Download abiotic factors

abiotic factors
nonliving parts of an organism’s environment.
acceleration
The rate at which the velocity of an object changes.
acid
any substance that forms hydrogen ions in water and has a pH
below 7.
actin
structural protein in muscle cells that makes up the thin
filaments of myofibrils; functions in muscle contraction.
activation energy
The minimum amount of energy required by reacting particles
in order to form the activated complex and lead to a reaction.
active transport
energy-expending process by which cells transport materials
across the cell membrane against a concentration gradient.
adaptation
evolution of a structure, behavior, or internal process that
enables an organism to respond to environmental factors and live
to produce offspring.
adaptive radiation
divergent evolution in which ancestral species evolve into an
array of species to fit a number of diverse habitats.
ADP (adenosine diphosphate)
molecule formed from the breaking off of a phosphate group for
ATP; results in a release of energy that is used for biological
reactions.
adrenal glands
pair of glands located on top of the kidneys that secrete
hormones, such as adrenaline, that prepare the body for stressful
situations.
aerobic
chemical reactions that require the presence of oxygen.
aggregate
Naturally accumulating mixture of sand, gravel, and crushed
stone found in floodplains, alluvial fans, or glacial deposits.
air mass
Large body of air that takes on the characteristics of the area
over which it forms; can be described by its stability,
temperature, and humidity.
albedo
Amount of sunlight that is reflected by the surface of a planet or
a satellite, such as the Moon.
algae
photosynthetic, plantlike, autotrophic protists.
alkali metals
Group 1A elements, except for hydrogen, that are on the left
side of the modern periodic table.
alkaline earth metals
Group 2A elements in the modern periodic table.
allele
alternative forms of a gene for each variation of a trait of an
organism.
allotropes
Forms of an element with different structures and properties
when they are in the same state—solid, liquid, or gas.
alloy
A mixture of elements that has metallic properties.
alpha particle
A particle with two protons and two neutrons, emitted during
radioactive decay.
alveoli
sacs in the lungs where oxygen diffuses into the blood and
carbon dioxide diffuses into the air.
amino acid
An organic molecule that has both an amino group (—NH2) and
a carboxyl group (—COOH).
amniotic egg
major adaptation in land animals; amniotic sac encloses an
embryo and provides nutrition and protection from the outside
environment.
amorphous solid
A solid in which particles are not arranged in a regular,
repeating pattern that often is formed when molten material
cools too quickly to form crystals.
amplitude
The height of a wave from the origin to a crest, or from the
origin to a trough.
anaerobic
chemical reactions that do not require the presence of oxygen.
analog forecast
Weather forecast that compares current weather patterns to
patterns that occurred in the past.
analogous structures
structures that do not have a common evolutionary origin but
are similar in function.
anaphase
third phase of mitosis in which the centromeres split and the
chromatid pairs of each chromosome are pulled apart by
microtubules.
anion
An ion that has a negative charge.
annual
anthophyte that lives for one year or less.
anode
In an electrochemical cell, the electrode where oxidation takes
place.
anterior
head end of bilateral animals where sensory organs are often
located.
anthropoids
antibodies
humanlike primates
proteins in the blood plasma produced in reaction to antigens
that react with and disable antigens.
antigens
foreign substances that stimulate an immune response in the
body.
aorta
largest blood vessel in the body; transports oxygen-rich blood
from the left ventricle of the heart to the arteries.
aphelion
Point in a planet’s orbit where it is farthest from the Sun.
aphotic zone
deep water that never receives sunlight.
appendicular skeleton
one of two main parts of the human skeleton, includes the bones
of the arms and legs and associated structures, such as the
shoulders and hip bones.
aqueous solution
A solution in which the solvent is water.
aquifer
archaebacteria
Permeable underground layer through which groundwater flows
relatively easily.
chemosynthetic prokaryotes that live in harsh environments.
armature
The wire coil of an electric motor, made up of many loops
mounted on an axle or shaft.
artery
large, thick-walled muscular vessel that carries blood away
from the heart.
artesian well
Fountain of water that spurts above the land surface when a well
taps a deep, confined aquifer containing water under pressure.
artificial selection
process of breeding organisms with specific traits in order to
produce offspring with identical traits.
asexual reproduction
type of reproduction where one parent produces one or more
identical offspring without the fusion of gametes.
asteroid
rocky remnant of the early solar system found mostly between
the orbits of Mars and Jupiter in the asteroid belt.
asthenosphere
Partially molten, plasticlike, flowing layer located below the
solid part of Earth’s mantle.
atom
Smallest particle of an element, having all the characteristics of
that element; the basic building block of matter, consisting of
protons, neutrons, and electrons.
atomic mass
The weighted average mass of the isotopes of that element.
atomic number
Number of protons contained in an atom’s nucleus.
atomic orbital
A three-dimensional region around the nucleus of an atom that
describes an electron’s probable location.
ATP
Adenosine triphosphate—a nucleotide that functions as the
universal energy-storage molecule in living cells.
atria
two upper chambers of the mammalian heart through which
blood enters.
australopithecine
early African hominid, genus Australopithecus, that had both
apelike and humanlike characteristics.
autonomic nervous system
(ANS)
in humans, portion of the peripheral nervous system that carries
impulses from the central nervous system to internal organs;
produces involuntary responses.
autosomes
pairs of matching homologous chromosomes in somatic cells.
autotrophs
organisms that use energy from the sun or energy stored in
chemical compounds to manufacture their own nutrients.
autumnal equinox
Occurs when the Sun is directly overhead at the equator and
results in day and night of equal length for both northern and
southern hemispheres.
Avogadro’s number
The number 6.022 1367 x 1023, which is the number of
representative particles in a mole.
axial skeleton
one of two main parts of the human skeleton, includes the skull
and the bones that support it, such as the vertebral column, ribs,
and sternum.
axon
a single cytoplasmic extension of a neuron; carries impulses
away from a nerve cell.