WGU C190 Intro to Biology (Complete) Questions and Answers

WGU C190 Intro to Biology (Complete) Questions and Answers Non-living, may be within or made by a living organism. --Abiotic Living. Matter is considered ______ if it was ever alive at some point in time --Biotic Smallest level. The basic unit of matter. Consists of a dense nucleus surrounded by electrons. --Atom Second level. A chemical structure consisting of at least two atoms held together by a chemical bond. --Molecule Third level. Biologically important molecules that are technically polymers. Example: DNA. --Macromolecule Fourth level. The fundamental unit of life. Essentially a tiny droplet of water and other molecules enclosed by a fluid "skin" or membrane. The smallest and simplest entity that possesses all the characteristics of life. --Cell Fifth level. Compartments inside the cell that contain specific groups of macromolecules and carry out specific cellular functions. One of these organelles is the nucleus; it encloses the DNA within the cell. --Organelle Sixth level. Single-celled life form. Consists of just one cell and include unicellular organisms such as bacteria and protists. --Microorganism Seventh level. Formed when similar cells work together to fulfill the same detailed function. --Tissue Eighth level. Collections of tissues that work together to carry out a common general function. Present not only in higher level animals but also in plants. --Organ Ninth level. Consists of functionally related organs. Mammals have many. --Organ System Tenth Level. Individual living entities that survive and reproduce as a unit. For example, each tree in a forest. --Organism Eleventh level. Consists of all the individuals of a species living within a specific area. --Population Twelfth level. Populations can interact with each other in positive and negative ways, and together they form this. --Community Thirteenth level. Consists of all the living things in a particular area together with the abiotic, or nonliving, parts of that environment. --Ecosystem Fourteenth level. The highest level of organization in living systems. The collection of all ecosystems on Earth. Includes all habitable zones on the planet, including land, soil, and rocks to a great depth in the Earth's crust; water and ice; and the atmosphere to a great height. --Biosphere Characteristics of a system that are not present in any of its component parts. --Emergent Properties The scientific study of life and is the branch of science that studies living organisms and the way organisms interact with their environments. --Biology The ability or tendency of organisms and cells to maintain stable internal conditions. --Homeostasis Any matter an organism needs but cannot make for itself. --Nutrient The capacity to do work or to make a change in the location, temperature, or structure of matter. Does not have mass and it does not take up space, but it can be measured in terms of what it does. --Energy An increase in size. --Growth Structure and function change in an orderly way as an organism passes through its life cycle. An individual's pattern of _______ is partly determined by genetic instructions. --Development Occurs when an individual organism passes on its genetic information to a newly independent organism, or offspring. --Reproduction A scientific theory that explains how and why life changes over time. Provides the explanation for why all living organisms share profound similarities, and yet, the life forms on our planet are so incredibly diverse. --Evolution Individuals are always a bit different from their parents and from each other, partly because of changes to their genes. These differences may be helpful or harmful to the individuals that inherit them. In nature, individuals often have very low odds of surviving to reproduce. Individuals with slightly harmful or even average characteristics might be less likely to make it, and those with traits that fit in very well with the local habitat will have the greatest chance to survive and reproduce. This sorting process goes on generation after generation. --Natural Selection The sum of the number of protons and the number of neutrons. The mass of an atom. --Atomic Mass The number of protons in an atom, displayed for each atom in the periodic table. --Atomic Number Attractions between atoms that hold atoms and molecules together. --Chemical Bonds Strongest chemical bond. Occurs between atoms of in the same molecule. Electron pairs are shared, creating a strong bond between atoms. --Covalent Bonds Subatomic particle, located in shells on the outside of the nucleus, has a negative charge and almost no mass. --electron A measure of the tendency of an atom to attract a bonding pair of electrons. How strongly does an atoms attract bonding electrons to itself? --electronegativity Atoms with unique properties, designated by the atomic number. --element Weak chemical bond. Occurs between atoms in different molecules or parts of molecules. Weak electrostatic attraction between areas of molecules with opposite partial charges. --hydrogen bond Positively or negatively charged atom. --ion Moderately strong chemical bond. Occurs between atoms in the same molecule. Electrons transfer from one atom to another. --ionic bond Any or two or more forms of a chemical element, having the same number of protons in the nucleus, or the same atomic number, but having different numbers of neutrons in the nucleus, or different atomic weights. --isotope Anything that occupies space and has mass. --matter A formula giving the number of atoms of each of the elements present in one molecule of a specific compound. --molecular formula Subatomic particle, electrically neutral, located in the nucleus. Mass of one amu --neutron Center of the atom. Contains equal number of protons and neutrons. --nucleus Chart organizing elements by atomic number and weight. --Periodic Table Subatomic particle, located in the nucleus, with a positive charge. Mass of one amu. --proton Electrons on the outermost shell of the atom. Involved in chemical bonds. --valence electron The attraction between water molecules and other molecules. --Adhesion Water molecules are attracted to each other, keeping the molecules together. --Cohesion Substances that will dissolve in water. Polar. They split into positive and negative ions and dissolve in water. Examples: sugars and alcohols. --Hydrophilic Substances that do not dissolve in water. Non-polar. Examples: hydrocarbons and fatty acids. --Hydrophobic The capacity of a liquid's surface to resist being ruptured when placed under tension or stress. --Surface Tension The component(s) present in lower quantities. --Solute Homogeneous mixtures, with 2 components: solvent and solutes. --Solution The component of the solution in the greatest quantity. --Solvent Biological macromolecule. Sugars. Essential for energy storage, cellular communication and structural support. Store energy; provide structural support; facilitate communication --Carbohydrate The energy stored in the chemical bonds of a substance. --Chemical potential energy Molecules like water, oxygen gas, carbon dioxide, and ionic salts. Relatively stable, simple, and store little chemical energy. --inorganic molecule Biological macromolecules. Fatty acids. Essential for energy storage and maintaining a boundary between the living organism and its environment. Provide energy (long term); serve as structural components of membranes --lipid Biological macromolecules. Nucleotides. Essential for information storage within a cell and passing on this information to the next generation. Examples: DNA. Store genetic information, used in protein synthesis. --nucleic acid Any molecule that contains a carbon to hydrogen covalent bond. Often complex and many store a lot of chemical potential energy. Examples: glucose, methane, DNA, protein and fat. --organic molecule Biological macromolecules. Amino acids. Essential for carrying out most of the necessary functions of life. Serve as structural components of tissues; facilitate and speed up biochemical reactions (enzymes); participate in communication --protein Indigestible carbohydrates, which cannot be degraded by human digestive enzymes. --Dietary Fiber 2 sugar subunits. Lactoss: dairy products. Sucrose: 'Table sugar', sugarcane, sugar beets, candy. Maltrose: germinating seeds, beer. --Disaccharide Polysaccharide. Mainly used for energy storage in animals. --Glycogen Simple sugars. 1 sugar subunit. Glucose: many plants and fruits, honey, sports drinks. Fructos: fruit, honey, sweetener in many processed foods. --Monosaccharide Complex carbohydrates. 3 or more sugar subunits. Starch: plants and roots, potatoes, wheat, corn, rice. Cellulose: plants. --Polysaccharide Polysaccharides. Mainly used for energy storage in plants. --Starch Used to build steroid hormones, including testosterone and estradiol. Precursor to vitamins D & K. Helps in the absorption of fats from the digestive system into the body. In animals, maintains the proper consistency of the cell membrane. --Cholesterol Animals that live in cold polar regions, like penguins, whiles and seals. They have thick insulating 'blubber' beneath the skin. --Endotherm Carboxylic acids consisting of hydrocarbon chain and a terminal carboxyl group, especially any of those occurring as esters in fats and oils. --Fatty Acid Carrier that transports cholesterol around the body to the cells that need it. --Lipoprotein Type of Lipid. Provides structure to cell membranes; a protective barrier surrounding the cell or separating compartments and forming organelles within the cell. Ex: lipid bilayer membrane. --Phospholipid Have 3 fatty acid 'tails' - all of which are linear in shape. Compact shape helps them pack together efficiently and form a solid at room temperature. --Saturated Fat Type of lipid. Provides structure to membranes; regulates many developmental, metabolic and energy processes. Ex: Cholesterol; naturally occurring hormones like estrogen and testosterone. --Steroid Type of lipid. Stores energy for use at a later time. Saturated fats, unsaturated fats, trans fats. --Triglyceride Have at least one fatty acid. 'Kinky' fatty acids. Do not pack into a regular structure and remain fluid at room temperature. --Unsaturated Fat Type of lipid. Forms protective layers on plants and animals that repel water. Ex" Beeswax, bird feathers, carnauba wax, jojoba oil, lanolin. --Wax The binding site on enzymes. contains amino acids that both bind the substrate and aid in its conversion to product. --Active Site Building block of proteins. A small organic chemical that is made up of four parts. One end has nitrogen-amino group, other end has carboxylic acid groups linked by a single carbon atom called the alpha carbon, and the variable 'R group' also attached to the alpha carbon. --Amino Acid A substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change. --Catalyst When a folded protein is unfolded but is irreversibly tangled, forming an aggregate and precipitating out of solution. Caused by extremes of temperature and ph. --Denatured State Proteins that catalyze chemical reactions by accelerating the rate at which chemical reactions take place in a cell. Ex: Amylase protein. --enzyme The bond between amino acids that make up proteins. --peptide bond Nitrogenous organic compound that consists of large molecules composed of one or more long chains of amino acids and are an essential part of all living organisms. --protein A substance on which an enzyme acts. --substrate Proteins that identify and neutralize foreign substances. Ex: IgE Protein --Antibodie Proteins that regulate the rate of cell processes (growth, metabolism, development). Ex: insulin. --Hormone Proteins that provide flexibility, elasticity, and support for movement. Ex: Actin and Myosin. --Mechanical Protein Proteins that provide support for growth and overall health. Ex: casein --Nutrient Protein Proteins that provide organisms with structure, support, and elasticity. Ex: collagen and keratin --Structural Protein Proteins that carry substances from one part of the organism to another. ex: hemoglobin protein --Transport Protein the genetic material that stores information for making proteins in all living organisms. Stores and transmits inherited genetic information; and contains the coded directions for making proteins --DNA (deoxyribonucleic acid) A type of organic molecule that consists of one or two ring structures. 5 types: adenine, guanine, cytosine, thymine, uracil. --Nitrogenous base macromolecules that carry out two main functions in the cell: storage of genetic information and synthesis of proteins. --Nucleic acid Base of nucleic acid. Chains of this make up nucleic acids. Contains a phosphate, a sugar and a nitrogenous base. --Nucleotide Transmits the information coded in the DNA so that it can be used to produce proteins. --RNA (ribonucleic acid) Function: Stores genetic information. Location: Remains in the nucleus. Structure: Double helix. Sugar: Deoxyribose. Pyrimidines: Cytosine, Thymine. Purines: Adenine, guanine. --Features of DNA Function: Involved in protein synthesis. Location: Leaves the nucleus. Structure: Usually single-stranded. Sugar: Ribose. Pyrimidines: Cytosine, uracil. Purines: Adenine, guanine. --Features of RNA Filament in the Cytoskeleton which has a prominent role in cell movement, maintaining cell shape, and connection to other cells, as well as intracellular transport. --Actin provides a barrier between the interior and exterior of the cell and it regulates the flow of substances in and out of the cell. --Cell Membrane Protective layer for prokaryotes, made of peptidoglycan. --Cell wall In a plant cell. can be a place of storage, degradation, defense, and even physical support for the cell. --central vacuole A barrel-shaped structure only present in animal cells. plays a role in the spatial organization of the cell and cell division. --centriole In a plant cell. Chloroplasts capture energy from the sun and use that energy to build sugar molecules. --chloroplast the material of which the chomrosomes of organisms are composed. Consists of protein, RNA and DNA --chromatin A single molecule of DNA. --chromosome a short, microscopic, hairlike vibrating structure. Occurs in large numbers on the surface of certain cells. --cilium the fluid that occupies the space inside the cell. the space in which the chemical reactions that enable life take place. --cytoplasm formed by a series of protein filaments, and is both a scaffold for the cell structure and a framework for many cellular activities, including movement and cell division. --cytoskeleton a series of sacs and tubes. put together or assemble the proteins and other cellular components. --endoplasmic reticulum (ER) larger, and most often they are multicellular organisms, including plants, animals, and fungi. --eukaryotic cell External appendage to a prokaryote. --flagellum include molds and mushrooms, are also eukaryotes. --fungus Where the proteins assembled in the ER are delivered to different parts of the cell, or in multicellular organisms, to different parts of the body. --golgi apparatus specialized vesicles found only in animal cells. Contain powerful digestive enzymes that can recycle cellular parts or destroy external invaders. --lysosome Formed by centrioles. filament type of the cytoskeleton. also form appendages such as the flagellum of the sperm cell and the cilia of the cells of the respiratory system. --microtubule takes fuel in the form of sugar (glucose) and convert it to usable energy ATP. --mitochondrion a double-layered membrane surrounding the nucleus. studded with pores that allow information from inside the nucleus to enter the cytoplasm. --nuclear envelope Region ina prokaryote, where the DNA molecule is present. Does not have a surrounding membrane. --nucleoid Within the nucleus. not bound by a membrane. Instead, it is an aggregate of molecules where ribosomes, another type of nonmembranous organelle, are assembled. --nucleoulus a specialized structure formed when a specific set of molecules bond, providing a subunit that performs a particular function within the cell. Many, but not all, are structures enclosed by a membrane. --organelle a genetic structure in a cell that can replicate independently of the chromosomes, typically a small circular DNA strand in the cytoplasm of a bacterium or protozoan. --plasmid small, simple, single-cell organisms; bacteria are the most prevalent kind. Do not contain a nucleus or any other organelle. --prokaryotic cell Single-celled eukaryote. --protist the molecular machines that use the instructions contained in the DNA to build all the proteins needed by the cell. --ribosome specialized mainly for storage. Their membranes do not fuse with the membranes of other cellular components. --vacuole specialized for transport and some other functions. Their membranes can fuse with the plasma membrane, allowing them to empty their contents into the extracellular space. Also may fuse with the membranes of the endoplasmic reticulum and Golgi apparatus, allowing them to empty their contents into those organelles. --vesicle describes a set of membranous structures found in eukaryotic cells that are related to the synthesis, packaging, and distribution of cellular molecules. includes the endoplasmic reticulum (rough and smooth), the Golgi apparatus, and vesicles. --endomembrane system role is to maintain the stability of the cell membrane and to facilitate cellular recognition, which is crucial to the immune response and in the connections that allow cells to connect to one another to form tissues. --glycolipid In order to carry out their functions, some proteins need to be embedded in the membrane. These proteins are called_____. --integral protein Proteins that are attached to the inner or outer surface of a membrane are called ____. --peripheral protein the fabric of the membrane. The structure causes the membrane to be semipermeable. The hydrophobic core blocks the diffusion of hydrophilic ions and polar molecules. Small hydrophobic molecules and gases, which can dissolve in the membrane's core, cross it with ease. --phospholipid bilayer used by some cells to maintain proper membrane fluidity. --sterol moving molecules against their concentration gradient. This is a non spontaneous process and requires the cell to do work to move the ions "uphill" against the concentration gradient. To do work, the cell must expend energy and actively move (pump)the ions. --Active Transport the process of particles, which are sometimes called solutes, moving through a solution or gas from an area with a higher number of particles to an area with a lower number of particles. The areas are typically separated by a membrane. --Concentration gradient The passing of molecules through the membrane into the cell. --diffusion material is engulfed within an infolding of the plasma membrane and then brought into the cell within a cytoplasmic vesicle. --endocytosis an internal vesicle fuses with the plasma membrane and releases its contents to the outside. --exocytosis The process of moving impermeable molecules across a membrane (down their concentration gradients) using channels or pores is referred to as _____ ________. --facilitated diffusion a process by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one, thus equalizing the concentrations on each side of the membrane. --osmosis The cell membrane provides a semipermeable barrier between the inside and the outside of the cell. The phospholipid bilayer structure of the membrane allows selected ions and organic molecules to pass through the plasma membrane and regulates the movement of molecular substances. --selective permeability both large and small molecules spontaneously move from areas of high concentration to areas of low concentration following random movements, referred to as Brownian motion. --simple diffusion a protein that serves the function of moving other materials within an organism. --transport protein any chemical reaction that combines simple molecules to build more-complex molecules --anabolic reaction any chemical reaction that breaks down complex molecules into simpler molecules --catabolic reaction the process by which cells use oxygen to produce energy from food --cellular respiration A green pigment found in the chloroplasts of plants, algae, and some bacteria --Chlorophyll A rapid reaction between oxygen and fuel that results in fire --Combustion Process by which cells release energy in the absence of oxygen --Fermentation begins with a specific molecule and ends with a product --metabolic pathway Conversion of light energy from the sun into chemical energy. --Photosynthesis A colored chemical compound that absorbs light, producing color. --Pigment series of events that cells go through as they grow and divide --cell cycle period of the cell cycle between cell divisions --Interphase original cell before cell division --parent cell cell division in which the nucleus divides into nuclei containing the same number of chromosomes --Mitosis Division of the cytoplasm during cell division --Cytokinesis a cell formed by the division or budding of another cell --daughter cell protein molecule around which DNA is tightly coiled in chromatin --Histone Folding up of the chromosomes prevents transcription --Chromosome Condensation Area where the chromatids of a chromosome are attached --Centromere containing two complete sets of chromosomes, one from each parent. --Diploid Chromosomes that have the same sequence of genes and the same structure --Homologous An alternative form of a gene. --Allele An organism or cell having only one complete set of chromosomes. --Haploid Region of a chromosome where the two sister chromatids attach --Centromere Any of the cells of a plant or animal except the reproductive cells. --somatic cell Cell division that produces reproductive cells in sexually reproducing organisms --Meiosis a reproductive cell --germ cell Specialized cell involved in sexual reproduction --Gamete Fertilized egg --Zygote a gene that codes for regulator proteins that prevent the cell from undergoing uncontrolled division --tumor suppressor gene Genes that encourage cell division. --Photo-oncogene A rare change in the DNA of a gene, ultimately creating genetic diversity. --Mutation A chemical or physical agent that interacts with DNA and causes a mutation. --Mutagen Cancer causing mutagen. --Carcinogen one of a pair of identical chromosomes created before a cell divides --sister chromatid Chromatin condenses into chromosomes --Prophase Chromosomes line up in the middle of the cell --Metaphase Phase of mitosis in which the chromosomes separate and move to opposite ends of the cell --Anaphase the final stage of meiosis when the chromosomes move toward opposite ends of the nuclear spindle --Telophase Process by which a single parent reproduces by itself --asexual reproduction An organism that is genetically identical to the organism from which it was produced --clone type of reproduction in which cells from two parents unite to form the first cell of a new organism --sexual reproduction Process in which homologous chromosomes exchange portions of their chromatids during meiosis. --crossing over Separates homologous chromosomes --Meiosis I sister chromatids separate --Meiosis II Pairs of homologous chromosomes move to the equator of the cell. --Metaphase I Homologous chrmosomes move to the oppisite poles of the cell. --Anaphase I Cytoplasm divides, 2 daughter cells are formed --Telophase I Homologous chromosomes separate. Ends with the production of 2 haploid daughter cells. --Meiosis I A cross between individuals that have different alleles for the same gene --dihybrid cross the first generation of offspring obtained from an experimental cross of two organisms --F1 generation Offspring resulting from interbreeding of the hybrid F1 generation. --F2 generation genetic makeup of an organism --Genotype An organism that has two different alleles for a trait --Heterozygous An organism that has two identical alleles for a trait --Homozygous the law that states that genes separate independently of one another in meiosis --law of independent assortment first law of heredity stating that pairs of alleles for a trait separate when gametes are formed --Law of Segregation DNA segments that serve as the key functional units in hereditary transmission. --Gene A cross between individuals that involves one pair of contrasting traits --monohybrid cross Parental generation, the first two individuals that mate in a genetic cross --P generation An organism's physical appearance, or visible traits. --Phenotype A chart that shows all the possible combinations of alleles that can result from a genetic cross --Punnett Square Mendel's second conclusion, which states that some alleles are dominant and others are recessive --principle of dominance An allele that is masked when a dominant allele is present --Recessive Characteristics that are inherited --Trait Organisms that, when reproducing, create offspring of all the same variety. --true-breeding A type of inheritance that does not follow strict patterns of dominant vs. recessive --Non-Mendelian Inheritance situation in which one allele is not completely dominant over another --incomplete dominance A condition in which neither of two alleles of a gene is dominant or recessive. --Codominance hereditary disorder of abnormal hemoglobin producing sickle-shaped erythrocytes and hemolysis --sickle cell anemia symptoms shown by those possessing a heterozygous genotype for sickle cell anemia --sickle cell trait combined effect of two or more genes on a single character --polygenic inheritance Two separate genes control one trait, but one gene masks the expression of the other gene --Epistasis single genes can affect multiple characteristics --plietropy inherited disorder in which the infant lacks a liver enzyme --Phenylketonuria (PKU) Referring to a phenotypic character that is influenced by multiple genes and environmental factors. --multifactorial The range of phenotypes produced by a single genotype, due to environmental influences. --norm of reaction 22 chromosome pairs that control traits NOT related to gender--same in females and males. --autosomal chromosome A chromosome that is not directly involved in determining sex, as opposed to a sex chromosome. --Autosome A display of the chromosome pairs of a cell arranged by size and shape. --Karyotype Abnormal number of chromosomes --Aneuploidy condition of premature old age occuring in childhood --Progeria in a nucleic-acid chain, a subunit that consists of a sugar, a phosphate, and a nitrogenous base --Nucleotide DNA segments that serve as the key functional units in hereditary transmission. --Genes type of RNA molecule that transfers amino acids to ribosomes during protein synthesis --Transfer RNA type of RNA that combines with proteins to form ribosomes --Ribosomal RNA Process by which mRNA is decoded and a protein is produced --Translation double-ring nitrogenous base --Purine single-ring nitrogenous base --Pyrimidine a gene that codes for regulator proteins that prevent the cell from undergoing uncontrolled division --tumor suppressor gene the change over time in populations of related organisms --biological evolution evolutionary change within a species or small group of organisms, especially over a short period. --Microevolution large-scale evolutionary changes that take place over long periods of time --Macroevolution differences that are passed on from parent to offspring --heritable variation A trait that helps an organism survive and reproduce --Adaptation The process in which DNA makes a duplicate copy of itself. --DNA replication An enzyme that catalyzes the formation of the DNA molecule. --DNA polymerase method of replication that implies that each new strand of DNA is half original and half new --semiconservative the strand of DNA that specifies the complementary mRNA molecule --template strand short segments of DNA that guide DNA polymerase to the section of DNA to copy --Primer An enzyme that untwists the double helix of DNA at the replication forks. --Helicase DNA segments that serve as the key functional units in hereditary transmission. --Gene A mutation that changes a single nucleotide, but does not change the amino acid created. --silent mutation subsitution of wrong nucleotide into DNA; still produces a protein --missense mutation subsitution of wrong nucleotide into DNA that produces an early stop codon --nonsense mutation mutation that involves the insertion or deletion of a nucleotide in the DNA sequence --frameshift mutation A rare change in the DNA of a gene, ultimately creating genetic diversity. --Mutation process by which a gene produces its product and the product carries out its function --gene expression DNA -- RNA -- Protein --Central Dogma of Molecular Biology DNA to RNA --Transcription Enzyme that links together the growing chain of ribonucleotides during transcription. --RNA polymerase Specific region of a gene where RNA polymerase can bind and begin transcription --Promoter In prokaryotes, a special sequence of nucleotides in DNA that marks the end of a gene. --terminator The three-base sequence of nucleotides in mRNA --Codon codon that signals to ribosomes to stop translation --stop codon codon that signals to ribosomes to begin translation; codes for the first amino acid in a protein --start codon group of three bases on a tRNA molecule that are complementary to an mRNA codon --Anticodon The form of RNA which is created as a blueprint from DNA; carries instructions for making a protein --mRNA (messenger RNA) The form of RNA that carries each amino acid to the ribsome to form the polypeptide chain (protein) --tRNA (transfer RNA) type of RNA that makes up the major part of ribosomes --rRNA (ribosomal RNA) A group of similar organisms that can breed and produce fertile offspring. --Species A group of individuals that belong to the same species and live in the same area --Population Combined genetic information of all the members of a particular population --gene pool success in passing genes to the next generation --evolutionary fitness a heritable trait that enhances an individuals fitness; an evolutionary adaption --adaptive trait when individuals select mates based on heritable traits --sexual selection selective breeding of plants and animals to promote the occurrence of desirable traits in offspring --artificial selection movement of alleles from one population to another --gene flow (migration) random change in allele frequencies that occurs in small populations --genetic drift a reduction in the genetic diversity of a population caused by a reduction in its size --bottleneck effect a change in a population descended from a small number of colonizing individuals --founder effect a group of species that includes an ancestral species and all its descendants --Clade A classification grouping that consists of a number of similar, closely related species --Genus (biology) taxonomic group containing one or more families --Order In classification, a group of closely related orders --Class (biology) the major taxonomic group of animals and plants --Phylum large taxonomic group, consisting of closely related phyla --Kingdom (biology) a taxonomic group containing one or more genera --Family the formation of new and distinct species in the course of evolution. --Speciation The formation of new species in populations that are geographically isolated from one another. --allopatric speciation The formation of new species in populations that live in the same geographic area --sympatric speciation A chromosomal alteration in which the organism possesses more than two complete chromosome sets. --Polyploidy species that are native to and found only within a limited area --endemic species similar features that originated in a shared ancestor --homologous feature A family tree that shows the evolutionary relationships thought to exist among groups of organisms --phylogenetic tree (phylogeny) Diagram that shows the evolutionary relationships among a group of organisms --Cladogram Scientific study of interactions among organisms and between organisms and their environment --Ecology the study of factors that cause populations to increase or decrease --population ecology group of species that live together and interact with each other --ecological community A relationship between individuals of two or more species in a community. --interspecific interaction A relationship between two species in which both species benefit --Mutualism An interaction in which one organism kills another for food. --Predation Interaction among organisms that vie for the same resource in an ecosystem --competition A close relationship between two species that benefits at least one of the species. --Symbiosis A relationship between two organisms in which one organism benefits and the other is unaffected --Commensalism species moved by humans to new geographic areas, either intentionally or accidentally --introduced species a species which often forms the major structural portion of the habitat --foundation species one species affects another through a third, intermediary species --indirect interaction A species that influences the survival of many other species in an ecosystem --keystone species each step in a food chain or food web --trophic level An organism that can make its own food. --Producer An organism that obtains energy by feeding on other organisms --Consumer organism that feeds on plant and animal remains and other dead matter --Detritivore An organism that breaks down wastes and dead organisms --Decomposer A diagram that shows the amount of energy that moves from one feeding level to another in a food web --energy pyramid the circulation of substances through living organisms from or to the environment. --biochemical cycle rapid algal growth caused by an excess of nitrates (NO3)- and phosphates (PO4)3- in water --Eutrophication anything that changes the physical structure of the habitat (fire, waves, tree-fall, plowing) --Physical Disturbance the act of using resources faster than they can be restored or replaced --resource depletion The destruction of habitats that usually results from human activities --habitat loss climate change which is human caused, either directly or indirectly --anthropogenic climate change