Glossary

abiotic

nonliving

abscission

shedding of leaves; falling off

acetylation

addition of an acetyl group, CH₃-CHOO-

acidic

having an excess of H⁺ ions and a low pH

acinus

one of the small divisions of a fruit such as a raspberry

action potential

wave of ionic movement down the length of a nerve cell

active site

surface region of an enzyme where it catalyzes its reaction

adaptive radiation

diversification of a group of organisms into several different forms that adapt to different environments

adhesion

attachment; sticking to the surface of

ADP

adenosine diphosphate, the low-energy form of ATP

adventitious

growing from a nonstandard location

aerobe

organism that needs oxygen

aerobic

with oxygen, or requiring it

aestivating

remaining dormant for the summer

affinity

attraction

aflatoxin

toxic compound produced by a mold fungus

agar

gel derived from algae

agnosia

"not knowing"; loss of ability to recognize familiar objects

agroecosystem

agricultural ecosystem

alkaline

chemically basic, with an excess of OH-ions

allele

a particular form of a gene

allelopathy

inhibition of one plant's growth by another plant

amino acid

a building block of protein

amoeba

a single-celled protist that moves by crawling

amoeboid

like an amoeba, especially in movement via extension of portions of the membrane

AMP

adenosine monophosphate, form of ATP after removal of two phosphate groups

amphipathic

having both polar and nonpolar regions

anabolic

characteristic of a reaction that builds complex molecules from simpler ones, and requires energy

anadromous

describes fish that return to the rivers where they were born in order to breed

anaerobe

organism not needing oxygen

anaerobic

without oxygen, or not requiring oxygen

anemia

lack of oxygen-carrying capacity in the blood

aneurysm

bulging of the wall of a blood vessel

antagonism

working against

antagonist muscle

muscle that works against the action undertaken

anterior

toward the front

anterograde

forward

anthocyanins

colored compounds made by plants

anthropogenic

of, or relating to, the influence of human beings or nature

antibody

immune system protein that binds to foreign molecules

antigen

foreign substance that provokes an immune response

antioxidant

substance that prevents damage from oxidation

antitoxin

molecule used to inactivate a toxin

aphasia

loss of the ability to form ideas into words

apical

at the tip

apical meristem

growing tip from which all plant tissues arise

appendage

attached organ or structure

aqueous

watery or water-based

areolar

related to a small space within a tissue

aromatic

compound including a double-bonded carbon ring

arterioles

any of the small, terminal twigs of an artery that ends in capillaries

arthropods

organisms with jointed appendages and exoskeletons, including insects, spiders, and crustaceans

asymptomatic

without symptoms

ATP

adenosine triphosphate, a high-energy nucleotide used by cells to power most energy-requiring reactions

atria

two upper chambers of the heart (singular, atrium)

attenuation

lessening over time

autoimmune disease

disease in which the immune system attacks the body's own tissues

autonomic

independent; regulating involuntary actions

autonomic nervous system

one of the branches of the motor system, controlling involuntary muscles and glands

autosomal dominant

pattern of inheritance in which inheritance of a single allele from either parent results in expression of the trait

avian

concerning birds

axon

long extension of a nerve cell down which information flows

B lymphocyte

white blood cell that makes antibodies

B.C.E.

before the Common Era, equivalent to B.C.

basal

lowest level

base pair

two nucleotides (either DNA or RNA) linked by weak bonds

basic

having an excess of OH^- ions and a high pH

bilaterally symmetric

symmetric, or similar, across a central line

bilayer

composed of two layers

bioaccumulate

build up within organisms

bioluminescence

production of light by biochemical reactions

biopharmaceuticals

drugs produced by and harvested from living organisms

biosynthetic

forming a complex molecule from simpler ones

biotic

living

bolting

sudden spurt of growth

boreal

of, relating to, or located in northern regions

brood parasite

organism of one species that lays its eggs in the nest of another species

C4 and CAM plants

plants that employ accessory systems for trapping carbon for photosynthesis

cadherins

family of calcium-dependent adhesion proteins

carbohydrates

sugars, starches, and other molecules combining carbon, hydrogen, and oxygen and serving as fuel or structural components

cardiomyopathy

heart muscle disease

catalysis

aiding in the reaction of

catalyst

substance that aids in a reaction without being used up

catalyze

aid in the reaction of

caudate

toward the tail

C.E.

Common Era; equivalent to AD

cell cycle

sequence of growth, replication, and division that produces new cells

cellulose

carbohydrate made by plants and some other organisms; part of the cell wall

central nervous system

brain and spinal cord

centromere

region of the chromosome linking chromatids

cerebral cortex

outermost wrinkled portion of the brain

chemiosmosis

use of proton gradients to make ATP

chitin

nitrogen-containing carbohydrate found in arthropod exoskeletons and fungus cell walls

chromatid

a replicated chromosome before separation from its copy

chromatin

complex of DNA, histones, and other proteins making up chromosomes

chromosomal analysis

staining, banding, and other techniques for detection of chromosomal abnormalities

chromosome

"colored body" in the cell nucleus; made of DNA and protein, and divided functionally into genes and non-gene regions

cilia

short, hairlike cell extensions of the cell membrane formed by the cytoskeleton

ciliated

possessing cilia, which are short, hairlike extensions of the cell membrane

circadian

related to a day or daylength

clavicle

collar bone

cloaca

common exit cavity for intestinal, genital, and urinary tracts

codon

sequence of three mRNA nucleotides coding for one amino acid

cognition

mental processes of thought and awareness

cognitive

related to thought or awareness

communicable

transmissible from person to person

complementary

matching opposite

complex carbohydrate

molecules formed by linking simpler carbohydrates such as sugars

condensation

compaction of chromosome strands into a tight structure

conformation

three-dimensional shape

congenital

present at birth; inherited

conjunctiva

eye membrane that helps seal the eye socket

connective tissue

one of four types of body tissue, characterized by few cells and extensive extracellular material

consanguineous

descended from the same ancestor

constitutive

at a constant rate or continually

contiguous

adjacent to or touching

continental shelf

submerged offshore area demarcated by land on one side and deep sea on the other

coralloid

resembling coral

coronary artery

artery supplying blood to the heart

cortical

related to the cortex, or outer portion

cotyledon

seed leaf, which stores food and performs photosynthesis after germination

cranial

related to the cranium, or brain cavity

cryptobiosis

when a plant or animal becomes so inactive that its life processes nearly come to a stop

cutaneous

related to the skin

cutaneous respiration

gas exchange through the skin

cytology

study of cells

cytoplasm

material in a cell, excluding the nucleus

cytoskeleton

internal scaffolding in a cell, composed of protein

cytosol

fluid portion of a cell, not including the organelles

Darwinian fitness

capacity to survive and reproduce

deciduous

trees that shed their leaves in the fall

deciliter

one-tenth of a liter; a unit of volume

dementia

neurological illness characterized by impaired thought or awareness

desiccation

drying out

desynchronized

not happening at the same time

deuterostome

"mouth second"; referring to the early development of the anal pore during gut tube formation

dialysis

cleansing by partial filtration

dicot

plant having two cotyledons, or seed leaves

dikaryotic cell

cell with a pair of nuclei

dilation

expansion or swelling

dimer

polymer formed from two molecules of a simple compound

dimerizes

forms a pair

diploid

having pairs of chromosomes in the nucleus

dissociate

break apart

distal

away from

diurnal

active during the daytime

dorsal

to the back of

ecosystem

an ecological community and its environment

effector

organ at the end of a nerve, such as a muscle or gland

efferent

conducting outward or directing away from

electrolytes

ions in body fluids

electromagnetic radiation

light, X rays, and other forms of radiant energy

electron transport system

membrane-bound system of proteins that extracts energy from high-energy electrons, found in mitochondria and chloroplasts

electrophoresis

technique that uses electricity to separate molecules based on size and electric charge

electrophoresis gel

porous medium through which molecules can be separated using an electric current

embalming

treating a dead body to protect it from decay

embryology

development of the embryo

emulsify

suspend in solution through interaction with soap or similar molecules

endocrine

related to the system of hormones and glands that regulate body function

endogenous

caused by factors inside the organism

endometriosis

disorder of the endometrium, the lining of the uterus

endoplasmic reticulum

network of membranes within the cell

endosperm

nutritive tissue within a seed

endosymbiosis

symbiosis in which one partner lives within the other

endothermic

characterized by regulation of body temperature through metabolic activity

Enlightenment

eighteenth-century philosophical movement stressing rational critique of previously accepted doctrines in all areas of thought

enzymatic

related to the function of an enzyme

enzyme

protein that controls a reaction in a cell

epidemic

rapid spread of disease through a population, or a disease that spreads in this manner

epistasis

supression of a characteristic of one gene by the action of another gene

epithelium

one of four tissue types found in the body, characterized by thin sheets and usually serving a protective or secretory function

esophagus

tube connecting the throat to the stomach

eudicot

"true dicot"; plants with two seed leaves that originated from the earliest of flowering plants

eukaryotic cell

a cell with a nucleus

eutrophication

process by which waters become enriched in dissolved nutrients that promote plant growth which results in depletion of dissolved oxygen

evapotranspiration

loss of water from a plant by evaporation within the leaf

evidentiary DNA profile

analyzed DNA from a sample used as evidence

excrete

deposit outside of

exocrine gland

gland that secretes substances to an external or internal surface rather than into the bloodstream

exoskeleton

external skeleton

extensibility

ability to expand or grow larger

fallopian tubes

tubes through which eggs pass to the uterus

fecundity

ability to reproduce

feedback

process in which the output or result influences the rate of the process

fertilization

union of sperm and egg

fibroblast

undifferentiated cell normally giving rise to connective tissue cells

filtrate

material passing through a filter

focal

at a point

follicle

a vesicle that contains a developing egg surrounded by a covering of cells

food web

set of feeding relations in an ecosystem

forb

broad-leaved herbaceous plant

forensic

related to legal proceedings

fulcrum

pivot point of a lever

fungi

major group of parasitic, lower plants that obtain their food from the products of organic decay (e.g. molds, smuts, etc.)

gamete

reproductive cell, such as sperm or egg

gametophyte

a haploid plant that makes gametes by mitosis

ganglia

cluster of nerve cell bodies

gastroenteritis

inflammation of the gastrointestinal tract, often from infection

gene

portion of DNA that codes for a protein or RNA molecule

gene expression

use of a gene to create the corresponding protein

genetic code

relationship between triples of RNA nucleotides and the amino acids they code for during protein synthesis

genitalia

reproductive organs

genome

total genetic material in a cell or organism

germ line

cells creating eggs or sperm

gestation

period of fetal development within the mother

glial

supporting tissue of the elements of nervous tissue, including the brain, spinal cord, and ganglia

glucose

simple sugar that provides energy to animal cells; it is the building block of cellulose in plants

glycogen

complex carbohydrate used as storage in animals and some other organisms

glycolysis

initial stages of sugar breakdown in a cell

gradient

difference in concentration between two places

grafting

attachment and fusing of parts from different plants

guard cells

paired cells on leaves that control gas exchange and water loss

gymnosperms

"naked seed" plants, including conifers

hallucination

altered sensory experience resulting in the perception of objects that are not real

haploid

having single, nonpaired chromosomes in the nucleus

hectare

10,000 square meters (2.47 acres)

heme

the deep red, iron containing, nonprotein portion of hemoglobin and myglobin

hemicellulose

complex carbohydrate related to cellulose and found in cell walls of plants and some other organisms

hemoglobin

oxygen-carrying protein complex in red blood cells

herbarium

a collection of dried plant specimens systematically arranged for reference

hermaphrodite

organism possessing both male and female reproductive structures

heterodimer

complex molecule composed of two different parts

heterogeneous

composed of, or containing, different parts or types

heterozygous

characterized by possession of two different forms (alleles) of a particular gene

hexamer

a structure composed of six parts

histogenesis

origin or production of tissues

histology

study of tissues

histone

protein around which DNA wraps to form chromosomes

homologous

similar in structure

homologous chromosomes

chromosomes carrying similar genetic information

homologous recombination

exchange of DNA segments between chromosomes

homozygous

containing two identical copies of a particular gene

hormone

molecule released by one cell to influence another

hybrid

combination of two different types

hydrocarbon

molecule or group composed only of C and H

hydrogen bond

weak bond between the H of one molecule or group and a nitrogen or oxygen of another

hydrolyze

to split apart using water

hydrophilic

"water loving"

hydrophobic

"water hating," such as oils

hydroponics

growing of plants without soil

hydroxyl

chemical group consisting of -OH

hypersalinity

very high level of salt

hypersecretion

excess secretion

hypersensitivity reaction

immune reaction characterized by rapid and severe response, often with swelling of airways

hyphae

threadlike part of the vegetative portion of the fungus

hyposecretion

lack of secretion

hypothermia

subnormal temperature of the body

ice-out

a thawing of ice covering a lake or other body of water

immunoglobulin

an immune protein, also called an antibody

immunosuppressant

inhibition of the immune response

in utero

inside the uterus

in vitro

"in glass"; in lab apparatus, rather than within a living organism

inbred

repeatedly bred with close relatives, creating organisms with very little genetic variation

inducible

able to be switched on

inflorescence

characteristic arrangement of flowers on a stalk

infrastructure

roads, phone lines, and other utilities that allow commerce

inorganic

not bonded to carbon

insectivorous

insect-eating

integrins

a family of transmembrane linking proteins

interferons

signaling molecules of the immune system

intermediate filament protein

one type of cytoskeleton protein

interspecific

between different species

interstitial space

space between cells in a tissue

intracellular

within a cell

intraocular

within the eyeball

intrinsic to

intimate part of; within

intron

untranslated portion of a gene that interrupts coding regions

ion

an electrically charged particle

ionic

based on or functioning by means of ions

ionizing radiation

high-energy radiation that destroys chemical bonds

isometric

relating to contraction without movement

isotopes

forms of an atom that differ by the number of neutrons in the nucleus

keratin

a major structural protein

kilobase

one thousand DNA bases; a measure of size of a piece of DNA

kilobasepair

one thousand DNA base pairs; a measure of size of a piece of DNA

kinase

enzyme that adds a phosphate group to another molecule, usually a protein

Krebs cycle

central metabolic pathway in mitochondria

lactation

production of milk by the mammary glands

laparoscopic surgery

surgery in which an instrument is inserted through a very small incision, usually guided by some type of imaging technique

larynx

"voice box"; muscles at the top of the trachea that control pitch and loudness

lateral

side-to-side

lethargy

lack of excitability; torpor

lignified

hardened by impregnation with lignin, a compound formed in plants

lignin

organic molecule used in plant cell walls to add stiffness to cellulose

lineage

ancestral line

lipid

fat or waxlike molecule, insoluble in water

lipoprotein

combination of protein and lipid, or fatlike molecule

locus

site on a chromosome (plural, loci)

lotic

of, relating to, or living in actively moving water

lymph

pale fluid that circulates in the lymphatic system, principally composed of blood plasma and cell fluid

lymphatic system

network of tubes that permeates the body for transport of lymph and combat of infection

lymphocyte

white blood cell found in lymph nodes

lyse

break apart

lysine

an amino acid

lysing

disintegration or dissolution of cells

macromolecules

large molecules such as proteins, carbohydrates, and nucleic acids

marsupials

kangaroos and other mammals that gestate young in an external pouch

materialism

the belief that life is due entirely to biochemical interactions, without the intervention of supernatural forces

matrix

a network, usually of threadlike fibers

medium

nutrient source

meiosis

cell division that forms eggs or sperm

membrane potential

electrical and chemical differences across a membrane leading to storage of energy and excitability

metabolism

chemical reactions within a cell

metabolite

molecule involved in a metabolic pathway

metamorphosis

development process that includes a larval stage with a different form from the adult

metaphase

intermediate stage in cell division, in which chromosomes line up before separating

metastasis

breaking away of cancer cells from a solid tumor to travel elsewhere in the body

metazoans

animals other than sponges

methylation

addition of the methyl group CH₃

micron

one-millionth of a meter; also called a micrometer

mid-dorsal

middle of the back

middle lamella

layer of material between two plant cells that holds them together

minerals

iron, calcium, sodium, and other elements needed by living organisms

missense mutation

nucleotide change that causes a change in the amino acid normally added to the protein

mitochondria

subcellular organelle that creates ATP used for energy-requiring processes in a cell

mitogen

substance that stimulates mitosis

mitosis

separation of replicated chromosomes

molecular hybridization

base-pairing among DNAs or RNAs of different origins

monocot

any of various flowering plants, such as grasses and orchids, that have a single cotyledon in the seed

monoculture

cultivation of a single type of crop in a large area

monomer

"single part"; monomers are joined to form a polymer

monophyletic

a group that includes an ancestral species and all its descendants

montane

mountainous region

morphology

related to shape and form

motile

able to move

motor neuron

nerve cell that controls a muscle or gland

mucous membrane

outer covering designed to secrete mucus, often found lining cavities and internal surfaces

multimer

composed of many similar parts

multinucleate

having many nuclei within a single cell membrane

muscle tone

low level, constant muscle contraction

mutualism

symbiosis between two organisms in which both benefit

mycorrhizae

symbiosis between soil fungus and plant root to maximize absorption

myxedema

thyroid disorder characterized by dry skin, swelling in the face, and mental deterioration

nanometer

10^-9 meters; one-billionth of a meter

natural selection

process by which organisms best suited to their environments achieve greater reproductive success thus creating more "fit" future generations

nematode

worm of the Nematoda phylum, many of which are parasitic

nephron

functional unit of the kidney that performs filtration, reabsorption, and excretion

neritic

zone near the shore

neural

related to nerve cells or the nervous system

neurologist

doctor who treats brain disorders

neuron

nerve cell

neurotransmitters

molecules released by one neuron to stimulate or inhibit another neuron or cell

niche

the habitat supplying the right environment for a particular species

nm

nanometer; one-billionth of a meter

nocturnal

characterized by activity at night, or related to the night

nondisjunction

failure of separation of homologous chromosomes during meiosis

nuclear envelope

double membrane surrounding the cell nucleus

nucleated

having a nucleus

nucleotide

the building block of RNA or DNA

nucleus

membrane-bound portion of cell containing the chromosomes

obligate

required or necessary, especially referring to a metabolic process or mode of nutrition

octomer

composed of eight parts

oligosaccharide

chain of several sugar molecules

oncogene

gene that causes cancer

oocyte

unfertilized egg

opportunistic

caused by a microorganism that is usually harmless but which causes infection in an immunosuppressed person

organelle

membrane-bound cell compartment

organic

composed of carbon, or derived from living organisms; also, a type of agriculture stressing soil fertility and avoidance of synthetic pesticides and fertilizers

osmosis

passage of water through a membrane in response to concentration differences

osseous

related to bone

outcross

fertilization between two different plants

ovipary

production of eggs that hatch outside the body

ovovivipary

production of eggs that hatch within the female's body

ovule

multicellular structure that develops into a seed after fertilization

oxidation

reaction characterized by loss of electrons, or reaction with oxygen

oxidation-reduction

oxidation is loss of electrons, and reduction is gain of electrons

oxidative

characterized by oxidation, or loss of electrons

oxidative phosphorylation

use of oxygen to make ATP

oxidize

to react or make react with oxygen

palatine bone

bone of the hard palate at the roof of the mouth

paleoanthropology

study of ancient humans

palindromic

reading the same forward and backward

pandemic

disease spread throughout an entire population

papillate

small, nipplelike projection

parasite

organism living in close association with another from which it derives most of its nutrition

parasitology

study of parasites

parasympathetic nervous system

branch of the nervous system promoting nutrient absorption and other maintenance activities

pathogen

disease-causing organism

pathogenesis

pathway leading to disease

pathologic

related to disease

pectin

carbohydrate in plants that forms crosslinks to stabilize cell walls

peptide bond

bond between two amino acids

peptidoglycans

polymer that is composed of polysaccharides and peptic chains

perianth

combined sepals and petals

peripheral

outside the central nervous system (brain and spinal cord)

pH

measure of acidity or alkalinity; numbers below 7 are acid, above are basic

phage

short for bacteriophage

phagocytosis

engulfing of cells or large fragments by another cell, including immune system cells

pharynx

throat

phase-contrast microscopy

technique that manipulates passage of light through transparent specimens to reveal internal features

phenotype

observable characteristics of an organism

pheromone

molecule released by one organism to influence another organism's behavior

phloem

plant tissue that conducts sugars from leaves to roots and other tissues

phosphodiester

the link between two nucleotides in DNA or RNA

phosphorylate

add a phosphate group to

phosphorylation

addition of the phosphate group PO₄^3-

phyletic gradualism

the belief that evolutionary change is slow and steady

phylogenetic

related to phylogeny, the evolutionary development of a species

phylum

taxonomic level below kingdom, e.g., arthropod or chordate

physiology

branch of biology that deals with the functions and activities of living matter

phytoplankton

microscopic floating creatures that photosynthesize

pinnate

featherlike

pinocytosis

introduction of fluids into a cell by enclosing it and pinching off the plasma membrane

pipette

lab instrument for precise measurement and transfer of small volumes of liquids

pistil

female reproductive organ of a flower

placental

related to mammals that nourish the fetus with a placenta, an exchange organ in the uterus

plankton

microscopic floating organisms

plant hybridization

creation of offspring by union of two different types of plants, such as wheat and rye

plasmid

small ring of DNA found in many bacteria

plasticity

change form

plate tectonics

the movement of large plates of Earth's crust

polar

partially charged, and usually soluble in water

polar covalent

bond in which electrons are unevenly shared

polymer

molecule composed of many similar parts

polymerase

enzyme complex that synthesizes DNA or RNA from individual nucleotides

polymerization

linking together of similar parts to form a polymer

polypeptide

chain of amino acids

polysaccharide

carbohydrate composed of many individual units of sugar

posterior

toward the back

postmortem

after death

prebiotic

before the origin of life

Precambrian

before the Cambrian era; before 600 million years ago

primer

short nucleotide sequence that helps begin DNA replication

progeny

offspring

prokaryote

single-celled organism without a nucleus

promoter

DNA sequence to which RNA polymerase binds to begin transcription

prostaglandins

hormonelike molecules released by one cell that affect nearby cells, including smooth muscle

prostrate

face downward

protein

complex molecule made from amino acids; used in cells for structure, signaling, and controlling reactions

proteolysis

breakdown of proteins

protoecology

early ecology

protoplasm

fluid portion of a plant cell within the cell wall

protostome

"mouth first"; referring to the early development of the oral pore during gut tube formation

protozoa

any of a phylum of minute protoplasmic animals present in almost every kind of habitat, some of which pose serious threats to humans and animals

pseudopod

"false foot"; an extension of the plasma membrane during locomotion by an amoeba or similar crawling cell

psychosis

severe mental disorder characterized by diminished connection with reality

psychotropic

affecting consciousness, thought, or emotion

punctuated equilibrium

pattern of evolution in which long periods of relatively little change are punctuated by rapid change

pyruvate

the ionized form of pyruvic acid, a key intermediate in cell metabolism

quarternary

fourth level

radially symmetric

symmetric, or similar, about a central point (a wheel is radially symmetric)

reproductive isolation

isolation of a population from other populations of the same species due to inability to successfully reproduce; an early stage in species formation

respire

use oxygen to burn cellular fuel

restriction enzyme

enzyme that cuts DNA at a particular sequence

restriction fragments

fragments of DNA created by restriction enzymes

reticular

netlike

retrograde

backward

reverse transcriptase

enzyme that copies RNA into DNA

reverse transcription

creation of DNA from an RNA template

ribonucleoprotein

combination of RNA and protein

ribosome

protein-RNA complex in cells that synthesizes protein

rickettsia

(pl. -sias or siae) any of a family of polymorphic microorganisms that cause various diseases

RNA polymerase

enzyme complex that creates RNA from DNA template

saline

of, or relating to, salt

saprophyte

plant that feeds on decaying parts of other plants

savanna

open grassland with sparse trees

sclerophyll

small, tough evergreen leaves

secretion

material released from the cell

secretory pathway

series of events within a cell by which molecules are brought to the plasma membrane for release from the cell

sepals

whorls of flower organs outside of the petals, usually green and serving to protect the flower before it opens

serotinous

developing late in the season

serotype

identity of an organism or virus based on reaction to an antibody

sessile

attached and remaining in one place

silviculture

cultivation of forest trees

sleep apnea

difficulty breathing while asleep

solenoid

cylindrical coiled structure

solute

dissolved substance

solvation

the process of dissolving

somatic

nonreproductive; not an egg or sperm

somatostatin

hormone produced by the hypothalamus that influences growth

spasticity

of, or relating to, spasms

spectroscopy

process using light or other emitted radiation to determine properties of a sample

sphincter

ring of muscle regulating passage of material through a tube such as the gastrointestinal tract

spontaneous generation

the theory that life began from nonliving matter

stasis

state of no change

steroid hormone

group of hormones that includes estrogen, testosterone, and progesterone

steroids

hormones such as testosterone or estrogens that control many aspects of physiology

stomata

openings in leaves for gas exchange, surrounded and regulated by guard cells

strong bond

high-energy arrangement between two atoms involving electron-sharing; strong bonds require more energy to break than weak bonds

subcutaneous

below the skin

substrate

the molecule acted on by an enzyme; also a surface for attachment

succession

series of changes seen in some plant communities over time, in which low-growing, rapidly reproducing species are replaced by taller and more slowly reproducing ones

superficial

on the surface; not deep

symbiont

organism living in close association with another organism

symbiosis

close relationship between two species in which at least one benefits

sympathetic nervous system

branch of the nervous system that promotes heightened awareness, increased nutrient consumption, and other changes associated with "fight or flight"

synaptic transmission

passage of chemicals between nerve cells to send messages or alter neuron firing

synchronously

at the same time

synergism

working together to create a larger product rather than a simple sum

systemic

throughout the body

T cell

white blood cell that controls the immune response

taxon

a level of classification, such as kingdom or phylum

tectonic plate

large segment of Earth's crust that moves in relation to other similar plates

template

master copy

teratogens

substances that cause birth defects

tertiary

third level

thermoregulation

temperature regulation

transcribe

creation of an RNA copy of a DNA gene

transcription

messenger RNA formation from a DNA sequence

transcription factor

protein that increases the rate of transcription of a gene

transduction

conversion of a signal of one type into another type

transgenic

characterized by presence of one or more genes from a different organism

translation

synthesis of protein using mRNA code

translocation

movement of sugars and other nutrients throughout a plant

transverse

situated or lying across

trimer

a structure composed of three parts

triploid

possessing three sets of chromosomes

trophic

related to feeding

trophic level

feeding level in an ecosystem

true breeding

giving only offspring identical to the parents

turgor

internal pressure

ubiquitous

found everywhere

ultrasonography

use of sound waves to produce an image

ungulate

hoofed mammals such as cattle

uninucleate

possessing one nucleus

vas deferens

tube through which sperm travel from testes to urethra

vector

carrier

ventral to

toward the belly side

ventricle

fluid-filled chamber

venule

any of the minute veins connecting the capillaries with the larger systemic veins

vesicle

membrane-bound sac

vestigial

no longer functional

visceral

related to the viscera, or internal organs

viscous

thick

vivipary

production of live young

volatile

easily vaporized

vulva

external female genitalia

weak bond

low-energy arrangement between two atoms involving electron-sharing; weak bonds require less energy to break than strong bonds

X-ray crystallography

use of X rays to determine the structure of a molecule

xylem

water-transporting system in plants

zygote

fertilized egg