Pre-AP Biology Spring Final Exam Vocabulary Review Flashcards

Terms Definitions
chitin
complex carbohydrate that makes up the cell walls of fungi, also found in the external skeletons of arthropods
hypha
tiny filament that makes up a multicellular fungus or a water mold
mycelium
many hyphae tangled together into a thick mass; comprises the bodies of multicellular fungi
fruiting body
slender reproductive structure that produces spores and is found in some funguslike protists; reproductive structure of fungus that develops from a mycelium
sporangia
structures in ferns and some fungi that contain spores
sporangiophores
specialized hyphae where sporangia are found
zygospore
resting spore that contains zygotes formed during the sexual phase of a mold's life cycle
rhizoid
in fungi, a rootlike hypha that penetrates the surface of an object; in mosses, a long, thin cell that anchors the moss to the ground and absorbs water and minerals from the surrounding soil
stolon
in fungi, a stemlike hypha that runs along the surface of an object; in plants, a long, trailing stem that produces roots when it touches the ground
gametangium
gamete-producing structure found in mold
conidium
tiny fungal spore that forms at the tips of specialized hyphae in ascomycetes
ascus
structure within the fruiting body of an ascomycete in which two nuclei of different mating types fuse
ascospores
haploid spore produced within the ascus of ascomycetes
budding
asexual process by which yeasts increase in number; process of attaching a bud to a plant to produce a new branch
basidium
spore-bearing structure of a basidomycete
basidiospores
spore in basidiomycetes that germinates to produce haploid primary mycelia
lichens
symbiotic association between a fungus and a photosynthetic organism
mycorrhizae
symbiotic associaion of plant roots and fungi
sporophyte
diploid, or spore-producing, phase of an organism
gamteophyte
haploid, or gamete-producing, phase of an organism
bryophyte
non vascular plant; example are mosses and their relatives
rhizoid
a long, thin cell that anchors the moss to the ground and absorbs water and minerals from the surrounding soil
vascular tissue
type of plant tissue specialized to conduct water and nutrients throughout a plant
tracheid
hollow plant cell in xylem tissue with thick cell walls that resist pressure
xylem
the vascular tissue through which water and nutrients move in some plants
phloem
vascular tissue responsible for the transport of nutrients and the carbohydrates produced by photosynthesis
lignin
substance in vascular plants that makes cell walls rigid
root
underground organ in plants that absorbs water and minerals
leaf
photosynthetic organ that contains one or more bundles of vascular tissue
vein
a cluster of vascular tissue in leaves
stem
supporting structure that connects roots and leaves and carries water and nutrients between them
rhizome
creeping or underground stem in ferns
frond
large leaf of a fern
sporangium
structure in ferns and some fungi that contains spores
sorus
cluster of sporangia on the underside of a fern frond
gymnosperm
seed plant that bears its seed directly on the surfaces of cones
angiosperm
flowering plants; bears its seeds with a layer of tissue that protects the seed
cone
in gymnosperms, a seed-bearing structure
flower
seed-bearing structure of an angiosperm
pollen grain
male gametophyte in seed plants
pollination
transfer of pollen from the male reproductive structure to the female reproductive structure
seed
embryo of a living plant that is encased in a protective covering and surrounded by a food supply
embryo
organism in its early stage of its development
seed coat
structure that surrounds and protects a plant embryo and keeps it from drying out
fruit
wall of tissue surrounding an angiosperm seed
monocot
angiosperm whose seeds have one cotyledon
dicot
angiosperm whose seeds have two cotyledons
cotyledon
first leaf or first pair of leaves produced by the embryo of a seed plant
annual
flowing plant that completes a life cycle within one growing season
biennial
flowering plant that completes its life cycle in two years
perennial
flowering plant that lives for more than two years
flower
the reproductive organ of angiosperms composed of sepals, petals, stamens, and carpals
sepal
outermost circle of flower parts that encloses a bud before it opens and protects the flower while it is developing
petal
brightly colored structure just inside the sepals; attracts insects and other pollinators to a flower
stamen
male part of the flower; made up of an anther and a filament
filament
in plants, a long, thin structure that supports the anther; part of the stamen
anther
flower structure in which haploid male gametophytes (pollen grains) are produced; part of the stamen; during reproduction, each cell undergoes meiosis and produces four haploid pollen grains, each of which contains two nuclei
carpel
innermost part of a flower that produces the female gametophytes; made up of a stigma, a style, and an ovary
ovary
in plants, a flower structure that contains one or more ovules from which female gametophytes are produced; the base of the carpel; in reproduction, one cell produces eight nuclei, one of which will be fertilized
style
narrow stalk of the carpel in a flower
stigma
sticky portion at the top of the style where pollen grains frequently land; part of the carpel
embryo sac
female gametophyte within the ovule of a flowering plant; consists of eight nuclei and the surrounding membrane, only one of which is the egg
endosperm
food-rich tissue that nourishes a tissue as it grows; formed when a sperm nucleus fertilizes the two polar nuclei in the embryo sac
double fertilization
fertilization in angiosperms, in which two distinct fertilization events take place between the male and female gametophytes (one sperm nuclei fertilizes the egg cell, while the other fertilizes the two polar nuclei)
fruit
any seed that is enclosed within its embryo wall; often fleshy and nutritious so that animals will eat and disperse seeds inside, or lightweight and aerodynamic so that seeds can be dispersed by wind and water
dormancy
period of time during which a plant embryo is alive but not growing; can be helpful for seeds that travel long distances or cannot survive during some seasons
germination
early growth stage of a plant embryo
protist
any eukaryote that is not a plant, an animal, or a fungus
pseudopod
temporary projection of cytoplasm, or a "false foot," used by some protists for feeding or movement
amoeboid movement
type of locomotion used by amoebas
food vacuole
small cavity in the cytoplasm of protists that temporarily stores food
cilium
short hairlike projection similar to a flagellum; produces movement in many cells
trichocyst
small, bottle-shaped structure used for defense by paramecia
macronucleus
the larger of a ciliate's two nuclei, contains multiple copies of most of the genes that the cell needs in its day-to-day existence
micronucleus
the smaller of a ciliate's two nuclei; contains a "reserve copy" of all of the cell's genes
gullet
indentation in one side of a ciliate that allows food to enter the cell
anal pore
region of the cell membrane of a ciliate where waste-containing food vacuoles fuse and are then emptied into the environment
contractile vacuole
cavity in the cytoplasm of some protists that collects water and discharges it from the cell
conjugation
form of sexual reproduction in which paramecia and some prokaryotes exchange genetic information
accessory pigment
compound other than chlorophyll that absorbs light at different wavelengths than chlorophyll
eyespot
group of cells that can detect changes in the amount of light in the environment
pellicle
cell membrane in euglenas
phytoplankon
population of algae and other small, photosynthetic organisms found near the surface of the ocean and forming part of plankton
phycobilin
accessory pigment found in red algae that is especially good at absorbing blue light
filament
in algae, a long threadlike colony formed by many green algae; in plants, a long, thin structure that supports an anther
alternation of generations
process in which many algae switch back and forth between haploid and diploid stages of their life cycles
gametophyte
haploid, or gamete-producing, phase of an organism
spore
haploid reproductive cell; a small usually single-celled reproductive body produced by many plants and some protozoans - this body can develop into a new individual
sporophyte
diploid, or spore-producing, phase of an organism
cellular slime mold
slime mold whose individual cells remain separated during every phase of the mold's life cycle
acellular slime mold
slime mold that passes through a stage in which its cells fuse to form large cells with many nuclei
plasmodium
structure with many nuclei formed by acellular slime molds
hypha
tiny filament that makes up a multicellular fungus or a water mold
zoosporangium
spore case
antheridium
male reproductive structure in some algae and plants
oogonium
specialized structure formed by hyphae that produces female nuclei
Radial Symmetry
body plan in which body parts repeat around the center of the body; characteristic of sea anemones and sea stars
Bilateral Symmetry
body plan in which only a single, imaginary line can divide the body into two equal halves; characteristic of worms, arthropods, and chordates
cephalization
concentration of sense organs and nerve cells at the front of an animal's body
coelom
fluid-filled body cavity lined with mesoderm
intracellular digestion
process in which food is digested inside cells
extracellular digestion
process in which food is broken down outside the cells in a digestive tract
open circulatory system
system in which blood is not always contained within a network of blood vessels
closed circulatory system
system in which blood is contained within a network of blood vessels
hydrostatic skeleton
layers of circular and longitudinal muscles, together with the water in the gastrovascular cavity, that enable movement
exoskeleton
external skeleton; tough external covering that protects and supports the body of many invertebrates
endoskeleton
structural support located inside the body of an animal
external fertilization
process in which eggs are fertilized outside the female's body
internal fertilization
process in which eggs are fertilized inside the female's body
Taxonomy
discipline classifying organisms and assigning each organism a universally accepted name.
Binomial nomenclature
classification system in which each species is assigned a two-part scientific name.
Genus
(biology) taxonomic group containing one or more species
Taxon
group or level of organization into which organisms are classified.
Family
(biology) a taxonomic group containing one or more genera
Order
group of similar families.
Class
group of similar orders.
Phylum
group of closely related classes.
Kingdom
large taxonomic group, consisting of closely related phyla.
Phylogeny
the study of evolutionary relationships among organisms.
Evolutionary classification
method of grouping organisms together according to their evolutionary history.
Derived character
Characteristic that appears in recent parts of a lineage, but not in its older members.
Cladogram
diagram that shows the evolutionary relationships among a group of organisms.
Molecular clock
model that uses DNA comparisons to estimate the length of time that 2 species have been evolving independently
Domain
most inclusive taxonomic category; larger than a kingdom.
Bacteria
domain of unicellular prokaryotes that have cell walls containing peptidoglycan.
Eubacteria
kingdom of unicellular prokaryotes whose cell walls are made up of peptidolycan.
Archaea
domain of unicellular prokaryotes that have cell walls that do not contain peptidoglycan.
Archaebacteria
kingdom of unicelllular prokaryotes whose cell walls do not contain peptidoglycan.
Eukarya
domain of all organisms whose cells have nuclei, including protists, plants, fungi, and animals.
Protista
kingdom composed of eukaryotes that are not classified as plants, animals, or fungi.
Fungi
kingdom composed of heterotrophs; many obtain energy and nutrients from dead organic matter.
Plantae
kingdom of multicellular photosynthetic autotrophs that have cell walls containing cellulose.
Animalia
kingdom of multicellular eukaryotic heterotrophs whose cells do not have cell walls.
Paleontologist
scientist who studies fossils.
Fossil record
information about past life, including the structure of organisms, what they ate, what ate them, in what environment they live, and the order in which they lived.
Extinct
term used to prefer to a species that died out.
Relative dating
method of determining the age of a fossil by comparing its placement with that of fossils in other alleles occur.
Index fossil
distinctive fossil used to compare the relative ages of fossils.
Half-life
length of time required for half of the radioactive atoms in a sample to decay.
Radioactive dating
technique in which scientists calculate the age of a sample based on the amount of remaining radioactive isotopes it contains.
Geologic time scale
scale used by paleontologists to represent evolutionary time.
era
one of several subdivisions of the time between the Precambrian and the present.
period
unit of time into which eras are subdivided.
Proteinoid microsphere
tiny bubble, formed of large organic molecules, that has some characteristics of a cell.
Microfossil
microscopic fossil (the name is basically the definition)
Endosymbiotic theory
theory that eukaryotic cells formed from a symbiosis among several different prokaryotic organisms.
Mass extinction
event in which many types of living things become extinct at the same time.
Macroevolution
large-scale evolutionary changes that take place over long period of time.
Adaptive radiation
process by which a single species on small group of species evolves into several different forms that live in different ways; rapid growth in the diversity of a group of organisms.
Convergent evolution
process by which unrelated organism independently evolve similarities when adapting to similar environments.
Coevolution
process by which two species evolve in response to changes in each other.
Punctuated equilibrium
pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change.
ecology
the scientific study of interactions among organisms and between organisms and their environment, or surroundings
biosphere
contains the combined portions of the planet in which all of life exists
Species
a group of organisms so similar to one another that they can breed and produce fertile offspring
populations
groups of individuals that belong to the same species and live in the same area
communities
assemblages of different populations that live together in a defined area
ecosystem
a collection of all the organisms that live in a particular place, together with their nonliving, or physical, environment
biome
group of ecosystems that have the same climate and dominant communities
autotrophs
organisms that make their own food (same thing as producers)
producers
organisms that make their own food (same thing as autotrophs)
photosynthesis
process by which plants and some other organisms use light energy to convert water and carbon dioxide into oxygen and high-energy carbohydrates such as sugars and starches
chemosynthesis
process by which some organisms, such as certain bacteria, use chemical energy to produce carbohydrates
heterotrophs
consumers (they rely on other organisms for their energy and food supply)
consumers
an organism that obtains energy and nutrients by feeding on other organisms or their remains
herbivores
an organism that eats only plants.
carnivores
consumers that eat only animals
omnivores
consumers that eat both plants and animals
detritivores
consumers that feed on plant and animal remains as well as other dead matter.
decomposer
organism that breaks down and obtains energy from dead organic matter (not detritivores)
food chain
a series of steps in which organisms transfer energy by eating and being eaten
food web
links all the food chains in an ecosystem together
trophic level
each step in a food chain or food web
ecological pyramid
diagram that shows the relative amounts of energy or matter within each trophic level in a food chain or food web
biomass
the total amount of living tissue within a given trophic level
biogeochemical cycles
process in which elements, chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another
evaporation
the process by which water changes from liquid form to an atmospheric gas
transpiration
evaporation of water from a plant's leaves
nutrients
all the chemical substances that an organism needs to sustain life
nitrogen fixation
process of converting nitrogen gas into ammonia (often by bacteria in the soil)
denitrification
conversion of nitrates into nitrogen gas
primary productivity
rate at which organic matter is created by producers in an ecosystem
limiting nutrient
single nutrient that either is scarce or cycles very slowly, limiting the growth of organisms in an ecosystem
algal bloom
when an aquatic ecosystem receives a large input of a limiting nutrient the result is often an immediate increase in the amount of algae and other producers
subsistence hunting
When groups supplement their diet with the meat of wild animals
renewable resource
a resource that can be replaced or used over and over again (ex. soil, water, plants, animals)
nonrenewable resource
a resource that cannot be reused or replaced easily (ex. gems, iron, copper, fossil fuels)
sustainable use
lets people use the resources of wilderness areas in ways that will not damage the ecosystem
soil erosion
wearing away of surface soil by water and wind
desertification
The transformation of normal land into desert either naturally or through human intervention
deforestation
widespread of cutting down trees
aquaculture
farming of aquatic organisms
smog
a mixture of chemicals that occur as a gray-brown haze in the atmosphere
pollutant
Anything in the air, water, or earth that is harmful or interferes with a desired activity
acid rain
rain that carries dangerous chemicals
biodiversity
the number and variety of organisms in a given area during a specific period of time.
ecosystem diversity
variety of habitats, living communities, and ecological processes in the living world
species diversity
Number of different species in the biosphere
genetic diversity
sum total of all the different forms of genetic information carried by all organisms living on Earth today
extinction
population dies out
endangered species
a species whose numbers are so small that the species is at risk of extinction
habitat fragmentation
breaking larger habitats into smaller, isolated pieces
biological magnification
process by which pollutants become more concentrated in successive trophic levels of a food web
invasive species
species that enter new ecosystems and multiply, harming native species and their habitats
conservation
the preservation and careful management of the environment and of natural resources
ozone layer
thin layer of gas in the upper atmosphere
global warming
A gradual increases in average global temperature.
population density
number of individuals per unit area
immigration
movement of individuals into an area
emigration
movement of individuals out of a population
exponential growth
type of growth that occurs when the individuals in a population reproduce at a constant rate (normal population growth)
logistic growth
this type of growth - when a population growth is at its carrying capacity, the birth rate equals the death rate and growth stops.
carrying capacity
largest number of individuals of a population that an environment can support
limiting factor
factor that causes the growth of a population to decrease
density-dependent limiting factor
a limiting factor that depends on population size
predator prey relationship
The regulation of population controlled by predation occurs within this
density-independent limiting factor
limiting factor that affects all populations in similar ways, regardless of population size
weather
the daily condition of the atmosphere at a certain time and place
climate
average year-to-year weather conditions of a particular area
greenhouse effect
a natural process in which greenhouse gases in the air hold heat
polar zone
cold climate zone where the sun's rays strike Earth at a very low angle
temperate zone
between the polar zones and the tropics, hot to cold year round
tropical zone
warm climate zone that receives direct or nearly direct sunlight year round
biotic factor
living influence or factor on organisms within an ecosystem
abiotic factor
physical or nonliving factor that shapes an ecosystem
habitat
the area where an organism lives, grows, and develops
niche
full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions
resource
any necessity of life, such as water, nutrients, light, food, or space
competitive exclusion principle
states that two species cannot coexist in a community if they share a niche
predation
an interaction in which one organism kills and eats another
symbiosis
any relationship in which two species live closely together
mutualism
symbiotic relationship in which both species benefit
commensalism
symbiotic relationship in which one species benefits, but the other is neither helped or harmed
parasitism
a relationship in which one organism lives on or inside another and harms it
ecological succession
series of predictable changes that occur in a community over time
primary succession
the series of changes that occur in an area where no ecosystem previously existed
pioneer species
first species to populate an area
secondary succession
the series of changes that occur after a disturbance of an existing ecosystem
microclimate
a climate of a small area differs dramatically from that of surrounding areas
disease
any change, other than an injury, that disrupts the normal functions of the body.
pathogen
disease-causing agent.
germ theory of disease
theroy/idea that infectious diseases are caused by microorganisms, or germs.
Koch's postulates
series of guidelines used to identify the microorganism that causes a specific disease.
vector
animal that carries pathogens from person to person.
antibiotic
Compound that blocks the growth and reproduction of bacteria.
immunity
Ability of the body to resist a specific pathogen.
inflammatory response
Nonspecific defense reaction to tissue damage caused by injury or infection.
fever
Elevated body temperature that occurs in response to infection.
interferon
One of a group of proteins that help cells resist viral infection.
immune response
the body's specific defenses that attack a disease-causing agent.
antigen
substance that triggers an immune response.
humoral immunity
immunity against antigens and pathogens in the body fluids.
cell-mediated immunity
immunity against abnormal cells and pathogens inside living cells.
antibody
protein that helps destroy pathogens.
vaccination
injection of a weakened or mild form of a pathogen to produce immunity.
active immunity
immunity produced by exposure to an antigen, as a result of the immune response.
passive immunity
short-term immunity caused when antibodies produced by other animals for a pathogen are injected into the body.
allergy
overreaction of the immune system to antigens (ex. molds, pollens, and foods)
histamine
chemical released by activated mast cells that increases the flow of blood and fluids to the surrounding area.
asthma
chronic respiratory disease in which the air passageways become narrower than normal.
risk factor
anything that increases the chance of disease or injury.
tumor
mass of growing tissue.
carcinogen
chemical compound known to cause cancer.
prokaryote
unicellular organism lacking a nucleus
bacillus
rod-shaped prokaryote
coccus
spherical prokaryote
chemoheterotroph
organism that must take in organic molecules for both energy and carbon
photoheterotroph
organism that is photosynthetic but needs organic compounds as a carbon source
photoautotroph
organism that uses energy from sunlight to convert carbon dioxide and water to carbon compounds
chemoautotroph
organism that makes organic carbon molecules from carbon dioxide using energy from chemical reactions
obligate aerobe
organism that requires a constant supply of oxygen in order to live
obligate anaerobe
organism that cannot live in the presence of oxygen
facultative anaerobe
organism that can survive with or without oxygen
binary fission
asexual reproduction in prokaryotes
conjugation
form of sexual reproduction in prokaryotes, exchanges genetic information
endospore
type of spore formed when a bacterium produces a thick internal wall that encloses its DNA and a portion of its cytoplasm
nitrogen fixation
process of converting nitrogen gas into ammonia
virus
particle made up of nucleic acid and protein, can replicate only by infecting living cells
capsid
outer protein coat of a virus
bacteriophage
virus that infects bacteria
lytic infection
process in which a virus enters a cell and replicates, causing the cell to burst
lysogenic infection
process by which a virus embeds its DNA into the DNA of the host cell and is replicated along with the host cells DNA
prophage
the viral DNA that is embedded in the host cells DNA
retrovirus
virus that contains RNA as its genetic information
pathogen
disease-causing agent
vaccine
a preperation of weakend or killed pathogens
antibiotic
compound that blocks the growth and reproduction of bacteria
viroid
single stranded RNA molecule that has no surrounding capsid
prion
infectious particle made up of protein rather than DNA or RNA
spirillum
spiral or corkscrew-shaped prokaryote
directional selection
form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than those in the middle or at the other end
stabilizing selection
form of natural selection when individuals near the center of the curve have higher fitness than those at either end of the curve
disruptive selection
form of natural selection in which a single curve splits into 2, occurs when individuals at both ends of a distribution curve have higher fitness than those in the middle
genetic drift
a random change in the frequency of alleles in a small population.
founder effect
change in allele frequencies as a result of the migration of a small sub group of a population.
Hardy-Weinberg principle
principle that allele frequencies in a population will remain constant unless one or more factors cause it to change
genetic equilibrium
situation in which allelic frequencies remain constant
speciation
formation of new species
reproductive isolation
separation of species or populations so that they cannot interbreed and produce fertile offspring.
behavioral isolation
form of reproductive isolation in which 2 populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding.
geographic isolation
form of reproductive isolation in which 2 populations are separated physically by geographic barriers such as rivers and mountains
temporal isolation
form of reproductive isolation in which 2 populations reproduce at different times
gene pool
the combined genetic information of all members of a population
relative frequency
number of times an allele occurs in a gene pool compared with the number of times other alleles occur
single-gene trait
trait controlled by a single gene that has two alleles
polygenic trait
trait controlled by two or more genes
evolution
changes in a kind of organism over time; process by which modern organisms have descended from ancient organisms
theory
well tested explanation that unifies a broad range of observations
fossil
preserved remains or evidence of an ancient organism
artificial selection
selection by humans for breeding of useful traits from the natural variation among different organisms
struggle for existence
competition among members of a species for food, living space and other necessities of life
fitness
ability of an organism to survive and reproduce in its environment
adaptation
inherited characteristic that increases an organism's chance of survival
survival of the fittest
process by which individuals that are better suited to their environment survive and reproduce most successfully, also called natural selection
natural selection
process by which individuals that are better suited to their environment survive and reproduce most successfully, also called survival of the fittest
descent with modification
principle that each living species has decended with changes from other species over time
common descent
principle that all living things were derived from common ancestors
homologous structure
structures that have different mature forms in different organisms but develop from the same embryonic tissues
vestigial organ
organ that serves no useful function in an organism
karyotype
photographs of chromosomes grouped in order in pairs
sex chromosomes
chromosomes that determine the gender of the organism
autosome
chromosomes that do not determine the gender of the organism
pedigree
chart that shows the relationships within a family
sex-linked gene
gene located on the X or Y chromosome
nondisjunction
error in meiosis in which homologous chromosomes fail to separate
DNA fingerprinting
analysis of sections of DNA that have little or no known function, but vary widely from one individual to another, in order to identify individuals
selective breeding
method of breeding that allows only individual organisms with desired characteristics to produce the next generation
hybridization
crossing dissimilar individuals to bring together the best of both organisms
inbreeding
continued breeding of individuals with similar characteristics to maintain the desired characteristics of a line of organisms
genetic engineering
process that involves genes or pieces of DNA being taken from one organism and transferred to another
restriction enzyme
the scissors-enzyme that cuts DNA at a specific sequence of nucleotides
gel electrophoresis
mixture of DNA fragments is placed at one end of a porous gel, and an electric voltage is applied to the gel (separating DNA)
recombinant DNA
pieces of DNA from 2 or more sources that are combined
polymerase chain reaction
technique that allows molecular biologists to make many copies of a particular gene
plasmid
small circular piece of DNA
genetic marker
a gene that makes it possible to distinguish bacteria that carry the plasmid (and the foreign DNA) from those that don't
transgenic
term used to refer to an organism that contains genes from other organisms
clone
member of population of genetically identical cells produced from a single cell
Invertebrate
Animal lacking a backbone
Vertebrate
Animal with a backbone
Feedback Inhibition
The product or result of a process stops or limits the process
Blastula
Hollow ball of cells
Endoderm
innermost germ layer
Mesoderm
middle germ layer
Ectoderm
outermost germ layer
Radial Symmetry
Describes animals that are symmetrical such that when divided in any way from the center there are two equal halves
Bilateral Symmetry
Describes animals who can only be divided into two equal parts one way
Cephalization
The concentration of sense organs and nerve cells in the front of the body
epidermal cells
cells that make up dermal tissue, which is the outer covering of a plant
sieve tube elements
main phloem cells that are arranged end to end, like vessel elements, in order to form sieve tubes
companion cells
phloem cells that surround sieve tube elements
meristems
clusters of tissue that are responsible for continuing growth throughout a plant's lifetime
meristematic tissue
plant tissue found only in the tips of shoots and roots; responsible for plant growth
apical meristem
group of undifferentiated cells that divide to produce increased length of stems and roots
differentiation
process where cells develop into mature cells with specialized structures and functions
taproot
primary root that grows long and thick (found mainly in dicots)
fibrous roots
roots that branch to such an extent that no single root grows larger than the rest (found mainly in monocots)
root hairs
tiny cellular projections that penetrate the spaces between soil particles and produce a large surface area through which water can enter the plant
cortex
spongy layer of ground tissue that is located just inside the epidermis
endodermis
layer of cells that completely encloses vascular tissue
vascular cylinder
central region of a root that includes the vascular tissue xylem and phloem
root cap
protects the root as it forces its way through the soil; secretes a slippery substance as it grow, in order to lubricate the progress of the root through the soil
Casparian strip
waterproof strip that surrounds individual cells that compose the vascular cylinder that is enclosed by the endodermis
vascular bundles
plant stem structure that contains xylem and phloem over time
blades
thin, flattened sections that make up the leaves and collect sunlight
petiole
thin stalk that attaches the blade to the stem
mesophyll
specialized ground tissue where photosynthesis in most plants occur
palisade mesophyll
layer of closely packed mesophyll cells under the epidermis that absorb light that enters the leaf
spongy mesophyll
loose tissue beneath the palisade layer and has many air spaces between its cells
stomata
pore-like openings in the underside of the leaf that allow carbon dioxide and oxygen to diffuse into and out of the leaf
guard cells
specialized cells in the epidermis that control the opening and closing of stomata by responding to changes in water pressure
transpiration
loss of water through the leaves of plants
adhesion
a force where unlike molecules are attracted towards one another
capillary action
tendency of water to rise in a thin tube
Mammary Glands
Glands in female mammals that produce milk for nourishing the young.
Subcutaneous Fat
A layer of fat located beneath the skin that also helps mammals conserve body heat.
Rumen
A special stomach chamber in herbivores in which newly swallowed plant food is stored and processed.
Diaphragm
A powerful muscle that pulls the bottom of the chest cavity downward increasing the volume of the chest cavity allowing air into the lungs.
Cerebral Cortex
The outer layer of a mammal's cerebrum that is the center of thinking and other complex behaviors.
Monotremes
All egg-laying mammals
Marsupial
Mammals bearing live young that usually complete their development in an external pouch. (Ex: Kangaroo, Koala)
Placenta
The characteristic defining placental mammals. A placenta is an internal structure formed when the embryo's tissues join with the tissues of the mother's body.
Binocular Vision
The ability to merge visual images from both eyes, thereby providing depth perception and a three dimensional view of the world.
Prosimians
Small, nocturnal primates with large eyes adapted to seeing in the dark.
Anthropoids
Humanlike primates. (Ex: Humans, apes, most monkeys)
Prehensile
A tail that can coiled tightly enough around a branch to function as a "fifth hand"
Hominoids
Great apes. (Includes gibbons, orangutans, gorillas, chimpanzees, and humans)
Hominid
The taxonomic family including modern humans and their closest relatives.
Bipedal
A form of two-foot locomotion
Opposable thumb
A part of the hand that enables the grasping of objects and use of hand tools.
alveolus
tiny air sac at the end of a bronchiole in the lungs that provides surface area for gas exchange to occur
notochord
long supporting rod that runs through a chordate's body just below the nerve cord
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