| A | B |
|---|
| Hooke | the first person to identify cells and name them |
| Leeuwenhoek | He made better lenses and observed cells in greater detail |
| Schwann | He concluded that all living things were made of cels |
| Virchow | Proposed that all cells come from other cells |
| Electron | A microscope that can directly study indivdual protein molecules, not living organisms. |
| Scanning Electron | A microscope that can form a 3-D image. |
| Transmission Electron | A microscope that makes a 2-D image of a slice of a specimen. |
| Dissecting | A low power microscope used to enhance items that can be seen with the naked eye. |
| Compound Light | A microscope with more than one lens that uses light to transmit images to your eye. |
| Cell theory | All organisms are made of cells, all existing cells are produced by other living cells, the cell is the most basic unit of life. |
| Theory | A proposed explanation for a wide range of observations and experimental results that is supported by a wide range of evidence. |
| Dependent | A variable that is observed and measured during an experiment. |
| Independent | A variable that is manipulated, or changed, by a scientist. |
| Abiotic | nonliving factor in an ecosystem. |
| Acid | A compound that donates a proton when dissolved in a solution. pH less than 7. |
| Activation Energy | Energy input to necessary to initate a chemical reaction. |
| Active Transport | Energy-Requiring movement of molecules across a membrane from a region of low concentration to a region of higher concentration. |
| Adaptation | Inherited trait that is selected for over time because it allows organisms to better survive their environment. |
| Adenosine Triphosphate | High-energy molecule that contains, within its bonds, energy that cells use. |
| Adhesion | Attraction between molecules of different substances. |
| Aerobic | process that requires oxygen to occur |
| Allele | Any of the alternative forms of a gene that occurs at a specific place on a chromosome. |
| Amino Acid | molecule that makes up proteins |
| Amniotic sac | fluid-filled organ that cushions and protects the developing embryo of some vertebrates |
| Anaerobic | process that does not require oxygen to occur. |
| Analogous | Body part that is similar in functionas a body part of another organism but is structurally different. |
| Anaphase | In mitosis where chromatids seperate and are pulled to opposite side of cell. |
| Antibiotic | Chemical that kills or slows the growth of bacteria |
| Antibody | Protein produced by B cells that aids in the destruction of pathogens. |
| Anticodon | Set of three nucleotides in a tRNA molecule that binds to a complimentary mRNA codon during translation. |
| Antigen | Protein marker that helps the immune system identify foreign particles. |
| Base | Compound that accepts protons, pH higher than 7 |
| Artificial Selection | process by which humans modify a species by breeding it for certain traits. |
| Asexual Reproduction | process by which offspring are produced from a single parent; does not involve the joining of gametes |
| Atom | basic unit of matter |
| Autosome | chromosome that contains genes for characteristics not directly related to the sex of the organism |
| Autotroph | Organism that obtains its energy from abiotic sources, such as sunlight or inorganic chemicals |
| Base pairing rules | Desribes how nucleotides form bonds in DNA |
| B cell | white blood cell that matures in the bone marrow and produces antibodies that fight off infection |
| Behavioral isolation | isolation between populations due to differences in courtship or mating behavior. |
| Benign | having no dangerous effect on health, especially referring to an abnormal growth of cells that are not cancerous. |
| Binary Fission | asexual reproduction in which a cell divides into two equal parts |
| Binomial Nomenclature | naming system in which each species is given a two-part scientific name. |
| Biodiversity | variety of life within an area |
| Biogeochemical cycle | movement of a chemical through the biological and geological, or living and nonliving, parts of an ecosystem |
| Biology | scientific study of all forms of life |
| Biomass | total dry ,ass of all organisms in a given area |
| Biome | regional or global community of organisms characterized by the climate conditions and plant communities that thrive there |
| Biosphere | All organisms and the part of Earth where they exist |
| Biotic | living things, such as plants, animals, fungi, and bacteria |
| Blastocyst | stage of development during which the zygote consist of a ball of cells |
| Blood pressure | force with which blood pushes against the wall of an artery |
| Bottleneck effect | genetic drift that results from an event that drastically reduces the size of a population |
| Brain stem | structure that connects the brain to the spinal cord and controls breathing and heartbeat. |
| Cancer | characterized by uncontolled cell division |
| Carbohydrate | molecule composed of carbon, hydrogen, and oxygen. |
| Carnivore | organism that obtains energy by eating only animals |
| Carrier | organism whose genome contains a gene for a certain trait or disease that is not expressed in the organism's phenotype |
| Carrying Capacity | number of individuals that the resources of an environment can normally and persistently support |
| Catalyst | substance that decreases activation energy and increases reaction rate in a chemical reaction |
| Cell | basic unit of life |
| Cell cycle | pattern of growth, DNA replication, and cell division that occurs in a eukaryotic cell |
| Cell membrane | double-layer of phospholipids that forms a boundary between a cell and the surrounding environment |
| Cellular respiration | process of producing ATP by breaking down carbon-based molecules when oxygen is present |
| Centriole | small cylinder-shaped organelle made of protein tubes arranged in a circle; aids mitosis |
| centromere | region of condensed chromosome that looks pinched; where spindle fibers attach during meiosis and mitosis |
| Cerebellum | part of the brain that coordinates and regulates all voluntary muscle movement and maintains posture and balance |
| Cerebrum | largest part of brain, coordinating movement, thought, reasoning, and memory |
| Chemical Reaction | process by which substances change into different substances through the breaking and forming of chemical bonds |
| Chlorophyll | light-absorbing pigment molecule in photosynthetic organisms |
| Chloroplast | organelle composed of numerous membranes that are used to convert solar energy into chemical energy |
| Chromatid | one half of a duplicated chromosome |
| Chromatin | loose combination of DNA and proteins that is present during interphase |
| Chromosome | long, continuous thread of DNA that consists of numerous genes and regulatory information |
| Cladogram | diagram that displays proposed evolutionary relationships |
| Codominance | heterozygous genotype that equally expresses the traits from both alleles |
| Codon | sequence of three nucleotides that codes for one amino acid |
| Cohesion | attraction between molecules of the same substance |
| Commensalism | one species benefit but the other species is not affected one way or another |
| Community | collection of all the different populations that live in one area |
| Competition | Ecological relationship in which two organisms attempt to obtain the same resource |
| competitive exclusion | theory that states that no two species can occupy the same niche at the same time |
| Compound | substance made of atoms of different elemetns that are bonded together |
| concentration gradient | difference in the concentration of a substance from one location to another |
| coniferous | tree that retains its needles year round and reproduces with cones |
| constant | condition that is controlled so that it does not change during an experiment |
| consumer | organism that obtains its energy and nutrients by eating otehr organisms |
| convergent evolution | evolution toward similar characteristics in unrelated species, resulting from adaptations to similar environmental conditions |
| covalent bond | chemical bond formed when two atoms share one or more pairs of electrons |
| crossing over | exchange of chromosome segments between homologous chromosomes during meiosis I |
| cytokinesis | process by which the cell cytoplasm divides |
| cytoplasm | jellylike substance inside cells that contains molecules and in some cells organelles |
| decomposer | detritivore that breaks down orgnaic matter into simpler compounds, returning nutrients back into an ecosystem |
| density-dependent limiting factor | environmental resistance that affects a population that has become overly crowded |
| density-independent limiting factor | environmental resistance that affects a population regardless of population density |
| detritivore | organism that eats dead organic matter |
| diffusion | movement of dissolved molecules in a fluid or gas from a region of higher concentration to a region of lower concentration |
| dihybrid cross | cross, or mating, between organisms involving two pairs of contrasting traits |
| diploid | cell that has two copies of each chromosome, one from an egg and one from a sperm |
| directional selection | pathway of natural selection in which one uncommon phenotype is selected over more common phenotypes |
| disruptive selection | pathway of natural selection in which two opposite, but equally uncommon, phenotypes are selected over the most common phenotype |
| divergent evolution | evolution of one or more closely related species into different species; resulting from adaptations to different environmental conditions |
| Deoxyribonucleic Acid | molecule that stores genetic information in all organisms |
| DNA polymerase | enzyme that makes bonds betweennucleotides, forming an identical strand of DNA during replication |
| Dominant | allele that is expressed when two differnet alleles are present in an organism's genotype |
| Double helix | model that compares the structure of a DNA molecule, in which two strands wind around one another, to that of a twisted ladder |
| Ecological Niche | all of the physical, chemical, and biological factors that a species needs to survive, stay healthy, and reproduce in an ecosystem |
| ecology | study of the interactions among living things and their surroundings |
| ecosystem | collection of all organisms and non-living things, such as climate, soil, water, and rocks, in an area |
| ectotherm | organism that regulates its body temperature by exchanging heat with its environment |
| egg | female gamete |
| embryo | stage of development after the fertilized cell implants into the uterus but before the cells take on a recognizable shape |
| emigration | movement of individuals out of a population |
| endocytosis | uptake of liquids or large molecules into a cell by inward folding of the cell membrane |
| endoplasmic reticulum | interconnected network of thin, folded membranes that produce, process, and distribute proteins |
| endosymbiosis | ecological relationship in which one organism lives within the body of another |
| endotherm | organism that produces its own heat through metabolic processes |
| energy pyramid | diagram that compares energy used by producers, primary consumers, and other trophic levels |
| enzyme | protein that catalyzes chemical reactions for organisms |
| equilibrium | condition in which reactants and products |
| eukaryotic cell | cell that has a nucleus and other memrane bound organelles |
| evolution | change in a species over time, process of biological change by which descendents come to differ from their ancestors |
| exocytosis | release of substances out a cell by diffusion |
| exon | sequence of DNA that codes information for protein synthesis |
| experiment | process that tests a hypothesis by collecting information under controlled conditions |
| exponential growth | dramatic increase in population over a short period of time |
| facillitated diffusion | diffusion of molecules assisted by protein channels that pierce a cell membrane |
| fatty acid | hydrocarbon chain often bonded to glycerol in a lipid |
| fermentation | anaerobic process by which ATP is produced by glycolysis |
| fetilization | fusion of an egg and sperm cell |
| fitness | measure of an organism's ability to survive and produce offspring relative to other members of a population |
| fluid mosaic model | model that describes the arrangement and movement of the molecules that make up a cell membrane |
| food chain | model that links organisms by their feeding relationships |
| food web | model that shows the complex network of feeding relationships withing an ecosystem |
| founder effect | genetic drift that occurs after a small number of individuals colonize a new area |
| frameshift mutation | mutation that involves the insertion or deletion of a nucleotide in the DNA sequence |
| gamete | sex cell; an egg or a sperm cell |
| gene | specific region of DNA that codes for a particular protein |
| gene flow | physical movement of alleles from one population to another |
| genetic drift | change in allele frequencies due to chance alone, occuring most commonly in small populations |
| genetics | study of the heredity patterns and variation of organisms |
| genome | all of an organism's genetic material |
| geographic isolation | isolation between populations due to physical barriers |
| golgi apparatus | stack of flat, membrane-enclosed spaces containing enzymes that process, sort, and deliver proteins |
| guard cell | one of a pair of cells that controls the opening and the closing of a stoma in plant tissue |
| habitat | combined biotic and abiotic factors found in the area where an organism lives |
| haploid | cell that has only one copy of each chromosome |
| herbivore | organism that eats only plants |
| heterotroph | organism that obstains its energy and nutrients by consuming other organisms |
| heterozygous | characteristic of having two different alleles appear at the same locus of sister chromatids |
| homologous chromosomes | chromosomes that have the same length, appearance, and copies of genes, although the alleles may differ |
| homologous structure | body part that is similar in structure on different organisms but performs different functions |
| homozygous | characteristic of having two of the same alleles at the same locus of sister chromatids |
| human genome project | project whose goal is to map, sequence, and identify all of the genes in the human genome |
| hydrogen bond | attraction between a slightly positive hydrogen atom and a slightly negative atom |
| hydrologic cycle | pathway of water from the atmosphere to Earth's surface, below ground, and back |
| hypertonic | solution that has a higher concentration of dissolved particles compared with another solution |
| hypothesis | proposed explanation or answer to a scientific question |
| hypotonic | solution that has a lower concentration of dissolved particles compared with another solution |
| immigration | movement of individuals into a population |
| immune system | body system that fights off infections |
| incomplete dominance | heterozygous phenotype that is a blend of the two homozygous phenotypes |
| indicator species | species whose presence in an ecosystem gives clues about the condition of that ecosystem |
| intron | segment of a gene that does not code for an amino acid |
| ion | atom that has gained or lost one or more electrons |
| ionic bond | chemical bond formed through the electrical force between oppositely charged ions |
| isotonic | solution that has an equal concentration of dissolved particles compared with another solution |
| karyotype | image of all of the chromosomes in a cell |
| keystone species | organism that has an unusually large effect on its ecosystem |
| lactic acid | product of fermentation in many types of cells |
| law of independent assortment | states that alleles pairs separate from one another during gamete formation |
| law of segregation | states that organisms inherit two copies of genes, one from each parent, and orgnanisms donate only one copy of each gene in their gametes because the genes separate during gamete formation |
| limiting factor | environmental factor that limits the growth and size of a population |
| lipid | nonpolar molecule composed of carbon, hydrogen, and oxygen |
| logistic growth | population growth that is characterized by a period of slow growt, followed by a period of exponential growth, followed by another period of almost no growth |
| lymphocyte | white blood cell that plays a role in an immune system |
| lysosome | organelle that contains enzymes |
| malignant | cancerous tumor in which cells break away and spread to other parts of the body, causing harm to the organism's health |
| meiosis | form of nuclear divisionthat divides a diploid cell into haploid cells; important in gamete formation |
| memory cell | specialized white blood cell that contributes to acquired immunity by acting quickly to a foreign substance that infected the body previously |
| messanger RNA | form of RNA that carries genetic information from the nucleus to the cytoplasm, where is serves as a template for protein synthesis |
| metabolism | all chemical processes that synthesize or break down materials within an organism |
| mitochondrial DNA | DNA found only in mitochondria, used as a molecular clock |
| mitochondrion | bean-shaped organelle that supplies energy to the cell and has its own ribosomes and DNA |
| mitosis | process by which a cell divides its nucleus and contents |
| molecule | two or more atoms held together by covalent bonds |
| monohybrid cross | cross, or mating between organisms that involves only one pair of contrasting traits |
| monomer | molecular subunit of a polymer |
| mutation | change in the DNA sequence |
| mutualism | ecological relationship between two species in which each species gets a benefit from the interaction |
| natural selection | mechanism by which individuals that have inhereited beneficial adaptations produce more offspring on average than do other individuals |
| nucleic acid | polymer of nucleotides, the genetic material of organisms |
| nucleotide | monomer that forms DNA and has a phosphate group, a sugar, and a nitrogen-containing base |
| nucleus | organelle composed of a double membrane that acts as the storehouse for most of a cell's DNA |
| omnivore | organism that eats both plants and animals |
| organ | group of different types of tissues that work together to perform a specific function or related functions |
| organelle | membrane-bound structure that is specialized to perform a distinct process within a cell |
| organism | any individual living thing |
| organ system | two or more organs that work in a coordinated way to carry out similar functions |
| osmosis | diffusion of water molecules across a semipermeable membrane from an area of higher water concentration to an area of lower water concentration |
| ovum | egg cell that is produced by the female reproductive system |
| parasitism | ecological relationship in which one organism benefits by harming another organism |
| passive immunity | immunity that occurs without the body undergoing an immune response |
| passive transport | movement of molecules across the cell membrane without energy input from the cell |
| pathogen | agent that causes disease |
| pedigree | chart of phenotypes and genotypes in a family that is used to determine whether an individual is a carrier of a recessive allele |
| pH | measure of acidity; related to free hydrogen ion concentration in solution |
| phagocyte | cell that destroys other cells by surrounding and engulfing them |
| phagocytosis | uptake of a solid particle into a cell by engulfing the particle |
| phenotype | collection of all of an organism's physical characteristics |
| phloem | tissue that transports sugars in vascular plants |
| phospholipid | molecule that forms a double-layer cell membrane |
| photosynthesis | process by which light energy is converted to chemical energy; produces sugar and oxygen from carbon dioxide and water |
| pioneer species | organism that is the first to live in a previously uninhabited area |
| placenta | organ that develops in female mammals during pregnancy and carries nutrients from the mother to the embryo |
| point mutation | involves a substitution of only one nucleotide |
| polygenic trait | trait that is produced by two or more genes |
| polymer | large, carbon-based molecule formed by monomers |
| polymerase chain reaction | method for increasing the quantity of DNA by separating it into two strands and adding primers and enzymes |
| population | all of the individuals of a species that live in the same area |
| population density | measure of individuals living in a defined area |
| predation | process by which one organism hunts and kills another organism for food |
| primary succession | establishment and development of an ecosystem in an area that was previously uninhabited |
| primer | short segment of DNA that intiates replication by DNA polymerase |
| producer | organism that obtains its energy from abiotic sources |
| prokaryotic cell | cell that does not have a nucleus or other membrane-bound organelles |
| promoter | section of DNA to which RNA polymerase binds, starting the transcription of mRNA |
| prophase | first phase of mitosis when chromatin condenses, the nuclear envelope breaks down, the nucleous disappears, and the centrosomes and centrioles migrate to opposite sides of the cell |
| protein | polymer composed of amino acids linked by peptide bonds |
| protist | eukaryote that is not an animal, plant, or fungus |
| punnett square | model for predicting all possible genotypes resulting from a cross, or mating |
| purebred | type of organism whose ancestors are gentically uniform |
| recessive | allele that is not expressed unless two copies are present in an organism's genotype |
| recombinant DNA | genetically engineered DNA that contains genes from more than one organism or species |
| replication | process by which DNA is copied |
| ribosomal RNA | RNA that is in the ribosome and guides the translation of mRNA into a protein |
| ribosome | organelle that links amino acids together to form proteins |
| RNA polymerase | enzyme that catalyzes the synthesis of a complimentary strand of RNA from a DNA template |
| secondary succession | reestablishment of a damaged ecosystem in an area where the soil was left intact |
| selective permeability | condition or quality of allowing some, but not all, materials to cross a barrier or membrane |
| sex chromosome | chromosome that directly controls the development of sexual characteristics |
| sex-linked gene | gene that is located on a sex chromosome |
| solute | substance that dissolves in a solvent and is present at a lower concentration than the solvent |
| solution | mixture that is consistent throughout |
| solvent | subtance in which solutes dissolve and that is present in greatest concentration in a solution |
| species | group of organisms so similar to one another that they can breed and produce fertile offspring |
| stabilizing selection | pathway of natural selcetion in which intermediate phenotypes are selceted over phenotypes at both extremes |
| start codon | codon signals to ribosomes to begin translation =; codes for the first amino acid in a protein |
| stomata | pores in the cuticle of a plant through which gas exchange occurs |
| stop codon | codon that signals to ribosomes to stop translation |
| succession | sequence of biotic changes that regenerate a damaged community or start a community in a previously uninhabited area |
| survivorship | probability of surviving to a particular age |
| survivorship curve | graph showing the surviving members of each group of a population over time |
| symbiosis | ecological relationship between members of at least two different species that live in direct contact with one another |
| T cell | white blood cell that matures in the thymus and destroys infected body cells by causing them to burst |
| theory | proposed explanationfor a wide varietyof observationsand experimental results |
| tissue | group of cells that work together to perform a similar function |
| trait | characteristic that is inherited |
| transcription | copying a nucleotide sequence of DNA to form a complementary strand of mRNA |
| transfer RNA | form of RNA that brings amino acids to ribosomes during protein synthesis |
| translation | mRNA is decoded and a protein is produced |
| transpiration | release of vapor through the pores of the skin or the stomata of plant tissue |
| tundra | biome with winters as long as 10 months |
| uterus | organ in female reproductive system in which egg attached and fetus develops |
| vaccine | substance that stimulates an immune response producing acquired immunity without illness or infection |
| vegetative reproduction | asexual reproduction in which a stem, leaf, or root will produce a new individual when detached from a parent plant |
| zygote | cell that forms when a male gamete fetilizes a female gamete |
