ILTS Biology (239) Vocab

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Biology

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117 Terms

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Quantitative observation
objective, involves \#s & measurements, can be made w/ instruments, results are based on statistics/numerical analyses, & used mostly in scientific research
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Qualitative observation
subjective, ex: human behavior, uses senses (sight, hearing, smell, touch, taste), & used in social sciences
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Hypothesis
sensible prediction/educated guess that answers the question introduced in the problem
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Independent variable
manipulated/varied during experiment
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Dependent variable
influenced by independent variable/being measured
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Experimental controls
factors that remain unchanged or are held constant, not being tested, used for comparison
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Scientific theories
broad, summarize several related hypotheses that have been supported by repeated tests as shown in accumulated data
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Scientific laws
based on observations from repeated experiments, concise statements that describe some phenomenon/relationship in the world
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Natural selection
means by which adaptations would arise over time, mechanism of evolution
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Accuracy
exactness of measurement, expresses how close a measurement is to the actual or true value
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Precision
repeatability/consistency of a measurement, expresses how close measurements are to one another
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Significant figures
indicate precision of a measured value, all measurements are approximations and have uncertainty
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Scientific notations
way to write \#s that are extremely large or small, way to correctly convey correct \# of significant figures in measurements/calculations
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Dimensional analysis
conversion unit factors are used the obtain the needed unit
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Linear scale
when moving from one data point to the next, the change in output is based on the difference between two values or addition
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Logarithmic scale
value of logarithm of a quantity is used instead of the quantity itself; cover broader range of values than for linear scales
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Pie charts, line graphs, bar graphs, & scatter plots
pie chart: comparing parts to the whole
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line graph: showing small or large changes over time

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bar graphs: compare groups/track large changes over time

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scatter plots: determine if there is a correlation between two sets of data

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Random errors
unpredictable because they are from unknown causes & cannot be eliminated
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Systematic errors
arise from faulty equipment/faulty procedures (these errors are difficult to predict, but can be eliminated)
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Personal errors
human error such as improper use of equipment/incorrectly following a procedure (can be eliminated/minimized by proper training)
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Percent error
subtract theoretical value from the experimental value and then divide by the theoretical value, then multiply by 100 & add %
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Models
visual representations/replicas of natural phenomena such as objects/processes that are based on scientific evidence
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Population models
mathematical models that are designed to study population dynamics
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Gel electrophoresis
technique used to separate macro-molecules sch as nucleic acids & proteins
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Light microscope
also known as compound microscope; use visible light to study samples, uses 2 types of lenses (occular & objective) to magnify objects
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Electron microscope
use beams of electrons instead of light, good for tiny samples (viruses, cell components, or individual molecules)
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Genetically modified foods
transgenic crops that have had their genes altered by technology
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Matter
substances that have mass and occupy space (or volume)
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Solid
structures are rigid or nearly rigid & have strong bonds
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Liquid
molecules/atoms move around and have weak bonds, although they are not weak enough to readily break
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Gas
molecule/atoms move almost independently of each other, typically far apart, and do not form bonds
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Plasma
ionized gas that has some electrons that are described as free because they are not bound to an atom/molecule
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Mass
measure of amount of substance in an object
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Weight
measure of gravitational pull of Earth on an object
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Volume
measure of amount of space occupied (many formulas to determine)
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Density
measure of amount of mass per unit volume
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Specific gravity
measure of ratio of a substance's density compared to the density of water
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Physical changes
Any change that DOES NOT alter the chemical composition of a substance.
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Negative ion
created when atoms gain electrons
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Positive ion
created when an atom loses electrons
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Ionic bond
formed between ions and opposite charges
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Ionization
process by which neutral particles are ionized into charged particles
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Covalent bond
electrons are shared
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Hydrogen bond
weak bond between a hydrogen atom and an electronegative atom
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Van der Waals force
weak force between molecules, much weaker than actual chemical bonds between atoms
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Combustion
(burning), sequence of chemical reactions involving fuel and an oxidant that produces heat and sometimes light
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Exothermic process
releases energy
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Exothermic energy
released as heat, but can take other forms, such as light, electricity, or sound
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Species (chemistry definition)
refers to any type of particle (atoms, ions, molecules, molecular fragments, or specific forms of elements)
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Element
substance that consists of only one type of atom
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Compound
substance containing two or more elements; formed by chemical reactions; decomposed by chemical reaction rather than separated by physical one
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Solution
homogeneous mixture composed of 2 or more substances that have become one
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Mixture
contain 2 or more substances that are combined, but have not reacted chemically w/ each other; can be separated using physical methods
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Heat
transfer of energy from a body/system as result of thermal contact; consists of random motion & vibration of atoms, molecules, & ions; higher the temp\=the greater atomic/molecular motion will be
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Energy
the ability to do work
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Work
quantity of energy transferred by one system to another due to the changes in a system that is the result of external forces or macroscopic variables (amount of energy that must be transferred to overcome a force); measured in Joules (J)
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Power
rate at which work is performed
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Thermal energy
energy present in a system due to temperature
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Thermal contact
energy transferred to a body by means other than work a system in thermal contact w/ another can exchange energy w/ it through the process of heat transfer
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Atomic radius
average distance between the nucleus and the outermost electron
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Atom
most basic unit of matter; consist of central nucleus surrounded by electrons (aka electron cloud)
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Nucleus (chemistry definition)
consist of protons & neutrons; positively charged, dense, and heavier than surrounding electrons; plural form\=nuclei
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Electrons
atomic particles that are negatively charged & orbit nucleus of an atom
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Protons
\# of protons\=atomic\# of element
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Atomic number
\# of protons present in nucleus of an atom; represented as Z; atoms w/ neutral charge have atomic \#\=\# of electrons
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Neutrons
uncharged atomic particles in nucleus; \# of neutrons in nucleus represented as N
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Atomic mass
mass \#; total \# of protons & neutrons in nucleus of atom; referred to as A; A\=Z+N
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Atomic weight
"relative atomic mass"; ratio of the average mass per atom of sample to 1/12 of the mass of an atom of carbon-12
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Radioactivity
particles emitted from nuclei as result of nuclear instability
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Radioisotopes
(radionucleide); atoms that have an unstable nucleus
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Radioactive decay
occurs when unstable atomic nucleus spontaneously loses energy by emitting ionizing particles/radiation
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Radioactive half life
time it takes for 1/2 radioactive nuclei in a sample
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Decay chains
series of decays that result in different products
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Stable isotopes
isotopes that have not yet been observed to decay (non-radioactive isotopes)
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Radioactive isotopes
have unstable nuclei & can undergo spontaneous nuclear reactions
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Ionizing radiation
causes an electron to detach from an atoms & occurs in radioactive reactions in 3 types (alpha, beta, gamma)
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Nuclear fusion
joining of two nuclei
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Nuclear fission
splitting of large nucleus into smaller pieces
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Radioactive waste
waste product that is considered dangerous because of either low/high levels of radioactivity
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Gamma wave radiation
fast moving radiation that can cause cancer & damage genetic information by crashing into DNA molecules/other cells
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electronegativity
measure of how capable an atom is of attracting a pair of bonding electrons
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dipole
one atom exerts slightly more force in a bond w/ another
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polar covalent bond
electronegative difference between 2 atoms is small
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pure nonpolar covalent bond
no electronegativity
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pauling scale
measures electronegativity, ranges from 4.0 (flourine) to 0.7 (francium)
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stable electron arrangement
atom has all its electrons in the lowest available positions
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valence shell
outermost electron shell of an atom in uncombined state
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oxidation numbers
roman numerals in parentheses that are used as part of the naming scheme for inorganic compounds
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oxidation state
hypothetical charge on an atom if all its bonds are 100% ionic
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oxidation
loss of electrons
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reduction
gain of electrons
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atomic spectral lines
indicate change in the electrical level of an atom
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emission line
formed when an electron transfers to a low energy level and a photon is emitted
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absorption line
formed when an electron transfers to a higher energy level and a photon is absorbed
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photon
elementary particle thought to be the basic unit, or quantum, of light
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atomic size
measured in Angstroms (A) or pictometers (pm)
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ionic radius
based upon nuclei when the ions are in a crystal lattice (atoms are organized in specific manner)