Download AP Biology vocabulary- Know AND understand these!! R Group: a

AP Biology vocabulary- Know AND understand these!!
R Group: a group where different chains of atoms are substituted in to make 20 different kinds of
amino acids.
Non-polar covalent bonds: A bond between 2 nonmetal atoms that have the same electronegativity and therefore have equal sharing of the bonding electron pair.
Functional Group: A functional group is a portion of a molecule that is a recognizable/classified
group of atoms. They give the molecule its properties, regardless of what molecule contains it;
they are centers of chemical reactivity.
Density Dependent: Describes a factor that influences individuals in a population to a degree that
varies in response to how crowded the population is. (Food)
Density Independent: A factor that influences individuals in a population in a manner that does
not vary with the extent of crowding present in the population. (Weather)
Coenzymes: are organic molecules that are required by certain enzymes to carry out catalysis.
Cofactor: inorganic substances that are required for or increase the rate of catalysis.
pH: (Potential Hydrogen) is a measure of how acidic or basic a solution is.
Hardy Weinberg: (Genetic Equilibrium) when the allele frequencies in a population remain
constant from generation to generation. Factors that normally change gene frequencies don’t
occur. There must be no natural selection, no mutations, no gene flow, no genetic drift, and
mating must be random.
MHC Proteins: a family of genes that code for a huge variety of cell surface proteins. When
cells become infected they display them on their surface.
Platelet-derived growth factor- one of many proteins that regulate cellular growth and division.
Specifically blood vessel formation (angiogenesis). Five different isoforms.
Cyclin- Group of proteins that control the development of cells through the cell cycle by
activating cyclin-dependent kinase.
Cyclin-dependent kinases- Group of proteins that regulate the cell cycle. Involved in
transcription, mRNA processing, and the differentiation of the nerve cells.
Homologous chromosomes- are pairs of chromosomes of about the same length, centromere
position, staining patterns, and also have gene with the same characteristics at corresponding
loci.
Crossing over- exchange of genetic material between homologous chromosomes that result in
recombinant chromosomes. This occurs in Prophase 1 of meiosis during synapsis.
Law of independent assortment- Mendel’s law that states alleles of a gene will separate
independently from alleles of another gene.
Law of segregation- Mendel’s law that states that a pair of alleles separate from its
corresponding allele into each of the gametes randomly.
Sex-linked traits- Traits that are controlled by an allele on one of the sex chromosomes
Autosomal- Traits that are controlled by an allele on a non-sex chromosome (autosomes)
Somatic cells- any biological cell that is produced in a multi-cellular organism other than
gametes, gametocytes, germ cells, or undifferentiated stem cells.
Inducible operon- Is a section of DNA that’s transcription can be turned on or off. An example
is the lac Operon.
Repressible operon- A section of DNA that’s transcription can be turned off but is usually on.
An example would be the trp Operon.
HOX genes- group of related genes that determine the basic structure and orientation of an
organism.
Cytokines- are small cell-signaling protein molecules that are secreted by numerous cells and are
a category of signaling molecules used extensively in intercellular. Cytokines can be classified
as proteins, peptides, or glycoproteins; the term "cytokine" encompasses a large and diverse
family of regulators produced throughout the body by cells of diverse embryological origin.
Important in the immune system.
cAMP- (cyclic adenosine monophosphate) is a second messenger important in many biological
processes.
SRY gene- (Sex-determining Region Y) is a sex-determining gene on the Y chromosome.
Giberrilins- Are plant hormones that regulate growth and influence various developmental
processes, including stem elongation, germination, dormancy, flowering, sex expression, enzyme
induction, and leaf and fruit senescence.
P53- is a tumor suppressor protein that in humans is encoded by the TP53 gene.
Transposons- are segments of DNA that can move around to different positions in the genome of
a single cell. In the process, they may cause mutations or affect the amount of DNA in the
genome.
Retrovirus- is an RNA virus that is duplicated in a host cell using the reverse
transcriptase enzyme to produce DNA from its RNA genome.
Lytic cycle- is one of the two cycles of viral reproduction, the other being the lysogenic cycle.
The lytic cycle is typically considered the main method of viral replication, since it results in the
destruction of the infected cell
Lysogenic cycle- integration of the bacteriophage nucleic acid into the host bacterium's genome.
Glycogen- is a molecule that serves as the secondary long-term energy storage
in animal and fungal cells, with the primary energy stores being held in adipose tissue. Glycogen
is made primarily by the liver and the muscles, but can also be made by glycogenesis within
the brain and stomach.
Epinephrine- (adrenaline) is a hormone and a neurotransmitter. Epinephrine has many functions
in the body, regulating heart rate, blood vessel and air passage diameters, and metabolic shifts;
epinephrine release is a crucial component of the fight-or-flight response of the sympathetic
nervous system.
Killer T cells- (Cytotoxic T Cells) belongs to a sub-group of T lymphocytes (a type of white
blood cell) that are capable of inducing the death of infected somatic or tumor cells; they kill
cells that are infected with viruses (or other pathogens), or are otherwise damaged or
dysfunctional.
Helper T cells- are a sub-group of lymphocytes, a type of white blood cell, that play an important
role in the immune system, particularly in the adaptive immune system. These cells have
no cytotoxic or phagocytic activity; they cannot kill infected host cells or pathogens. Rather, they
help other immune cells; they activate and direct other immune cells.
Neurotransmitters- are endogenous chemicals that transmit signals from a neuron to a
target cell across a synapse. Neurotransmitters are packaged into synaptic vesicles clustered
beneath the membrane in the axon terminal, on the presynaptic side of a synapse. They are
released into and diffuse across the synaptic cleft, where they bind to specific receptors in the
membrane on the postsynaptic side of the synapse. Release of neurotransmitters usually follows
arrival of an action potential at the synapse, but may also follow graded electrical potentials.
Plasmodesmata- are microscopic channels which traverse the cell walls of plant cells and
some algal cells, enabling transport and communication between them.
Insulin- is a hormone, produced by the pancreas, which is central to
regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, muscle,
and fat tissue to take up glucose from the blood, storing it as glycogen inside these tissues.
Human growth hormone- is a peptide hormone that stimulates growth, cell reproduction and
regeneration in humans.
Testosterone- is a steroid hormone from the androgen group and is found in mammals,
reptiles, birds, and other vertebrates. In mammals, testosterone is primarily secreted in
the testicles of males and the ovaries of females, although small amounts are also secreted by
the adrenal glands. It is the principal male sex hormone and an anabolic steroid.
Estrogen- Estrogen is a hormone that comprises a group of compounds, including
estrone, estradiol and estriol. It is the main sex hormone in women and is essential to the
menstrual cycle. Although estrogen exists in men as well as women, it is found in higher
amounts in women, especially those capable of reproducing.
Thyroid hormone- hormones produced by the thyroid gland primarily responsible for regulation
of metabolism.
Ligand- Any substance (e.g. hormone, drug, functional group, etc.) that binds specifically and
reversibly to another chemical entity to form a larger complex.
Receptor tyrosine kinase- Are the high-affinity cell surface receptors for many
polypeptide growth factors, cytokines, and hormones.
G-receptor protein receptors- comprise a large protein family of trans membrane receptors that
sense molecules outside the cell and activate inside signal transduction pathways and, ultimately,
cellular responses. Only in Eukaryotic cells.
Second messengers- are molecules that relay signals from receptors on the cell surface to target
molecules inside the cell, in the cytoplasm or nucleus. They relay the signals of hormones like
epinephrine (adrenalin), growth factors, and others, and cause some kind of change in the
activity of the cell. They greatly amplify the strength of the signal.
Neuron- is an electrically excitable cell that processes and transmits information by electrical and
chemical signaling. Chemical signaling occurs via synapses, specialized connections with other
cells. Neurons connect to each other to form neural. Neurons are the core components of
the nervous system, which includes the brain, spinal cord, and peripheral ganglia.
Schwann cells- (neurolemmocytes) are the principal glia of the peripheral nervous system (PNS).
Glial cells function to support neurons and in the PNS, also include satellite cells, olfactory
unsheathing cells, enteric glia and glia that reside at sensory nerve endings, such as the Pacinian
corpuscle.
Action potential- is a short-lasting event in which the electrical membrane potential of
a cell rapidly rises and falls, following a consistent trajectory. Action potentials occur in several
types of animal cells, called excitable cells, which include neurons, muscle cells,
and endocrine cells, as well as in some plant cells. In neurons, they play a central role in cell-tocell communication. In other types of cells, their main function is to activate intracellular
processes. In muscle cells, for example, an action potential is the first step in the chain of events
leading to contraction. Action potentials in neurons are also known as "nerve impulses" or
"spikes".
Depolarize- is a change in a cell's membrane potential, making it more positive, or less negative.
In neurons and some other cells, a large enough depolarization may result in an action potential.
Membrane potential- is the difference in electrical potential between the interior and the exterior
of a biological cell. All animal cells are surrounded by a plasma membrane composed of a lipid
bilayer with a variety of types of proteins embedded in it. The membrane potential arises
primarily from the interaction between the membrane and the actions of two types of membrane
proteins embedded in the plasma membrane. The two main proteins are ion channels and
pumps.
Acetylcholine- is an organic, polyatomic ion that acts as a neurotransmitter in both the peripheral
nervous system (PNS) and central nervous system (CNS) in many organisms including humans.
Acetylcholine is one of many neurotransmitters in the autonomic nervous system (ANS) and the
only neurotransmitter used in the motor division of the somatic nervous system (sensory neurons
use glutamate and various peptides at their synapses).
Norepinephrine- is a catecholamine with multiple roles including as a hormone and
a neurotransmitter. Areas of the body that produce or are affected by norepinephrine are
described as noradrenergic.
Dopamine- a simple organic chemical in the catecholamine family, plays a number of important
physiological roles in the bodies of animals. In the brain, dopamine functions as
a neurotransmitter.
Serotonin- Approximately 90% of the human body's total serotonin is located in
the enterochromaffin cells in the gut, where it is used to regulate intestinal movements. The
remainder is synthesized in serotonergic neurons of the CNS, where it has various functions.
These include the regulation of mood, appetite, and sleep. Serotonin also has some cognitive
functions, including memory and learning.
GABAA - is an inotropic receptor and ligand-gated ion channel. Its endogenous ligand is γ-amino
butyric acid (GABA), a major neurotransmitter in the central nervous system. Although GABA
ends up producing an inhibitory effect on neurotransmitter release, GABA is not an inhibitory
neurotransmitter itself as it stimulates the GABA receptor; therefore, directly it is a stimulatory
neurotransmitter. Upon activation, the GABAA receptor selectively conducts Cl- through its pore,
resulting in hyperpolarization of the neuron.
Phylogenetic tree- is a branching diagram or showing the inferred evolutionary relationships
among various biological species or other entities based upon similarities and differences in their
physical and/or genetic characteristics
Protobionts- are systems that are considered to have possibly been the precursors to prokaryotic
cells
Prokaryotes- are a group of organisms that lack a cell nucleus or any other membrane-bound
organelles.
Eukaryote- is an organism whose cells contain complex structures enclosed within membranes.
Eukaryotes may more formally be referred to as the taxon Eukarya or Eukaryota
Fitness- the ability to both survive and reproduce, and is equal to the average contribution to the
gene pool of the next generation that is made by an average individual of the specified genotype
or phenotype.
Genotype- the genetic makeup of a cell, an organism, or an individual (i.e. the specific allele
makeup of the individual) usually with reference to a specific character under consideration
Phenotype- is the composite of an organism's observable characteristics or traits
Natural selection- the gradual, non-random, process by which biological traits become either
more or less common in a population as a function of differential reproduction of their bearers. It
is a key mechanism of evolution.
Adaptation- an alteration in the structure or function of an organism or any of its parts that
results from natural selection and by which the organism becomes better fitted to survive and
multiply in its environment.
Genetic drift- or allelic drift is the change in the frequency of a gene variant (allele) in a
population due to random sampling
Radioactive Isotope- An isotopic form of an element with an unstable nucleus that stabilizes
itself by emitting ionizing radiation.
Nuclear Decay- is the process by which an unstable atomic nucleus losses energy by emitting
ionizing particles or radiation.
Carbon Dating- a method of establishing the approximate age of carbonaceous materials, such as
fossil remains or archaeological specimens, by measuring the amount of radioactive carbon-14
remaining in them
Vestigial Structures- structures that are now useless to the organism, example would be ostrich
wings.
Chromosomes- Usually in the form of chromatin, Contains genetic information, Composed of
DNA, Thicken for cellular division, Set number per species (i.e. 23 pairs for human)
Nuclear membrane- Surrounds nucleus, Composed of two layers, Numerous openings for
nuclear traffic
Nucleolus- Spherical shape, Visible when cell is not dividing, Contains RNA for protein
manufacture
Centrioles- Paired cylindrical organelles near nucleus, Composed of nine tubes, each with three
tubules, Involved in cellular division, Lie at right angles to each other
Chloroplasts- A plastid usually found in plant cells, Contain green chlorophyll where
photosynthesis takes place
Cytoskeleton- Composed of microtubules, Supports cell and provides shape, Aids movement of
materials in and out of cells
Endoplasmic reticulum- Tubular network fused to nuclear membrane, Goes through cytoplasm
onto cell membrane, Stores, separates, and serves as cell's transport system, Smooth type: lacks
ribosomes, Rough type: ribosomes embedded in surface
Golgi apparatus- Protein 'packaging plant', A membrane structure found near nucleus, Composed
of numerous layers forming a sac
Lysosome- Digestive 'plant' for proteins, lipids, and carbohydrates, Transports undigested
material to cell membrane for removal, Vary in shape depending on process being carried out,
Cell breaks down if lysosome explodes
Mitochondria- Second largest organelle with unique genetic structure, Double-layered outer
membrane with inner folds called cristae, Energy-producing chemical reactions take place on
cristae, Controls level of water and other materials in cell, Recycles and decomposes proteins,
fats, and carbohydrates, and forms urea
Ribosomes- Each cell contains thousands, Miniature 'protein factories', Composes 25% of cell's
mass, Stationary type: embedded in rough endoplasmic reticulum, Mobile type: injects proteins
directly into cytoplasm
Vacuoles- Membrane-bound sacs for storage, digestion, and waste removal, Contains water
solution, Contractile vacuoles for water removal (in unicellular organisms)
Cell wall- Most commonly found in plant cells, Controls turgity, Extracellular structure
surrounding plasma membrane, Primary cell wall: extremely elastic, Secondary cell wall: forms
around primary cell wall after growth is complete
Plasma membrane- Outer membrane of cell that controls cellular traffic, Contains proteins (left,
gray) that span through the membrane and allow passage of materials, Proteins are surrounded
by a phospholipid bi-layer.
Endomembrane system- In eukaryotes, the functional continuum of membranous cell
components consisting of the nuclear envelope, endoplasmic reticulum, and Golgi apparatus as
well as vesicles and other structures derived from these major components.
Speciation- The process in which new genetically distinct species evolve usually as a result of
genetic isolation from the main population.
Adaptive radiation- evolution of a number of divergent species from a common ancestor, each
species becoming adapted to occupy a different environment
Viable- capable of living.
Pre-zygotic reproductive isolation- factors causing two species not to make before reproduction
is attempted
Post- zygotic reproductive isolation- factors either causing to the zygote to die or to not be able
to reproduce
Stanley Miller- he did an experiment that simulated hypothetical conditions thought at the time
to be present on the early Earth, and tested for the occurrence of chemical origins of life.
Photosynthesis- the complex process by which carbon dioxide, water, and certain inorganic salts
are converted into carbohydrates by green plants, algae, and certain bacteria, using energy from
the sun and chlorophyll
Light reactions in photosynthesis- The light-independent reactions of photosynthesis are
chemical reactions that convert carbon dioxide and other compounds intoglucose. These
reactions occur in the stroma, the fluid-filled area of a chloroplast outside of the thylakoid
membranes. These reactions take the light-dependent reactions and perform further chemical
processes on them. There are three phases to the light-independent reactions, collectively called
the Calvin cycle: carbon fixation, reduction reactions, and ribulose 1,5-bisphosphate (RuBP)
regeneration.
Ectothermy- the ability of an organism maintain their body temperature by absorbing heat from
their environment.
Hydrolysis- The chemical breakdown of a compound due to reaction with water.
NADPH- Nicotinamide adenine dinucleotide phosphate
chlorophyll- A green pigment, present in all green plants and in cyanobacteria, responsible for
the absorption of light to provide energy for photosynthesis. Its molecule contains a magnesium
atom held in a porphyrin ring
Photosystem I- One of two reaction sequences of the light phase of photosynthesis in green
plants that involves a pigment system which is excited by wavelengths shorter than 700
nanometers and which transfers this energy to energy carriers such as NADPH that are
subsequently utilized in carbon dioxide fixation.
Photosystem II- is the first protein complex in the Light-dependent reactions. It is located in the
thylakoid membrane of plants, algae, and cyanobacteria. The enzyme uses photons of light to
energize electrons that are then transferred through a variety of coenzymes and cofactors to
reduce plastoquinone to plastoquinol. The energized electrons are replaced by oxidizing water to
form hydrogen ions and molecular oxygen
Electrochemical gradient- is a gradient of electrochemical potential, usually for an ion that can
move across membrane. The gradient consist of two parts, the electrical potential and a
difference in the chemical concentration across a membrane.
ATP synthase- is an important enzyme that provides energy for the cell to use through the
synthesis of adenosine triphosphate (ATP).
Enzyme- A substance produced by a living organism that acts as a catalyst to bring about a
specific biochemical reaction
Pyruvate- (CH3COCOOH) is an organic acid, a ketone, as well as the simplest of the alpha-keto
acids. The carboxylate (COO−) anion of pyruvic acid, its Brønsted–Lowry conjugate base,
CH3COCOO−, is known as pyruvate, and is a key intersection in several metabolic pathways.
Pyruvate can be made from glucose through glycolysis, converted back to carbohydrates (such as
glucose) via gluconeogenesis, or to fatty acids through acetyl-CoA. It can also be used to
construct the amino acid alanine and be converted into ethanol
Oxidation reactions- reaction where a substance loses electrons
Reduction reactions- reaction where a substance gains electrons
FADH2- is to carry high-energy electrons used for oxidative phosphorylation.
Proton gradient- The product of the electron transport chain. A higher concentration of protons
outside the inner membrane of the mitochondria than inside the membrane is the driving force
behind ATP synthesis.
Oxidative phosphorylation- an enzymatic process in cell metabolism that synthesizes ATP from
ADP.
Substrate level phosphorylation- Synthesis of high-energy phosphate bonds through reaction of
inorganic phosphate with an activated (usually) organic substrate
Photophosphorylation- The production of ATP using the energy of sunlight
Properties of water- adhesive, cohesive, high specific heat, universal solvent, ice floats
Fluid mosaic model- biological membrane separating the interior of a cell from the outside
environment.
Passive transport- moving biochemicals and atomic or molecular substances across the cell
membrane
Osmosis- A process by which molecules of a solvent tend to pass through a semipermeable
membrane from a less concentrated solution into a more concentrated one, thus equalizing the
concentrations on each side of the membrane
Facilitated diffusion- is a process of passive transport, aided by integral membrane proteins.
Active transport- The movement of ions or molecules across a cell membrane into a region of
higher concentration, assisted by enzymes and requiring energy.
Diffusion- the act of a substance going from high concentration to an area of lower
concentration.
Conserved processes- processes that are continues in the environment, such as DNA replication
in animals.
Concentration Gradient – A region along which the density of a chemical substance increases or
decreases.
Sodium/Potassium Pump (PumpKin) – A transport protein in the plasma membrane of animal
cells that actively transports sodium out of the cell and potassium into the cell.
Endocytosis – the capture of a substance outside the cell when the plasma membrane merges to
engulf it, it enters the cell in this new vesicle. (3 types: Phagocytosis, Pinocytosis, receptormediated).
Exocytosis – the process of vesicles fusing with the plasma membrane and releasing their
contents to the outside of the cells.
Glycoprotein – A protein with one or more carbohydrates covalently attached to it.
Glycolipid – A lipid with covalently attached carbohydrate(s).
Phospholipid – A lipid made up of glycerol joined to two fatty acids and a phosphate group. The
hydrocarbon chains of the fatty acids act as nonpolar, hydrophobic tails while the rest of the
molecules acts as a polar, hydrophilic head. Phospholipids form bilayers that function as
biological membranes.
Polar molecules – A molecule with opposite charges on different ends of the molecule. Ex: water
Nonpolar molecules – Molecule where atoms share electrons equally so that no end is polar.
Cellulose – A structural polysaccharide of plant cell walls, consisting of glucose monomers
joined by B glycosidiclinkages.
Hypotonic – A solution that, when surrounding a cell, will cause the cell to take up water.
Hypertonic – A solution that, when surrounding a cell, will cause the cell to lose water.
Isotonic – A solution that, when surrounding a cell, has no effect on the passage of water into or
out of the cell.
Photoperiodism - A physiological response to photoperiod, the relative lengths of night and day.
Diabetes mellitus – An endocrine disorder marked by inability to maintain glucose homeostasis.
The type 1 form results from autoimmune destruction of insulin-secreting cells; treatment usually
requires daily insulin injections. The type 2 form most commonly results from reduced
responsiveness of target cells to insulin; obesity and lack of exercise are risk factors.
ADH (Antidiuretic hormone) – Increases the reabsorption of water by the body and increases the
concentrations of salts in the urine by increasing the permeability of the collecting duct to water
Produced by the hypothalamus and released from the posterior pituitary.
Graves Disease – Autoimmune disorder where the immune system produces antibodies that bind
to the receptor for TSH and activate sustained thyroid hormone production. The most common
hyperthyroidism.
Operon – A unit of genetic function found in bacteria and phages, consisting of a promoter, an
operator, and a coordinately regulated cluster of genes whose products function in a common
pathway.
-Lac – Operon that produces Inducable Enzymes (lactase) that breakdown lactose.
-Trp – Operon that produces repressible enzymes (tryptophan) when around the cell,
tryptophan serves as a corepressor to stop the production of tryptophan by the E. coli.
Phototropism – growth of a plant shoot toward or away from light.
Taxis – an oriented movement toward or away from a stimulus.
Kinesis – A change in activity or turning rate in response to a stimulus.
Osmoregulation – Regulation of solute concentrations and water balance by a cell or organism.
Monosaccharides- A simple sugar (ex. Fructose, Glucose and Ribose.).
Biotechnology- The exploitation of biological processes for industrial and other purposes
Cytokinesis- the division of a cell’s cytoplasm at the end of mitosis or meiosis. It brings about
the separation into 2 daughter cells
Mitosis- a type of cell division that results in 2 daughter cells that are identical to the parent cell
(nucleus)
Interphase- the period of the cell cycle during which the nucleus is not undergoing division.
Typically occurring between mitotic or meiotic divisions. Contains G1 phase, G2 phase, and S
phase.
Daughter cell- A cell formed by the division of another cell. Can be haploid or diploid,
depending on the type of division: Mitosis/meiosis
Progeny- a descendant(s) of a person, animal, or plant. AKA offspring
Asexual reproduction- reproduction without the fusion of gametes
Sexual reproduction- the production of new living organisms by combining genetic information
from 2 individual of different sexes.
Gregor Mendel- A 19th century monk/Botanist whose experiments in breeding peas led to his
eventual recognition of genetics
Gene expression- a conversion of the information encoded in a gene first into messenger RNA
and then to a protein.
Zygotes- a diploid cell resulting from the fusion of 2 haploid gametes; a fertilized ovum.
Spores- a reproductive unit capable of giving rise to a new individual without sexual fusion. A
haploid sex cell that gives rise to a gametophyte (in a plant exhibiting alternation of generations)
Signal transduction pathway- a mechanism that converts a mechanical/chemical stimulus to a
cell into a specific cellular response.
Gametes-A mature haploid male or female germ cell that is able to unite with another of the
opposite sex in sexual reproduction to form a zygote.
Circular chromosomes- usually found in prokaryotes, containing DNA
Watson- along with Crick, proposed a model for the structure of a DNA in the form of a double
helix.
Crick- along with Watson, he proposed a model for the structure of a DNA molecule. Their
model is still accepted today.
Franklin- the true founder of Watson and Crick’s DNA molecule model… they stole it from her.
Avery- MacLeod-McCarthy experiment –first proved that DNA contains hereditary information
Hershey-Chase experiment- confirmed that DNA was genetic material. Conducted in 1952
DNA replication- The use of existing DNA as a template for the synthesis of new DNA strands.
In humans and other eukaryotes, replication occurs in the cell nucleus.
Transcription- the process of creating an equivalent RNA copy of a DNA sequence.
Translation-Translation is the process in which the genetic information on an mRNA molecule is
used to make proteins.
DNA polymerase- the enzyme responsible for DNA Replication
Ligase- An enzyme which is capable of binding two smaller components into one single
structure.
RNA polymerase- the enzyme responsible for RNA replication
Helicase- the enzyme responsible for “unzipping” the DNA molecule in preparation for
replication.
Topisomerase- zips the DNA back up
3’ end of DNA- the end of a DNA strand. Contains several A’s in a row (5-250) that signal the
end for RNA to copy.
5’ end of DNA- the beginning of a DNA strand
Purines- A double-ringed, crystalline organic base, C5 H4 N 4 , not known to occur naturally,
from which is derived the nitrogen bases adenine and guanine
Pyrimidines-A single-ringed, crystalline organic base, C4H4N2, that forms uracil, cytosine, or
thymine.
mRNA- RNA, synthesized from a DNA template during transcription, that mediates the transfer
of genetic information from the cell nucleus to ribosomes in the cytoplasm, where it serves as a
template for protein synthesis. Also called messenger RNA
tRNA- One of a class of RNA molecules that transports amino acids to ribosomes for
incorporation into a polypeptide undergoing synthesis. Also called transfer RNA
rRNA-any of a class of single-stranded molecules transcribed from DNA in the cell nucleus or in
the mitochondrion or chloroplast, containing along the strand a linear sequence of nucleotide
bases that is complementary to the DNA strand from which it is transcribed: the composition of
the RNA molecule is identical with that of DNA except for the substitution of the sugar ribose
for deoxyribose and the substitution of the nucleotide base uracil for thymine.
cAMP-A cyclic form of adenosine monophosphate (adenylic acid) that helps control many
enzyme-catalyzed processes in living cells
RNA processing- the splicing, 5-capping, and 3-polyadenylation by which eukaryotic pre-mRNA
is converted into mature mRNA
Intron- A segment of a DNA or RNA molecule that does not code for proteins and interrupts the
sequence of genes.
Exon- A segment of a DNA or RNA molecule containing information coding for a protein or
peptide sequence.
Codon-A sequence of three nucleotides which together form a unit of genetic code in a DNA or
RNA molecule.
Anticodon- a sequence of the complements of the 3 nucleotides that make up the codon, found
on the ribosome.
Gel electrophoresis-Gel electrophoresis is a technique used for the separation of
deoxyribonucleic acid (DNA), ribonucleic acid (RNA by using restriction enzymes to cut the
DNA, in which the smaller DNA fragments move to the farthest end of the gel.
Plasmid-based transformation- introducing bacteria to a plasmid which alters their DNA. Giving
the specimen the genetic quality found in the plasmid.
Restriction enzyme- enzymes that are specifically designed to cut DNA after certain sequences
Polymerase chain reaction- heating and cooling DNA to amplify the DNA strand’s qualities.
Checkpoints of the cell cycle- are control mechanisms that ensure the fidelity of cell division in
eukaryotic cells.
Mitosis-promoting factor- factors that initiate mitosis, ex: nuclear envelope breakdown.
Organic- Of, relating to, or derived from living organisms. An organic compound; or any
substance containing carbon-based compounds, especially produced by or derived from living
organisms.
Inorganic- Of or pertaining to substances that are not of organic origin. Relating to a substance
that does not contain carbon.
Free energy- the energy in a physical system that can be converted to do work
Monomers- is a molecule that may bind chemically to other molecules to form a polymer [
polymers- A polymer is a large molecule (macromolecule) composed of repeating structural
units(monomers).
Amino acids- contain an amine group, a carboxylic acid group, and a side-chain that is specific
to each amino acid. The key elements of an amino acid are carbon, hydrogen, oxygen, and
nitrogen.
Nucleotides- An organic molecule consisting of joined phosphate, five-carbon sugar
(deoxyribose or ribose), and a purine or a pyrimidine (adenine, guanine, uracil, thymine, or
cytosine)
Monosaccharide- A simple sugar; a five- or six- carbon sugar(e.g., ribose or glucose)
Lipids- Fat or oil (e.g., Fatty acids, Glycerolipids, Glycerophospholipids, etc)
Carbohydrate- An organic compound to which hydrogen and oxygen are attached; the hydrogen
and oxygen are in a 2:1 ratio; examples include sugars, staches, and cellulose.
Protein (polypeptide)- One of class of organic compounds that is composed of many amino
acids; contains C, H, O, and N.
DNA- Deoxyribonucleic acid; found in the cell nucleus, its basic unit is the nucletide; contains
coded genetic information can replicate on the basis of heredity.
RNA- Ribonucleic acid, a nucleic acid in which the sugar is ribose; a product of DNA
transcription that serves to control certain cell activities; acts as a template for protein translation;
types include mRNA (messenger), tRNA (transfer), and rRNA(ribosomal)
Gene pool- is the complete set of unique alleles in a species or population.
Recombination- breaking and rejoining of DNA strands to form new molecules of DNA
encoding a novel set of genetic information. Recombination can occur between similar
molecules of DNA, as in the homologous recombination of chromosomal crossover, or dissimilar
molecules, as in non-homologous end joining.
Meiosis- special type of cell division necessary for sexual reproduction in eukaryotes. The cells
produced by meiosis are gametes or spores. In many organisms, including all animals and land
plants (but not some other groups such as fungi), gametes are called sperm and egg cells.
Diploid- describes cells that have a double set of chromosomes in homologous pairs(2n)
Haploid- Describe cells(gametes) that have half the chromosome number typical of the species(n
chromosome number)
Triploid- rare lethal chromosome abnormality caused by the presence of an entire extra set of
chromosomes.
Polyploidy- A condition in which an organism may have a multiple of the normal number of
chromosomes (4n, 6n, etc.).
Mitosis- A type of nuclear division that is characterized by complex chromosomal movement
and the exact duplication of chromosomes; occurs in somatic cells.
Metabolic (metabolism) - A group of life-maintaining processes that includes nutrition,
respiration (the production of usable energy), and the synthesis and degradation of biochemical
substances.
Calvin cycle- Cycle in photosynthesis that reduces fixed carbon to carbohydrates through the
addition of electrons (also known as the “dark cycle”)
Chemosynthesis- biological conversion of one or more carbon molecules (usually carbon dioxide
or methane) and nutrients into organic matter using the oxidation of inorganic molecules(e.g.
hydrogen gas, hydrogen sulfide) or methane as a source of energy, rather than sunlight, as in
photosynthesis.
Cellular respiration- the set of the metabolic reactions and processes that take place in the cells of
organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and
then release waste products.
Glycolysis- The anaerobic respiration of carbohydrates
Kreb’s cycle- Process of aerobic respiration that fully harvests the energy of glucose; also known
as the citric acid cycle.
Electron transport chain- A complex carrier mechanism located on the inside of the inner
mitochondrial membrane of the cell; releases energy, and is used to form ATP
Chemiosmosis- The coupling of enzyme catalyzed reactions.
Fermentation- metabolic process whereby electrons released from nutrients are ultimately
transferred to molecules obtained from the breakdown of those same nutrients
ATP- Adenosine-5'-triphosphate (ATP) is a multifunctional nucleoside triphosphate used in cells
as a coenzyme.
ADP- Energy-storage molecules
Surface-to-volume ratio- amount of surface area per unit volume of an object or collection of
objects. The surface-area-to-volume ratio is measured in units of inverse distance.
Apoptosis- process of programmed cell death (PCD) that may occur in multicellular organisms.
Biochemical events lead to characteristic cell changes (morphology) and death.
Differentiation- A progressive change from which a permanently more mature or advanced state
results; for example, a relatively unspecialized cell’s development into a more specialized one.
Morphogenesis- Biological process that causes an organism to develop its shape. It is one of
three fundamental aspects of developmental biology along with the control of cell growth and
cellular differentiation.
Negative feedback- serves to stabilize a system, e.g., maintain temperature, concentration,
direction, etc.
Positive feedback- Process in which the effects of a small disturbance on a system include an
increase in the magnitude of the perturbation.
1st law of thermodynamics- Heat and work are forms of energy transfer.
2nd law of thermodynamics- The entropy of any isolated system not in thermal equilibrium
almost always increases.
Entropy- thermodynamic property that can be used to determine the energy not available for
work in a thermodynamic process, such as in energy conversion devices, engines, or machines.
Endothermy- Pertaining to organisms which are capable of maintaining their bodily temperature
above the temperature of the external environment
Ground tissues of plants include the following three types of cells:
-parenchyma cell- the most common component of ground tissue, have thin walls and
serve various functions including storage, photosynthesis and secretion
-collenchyma cell-thick but flexible cell walls, serve as mechanical support functions
-sclerenchyma cell-thickest cell wall, serve as mechanical support
Dermal tissues of plants- consists of epidermis cells that cover the outside of plant parts, guard
cells that surround stomata, and various specialized surface cells such as hair cells, stinging cells,
and glandular cells- these cells secrete cuticle.
Vascular tissues of plants (usually occur together to form vascular bundles):
- Xylem- functions in the conduction of water and minerals and also mechanical supporttwo cell walls, primary and secondary-dead at maturity (completely lacking cellular
components)
o Two types: tracheids (long and tapered) and vessel elements (shorter and thicker)-
- Pits- places in xylem where secondary wall is absent
- Phloem-functions in the conduction of sugar
o sieve-tube members- form fluid conducting tubes called sieve tubes- no nuclei or
ribosomes- pores form sieve plates
o Companion cells- associated with sieve tubes- connected by plasmodesmata to
help the sieve tubes that lack nuclei
-apical meristem- contains actively dividing cells that increase length
-primary structure of roots: Epidermis of roots (lines the outside surface of the root), root hairs
(produced by epidermal cells), cortex (makes up bulk of roots), endodermis (ring of tightly
packed cells at the innermost portion of the cortex), Casparian strip (creates a water-impenetrable
barrier between the cells), vascular cylinder/stele (tissues inside endodermis), pericycle (lateral
roots arise)
-primary structure of stems: Epidermis of stems (cells contain cutin, which forms cuticle), cortex
(consists of ground tissue types that lie between the epidermis and the vascular cylinder),
vascular cylinder (contains various arrangements of xylem, phloem, pith)
-lateral meristem- contains actively dividing cells that increase girth
-Cork cambium (produces new cells on its outside and sometimes on its inside)
-palisade mesophyll- consists of parenchyma cells equipped with numerous chloroplasts and
large surface areas, specializations for photosynthesis
-spongy mesophyll-consists of parenchyma cells loosely arranged below the palisade mesophyllnumerous spaces provide air chambers that provide carbon dioxide to photosynthesizing cells
-guard cells- specialized epidermal cells that control opening and closing of stomata-put pic on
card with definition
-mechanisms that control opening and closing stomata: high temperatures close them,
low CO2 open them
-stomatal opening is accompanied by diffusion of potassium ions into the guard cells
which is followed by water, which causes guard cell expansion
-osmosis- water enters roots through this process
-two pathways the water move towards center of root
-apoplast- water moves through cell walls
-symplast-water moves through cells
- root pressure- an osmotic force that can be seen as guttation (formation of small droplets
-
of sap [water and minerals]- occurs because of the continuous movement of water out of
the root by xylem and by the higher mineral concentration inside the stele maintaining by
the selective passage of ions throughout the endodermis
capillary action- rise of liquids in narrow tubes because of adhesion and cohesion
cohesion-tension theory-transpiration (evaporation of water from plants, removes water
from leaves, causing a negative pressure), cohesion (produces a single, polymerlike
column of water from roots to leaves), bulk flow (water through xylem cells occurs as
water molecules evaporate from the leaf surface), sun- the driving force for the ascent of
sap through plants- use pic as reference
-translocation- movement of carbohydrates through phloem from a source (leaves) to a sink (site
of carb utilization)- described by the pressure-flow hypothesis
-pressure-flow hypothesis- sugar enters sieve tube members by active transport, which develops
a concentration gradient of solutes in source versus sink, then water enter sieve tube members
(water potential) moving down water concentration gradient, pressure builds up and water and
sugars move by bulk flow through sieve tubes, pressure is reduced in sieve-tube members at the
sink as sugars are
Hypocotyl-below the epicotyl and attached to the cotyledons- becomes the young shoot
Radicle-below the hypocotyl and develops into the root
Epicotyl-top portion of the embryo and it becomes the shoot tip
Plumule-attached to the epicotyl-these are the young leaves
Coleoptile- a sheath that surrounds and protects the epicotyl- these emerge first and appears as
leaves, but the first true leaves emerge from the plumule within the coleoptile
seed- consists of an embryo and a seed coast and storage material
endosperm-storage material-formed in double fertilization
cotyledons- formed by using the storage material in the endosperm
Flower- reproductive shoot; bears structures that function in sexual reproduction
Sepal-modified leaf that helps enclose and protect a flower bud before it opens
Petal-attract pollinators
Stamen-male reproductive structure that consists of a pollen-bearing anther and its filament
(stalk)
Pistil- female reproductive structure and consists of three parts: an egg-bearing ovary, a style and
a stigma
fruit-fosters dispersal of seeds-developed from the ovary
pollen grains-matured from microspores- male gametophyte in conifers
embryo sac-the plasma membrane that forms from six nuclei undergoing cytokinesis
double fertilization-the fertilization of the egg and the polar nuclei each by a separate sperm
nucleus
Auxin-plant hormone that promotes plant growth by facilitating the elongation of developing
cells- produced at tips of roots and shoots, where, in concert with other hormones it influences
plant responses to light (phototropism) and gravity (geotropism/ gravitropism)
Cytokinins- plant hormones that stimulat cytokinesis- produced in roots and transported to other
parts of the plant-variety of effects depending on the target- could weaken apical dominance (the
dominant growth of the apical meristem) and delay senescence (aging) of leaves
Gibberellins- plant hormones promote cell growth- made in young leaves, roots and seeds then
transported to other parts-promote fruit development, inhibits aging, and can cause bolting (rapid
elongation of stem)
abscisic acid ( ABA) plant hormone-growth inhibitor-maintains dormancy in seeds
ethylene plant hormone-gaseous hormone that promotes the ripening of fruit
tropism- growth pattern in response to an environmental stimulus
-phototropism- response to light is achieved by the action of the hormone auxin- auxin is
produced in the apical meristem, moves downward by active transport into the zone of
elongation and generates growth by stimulating elongation- concentrates on shady side
-gravitropism (geotropism)-the response to gravity by stems and roots- auxin and
gibberllins are involve, but their action depends on concentration and the target (i.e. root/stem)
statoliths-specialized starch-storing plastids that settle at the lower ends of cells, somehow
influence the direction of auxin movement
circadian rhythm-a clock that measures the length of daylight and night in plants
photoperiodism- response of plants to changes in the photoperiod (relative length of daylight and
night)
mechanism for maintaining circadian rhythmn:
- Phytochrome ( a protein modified with a light-absorbing chromophore) is involved- there
-
are two forms: Pfr (far red light- P730) and Pr (red light- P600)- the two forms are
photoreversible (when Pr is exposed to red light it is converted to Pfr- and visa versa)Label picture below
Pfr resets the circadian rhythmn clock
Pr is made naturally in the plants leaves
During the daylight both forms are in equilibrium because Pr is made naturally than
converted by sunlight to Pfr then Pfr is converted by to Pr because the sun also has far red
light
At night Pr accumulates because there is no sunlight to convert it to Pfr
Night length is responsible for resetting the circadian-rhythm clock
short-day plant-these flower when daylight length is shortened
long-day plant-these flower in the spring when the daylight length is increasing
day-neutral plant-do not flower in response to daylight length- other stimuli cause them to bloom
Florigen-a flowering hormone that is produced in the leaves and travels to shoot tips
Taproot- a large single root
fibrous root (adventitious)- a cluster of many fine roots
annuals, mineral nutrients, essential nutrient, macronutrients, micronutrients, nitrogen-fixing
bacteria, nitrogen fixation
energy transfer-the transfer of energy from one material to another
abiotic - non-living components of an ecosystem ex. Wind, rain, sun, rocks
biotic- living components of an ecosystem ex. Plants and animals
habitat-The area or environment where an organism or ecological community normally lives or
occurs
population- a group of individuals of the same species that can interbreed
community- a group of populations that live close enough for interaction
biogeography- study of past and present distribution of species
biome- terrestrial or aquatic life zones characterized by vegetation type in terrestrial biomes or
physical environment in aquatic biomes
Ex. Lakes (freshwater biome- may have seasonal thermocline), Wetlands (a habitat that is
inundated by water at least some of the time and that supports plants adapted to water-saturated
soil), Streams and Rivers (fresh water biome with current), Estuaries (transition area between
river and sea ex. Sounds, bays, inlets), Intertidal zone (periodically submerged and exposed by
the tides), Oceanic Pelagic zone (open ocean), Coral reef (formed largely from the calcium
carbonate skeletons of corals), Marine benthic zone [neritic] (seafloor- generally does not receive
light), tropical rain forest (high temperature and heavy rain- epiphytes and vines are commonusually nothing grows on floor), desert (hot and dry), savanna (grasslands with scattered treesthey are tropical with high temperatures, but little rainfall), Chaparral (midlatitude regions of
continents- rainfall is seasonal with moderate temperature- far-flung distribution), temperate
grassland (less water and subject to lower temperatures than savannas- ex American prairie),
northern coniferous forest [taiga] (winters are cold and precipitation is in the form of snow- ex.
pine forests), temperature broadleaf/deciduous forest (occupy regions that have warm summers,
cold winters and moderate precipitation- trees that shed their leaves during the winter ), tundra
(temperatures during winter are so cold that ground freezes (permafrost)- during summer melted
topsoil supports a grassland type of community)
Zonation in aquatic environments: Draw and label -photic zone, aphotic zone, benthic zone,
littoral zone, limnetic zone, profundal zone
oligotrophic- type of lake that is usually nutrient poor and oxygen rich.
Eutrophic- type of lake that is usually nutrient rich and oxygen poor.
Canopy-the uppermost layer of vegetation in a terrestrial biome
Permafrost- a permanently frozen soil layer
Regulator- an animal for which mechanisms of homeostasis moderate internal changes in the
face of external fluctuations
Conformer- an animal for which an internal condition conforms with a change in an
environmental variable
Size of a population (N)- the number of individuals living within specific boundaries
Density- number of individuals per unit area (or volume) Ex. The number of oak tress per square
kilometer in the Minnesota Co.
Dispersion- pattern of spacing among individuals within the boundaries of the population
Examples: Uniform, Clumped, Random
age structure- relative number of individuals of each age in the population Ex. Human growth
fecundity- The power of reproducing abundantly; fruitfulness or fertility
life table- used to estimate how long individuals (on average) can be expected to live; agespecific summaries of the survival pattern of a population
survivorship curves- a graphic method of representing the data in a life table; a plot of
proportions in a cohort still alive at each age; 3 types- I, II, III
zero population growth (ZPG)- death rate and birth rate are equal Ex. Two mice reproduce, but
usually only two of their offspring survive to reproductive age
reproductive rate- r= (births-deaths)/N [N- population size at beginning of interval]
Biotic potential (intrinsic rate of growth)- when reproductive rate is at maximum
exponential (geometric) population growth- assumes resources are unlimited, size of a
population grows exponentially (growth rate is at max); J-shaped curve Example African
elephants
carrying capacity (K)- maximum population size that a particular environment can sustain
logistic population growth- growth rate nears zero as the carrying capacity is reached; S-shaped
curve Example Paramecium and Daphnia
K-selected populations- a.k.a density dependent selection- type of selection that operates in
populations that are living near the limit imposed by resources (its carrying capacity);
competition for resources is strong Example- mature trees growing in a old-growth forest
r-selected populations- a.k.a density independent selection- maximizes growth rate and occurs in
environments in which population densities are well below carrying capacity; characterized by
opportunistic species (grasses, insects) that quickly invade a habitat, quickly reproduce and then
die
intraspecific competition- competition for resources between individuals of the same specie
interspecific competition- competition for resources between different species
limiting factor- elements that prevent a population from attaining its biotic potential Ex. densitydependent factor (agents wholse limiting effect becomes more intense as the population density
increases- ex disease and competition), density-independent factor (occur independently of the
density of the population- ex natural disasters)
species diversity- the variety of different kinds of organisms that make up the community Ex.
species richness ( number of different species), relative abundance (the proportion each species
represents of all individuals)
predation- +/- interaction between species in which one kills and eats the other
defensive adaptations of prey- cryptic coloration (camouflage), aposematic coloration (warning
coloration), Batesian mimicry (harmless/unpalatable mimics harmful/palatable), Mullerian
mimicry (two or more unpalatable/harmless species resemble each other- if there are more
predator will adapt and avoid those characteristics)
Ecological succession- the process of a disturbed area possibly being colonized by a variety of
species, which are gradually replaced by other species, which are in turn replaced by still other
species Examples- primary succession (begins on a virtually lifeless area, such as a new volcanic
island), secondary succession (occurs when an existing community has been cleared by a
disturbance that leaves the soil intact, such as the 1988 fire in Yellowstone)
Coevolution (predator/prey evolution)- the evolution of one species in response to new
adaptations that appear in another species
Symbiosis- when two or more species live in direct and intimate contact with each other
(sometimes synonymous with mutualism)
Commensalism- +/0 relationship; Ex barnacles attached to whales
Mutualism- +/+ relationship; Ex. Nitrogen fixing bacteria on root nodules of legumes
Parasitism- +/- relationship; Ex. Ectoparasite= ticks; endoparasite= tapeworm
Parasitoid- a parasite that kills
Competitive exclusion principle (Gause’s)- no two species can sustain coexistence if they occupy
the same niche; when two species compete for the same resource only one will be successful ex.
Paramecium
ecological niche- describes all the biotic and abiotic resources in the environment used by an
organism Ex. fundamental niche (the niche that an organism occupies in the absence of
competing species), Realized niche (when predators are present both by be able to survive by
occupying their realized niche that part of their existence where niche overlap is absent)
character displacement (niche shift)- result of resource portioning, certain characteristics may
enable individuals to obtain resources more successfully
resource partitioning- in an effort to minimize competition and maximize success species will
coexist and occupy slightly different niches
keystone species- a species that has a pivotal ecological role; not necessarily the most abundant
trophic structure- the different feeding relationships in an ecosystem which determine the route
of energy flow and the pattern of chemical cycling
trophic level- organization of animal and plants that reflect their main energy source; primary
producers (autotrophs that convert sun energy into chemical energy- ex plants and photosynthetic
protists), primary consumers (eat primary producers- ex herbivores), secondary consumers
(primary carnivores- eat primary consumers), tertiary consumers (secondary carnivores- eat the
secondary consumers)
Detritivores- consumers that obtain their energy by bonsuming dead plants and animals
(detritus)- decomposers are very small detritivores (ie bacteria)
food chain- the pathway along which food energy is transferred from trophic level to trophic
level (starts with producers)
food web- interconnected feeding relationships in an ecosystem
production/comsumption- in ecology it refers to the synthesis/degradation of organic compounds
by an organism
ecological (trophic) efficiency- the proportion of energy represented at one trophic level that is
transferred to the next level; the sizes of the tiers in an energy pyramid indicate the efficiency;
average efficiency is 10%, so 10% of energy is passed to next level
ecological pyramids- used to show relationships between trophic levels
primary productivity- the amount of light energy converted to chemical energy by autotrophs in a
given time period; gross primary productivity [GPP] (total primary production in an ecosystem),
net primary productivity [NPP] (is equal to GPP minus the energy used by the primary producers
for respiration [R]- the formula:NPP = GPP -R)
biomass- the total mass of organic matter of a group of organisms in a particular habitat
standing crop biomass- the total biomass of photosynthetic autotrophs present at a given time
biogeochemical cycles- describe the flow of essential elements from the environment to living
things and back to the environment; hydrologic (Reservior-oceans, groundwater, glaciers;
Assimilation-plants absorb water from soil, animals drink; Release- plants transpire,
animals/plants decompose), Carbon (Reservior- atomosphere as CO2, fossil fuels; Assimilationplants use in photosynthesis, animals consume plants; Release- plants/animals release through
cell respiration, burning of fossil fuels), Nitrogen (Reservior- atmosphere as N2, soil as
ammonium, ammonia, nitrite or nitrate; Assimilation- plants absorb, animals eat plants; nitrogen
fixation[N2 to ammonia or nitrate], nitrification [ammonium to nitrite and nitrite to nitrate OR
ammonium to nitrate Release-denitrification [nitrate back to nitrogen gas], ammonification
[organic molecules back to ammonium), Phosphorus (Reservior- rocks and ocean sediment;
Assimilation- plants absorb phosphate from soil and animals eat plants; Release- plants/animals
decompose and animals excrete in wastes)
biological magnification- toxin accumulation in tissues; toxins become more concentrated in
successive levels of a food web (i.e. humans and top consumers are affected most by toxic
compounds in environment)
conservation biology- integrates ecology physiology molecular biology genetics and
evolutionary biology to conserve diversity at all levels
bioremediation- the use of organisms to detoxify and restore polluted and degraded ecosystems
(i.e. oil spill)
Pictures came from:
Campbell, AP Biology
http://scienceaid.co.uk/biology/ecology/food.html