AP Biology Final Exam Review

emergent properties
new properties that emerge with each step upward in the hierarchy of life, owing to the arrangement and interactions of parts as complexity increases

negative feedback
a mechanism of response in which a stimulus initiates reactions that reduce the stimulus

positive feedback
a physiological control mechanism in which a change in a variable triggers mechanisms that amplify the change

inductive reasoning
reasoning based on observed patterns

polymer
large compound formed from combinations of many monomers

hydrolysis
a chemical process in which a compound is broken down and changed into other compounds by taking up the elements of water

enzyme
protein that acts as a biological catalyst

phospholipids
a molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail

cellular respiration
process that releases energy by breaking down glucose and other food molecules in the presence of oxygen

phosphorylation
the transfer of a phosphate group, usually from ATP, to a molecule. Nearly all cellular work depends on ATP energizing other molecules by phosphorylation

chemiosmosis
a process for synthesizing ATP using the energy of an electrochemical gradient and the ATP synthase enzyme.

fermentation
the process by which cells break down molecules to release energy without using oxygen

gametes
reproductive cells, have only half the number of chromosomes as body cells

meiosis
a process in cell division during which the number of chromosomes decreases to half the original number by two divisions of the nucleus, which results in the production of sex cells

somatic cell
cell that makes up all of the body tissues and organs, except gametes

crossing over
the interchange of sections between pairing homologous chromosomes during the prophase of meiosis

transcription
process in which part of the nucleotide sequence of DNA is copied into a complementary sequence in mRNA

codons
a three-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal; the basic unit of the genetic code.

RNA splicing
process by which the introns are removed from RNA transcripts and the remaining exons are joined together

mutations
random errors in gene replication that lead to a change in the sequence of nucleotides; the source of all genetic diversity

repetitive DNA
nucleotide sequences, usually noncoding, that are present in many copies in a eukaryotic genome.

transposons
small mobile DNA segments

homeobox
one of various similar homeotic genes that are involved in bodily segmentation during embryonic development

genome project
Research and technology development effort aimed at mapping and sequencing some or all of the genome of human beings and other organisms

adaptations
the behaviors and physical characteristics that allow organisms to live successfully in their environments

natural selection
process by which individuals that are better suited to their environment survive and reproduce most successfully

vestigial structures
remnant of a structure that may have had an important function in a species’ ancestors, but has no clear function in the modern species

convergent evolution
process by which unrelated organisms independently evolve similarities when adapting to similar environments

protists
single-celled or simple multicellular eukaryotic organisms that generally do not fit in any other kingdom

diatoms
unicellular algae that have a unique glass-like wall made of hydrated silica embedded in an organic matrix

ciliates
a group of protozoans that move by waving tiny, hair-like organelles called cilia

amoeba
A type of protist characterized by great flexibility and the presence of pseudopodia

gastrula
an embryonic stage in animal development encompassing the formation of three layers: ectoderm, mesoderm, and endoderm

cephalization
the concentration of nerve tissue and sensory organs at the anterior end of an organism

symmetry
the way an animal’s body parts match up around a point or central line

coelom
fluid-filled body cavity lined with mesoderm

sustainable agriculture
farming method that preserves long-term productivity of land and minimizes pollution

nitrogen fixation
process of converting nitrogen gas into nitrogen compounds that plants can absorb and use (ammonia)

crop rotation
the system of growing a different crop in a field each year to preserve the fertility of the land

epiphyte
plant that is not rooted in soil but instead grows directly on the body of another plant

physiology
processes and functions of an organism

epithelium
membranous tissue covering internal organs and other internal surfaces of the body

thermoregulation
the maintenance of body temperature within a range that enables cells to function efficiently

metabolic rate
the amount of energy an animal uses in a unit of time

acquired immunity
immunity that the body develops after it overcomes a disease, or through inoculation (such as vaccination)

macrophages
engulf bacteria and cellular debris by phagocytosis

inflammatory response
nonspecific defense against infection, characterized by redness, heat, swelling, and pain

antigen
substance that triggers an immune response

sexual reproduction
process in which genetic material from two parents combines and produces offspring that differ genetically from either parent

parthenogenesis
asexual reproduction in which females produce offspring from unfertilized eggs

gametogenesis
the development and maturation of sex cells through meiosis

endometrium
inner lining of the uterus

perception
the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events

sliding filament model
The theory explaining how muscle contracts, based on change within a sarcomere, the basic unit of muscle organization, stating that thin (actin) filaments slide across thick (myosin) filaments, shortening the sarcomere; the shortening of all sarcomeres in a myofibril shortens the entire myofibril

smooth muscle
a muscle that contracts without conscious control and found in walls of internal organs such as stomach and intestine and bladder and blood vessels (excluding the heart)

exoskeleton
the exterior protective or supporting structure or shell of many animals (especially invertebrates) including bony or horny parts such as nails or scales or hoofs

compound
a substance formed by chemical union of two or more elements or ingredients in definite proportion by weight

hydrogen bond
weak chemical bond formed by the attraction of positively charged hydrogen atoms to other negatively charged atoms

covalent bond
a chemical bond that involves sharing a pair of electrons between atoms in a molecule

ion
atom that has a positive or negative charge

eukaryotic cells
contain a nucleus and other organelles that are bound by membranes

ribosomes
non membrane bounded organelles responsible for protein synthesis

mitochondria
powerhouse of the cell, produces energy (ATP) from oxygen and sugar

prokaryotic
describes a cell that does not have a nucleus or anyother membrane-covered organelles; also called bacteria

thylakoids
A flattened membrane sac inside the chloroplast, used to convert light energy to chemical energy

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

autotrophs
organisms that make their own food

CAM plants
store the organic acids made at night in vacuoles and use them for photosynthesis during the day when stomata are closed

hybridization
the act of mixing different species or varieties of animals or plants and thus to produce hybrids

alleles
different forms of a gene

heterozygous
having two different alleles for a trait

pleiotrophy
the ability of a single gene to have multiple effects

operon
a group of genes that operate together

cell differentiation
the process of cell specialization

homeotic genes
any of the genes that control the overall body plan of animals and plants by controlling the developmental fate of groups of cells

oncogenes
cancer-causing genes

community
a group of interdependent organisms inhabiting the same region and interacting with each other

niche
the status of an organism within its environment and community (affecting its survival as a species)

mimicry
the resemblance of an animal species to another species or to natural objects

keystone species
a species that influences the survival of many other species in an ecosystem

geographic variation
differences in the genetic composition of separate populations

Hardy-Weinberg equilibrium
theory of a stable, nonevolving population in which frequency of alleles do not change; only occurs in large, isolated populations with random mating, and no natural selection or mutations

gene flow
movement of alleles into or out of a population due to the migration of individuals to or from the population

disruptive selection
form of natural selection in which a single curve splits into two; occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle

vascular tissue
tissue that conducts water and nutrients through the plant body in higher plants

bryophyte
nonvascular plant; examples are mosses and their relatives

seed
embryo of a living plant that is encased in a protective covering and surrounded by a food supply

roots
underground organs that absorb water and minerals

invertebrates
animals without a backbone

hermaphrodite
individual that has both male and female reproductive organs

complete metamorphosis
the transformation of a larva into an adult that looks very different, and often functions very differently in its environment, than the larva

echinoderms
invertebrates with an internal skeleton and a system of fluid-filled tubes called a water vascular system

complete flowers
a flower that has all four basic floral organs: sepals, petals, stamens, and carpals

pollen grain
male gametophyte in seed plants

dormancy
period of time during which a plant embryo is alive but not growing

fruit
a mature ovary of a flower that protects dormant seeds and aids in their dispersal

hemoglobin
iron-containing protein in red blood cells that transports oxygen from the lungs to the tissues of the body

sinoatrial node
the heart’s pacemaker, located in the wall of the right atrium

vasoconstriction
narrowing of blood vessels

platelets
tiny, disk-shaped bodies in the blood, important in blood clot formation

endocrine glands
glands of the endocrine system that release hormones into the bloodstream

pheromones
chemicals secreted by animal species that influence the behavior of other animals of the same species

insulin
protein hormone that helps to decrease blood sugar

hypothalamus
a neural structure lying below the thalamus; directs eating, drinking, body temperature; helps govern the endocrine system via the pituitary gland, and is linked to emotion

acrosomal reaction
the discharge of hydrolytic enzymes from the acrosome, when the sperm contacts an egg

cleavage
the process of cytokinesis in animal cells, characterized by pinching of the plasma membrane; specifically, the succession of rapid cell divisions without growth during early embryonic development that converts the zygote into a ball of cells

germ layer
any of the 3 layers of cells differentiated in embryos following gastrulation

amniotes
their embryos are protected by external membranes

demography
study of populations

survivorship curve
graph showing the number of survivors in different age groups for a particular species

emigration
movement of individuals out of an area

exponential growth
growth of a population that multiplies by a constant factor at constant time intervals

cohesion
attraction between molecules of the same substance

adhesion
an attraction between molecules of different substances

polar molecule
molecule with an unequal distribution of charge, resulting in the molecule having a positive end and a negative end

hydrophobic
avoids water molecules

peripheral proteins
protein appendages loosely bound to the surface of the membrane and not embedded in the lipid bilayer

osmosis
diffusion of water through a selectively permeable membrane

hypertonic
when comparing two solutions, the solution with the greater concentration of solutes

endocytosis
process by which a cell takes in a substance by surrounding it with the cell membrane

signal transduction pathway
a series of steps linking a mechanical or chemical stimulus to a specific cellular response

hormones
chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues

ligand
a molecule that binds specifically to a receptor site of another molecule

protein kinase
an enzyme that transfers phosphate groups from ATP to a protein

sex-linked gene
gene located on the X or Y chromosome

barr body
Inactivated X chromosome in females

nondisjunction
error in meiosis in which homologous chromosomes fail to separate

linkage map
a genetic map based on the frequencies of recombination between markers during crossing over of homologous chromosomes

caspid
protein covering that surrounds a virus

pandemic
disease that occurs over a wide geographic area and affects a very high proportion of the population

vaccine
a substance that stimulates the body to produce chemicals that destroy viruses or bacteria

prions
infectious protein particles that do not have a genome

kinesis
a change in activity or turning rate in response to a stimulus

migration
movement from one place to another

habituation
decreasing responsiveness with repeated stimulation

altruism
unselfish regard for the welfare of others

symbiosis
living together in mutually helpful association of two dissimilar organisms

endospore
type of spore formed when a bacterium produces a thick internal wall that encloses its DNA and a portion of its cytoplasm

conjugation
form of sexual reproduction in which paramecia and some prokaryotes exchange genetic information

pathogens
disease producing microorganisms

pollination
the transfer of pollen from male reproductive structures to female reproductive structures in plants

flower
the reproductive structure of an angiosperm

endosperm
the food supply for a plant embryo found inside a seed

angiosperm
a flowering plant, which forms seeds inside a protective chamber called an ovary

chordates
an animal phylum that has a notochord, a dorsal hollow nerve cord, and gill slits at some time in its life cycle

viviparous
producing living young (not eggs)

endothermic
dependent on or capable of the internal generation of heat

placentals
mammals who have offspring who develop inside placenta (humans)

phototropism
tendency of plants to grow toward a source of light

gibberellins
Plant hormones that promote stem and leaf elongation

apoptosis
a type of cell death in which the cell uses specialized cellular machinery to kill itself

circadian rhythms
the 24-hour biological cycles found in humans and many other species

excretion
the process by which wastes are removed from the body

nephron
any of the small tubules that are the excretory units of the vertebrate kidney

urea
the chief solid component of mammalian urine

antidiuretic hormone
hormone secreted by the posterior pituitary gland to prevent the kidneys from expelling too much water

reflexes
an automatic and often inborn response to a stimulus that involves a nerve impulse

cerebral cortex
the intricate fabric of interconnected neural cells that covers the cerebral hemispheres; the body’s ultimate control and information-processing center

short term memory
activated memory that holds a few items briefly, before information is stored or forgotten

amygdale
brain region that regulates emotions

phylogeny
the sequence of events involved in the evolutionary development of a species or taxonomic group of organisms

taxonomy
study of the general principles of scientific classification

cladistics
a system of phylogenetic analysis that uses shared and derived characters as the only criteria for grouping taxa

species
taxonomic group whose members can interbreed

producers
organisms that make their own food

ecology
the branch of biology concerned with the relations between organisms and their environment

biological magnification
increasing concentration of a harmful substance in organisms at higher trophic levels in a food chain or food web

greenhouse effect
process by which atmospheric gases trap heat close to Earth’s surface and prevent it from escaping into space

hydrocarbons
organic molecules that are composed of only carbon and hydrogen

isomers
compounds with the same formula but different structure

adenosine triphosphate
the molecule that stores energy that can be used by the cell

organic chemistry
the chemistry of compounds containing carbon (originally defined as the chemistry of substances produced by living organisms but now extended to substances synthesized artificially)

catabolic
A process in which large molecules are broken down

entropy
a thermodynamic quantity representing the unavailability of a system’s thermal energy for conversion into mechanical work, often interpreted as the degree of disorder or randomness in the system

endergonic reaction
a non-spontaneous chemical reaction in which free energy is absorbed from the surroundings

substrate
specific reactant acted on by an enzyme

chromatin
long strands of DNA found in the eukaryotic cell nucleus; condense to form chromosomes

cancer
a disease in which abnormal cells multiply out of control, spread into surrounding tissues and other body parts, and disrupt normal functioning of one or more organs

binary fission
type of asexual reproduction in which an organism replicates its DNA and divides in half, producing two identical daughter cells

mitosis
in eukaryotic cells, a process of cell division that forms two new nuclei, each of which has the same number of chromosomes

transformation
modification of a cell or bacterium by the uptake and incorporation of exogenous DNA

helicases
enzymes that untwist the double helix at the replication forks

okazaki fragments
short fragments of DNA that are a result of the synthesis of the lagging strand during DNA replication

telomerase
an enzyme that catalyzes the lengthening of telomeres; the enzyme includes a molecule of RNA that serves as a template for new telomere segments

recombinant DNA
DNA produced by combining DNA from different sources

plasmids
the small, circular segments of DNA that are found in bacteria and that stay sparate from the bacterial chromosomes; used in genetic engineering

polymerase chain reaction
technique that allows molecular biologists to make many copies of a particular gene

gel electrophoresis
the separation of nucleic acids or proteins, on the basis of their size and electrical charge, by measuring their rate of movement through an electrical field in a gel

microevolution
evolution resulting from small specific genetic changes that can lead to a new subspecies

pre-zygotic barriers
a reproductive barrier that impedes mating between species or hinders fertilization if interspecific mating is attempted

allopatric speciation
the formation of new species in populations that are geographically isolated from one another

polyploidy
the condition in which an organism has extra sets of chromosomes

protobionts
collections of abiotically produced molecules surrounded by a membrane-like structure

half-life
the period of time in which half of a radioactive substance decays

endosymbiosis
process through which early prokaryotic cells are thought to have engulfed other, smaller cells and eventually incorporated them as organelles; these cells evolved into modern-day eukaryotes

pangea
the name of the single landmass that broke apart 200 million years ago and gave rise to today’s continents

hyphae
the branching, threadlike tubes that make up the bodies of multicellular fungi

molds
a type of fungus that consists of chains of cells and appears as a fuzzy mass of thin filaments in culture

lichen
symbiotic association between a fungus and a photosynthetic organism

club fungi
a type of fungus that bears reproductive sperm externally, on club-shaped structures (basidia) at the tips of hyphae

tissue
a part of an organism consisting of an aggregate of cells having a similar structure and function

stem
supporting structure that connects roots and leaves and carries water and nutrients between them

apical meristems
embryonic plant tissue in the tips of roots and in the buds of shoots that supplies cells for the plant to grow in length

stomata
the small openings on the undersides of most leaves through which oxygen and carbon dioxide can move

carnivore
organism that obtains energy by eating animals

vitamins
compounds that help regulate many vital body processes, including the digestion, absorption, and metabolism of other nutrients

malnourishment
a nutritional imbalance caused by lack of specific dietary components or inability to absorb or utilize essential nutrients

peristalsis
the process of wave-like muscle contractions of the alimentary tract that moves food along

ganglia
groups of nerve cell bodies that coordinate incoming and outgoing nerve signals

neurotransmitters
chemical messengers that traverse the synaptic gaps between neurons

action potential
a neural impulse; a brief electrical charge that travels down an axon; the action potential is generated by the movement of positively charged atoms in and out of channels in the axon’s membrane

synaptic cleft
space between two connecting neurons where neurotransmitters are released

biotic factor
all the living things in an ecosystem

dispersal
the movement of organisms from one place to another

cline
a graded change in a trait along a geographic axis

biomes
a broad, regional type of ecosystem characterized by distinctive climate and soil conditions and a distinctive kind of biological community adapted to those conditions

turgid
swollen and distended or congested

plasmodesmata
channels through cell walls that connect the cytoplasms of adjacent cells

aquaporins
a transport protein in the plasma membrane of a plant or animal cell that specifically facilitates the diffusion of water across the membrane

transpiration
the emission of water vapor from the leaves of plants

conservation
the preservation and careful management of the environment and of natural resources

introduced species
nonnative species that are either intentionally or unintentionally transported to a new habitat

bioremediation
the use of living organisms to detoxify and restore polluted and degraded ecosystems

minimum viable population
the smallest population size at which a species is able to sustain its numbers and survive