ILTS Biology (239) Vocab

Quantitative observation

objective, involves \#s & measurements, can be made w/ instruments, results are based on statistics/numerical analyses, & used mostly in scientific research

Qualitative observation

subjective, ex: human behavior, uses senses (sight, hearing, smell, touch, taste), & used in social sciences

Hypothesis

sensible prediction/educated guess that answers the question introduced in the problem

Independent variable

manipulated/varied during experiment

Dependent variable

influenced by independent variable/being measured

Experimental controls

factors that remain unchanged or are held constant, not being tested, used for comparison

Scientific theories

broad, summarize several related hypotheses that have been supported by repeated tests as shown in accumulated data

Scientific laws

based on observations from repeated experiments, concise statements that describe some phenomenon/relationship in the world

Natural selection

means by which adaptations would arise over time, mechanism of evolution

Accuracy

exactness of measurement, expresses how close a measurement is to the actual or true value

Precision

repeatability/consistency of a measurement, expresses how close measurements are to one another

Significant figures

indicate precision of a measured value, all measurements are approximations and have uncertainty

Scientific notations

way to write \#s that are extremely large or small, way to correctly convey correct \# of significant figures in measurements/calculations

Dimensional analysis

conversion unit factors are used the obtain the needed unit

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

Logarithmic scale

value of logarithm of a quantity is used instead of the quantity itself; cover broader range of values than for linear scales

Pie charts, line graphs, bar graphs, & scatter plots

pie chart: comparing parts to the whole

line graph: showing small or large changes over time

bar graphs: compare groups/track large changes over time

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

Random errors

unpredictable because they are from unknown causes & cannot be eliminated

Systematic errors

arise from faulty equipment/faulty procedures (these errors are difficult to predict, but can be eliminated)

Personal errors

human error such as improper use of equipment/incorrectly following a procedure (can be eliminated/minimized by proper training)

Percent error

subtract theoretical value from the experimental value and then divide by the theoretical value, then multiply by 100 & add %

Models

visual representations/replicas of natural phenomena such as objects/processes that are based on scientific evidence

Population models

mathematical models that are designed to study population dynamics

Gel electrophoresis

technique used to separate macro-molecules sch as nucleic acids & proteins

Light microscope

also known as compound microscope; use visible light to study samples, uses 2 types of lenses (occular & objective) to magnify objects

Electron microscope

use beams of electrons instead of light, good for tiny samples (viruses, cell components, or individual molecules)

Genetically modified foods

transgenic crops that have had their genes altered by technology

Matter

substances that have mass and occupy space (or volume)

Solid

structures are rigid or nearly rigid & have strong bonds

Liquid

molecules/atoms move around and have weak bonds, although they are not weak enough to readily break

Gas

molecule/atoms move almost independently of each other, typically far apart, and do not form bonds

Plasma

ionized gas that has some electrons that are described as free because they are not bound to an atom/molecule

Mass

measure of amount of substance in an object

Weight

measure of gravitational pull of Earth on an object

Volume

measure of amount of space occupied (many formulas to determine)

Density

measure of amount of mass per unit volume

Specific gravity

measure of ratio of a substance's density compared to the density of water

Physical changes

Any change that DOES NOT alter the chemical composition of a substance.

Negative ion

created when atoms gain electrons

Positive ion

created when an atom loses electrons

Ionic bond

formed between ions and opposite charges

Ionization

process by which neutral particles are ionized into charged particles

Covalent bond

electrons are shared

Hydrogen bond

weak bond between a hydrogen atom and an electronegative atom

Van der Waals force

weak force between molecules, much weaker than actual chemical bonds between atoms

Combustion

(burning), sequence of chemical reactions involving fuel and an oxidant that produces heat and sometimes light

Exothermic process

releases energy

Exothermic energy

released as heat, but can take other forms, such as light, electricity, or sound

Species (chemistry definition)

refers to any type of particle (atoms, ions, molecules, molecular fragments, or specific forms of elements)

Element

substance that consists of only one type of atom

Compound

substance containing two or more elements; formed by chemical reactions; decomposed by chemical reaction rather than separated by physical one

Solution

homogeneous mixture composed of 2 or more substances that have become one

Mixture

contain 2 or more substances that are combined, but have not reacted chemically w/ each other; can be separated using physical methods

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

Energy

the ability to do work

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)

Power

rate at which work is performed

Thermal energy

energy present in a system due to temperature

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

Atomic radius

average distance between the nucleus and the outermost electron

Atom

most basic unit of matter; consist of central nucleus surrounded by electrons (aka electron cloud)

Nucleus (chemistry definition)

consist of protons & neutrons; positively charged, dense, and heavier than surrounding electrons; plural form\=nuclei

Electrons

atomic particles that are negatively charged & orbit nucleus of an atom

Protons

\# of protons\=atomic\# of element

Atomic number

\# of protons present in nucleus of an atom; represented as Z; atoms w/ neutral charge have atomic \#\=\# of electrons

Neutrons

uncharged atomic particles in nucleus; \# of neutrons in nucleus represented as N

Atomic mass

mass \#; total \# of protons & neutrons in nucleus of atom; referred to as A; A\=Z+N

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

Radioactivity

particles emitted from nuclei as result of nuclear instability

Radioisotopes

(radionucleide); atoms that have an unstable nucleus

Radioactive decay

occurs when unstable atomic nucleus spontaneously loses energy by emitting ionizing particles/radiation

Radioactive half life

time it takes for 1/2 radioactive nuclei in a sample

Decay chains

series of decays that result in different products

Stable isotopes

isotopes that have not yet been observed to decay (non-radioactive isotopes)

Radioactive isotopes

have unstable nuclei & can undergo spontaneous nuclear reactions

Ionizing radiation

causes an electron to detach from an atoms & occurs in radioactive reactions in 3 types (alpha, beta, gamma)

Nuclear fusion

joining of two nuclei

Nuclear fission

splitting of large nucleus into smaller pieces

Radioactive waste

waste product that is considered dangerous because of either low/high levels of radioactivity

Gamma wave radiation

fast moving radiation that can cause cancer & damage genetic information by crashing into DNA molecules/other cells

electronegativity

measure of how capable an atom is of attracting a pair of bonding electrons

dipole

one atom exerts slightly more force in a bond w/ another

polar covalent bond

electronegative difference between 2 atoms is small

pure nonpolar covalent bond

no electronegativity

pauling scale

measures electronegativity, ranges from 4.0 (flourine) to 0.7 (francium)

stable electron arrangement

atom has all its electrons in the lowest available positions

valence shell

outermost electron shell of an atom in uncombined state

oxidation numbers

roman numerals in parentheses that are used as part of the naming scheme for inorganic compounds

oxidation state

hypothetical charge on an atom if all its bonds are 100% ionic

oxidation

loss of electrons

reduction

gain of electrons

atomic spectral lines

indicate change in the electrical level of an atom

emission line

formed when an electron transfers to a low energy level and a photon is emitted

absorption line

formed when an electron transfers to a higher energy level and a photon is absorbed

photon

elementary particle thought to be the basic unit, or quantum, of light

atomic size

measured in Angstroms (A) or pictometers (pm)

ionic radius

based upon nuclei when the ions are in a crystal lattice (atoms are organized in specific manner)