsible for phototropisms and apical dominance, the preferential growth of a plant towards the sun
Backcross: Testcross. a technique to determine whether an individual plant or animal showing the dominant trait is homozygous dominant or heterozygous
Bacterial transformation: the ability of bacteria to alter their genetic makeup by uptaking foreign DNA from another bacerial cell and incorporating it into their own. Discovered by Griffith
Base-pair substitution: a mutation where one nucleotide is substituted for a correct one in a DNA strand
Bicarbonate ion: the most important buffer in human blood. It is responsible for keeping the pH of blood at 7.4
Bile: chemical produced in the liver and released from the gallbladder that emulsifies fats. It is not an enzyme.
Binomial nomenclature: system of taxonomy that we use today, developed by Carl von Linné. In this system, every organism has a two part name, like Homo Sapiens.
Biosphere: the global ecosystem
Biotechnology: branch of science that uses recombinant DNA techniques for practical purposes, also called genetic engineering
Biotic factor: includes all the organisms with which an organism might react in an ecosystem
Biotic potential: the maximum rate at which a population could increase under ideal conditions
Bottleneck effect: natural disasters such as fire, earthquake, and flood reduce the size of a population nonselectively, resulting in a loss of genetic variation. The resulting population is much smaller and not representative of the original one. Certain alleles may be under or overrepresented compared with the original population.
Budding: splitting off of new individuals from existing ones. how reproduction occurs in hydra.
Buffers: chemicals that resist a change in pH
C-4 photosynthesis: modification for dry environments. C-4 plants exhibit modified anatomy and biochemical pathways, which enable them to minimize excessive water loss and maximize sugar production.
Calvin cycle: cyclical process that produces sugar. It occurs during the light-independent reactions.
Carbon fixation: incorporation of carbon dioxide into a sugar. Occurs during the Calvin cycle.
Cardiac sphincter: band of muscle at the top of the stomach that keeps acidified food in the stomach from backing up into the esophagus and burning it.
Carotenoids: photosynthetic antennae pigments. they are orange and yellow.
Carpel: Female part of the flower, produce the female gametophytes, ova. Each consists of an ovary, stigma and style. Also called the pistil.
Carrying Capacity (K): a limit to the number of individuals that can occupy one area at a particular time.
Cation: a positive ion.
Centrioles: responsible for division of the cytoplasm in animal cells; they are not present in plant cells. They consist of 9 triplets of microtubules arranged in a circle.
Centromere: specialized region of a chromosome that holds two sister chromatids together
Centrosome: consist of two centrioles at right angles to each other. Important during cell division in animal cells.
Chemiosmosis: how ATP is produced during oxidative phosphorylation. Protons only flow through the special ATP synthetase channels and transfer energy to molecules of ATP.
Chitin: a polysaccharide that makes up the exoskeleton of insects and the cell walls of fungi.
Chloroplasts: type of plastid that carries out photosynthesis
Chorion: membrane that lies under the shell of an egg and allows for diffusion of respiratory gases between the outside environment and the inside of the shell.
Chromatin network: DNA in the nucleus that is wrapped with special proteins called histones into a visible network.
Chromoplasts: type of plastid that stores pigments that are responsible for the bright colors in fruit and flowers
Classical conditioning: type of associative learning. Pavlov trained dogs to associate the sound of a bell with food. The result was that dogs would salivate upon merely hearing the sound of the bell even though no food was present.
Cleavage: rapid mitotic cell division of the zygote that begins immediately after fertilization
Cnidocytes: cells that house the stingers in cnidarians
Codominance: an inheritance pattern where both traits show at once. In humans, a person who had 2 different genes for blood type, A and B, has type AB blood.
Codon: the three-nucleotide sequence associated with mRNA.
Coelomate: an animal that has a true coelom; all chordates are coelomates
Coenzymes: vitamins that assist in the normal functioning of enzymes
Coevolution: the mutual evolutionary set of adaptations of two interacting species
Cofactors: Minerals that assist in the normal functioning of enzymes
Cohesion tension: The attraction of like molecules to stick together. water molecules tend to stick together because they exhibit strong cohesion tension.
Collenchyma cells: Plant cells that have unevenly thickened cell walls but lack secondary cell walls. The strings of celery consist of collenchyma cells.
Colon: another name for large intestine
Commensalism: symbiotic relationship in which one organism benefits and one is not affected by another organism.
Community: Consists of all the organisms living in one area
Companion cells: make up phloem vessels, along with sieve tube elements
Conjugation: a primitive form of sexual reproduction where individuals exchange genetic material.
Continental drift: The theory that states that the continents are floating and moving very slowly. Over millions of years, seven separate continents formed from Pangea.
Contractile vacuole: structure found in freshwater protista, like paramecia and amoeba, that pumps out excess water that diffuses inward because the organisms live in an environment that is hypotonic.
Convergent evolution: type of evolution where unrelated species occupying the same environment and subjected to similar selective pressures show similar adaptations. The classic example is the whale and the fish.
Cortex: Specialized region in a plant root or stem for storage and support.
Cotyledon: Food for the growing embryo in a dicot seed. The cells that make this up are triploid.
Covalent bonds: bonds formed between atoms where electrons are shared.
CAM (Crassulacean acid metabolism ): a form of photosynthesis that is an adaptation for dry conditions. These plants keep there stomates closed during the day and open at night, the reverse of how most plants behave.
Cristae: series of inner membranes in mitochondria where cell respiration occurs
Crop: structure in birds, insects, and earthworms, among others, for temporary storage of food.
Crossing over: A normal process in which homologous chromatids exchange genetic material. Crossover is important because it increases variation in the gametes.
Cutin: waxy coating on the leaves that helps prevent excess water loss from the plant
Cyclosis: Movement of cytoplasm around the cell
Cystic fibrosis: the most common lethal genetic disease in the United States, 1 out of 25 caucasians is a carrier. Characterized by build up of extracellular fluid in the lungs and digestive tract.
Cytochromes: proteins that play a key role in electron transport chains in mitochondria and chloroplasts
Cytokinesis: division of the cytoplasm. In animal cells, a cleavage furrow forms down the middle of the cell as the cytoplasm pinches inward and the two daughter cells separate from each other. In plant cells, a cell plate forms down the middle of the cell.
Cytokinins: Plant hormones that stimulate cell division and cytokinesis
Cytoplasm: The entire region between the nucleus and plasma membrane
Cytosol: Semiliquid portion of the cytoplasm
Decomposer: Organisms that play a vital role in the ecosystem and that recycle dead organic matter.
Dehydration synthesis: Also known as synthesis. Process by which molecules are bonded together to form a larger molecule with the removal of water.
Deletion: A mutation where a piece of gene, or chromosome is lost
Denature: Characteristic of proteins; a change in shape that stops the protein from functioning.
DNA: the heritable material, passed from parent to offspring
Diastole: Relaxation of the ventricles of the heart. Normal diastolic pressure is 120 mm Hg.
Dicotyledon: Plant whose seed easily breaks in two
Diffusion: The flow of molecules from a higher concentration to a lower concentration. There are two types: simple and facilitated.
Digestion: Enzymatic breakdown, hydrolysis, of food so it is small enough to be assimilated into the body.
Dipeptide: A molecule consisting of two animo acids
Directional Selection: Changing environmental conditions give rise to this type of natural selection. One phenotype replaces another in the gene pool.
Disruptive Selection: This typeof natural selection increases the number of extreme types in a population at the expense of intermediate forms.
Divergent Evolution: Occurs when a population becomes isolated (for any reason) from the rest of the species and becomes exposed to new selective pressures, causing it to evolve into a new species. Homologous structures are evidence of this.
DNA polymerase: the enzyme that catalyzes the elongation of the new DNA strands during replication.
Domain: In the newest system of classification, all organism are classified in one of three domains, which are further divided into kingdom, phylum, class, order, family, genus, and species.
Duodenum: The first 10 inches of the small intestine; where all the digestion is completed
Ecosystem: Includes all the organisms in a given area as well the abiotic factors with which they interact.
Ectotherm: An animal, such as a fish, amphibian, or reptile, that must use environmental energy or behavioral adaptations to its body temperature, cold-blooded.
Egestion: Removal of metabolic waste
Electron transport chain (ETC): consists of a series of molecules within the cristae membrane of mitochondria that provides the energy to phosphorylate ADP into ATP during oxidative phosphorylation.
Endoderm: The innermost layer of an embryo, which develops into the viscera or the digestive system.
Endoplasmic Reticulum: system of transport channels within the cytoplasm of a eukaryotic cell.
Endosperm: Food dor the growing embryo in a monocot seed. The cells that make up the endosperm are triploid.
Endotherm: An animal that uses metabolic energy to maintain constant body temperature; warm-blooded.
Energy of Activation: The amount of energy required to start a reaction.
Eohippus: a transition fossil that demonstrates that the ancient horse is an ancestor of the modern horse, Equus.
Epicotyl: Part of the embryo in a seed that becomes the upper part of the stem and leaves
Epididymis: Part of the testes where the sperm becomes motile
Epiglottis: Flap of cartilage in the back of the throat that directs food to the esophagus
Erythrocytes: red blood cells
Ethylene: Gaseous plant hormone that promotes fruit ripening
Eukaryotes: Cells that contain internal membranes; opposite of prokaryotes
Excited state: when an atom absorbs energy, its electrons move to a higher energy level
Excretion: Removal of metabolic wastes
Exocytosis: The release of substances from a cell
Exons: expressed sequences of DNA. DNA that codes for particular polypeptides
Extremophiles: organisms that live in extreme environments, like methanogens, halophiles, and thermophiles. Make up the domain Archaea
flavin adenine dinucleotide (FAD): coenzyme that shuttles protons and electrons from glycolysis and the Krebs cycle to the electron transport chain
Fermentation: Anaerobic phase of cell respiration
Filament: Threadlike structure that holds up the anther in the male part of a flower.
Filtration: Process that occurs in the nephron where nutrients and wastes diffuse from the glomerulus into Bowman's capsule
Final transcript: the strand of mRNA that is sent to the ribosome after processing. It is much shorter than the initial transcript.
Fission: Division of an organism into two new cells. Reproduction in protists.
Fixed action pattern: Innate, highly stereotypical behavior, which once begun is continued to completion, no matter how useless or silly looking. They are initiated by external stimula called sign stimuli.
Food chain: pathway along which food is transferred from one trophic or feeding level to another.
Founder Effect: a small population, which is not representative of the largest population, breaks away form the larger one to colonize a new area. Rare alleles may be under or overrepresented.
Fragmentation: a single parent organism breaks into parts that regenerate into new individuals. Reproduction in sponges, planaria, and sea stars.
Frameshift: an error in the DNA in which the entire reading frame is altered. This can be caused by an insertion or deletion.
glyceraldhyde-3-phosphate (G3P) (PGAL): First sugar produced by photosynthesis
Gametangia: in primitive plants, a protective jacket of cells in which gametes and zygotes develop and which prevents drying out.
Gametophyte: Monoploid generation of a plant
Gastrin: Digestive hormone that stimulates sustained secretion of gastric juice from the stomach