floral arrangements can be in the form of a panicle
[slightly elongated with central axis with branches that
branch themselves]. Examples of racemose inflores-
cence are: raceme (elongated with central axis com-
posed of simple pedicels of about equal length); spike
(elongated with central axis with sessile/subsessile flow-
ers); corymb (flat topped with vertical axis with
pedicels or branches of unequal length); or umbel (sev-
eral branches from a common point of the peduncle).
ingestion The process of obtaining nutrients by het-
erotrophic organisms by eating other organisms or
other organic matter.
inhibition The decrease in the rate of a reaction
brought about by the addition of a substance
(INHIBITOR).
inhibitor A substance that decreases the rate of
ENZYMEcatalysis or other chemical reaction.
inhibitory postsynaptic potential(IPSP) A small
electrical charge of a few millivolts, creating a local
hyperpolarization (increase in membrane potential on
the negativity of the inside of the neuron) in the mem-
brane of a postsynaptic neuron. Caused when an
inhibitory neurotransmitter from a presynaptic cell
binds to a postsynaptic receptor, which makes it diffi-
cult for a postsynaptic neuron to generate an action
potential.
innate behavior Behavior that is performed without
prior learning; considered hardwired in the nervous sys-
tem. Usually a behavior that is inflexible and built in.
inner cell mass After a sperm fertilizes an egg, the
resulting single cell that is produced is referred to as
totipotent, meaning that it has the potential to forman
entire organism. Cell division begins immediately, and
after a few days the cells begin to specialize, forming a
blastocyst, a hollow sphere of cells. The blastocyst has
an outer layer of cells, and inside the sphere is the inner
cell mass, a cluster of cells that protrude into one end
of the cavity and will develop into virtually all of the
human tissues.inositol 1,4,5 triphosphate(IP3) Acts as a second
messenger; increases intracellular calcium and activates
calcineurin, an intermediate in the T cell activation
pathway; binds to and activates a calcium channel in
the endoplasmic reticulum. A second messenger func-
tions as an intermediate between certain nonsteroid
hormones and the third messenger, resulting in a rise in
cytoplasmic Ca2+concentration.inquiline Any organism that lives in the home of
another and shares its food or home (e.g., scarab bee-
tle, which lives in ant nests).Insecta The class of animals that contain more than
1 million named species and perhaps millions more
that are not scientifically named as of yet. Found in
almost every habitat worldwide, they are found in
everyshape and form, small and large. They all share a
body composed of a head, thorax, and abdomen; a pair
of relatively largecompound eyes; usually three ocelli
(simple eyes) and pair of antennae located on the head;
mouthparts consisting of a labrum, a pair of mandibles
and maxillae, a labium, and a tonguelike hypopharynx;
two pairs of wings, derived from outgrowths of the
body wall, and three pairs of walking legs.insectivorous Refers to an animal or plant that eats
insects.
See alsoCARNIVORE.insertion Amutation that occurs when one or more
nucleotide pairs are added to a gene, causing a frame
shift, which is a change in how the information in a gene
is translated by the cell. Two other mutations include a
deletion mutation, where one or more bases are removed
from the DNA sequence of a gene, and substitution
mutation, where one base is replaced by another at a
single position in the DNA sequence of a gene.
See alsoDELETION.176 ingestion