Biology Finals
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Finalspractice on December 5, 2010
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151 terms
Terms | Definitions |
|---|---|
 science | organized way of using evidence to learn about the natural world; also, the body of knowledge that scientists have built up after years of using this process |
| observation | use of one or more of the senses—sight, hearing, touch, smell, and sometimes taste—to gather information |
| data | evidence; information gathered from observations |
| inference | logical interpretation based on prior knowledge and experience |
| hypothesis | possible explanation for a set of observations or possible answer to a scientific question |
| spontaneous generation | hypothesis (disproven) stating that life could arise from nonliving matter |
| controlled experiment | a test of the effect of a single variable by changing it while keeping all other variables the same |
| manipulated variable | factor in an experiment that a scientist purposely changes; also known as independent variable |
| responding variable | factor in an experiment that a scientist wants to observe, which may change in response to the manipulated variable; also known as a dependent variable |
| theory | well-tested explanation that unifies a broad range of observations |
| biology | science that seeks to understand the living world |
| cell | collection of living matter enclosed by a barrier that separates the cell from its surroundings; basic unit of all forms of life |
| sexual reproduction | process by which cells from two different parents unite to produce the first cell of a new organism |
| asexual reproduction | process by which a single parent reproduces by itself |
| metabolism | set of chemical reactions through which an organism builds up or breaks down materials as it carries out its life processes |
| metric system | decimal system of measurement based on certain physical standards and scaled on multiples of 10 |
| microscope | device that produces magnified images of structures that are too small to see with the unaided eye |
| compound light microscope | microscope that allows light to pass through a specimen and uses two lenses to form an image |
| electron microscope | microscope that forms an image by focusing beams of electrons onto a specimen |
| cell culture | group of cells grown in a nutrient solution from a single original cell |
| cell fractionation | technique in which cells are broken into pieces and the different cell parts are separated |
| atom | basic unit of matter |
| nucleus | the center of the atom which contains the protons and neutrons; in cells, structure that contains the cell's genetic material (DNA) and controls the cell's activities |
| electron | negatively charged particle; located outside the atomic nucleus |
| element | substance consisting entirely of one type of atom |
| isotope | atom of an element that has a number of neutrons different from that of other atoms of the same element |
| compound | substance formed by the chemical combination of two or more elements in definite proportions |
| chemical bond | link that holds together atoms in compounds |
| ionic bond | bond formed when one or more electrons are transferred from one atom to another |
| ion | atom that has a positive or negative charge |
| covalent bond | bond formed by the sharing of electrons between atoms |
| molecule | smallest unit of most compounds |
| van der Waals forces | a slight attraction that develops between the oppositely charged regions of nearby molecules |
| cohesion | attraction between molecules of the same substance |
| adhesion | attraction between molecules of different substances; in plants, attraction between unlike molecules |
| mixture | material composed of two or more elements or compounds that are physically mixed together but not chemically combined |
| solution | mixture of two or more substances in which the molecules of the substances are evenly distributed |
| solute | substance that is dissolved in a solvent to make a solution |
| solvent | substance in which a solute is dissolved to form a solution |
| suspension | mixture of water and nondissolved materials |
| pH scale | measurement system used to indicate the concentration of hydrogen ions (H+) in solution; ranges from 0 to 14 |
| acid | compound that forms hydrogen ions (H+) in solution |
| base | compound that produces hydroxide ions (OH+) in solution |
| buffer | weak acid or base that can react with strong acids or bases to help prevent sharp, sudden changes in pH |
| monomer | small unit that can join together with other small units to form polymers |
| polymer | large compound formed from combinations of many monomers |
| carbohydrate | compound made up of carbon, hydrogen, and oxygen atoms; major source of energy for the human body |
| monosaccharide | single sugar molecule |
| polysaccharide | large macromolecule formed from monosaccharides |
| lipid | macromolecule made mainly from carbon and hydrogen atoms; includes fats, oils, and waxes |
| nucleic acid | macromolecule containing hydrogen, oxygen, nitrogen, carbon, and phosphorus |
| nucleotide | monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base |
| ribonucleic acid (RNA) | single-stranded nucleic acid that contains the sugar ribose |
| deoxyribonucleic acid (DNA) | nucleic acid that contains the sugar deoxyribose |
| protein | macromolecule that contains carbon, hydrogen, oxygen, and nitrogen; needed by the body for growth and repair and to make up enzymes |
| amino acid | compound with an amino group (−NH2) on one end and a carboxyl group (−COOH) on the other end |
| chemical reaction | process that changes one set of chemicals into another set of chemicals |
| reactant | element or compound that enters into a chemical reaction |
| product | element or compound produced by a chemical reaction |
| activation energy | energy needed to get a reaction started |
| catalyst | substance that speeds up the rate of a chemical reaction |
| enzyme | protein that acts as a biological catalyst |
| substrate | reactant of an enzyme-catalyzed reaction |
| cell | collection of living matter enclosed by a barrier that separates the cell from its surroundings; basic unit of all forms of life |
| cell theory | idea that all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells |
| nucleus | the center of the atom which contains the protons and neutrons; in cells, structure that contains the cell's genetic material (DNA) and controls the cell's activities |
| eukaryote | organism whose cells contain nuclei |
| prokaryote | unicellular organism lacking a nucleus |
| organelle | specialized structure that performs important cellular functions within a eukaryotic cell |
| cytoplasm | material inside the cell membrane—not including the nucleus |
| nuclear envelope | layer of two membranes that surrounds the nucleus of a cell |
| chromatin | granular material visible within the nucleus; consists of DNA tightly coiled around proteins |
| nucleolus | small, dense region within most nuclei in which the assembly of proteins begins |
| ribosome | small particle in the cell on which proteins are assembled; made of RNA and protein |
| endoplasmic reticulum | internal membrane system in cells in which lipid components of the cell membrane are assembled and some proteins are modified |
| Golgi apparatus | stack of membranes in the cell that modifies, sorts, and packages proteins from the endoplasmic reticulum |
| lysosome | cell organelle filled with enzymes needed to break down certain materials in the cell |
| vacuole | cell organelle that stores materials such as water, salts, proteins, and carbohydrates |
| mitochondrion | cell organelle that converts the chemical energy stored in food into compounds that are more convenient for the cell to use |
| chloroplast | organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy |
| cytoskeleton | network of protein filaments within some cells that helps the cell maintain its shape and is involved in many forms of cell movement |
| centriole | one of two tiny structures located in the cytoplasm of animal cells near the nuclear envelope |
| cell membrane | thin, flexible barrier around a cell; regulates what enters and leaves the cell |
| cell wall | strong supporting layer around the cell membrane in plants, algae, and some bacteria |
| lipid bilayer | double-layered sheet that forms the core of nearly all cell membranes |
| concentration | the mass of solute in a given volume of solution, or mass/volume |
| diffusion | process by which molecules tend to move from an area where they are more concentrated to an area where they are less concentrated |
| equilibrium | when the concentration of a solute is the same throughout a solution |
| osmosis | diffusion of water through a selectively permeable membrane |
| isotonic | when the concentration of two solutions is the same |
| hypertonic | when comparing two solutions, the solution with the greater concentration of solutes |
| hypotonic | when comparing two solutions, the solution with the lesser concentration of solutes |
| facilitated diffusion | movement of specific molecules across cell membranes through protein channels |
| active transport | energy-requiring process that moves material across a cell membrane against a concentration difference |
| endocytosis | process by which a cell takes material into the cell by infolding of the cell membrane |
| phagocytosis | process in which extensions of cytoplasm surround and engulf large particles and take them into the cell |
| pinocytosis | process by which a cell takes in liquid from the surrounding environment |
| exocytosis | process by which a cell releases large amounts of material |
| cell specialization | the process in which cells develop in different ways to perform different tasks |
| tissue | group of similar cells that perform a particular function |
| organ | group of tissues that work together to perform closely related functions |
| organ system | group of organs that work together to perform a specific function |
| autotroph | organism that can capture energy from sunlight or chemicals and use it to produce its own food from inorganic compounds; also called a producer |
| heterotroph | organism that obtains energy from the foods it consumes; also called a consumer |
| adenosine triphosphate (ATP) | one of the principal chemical compounds that living things use to store and release energy |
| photosynthesis | process by which plants and some other organisms use light energy to convert water and carbon dioxide into oxygen and high-energy carbohydrates such as sugars and starches |
| pigment | light-absorbing molecule |
| chlorophyll | principal pigment of plants and other photosynthetic organisms; captures light energy |
| thylakoid | saclike photosynthetic membrane found in chloroplasts |
| photosystem | light-collecting units of the chloroplast |
| stroma | region outside the thylakoid membranes in chloroplasts |
| NADP+ (nicotinamide adenine dinucleotide phosphate) | one of the carrier molecules that transfers high-energy electrons from chlorophyll to other molecules |
| light-dependent reactions | reactions of photosynthesis that use energy from light to produce ATP and NADPH |
| ATP synthase | large protein that uses energy from H+ ions to bind ADP and a phosphate group together to produce ATP |
| Calvin cycle | reactions of photosynthesis in which energy from ATP and NADPH is used to build high-energy compounds such as sugars |
| calorie | amount of energy needed to raise the temperature of 1 gram of water by 1 degree Celsius |
| glycolysis | first step in releasing the energy of glucose, in which a molecule of glucose is broken into two molecules of pyruvic acid |
| cellular respiration | process that releases energy by breaking down glucose and other food molecules in the presence of oxygen |
| NAD+ (nicotinamide adenine dinucleotide) | electron carrier involved in glycolysis |
| fermentation | process by which cells release energy in the absence of oxygen |
| anaerobic | process that does not require oxygen |
| aerobic | process that requires oxygen |
| Krebs cycle | second stage of cellular respiration, in which pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions |
| electron transport chain | a series of proteins in which the high-energy electrons from the Krebs cycle are used to convert ADP into ATP |
| transformation | process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria |
| bacteriophage | virus that infects bacteria |
| nucleotide | monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base |
| base pairing | principle that bonds in DNA can form only between adenine and thymine and between guanine and cytosine |
| chromatin | granular material visible within the nucleus; consists of DNA tightly coiled around proteins |
| histone | protein molecule around which DNA is tightly coiled in chromatin |
| replication | copying process by which a cell duplicates its DNA |
| gene | sequence of DNA that codes for a protein and thus determines a trait |
| messenger RNA (mRNA) | RNA molecule that carries copies of instructions for the assembly of amino acids into proteins from DNA to the rest of the cell |
| ribosomal RNA (rRNA) | type of RNA that makes up the major part of ribosomes |
| transfer RNA (tRNA) | type of RNA molecule that transfers amino acids to ribosomes during protein synthesis |
| transcription | process in which part of the nucleotide sequence of DNA is copied into a complementary sequence in RNA |
| RNA polymerase | enzyme similar to DNA polymerase that binds to DNA and separates the DNA strands during transcription |
| promoter | region of DNA that indicates to an enzyme where to bind to make RNA |
| intron | sequence of DNA that is not involved in coding for a protein |
| exon | expressed sequence of DNA; codes for a protein |
| codon | three-nucleotide sequence on messenger RNA that codes for a single amino acid |
| translation | decoding of a mRNA message into a polypeptide chain |
| anticodon | group of three bases on a tRNA molecule that are complementary to an mRNA codon |
| mutation | change in a DNA sequence that affects genetic information |
| point mutation | gene mutation involving changes in one or a few nucleotides |
| frameshift mutation | mutation that shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide |
| polyploidy | condition in which an organism has extra sets of chromosomes |
| operon | group of genes operating together |
| operator | region of chromosome in an operon to which the repressor binds when the operon is "turned off" |
| differentiation | process in which cells become specialized in structure and function |
| hox genes | series of genes that controls the differentiation of cells and tissues in an embryo |
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