MCAS Biology Terms - All
Terms
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- allele frequency
- how often a form of a gene appears in a gene pool
- cellular respiration
- process that breaks down food to make ATP and release carbon dioxide as waste
- digestive system
- body system the breaks down food and absorbs nutrients
- mRNA
- messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosome
- rRNA
- ribosomal RNA; type of RNA that makes up part of the ribosome
- food chain
- series of steps in which organisms transfer energy by eating and being eaten
- greenhouse effect
- heat reatined by the the gases of the Earth's atmosphere to maintain the Earth's temperature range
- nucleolus
- helps to assemble ribosomes
- molecular clock
- model that uses DNA comparisons to estimate how long two organisms evolved from a common ancestor
- commensalism
- symbiotic relationship in which one organism benefits and the other organism is not affected
- nucleus
- contains the DNA and controls all of the cell's acitivities
- denitrification
- conversion of nitrates in the soil by bacteria into nitrogen gas
- amino acid
- building block or monomer of a protein
- homeostasis
- the process by which organisms keep their internal environment relatively stable
- monosaccharide
- building block of a carbohydrate; simple sugar
- nucleotide
- building block of a nucleic acid (DNA and RNA)
- large intestine
- organ that absorbs water from undigested material
- plasma membrane
- thin flexible barrier that regulates what enters and exits the cell; composed of two layers of lipids
- chemical digestion
- the digestion process in which enzymes are used to break foods into their smaller chemical buiding blocks
- passive transport
- movement of molecules across a membrane from high to low concentration without energy, ex. diffusion, osmosis, facilitated diffusion
- hybrid
- offspring of a cross between parents with different traits; heterozygous
- small intestine
- organ that completes the chemical digestion of food and absorbs the nutrients
- independent assortment
- principle that genes do not influence each other's inheritance because they are separated independently during meiosis
- vein
- blood vessel that carries blood toward the heart when pumped by skeletal muscles
- incomplete dominance
- creates a blended phenotype; one allele is not completely dominant over the other
- nitrogen fixation
- process in which bacteria convert nitrogen gas into nitrogen compounds plants can use to make proteins
- gland
- an organ that secretes hormones into the bloodstream
- ecology
- study of interactions between organisms and their environment
- glycogen
- compound used by animals to store carbohydrates in the liver and skeletal muscles
- axon
- long fiber that carries electrical impulses away from the nerve cell body
- RNA
- single stranded nucleic acid used for protein synthesis
- respiratory system
- system responsible for taking in oxygen and releasing carbon dioxide using the lungs
- polygenic trait
- trait controlled by two or more genes; shows a wide variety of phenotypes
- evolution
- change over time; process by which modern organisms descended from ancient organisms
- chromatin
- DNA that is coiled around proteins
- biodiversity
- variety of organisms that exist in the biosphere
- red blood cells
- blood cells containing hemoglobin that carry oxygen through the bloodstream
- dominant
- trait that will show up in an organism's phenotype if gene is present
- cell wall
- provides structure and support around cell membrane of plants, fungi, and some bacteria
- cell cycle
- cell grows, prepares to divide, then divides to start growth process again; interphase + M phase
- systemic circulation
- circulation of oxygenated blood from the left side of the heart to the body and back to the right side of the heart
- atria
- two upper chambers of the heart pump blood into the ventricles
- mitosis
- division of the nucleus or chromosomes
- multiple alleles
- three or more alleles exist for a particular trait
- cholesterol
- specialized lipid that is used in cell membranes and making hormones
- fitness
- ability of an organism to survive and reproduce in its environment
- consumer
- organism that relies on other organisms for food; heterotroph
- carbon dioxide
- gas that is a reactant of photosynthesis and a waste product of cellular respiration
- abiotic factor
- non-living factor that affects an ecosystem
- polypeptide
- synonym for protein; chain of amino acids
- vestigial organ
- organ so reduced in size, it does not serve an important function; may be homologous to structures in other organisms
- trait
- specific characteristic that varies from one individual to another
- starch
- polysaccharide made up of a chain of glucose molecules; food storage molecule for plants
- common descent
- principle that all living things have a common ancestor
- cladogram
- diagram that shows the evolutionary relationships among organisms based on derived characters; resembles a timeline
- decomposer
- organism that breaks down and absorbs nutrients from dead organisms
- compound
- the chemical combination of 2 or more elements in specific amounts
- osmosis
- movement of water across a membrane from high to low concentration without energy
- spindle
- microtubule structure that separates chromosomes during mitosis
- carnivore
- consumer that eats animals or meat
- binomial nomenclature
- two part scientfic name for an organism; its genus is listed first, followed by its species
- circulatory system
- body system consisting of the heart and blood vessels that circulate blood through the body
- insulin
- protein hormone that helps to decrease blood sugar
- pH scale
- measurement system used to indicate how acidic or basic a substance is; measures the concentration of H+ ions
- polysaccharide
- large carbohydrate made up of monosaccharides, ex. starch and glycogen
- nondisjunction
- error in meiosis in which homologous chromosomes don't separate; gametes end up with wrong number of chromosomes
- substrate
- reactant in a chemical reaction that happens in a living thing
- diffusion
- movement of molecules across a membrane from high to low concentration without energy
- codominance
- both genes contribute to the phenotype of the organism, ex. spotted or striped
- chemical reaction
- process that changes one set of chemicals into another set of chemicals
- speciation
- formation of a new species as a result of reproductive isolation
- genus
- first part of an organism's scientific name
- eukaryote
- cell with a nucleus and membrane bound organelles; animals, plants, protists, fungi
- chemical bond
- link formed by two electrons that binds atoms together; where the energy in a compound is stored
- cartilage
- tough, flexible tissue that covers the ends of bones and decreases friction
- photosynthesis
- using sunlight and carbon dioxide to make food (carbohydrates)
- reactant
- chemical that enters a chemical reaction
- nucleotide
- building block or monomer of a nucleic acid; commonly recognized by its nitrogen bases as A, T, C, or G
- artery
- thick-walled muscular blood vessel that carries blood away from the heart
- centriole
- structure that helps to form the spindle
- struggle for existence
- competition between organisms for food and space
- evaporation
- process by which liquid water turns into a gas (water vapor) when heated
- endocrine system
- collection of glands that secrete hormones into the blood which regulate growth, development, and homeostasis
- skeletal muscle
- voluntary, striated, multi-nucleate muscle that moves bones
- bone marrow
- soft tissue found in the center of bone that produces blood cells
- organic compound
- compound that contains carbon bonded to hydrogen and is found in living things
- ligament
- band of connective tissue that holds the bones together
- genotype
- genetic makeup of an organism
- facilitated diffusion
- movement of molecules through protein channels in the membrane from high to low concentration
- tendon
- a band of fibrous tissue that connects muscle to bone
- autotroph
- organism that makes its own food using sunlight or chemicals; producer
- reproductive isolation
- separation of species that prevents them from interbreeding and producing fertile offspring
- food web
- network of all the food chains in an ecosystem
- fossil
- preserved remains of an ancient organism
- homologous structure
- structures that have different mature forms but develop from the same embryonic tissues
- habitat
- where an organism lives
- carrying capacity
- largest number of individuals of a population that the environment can support
- mutualism
- symbiotic relationship in which both organisms benefit
- phylogenetic tree
- diagram showing evolutionary relationships of organisms with a common ancestor; resembles a tree
- emigration
- individuals leaving a population
- temporal isolation
- type of reproductive isolation in which two organisms reproduce at different times
- biodiversity
- the variety of all living things in the biosphere
- neuron
- nerve cell; conducts electrical signals
- gene pool
- combined genetic information of of all the members of a population
- translation
- process by which a ribosome uses the code on mRNA to make proteins
- acid
- compound that release H+ ions in solution; pH less than 7
- Golgi apparatus
- stack of membranes that modify proteins and creates "packages" to send them to other locations
- amino acid
- building block of a protein
- tRNA
- transfer RNA; type of RNA that carries amino acids to the ribosome
- monomer
- building block or small unit of a polymer; can be linked into chains
- gamete
- sex cell; sperm or egg
- sex-linked trait
- trait related to a gene that is found on the X or Y chromosomes
- stomach
- muscular sac that churns food and secretes hydrochloric acid to start breaking down proteins
- cellulose
- polysaccharide that is the main component of plant
- transpiration
- evaporation of water from plant leaves
- replication
- process in which DNA is duplicated
- Protista
- a single celled plant or animal, ex. amoeba, paramecia, euglena
- capillary
- tiny, thin-walled blood vessel where substances (gases and nutrients) are exchanged between the blood and the body cells
- larynx
- voice box; passageway for air moving from pharynx to trachea; contains vocal cords
- divergent evolution
- pattern of evolution in which two species become more and more dissimilar
- natural selection
- individuals that are better suited to their environment survive and reproduce most successfully; survival of the fittest
- liver
- organ that makes bile to break down fats; also filters poisons and drugs out of the blood
- ventricles
- two lower, muscular chambers of the heart which pump blood to the lungs and the rest of the body
- prokaryote
- cell without a nucleus, it contains a cell membrane, cytoplasm, and ribosomes; bacteria
- sensory neurons
- neurons that carry sensory information from receptors to the central nervous system
- codon
- three mRNA nucleotides that code for a specific amino acid
- centriole
- organize the spindle fibers to separate chromosomes during animal cell mitosis
- active transport
- movement of molecules through protein channels in the membrane from low to high concentration requiring energy (ATP)
- pseudopod
- projection of cytoplasm that some protists use for movement and feeding
- heterozygous
- has two different alleles for a particular trait; hybrid, ex. Pp
- telophase
- last phase of mitosis, chromosome are in two new cells and nuclear membranes start to reform
- lysosome
- filled with enzymes to breakdown dead cell parts and foreign objects; only found in animal cells
- spinal cord
- cord of nerve tissue that conducts messages between the brain and the peripheral nerves
- nucleic acid
- contains carbon, hydrogen, oxygen, nitrogen, and phosphorous; involved in protein synthesis
- symbiosis
- relationship in which two species live closely together
- predation
- interaction in which one organism hunts, captures, and feeds on another organism
- cell division
- division of a parent cell into two identical daughter cells
- species
- two organisms that are so similar they can interbreed in nature and produce fertile offspring
- theory
- well-tested, well-supported explanation that unifies a broad range of observations
- cytoplasm
- material between the cell membrane and the nucleus
- S phase
- stage of interphase in which DNA is replicated
- phenotype
- physical characteristics of an organism
- mitochondrion
- breaks down food to make ATP
- catalyst
- substance that speeds up the rate of a chemical reaction
- metaphase
- phase of mitosis in which chromosomes line up in the center of the cell
- anaphase
- phase of mitosis in which sister chromatids are pulled to opposite sides of the cell
- trophic level
- step in a food chain, food web, or ecological pyramid
- G2 phase
- stage of interphase in which cell duplicates its cytosol and organelles
- negative feedback loop
- an opposite action to what is occurring in the body to regain homeostasis, ex. if body temperature rises too high, body tries to lower it
- semi-permeable
- characteristic of a cell membrane which allows some molecules to pass through but not others
- denaturation
- when an enzyme changes shape and no longer functions due to high temperatures or wrong pH
- homozygous
- has two identical alleles for a particular trait; true-breeding or purebred, ex. PP or pp
- carbohydrate
- contains carbon, hydrogen, and oxygen; main source of energy for body, commonly end in "ose"
- biosphere
- part of Earth that living organisms inhabit
- atom
- particle made up of protons, neutrons, and electrons
- kidneys
- organs that filter nitrogen wastes from blood to make urine
- meiosis
- type of cell division that creates gametes; cell divides twice to create four cells that are genetically unique
- motor neurons
- neurons that carry outgoing information from the central nervous system to the muscles and glands
- immigration
- individuals joining a population
- prophase
- first phase of mitosis in which chromosomes become visible and nuclear membraine disappears
- parasitism
- symbiotic relationship in which one organism benefits and the other organism is harmed
- population
- members of a species in a defined area
- energy pyramid
- diagram that shows the energy available to each trophic level in an ecosystem; 10% is passed on to upper levels, the rest is lost as heat
- esophagus
- muscular tube connecting the pharynx to the stomach
- Fungi
- kingdom of hetertrophs that obtain nutrients through absorption, ex. mushrooms, yeasts
- mechanical digestion
- the physical breakdown of food into smaller pieces
- hemoglobin
- specialized protein that carries oxygen on red blood cells
- polymer
- large molecule made up of smaller building blocks or monomers
- flagellum
- whiplike structure some cells use for propulsion
- cytoskeleton
- network of proteins in the cytoplasm that help cell maintain its shape
- natural variation
- differences among individuals of a species; results from mutation and sexual reproduction
- species
- two organisms that are so similar they can interbreed in nature and produce fertile offspring
- herbivore
- consumer that eats plants
- interphase
- cell grows, performs its normal functions, and prepares for division; consists of G1, S, and G2 phases
- mutation
- a change or error in the DNA sequence
- ecosystem
- all the organisms in a particular location, including their non-living environment
- chloroplast
- uses sunlight to make carbohydrates in plants, some bacteria and protists
- population density
- number of individuals per unit area
- chemosynthesis
- using inorganic chemicals to make food (carbohydrates)
- survival of the fittest
- individuals that are better suited to their environment survive and reproduce most successfully; natural selection
- allele
- form of a gene
- antibody
- specialized protein made by the body to fight off future infections from a disease-causing organism
- ribosome
- synthesizes proteins
- biotic factor
- living factors or organisms that affect an ecosystem
- transcription
- copying the code from DNA onto mRNA
- organelle
- a specialized cell structure that performs a specific job within a cell
- excretion
- elimination of wastes from the body (urine, carbon dioxide, sweat)
- lipid
- huge molecule that contains carbon, hydrogen, and a little oxygen; includes fats, oils, and waxes
- glucose
- simple sugar that is used to make ATP through cellular respiration
- invasive (non-native) species
- plants and animals that have migrated to areas where they did not originate; often displace native species by outcompeting them for resources
- probability
- likelihood an event will occur
- domain
- most inclusive taxonomic group, larger than kingdom; three exist - bacteria, archaea, eukaryota
- cytokinesis
- division of the cytoplasm (cytosol and organelles)
- omnivore
- consumer that eats both plants and animals
- biogeochemical cycle
- process in which nutrients are recycled through the biosphere, ex. carbon, nitrogen, and phosphorous
- cilium
- hairlike projections that help some cells move
- protein
- contains carbon, hydrogen, oxygen, and nitrogen; makes up cell/body structures and enzymes
- cardiac muscle
- type of muscle found in the heart which generates its own electrical signal to contract
- recessive
- trait that will only appear in the phenotype if organism inherits two of them; covered up by the dominant gene
- cancer
- uncontrolled cell division
- glycerol
- with fatty acids, make up the building blocks of lipids
- concentration gradient
- difference in concentration of a substance on two sides of a membrane
- detritivore
- organism that feeds on animal and plant remains that it did not capture; scavenger
- heterotroph
- organism that relies on other organisms for food; consumer
- pharynx
- the throat; last place food and air mix
- vacuole
- stores water and nutrients for the cell; very large in plant cells
- base
- compound that releases OH- ions in solution; pH greater than 7
- metabolism
- all of the chemical reactions that build or break down materials within an organism
- nervous system
- consists of brain, spinal cord, and nerves and regulates the body's responses to internal and external stimuli
- adaptation
- inherited characteristic that increases an organism's chance of survival
- segregation
- separation of alleles during meiosis or gamete formation
- Eukaryota
- domain of organisms that contain nuclei, includes animals, plants, fungi, and protists
- impermeable
- molecules are not able to pass through the membrane
- true-breeding
- inherited two identical alleles for a trait; homozygous or purebred
- gene
- section of DNA that codes for a protein and determines a trait
- producer
- organism that makes its own food using sunlight or chemicals; autotroph
- DNA
- double stranded nucleic acid that stores and transmits genetic information
- endoplasmic reticulum
- internal transport system of the cell, modifies proteins, and synthesizes lipids
- alveoli
- thin-walled microscopic air sacs in the lungs where the exchange of oxygen and carbon dioxide takes place
- trachea
- windpipe; airway connecting the pharynx to the bronchi
- pulmonary circulation
- circulation from the right side of the heart to the lungs and back to the left side of the heart
- product
- chemical that results from a chemical reaction
- hormone
- chemical messengers secreted by glands into the blood
- gamete
- sex cell, sperm or egg
- rectum
- the lower part of the large intestine where feces are stored
- kingdom
- second largest taxonomic group; there are six - animalia, plantae, protista, eubacteria, archaebacteria, fungi
- enzyme
- specialized protein that speeds up a chemical reaction by decreasing activation energy; typically end in "ase"
- activation energy
- energy needed to start a reaction
- community
- populations of different organisms living in a defined area
- nutrient
- chemical that an organism needs to live
- smooth muscle
- involuntary muscle found in internal organs
- Punnett square
- diagram that shows the possible results of a genetic cross; parents' gametes on top and left, offsprings' genotypes inside
- geographic isolation
- type of reproductive isolation in which two populations are separated by geographic barries like mountains or bodies of water
- ATP
- molecule that stores the useable energy created during cellular respiration
- nuclear envelope
- membrane surrounding the nucleus
- G1 phase
- stage of interphase in which cell grows and performs its normal functions
- crossing-over
- process by which homologous chromosomes exchange pieces, resulting in greater genetic variety
- resource
- anything that an organism needs to live, ex. food, water, space
- taxonomy
- classification of organisms
- behavioral isolation
- type of reproductive isolation in which two organisms have different mating rituals that prevent them from interbreeding
- fatty acid
- with glycerol, make up the building blocks of lipids