abiotic factors = non-living conditions in a habitat
activation energy = the energy required to initiate a reaction.
active site = area of an enzyme with a shape complementary to a
specific substrate, allowing the enzyme to bind a substrate with
specificity.
active transport = movement of particles across a plasma membrane
against a concentration gradient. Energy is required. (ATP)
adenosine diphosphate (ADP) = a nucleotide composed of a
nitrogenous base (adenine), a
pentose sugar and two phosphate groups. Formed by the hydrolysis of
ATP, releasing a phosphate ion and energy.
adenosine triphosphate (ATP) = a nucleotide composed of a
nitrogenous base (adenine), a
pentose sugar and three phosphate groups. The universal energy
currency for cells.
agglutinins = chemicals (antibodies) that cause pathogens to clump
together so they are easier for phagocytes to engulf and digest.(caused
by cross linking by antibodies that have a number of binding sites)
alleles = different versions of the same gene.
amino acids = monomer used to build polypeptides and thus proteins
anabolism (anabolic) = reactions of metabolism that construct
molecules from smaller units. These reactions require energy from the
hydrolysis of ATP.
analogous structures = structures that have adapted to perform the
same function but have a different origin.
anaphase = third stage of mitosis when chromatids are separated to
opposite poles of the cell.
antibiotic-resistant bacteria = bacteria that undergo mutation to
become resistant to an antibiotic and then survive to increase in
number.
antibiotics = a chemical or compound that kills or inhibits the growth
of bacteria
antibodies = Y-shaped glycoproteins made by B cells of the immune
system in response to the
presence of an antigen.
antigen = identifying chemical on the surface of a cell that triggers an
immune response
antigen−antibody complex = the complex formed when an antibody
binds to an antigen.
antigen-presenting cell (APC) = a cell that displays foreign antigens
complexed with major histocompatibility complexes on their surface
plasma membranes, so it can be recognised by other cells
antisense strand 'lagging strand' = the strand of DNA that runs 3' to 5'
and is complementary to the sense strand. It acts as a template strand
during transcription.
anti-toxins = chemicals (antibodies) that bind to toxins produced by
pathogens so they no longer have an effect.
apoplast = the cell walls and intercellular spaces of plant cells.
apoplast route = movement of substances through the cell walls and
cell spaces by diffusion and into cytoplasm by active transport.
arrhythmia = an abnormal rhythm of the heart.
artefacts = objects or structures seen through a microscope that have
been created during the processing of the specimen.
artificial active immunity = immunity which results from exposure to
a safe form of a pathogen, for example, by vaccination.
artificial passive immunity = immunity which results from the
administration of antibodies from
another animal against a dangerous pathogen.
asexual reproduction = the production of genetically identical
offspring from a single parent.
assimilates = the products of photosynthesis that are transported
around a plant, e.g., sucrose
atrial fibrillation = an abnormal rhythm of the heart when the atria
beat very fast and incompletely.
atrio-ventricular node (AVN) = stimulates the ventricles to contract
after imposing a slight delay to ensure atrial contraction is complete.
autoimmune disease = a condition or illness resulting from an
autoimmune response.
autoimmune response = response when the immune system acts
against its own cells and destroys healthy tissue in the body.
autotrophic = organisms that acquire nutrients by photosynthesis.
B effector cells = B lymphocytes that divide to form plasma cell
clones
B lymphocytes (B cells) = lymphocytes which mature in the bone
marrow and that are involved in the production of antibodies
B memory cells = B lymphocytes that live a long time and provide
immunological memory of the
antibody needed against a specific antigen.
belt transect = two parallel lines are marked along the ground and
samples are taken of the area
at specified points.
Benedict's reagent = an alkaline solution of copper(II)sulfate used in
the chemical tests for reducing sugars and non-reducing sugars. A
brick-red precipitate indicates a positive result.
beta pleated sheet = sheet-like secondary structure of proteins
binomial nomenclature = the scientific naming of a species with a
Latin name made of two parts − the first indicating the genus and the
second the species.
biodiversity = the variety of living organisms present in an area
biuret test = the chemical test for proteins; peptide bonds form violet
coloured complexes with
copper ions in alkaline solutions.
Bohr effect = the effect of carbon dioxide concentration on the uptake
and release of oxygen by
haemoglobin
bradycardia = a slow heart rhythm of below 60 beats per minute
breathing rate = the number of breaths (inhalation and exhalation)
taken per minute.
bulk transport = a form of active transport where large molecules or
whole bacterial cells are
moved into or out of a cell by endocytosis or exocytosis
bundle of his = conducting tissue composed of purkyne fibres that
passes through the septum of
the heart
alpha-glucose = glucose in which the hydrogen atom on carbon no.1
projects above the plane of the ring
ab initio protein modelling = a model is built based on the physical
and electrical properties of the atoms in each amino acid in the
sequence
accuracy = how close a measured or calculated value is to the true
value
active immunity = where the immune system is activated and
manufactures its own antibodies
adaption = a characteristic that enhances survival in the habitat
adhesion = the attraction between water molecules and the walls of
the xylem vessels
affinity = a strong attraction
alveoli = tiny folds of the lung epithelium to increase the surface area
amphiphilic = attracted to both water and fat - containing hydrophobic
and hydrophilic parts
amylopectin molecule = a molecule of polysaccharide with glycosidic
bonds between carbon 1 and 4, and branches formed by glycosidic
bonds between 1 and 6. It is a constituent of starch
amylose molecule = a molecule of polysaccharide with long straight
chains of between 100 and 1000 alpha glucose molecules. It is a
constituent of starch. Like maltose, it has glycosidic bonds between
carbon 1 and 4
anatomical adaptations = structural features
anatomy = a branch of science that concerns the studying of the
structure of living organisms
angina pectoris = a condition marked by severe pain in the chest,
resulting from an inadequate blood supply, and therefore a lack of
oxygen to the heart muscle that causes the coronary arteries to spasm
anion = a negatively charged ion
anomaly = result that does not fit the expected trend nor pattern
aorta = the main artery of the body in mammals
apoptosis = the death of cells which happens as a normal part of an
organism's growth and development
archaea = prokaryotic microorganisms of similar size to bacteria but
have some differences of metabolism
arteries = vessels that carry blood away from the heart
arterioles = small blood vessels that distribute the blood from an
artery to the capillaries
artificial classification = a classification based on just one or a few
characteristics
artificial immunity = immunity that is achieved as a result of medical
intervention
artificial insemination = the medical procedure of injecting semen
into the uterus of a female of the same species
asymptomatic = having no symptoms
atria = thin walled chambers of the heart that receive the blood from
the veins and then pass it to the ventricles
atrio-ventricular valves = valves between the atria and the ventricles,
which ensure that the blood flows in the correct direction
callose = a polysaccharide containing β 1-3 linkages and β 1-6
linkages between the glucose monomers that is important in the plant
response to infection.
carbaminohaemoglobin = the compound formed when carbon dioxide
combines with haemoglobin.
carbohydrates = organic polymers composed of the elements carbon,
hydrogen and oxygen in the ratio Cx(H2O)y. Also known as
saccharides or sugars.
carbonic anhydrase = enzyme which catalyses the reversible reaction
between carbon dioxide and water to form carbonic acid.
cardiac cycle = the events of a single heartbeat, composed of diastole
and systole.
carrier proteins = membrane proteins that play a part in the transport
of substances through a membrane.
cartilage = strong, flexible connective tissue found in many areas of
the bodies of humans and other animals
catabolism (catabolic) = reactions of metabolism that break molecules
down into smaller units. These reactions release energy.
catalase = an enzyme that catalyses the breakdown of hydrogen
peroxide.
cell cycle = the highly ordered sequence of events that takes place in a
cell, resulting in division of
the nucleus and the formation of two genetically identical daughter
cells
cell signalling = a complex system of intercellular communication.
cellulose = a polysaccharide formed from beta glucose molecules
where alternate beta glucose molecules are turned upside down. It is
unable to coil or form branches but makes hydrogen bonds with other
cellulose molecules to produce strong and insoluble fibres. Major
component of plant cell walls.
cell wall = a strong but flexible layer that surrounds some cell-types.
centrioles = component of the cytoskeleton of most eukaryotic cells,
composed of microtubules.
centromere = region at which two chromatids are held together
channel proteins = membrane proteins that provide a hydrophilic
channel through a membrane.
checkpoints = control mechanisms of the cell cycle.
chiasmata = sections of DNA, which became entangled during
crossing over, break and rejoin
during anaphase 1 of meiosis sometimes resulting in an exchange of
DNA between bivalent chromosomes, forming recombinant
chromatids and providing genetic variation.
chloride shift = the movement of chloride ions into the red blood cells
as hydrogen ions move out
to maintain the electrochemical equilibrium.
chloroplasts = organelles that are responsible for photosynthesis in
plant cells. Contain
chlorophyll pigments, which are the site of the light reactions of
photosynthesis
chromatids = two identical copies of DNA (a chromosome) held
together at a centromere.
chromatin = uncondensed DNA in a complex with histones.
chromosomes = structures of condensed and coiled DNA in the form
of chromatin. Chromosomes
become visible under the light microscope when cells are preparing to
divide.
circulatory system = the transport system of an animal.
clonal expansion = the mass proliferation of antibody-producing cells
by clonal selection.
clonal selection = the theory that exposure to a specific antigen
selectively stimulates the
proliferation of the cell with the appropriate antibody to form
numerous clones of these specific antibody-forming cells (clonal
expansion).
closed circulatory system = a circulatory system where the blood is
enclosed in blood vessels and does not come into direct contact with
the cells of the body beyond the blood vessels.
Clostridium difficile (C. difficile) = a species of Gram positive
bacteria that is resistant to most antibiotics
codon = a three-base sequence of DNA or RNA that codes for an
amino acid.
cofactors = non-protein components necessary for the effective
functioning of an enzyme.
cohesion-tension theory = the best current model explaining the
movement of water through a
plant during transpiration
communicable diseases = diseases that can be passed from one
organism to another, of the same or different species.
community = all the populations of living organisms in a particular
habitat.
companion cells = the active cells found next to sieve tube elements
that supply the phloem vessels with all of their metabolic needs
competitive inhibitor = an inhibitor that competes with substrate to
bind to active site on an enzyme.
complementary base pairing = specific hydrogen bonding between
nucleic acid bases. Adenine (A) binds to thymine (T) or uracil (U) and
cytosine (C) binds to guanine (G).
compound light microscope = a light microscope which uses two
lenses to magnify an object; the objective lens, which is placed near to
the specimen and an eyepiece lens, through which the specimen is
viewed.
condensation reaction = a reaction between two molecules resulting in
the formation of a larger molecule and the release of a water
molecule. The opposite reaction to a hydrolysis reaction
continuous variation = a characteristic that can take any value within
a range, e.g. height.
contrast = staining or treating specific cell components so they are
visible compared to untreated components
convergent evolution = organisms evolve similarities because the
organisms adapt to similar environments or other selection pressures.
correlation coefficient = statistical test used to consider the
relationship between two sets of data.
countercurrent exchange system = a system for exchanging materials
or heat when the two different components flow in opposite directions
past each other
counterstain = application of second stain with a contrasting colour to
sample for microscopy
crossing over = see chiasmata
cytokines = cell-signalling molecules produced by mast cells in
damaged tissues that attract
phagocytes to the site of infection or inflammation.
cytokinesis = cell division stage in the mitotic phase of the cell cycle
that results in the production
of two identical daughter cells.
cytolysis = the bursting of an animal cell caused by increasing
hydrostatic pressure as water
enters by osmosis.
cytoplasm = internal fluid of cells, composed of cytosol (water, salts
and organic molecules), organelles and cytoskeleton.
cytoskeleton = a network of fibres in the cytoplasm of a eukaryotic
cell
denatured (denaturation) = change in tertiary structure of a protein or
enzyme, resulting in loss of normal function.
deoxyribonucleic acid (DNA) = the molecule responsible for the
storage of genetic information.
diastole = the stage of the cardiac cycle in which the heart relaxes and
the atria and then the ventricles fill with blood.
dicotyledonous plants (dicots) = plants that produce seeds containing
two cotyledons, which act as food stores for the developing embryo
and form the first leaves when the seed germinates.
differential staining = using specific stains to distinguish different
types of cell.
differentiation = the process of a cell becoming differentiated.
Involves the selective expression of genes in a cell's genome.
diploid = normal chromosome number; two chromosomes of each
type − one inherited from each parent.
disaccharide = a molecule comprising two monosaccharides, joined
together by a glycosidic bond.
discontinuous variation = a characteristic that can only result in
certain discrete values, for example, blood type.
divergent evolution = species diverge over time into two different
species, resulting in a new species becoming less like the original one.
DNA helicase = enzyme that catalyses the unwinding and separating
of strands in DNA replication.
DNA polymerase = enzyme that catalyses the formation of
phosphodiester bonds between adjacent nucleotides in DNA
replication.
DNA replication = the semi-conservative process of the production of
identical copies of DNA molecules.
double circulatory system = a circulatory system where the blood
travels twice through the heart for each complete circulation of the
body. In the first circulation blood is pumped by the heart to the
lungs. In the second circulation oxygenated blood is pumped by the
heart to the brain and body to supply cells with oxygen.
ectopic heartbeat = extra heartbeats that are out of the normal rhythm.
elastic recoil = the ability to return to original shape and size
following stretching. Particularly of the alveoli of the lungs and of the
arteries.
electrocardiogram (ECG) = a technique for measuring tiny changes in
the electrical conductivity of the skin that result from the electrical
activity of the heart. This produces a trace which can be used to
analyse the health of the heart.
electron microscopy = microscopy using a microscope that employs a
beam of electrons to illuminate the specimen. As electrons have a
much smaller wavelength than light they produce images with higher
resolutions than light microscopes.
emulsion test = laboratory test for lipids using ethanol; a white
emulsion indicates the presence of a lipid.
endocytosis = the bulk transport of materials into cells via
invagination of the cell-surface membrane forming a vesicle.
endosymbiosis = the widely-accepted theoretical process by which
eukaryotic cells evolved from prokaryotic cells.
end-product inhibition = the product of a reaction inhibits the enzyme
required for the reaction.
enzyme−product complex = complex formed as a result of an
enzyme-catalysed reaction, when a substrate is converted to a product
or products while bound to the active site of an enzyme.
enzymes = biological catalysts that interact with substrate molecules
to facilitate chemical reactions. Usually globular proteins.
enzyme-substrate complex = complex formed when a substrate is
bound to the active site of an enzyme.
epidemic = when a communicable disease spreads rapidly to a lot of
people at a local or national level.
eukaryotes = multicellular eukaryotic organisms like animals, plants
and fungi and single-celled protoctista.
eukaryotic cells = cells with a nucleus and other membrane-bound
organelles.
ex situ conservation = conservation methods out of the natural habitat.
exchange surfaces = surfaces over which materials are exchanged
from one area to another.
exocytosis = the bulk transport of materials out of cells. Vesicles
containing the material fuse with the cell-surface membrane and the
contents are released to the outside of the cell.
exoskeleton = an external skeleton of some organisms, e.g. insects.
expiratory reserve volume = the extra amount of air that can be forced
out of the lungs over and above the normal exhalation (tidal volume).
facilitated diffusion = diffusion across a plasma membrane through
protein channels.
fatty acids = long chain carboxylic acids used in the formation of
triglycerides.
fibrous proteins = long, insoluble, structural proteins.
fluid-mosaic model = model of the structure of a cell membrane in
which phospholipids within the phospholipid bilayer are free to move
and proteins of various shapes and sizes are embedded in various
positions.
fossils = the remains or impression of a prehistoric plant or animal
preserved in rock.
founder effect = when a few individuals of a species colonise a new
area, their offspring initially experience a loss in genetic variation,
and rare alleles can become much more common in the population.
Fungi = biological kingdom containing yeasts, moulds and
mushrooms.
gametes = haploid sex cells produced by meiosis in organisms that
reproduce sexually.
gaseous exchange system = the complex systems in which the
respiratory gases oxygen and carbon dioxide are exchanged in an
organism.
gene = a section of DNA that contains the complete sequence of bases
(codons) to code for a protein.
gene flow = when alleles are transferred from one population to
another by interbreeding.
genetic bottleneck = when large numbers of a population die prior to
reproducing, leading to reduced genetic biodiversity within the
population.
genetic code = the sequences of bases in DNA are the 'instructions'
for the sequences of amino acids in the production of proteins.
genetic variation = a variety of different combinations of alleles in a
population.
gills = the gaseous exchange organs of fish, comprised of gill plates,
gill filaments and gill lamellae.
globular proteins = spherical, water-soluble proteins.
glucose = a monosaccharide with the chemical formula C6H12O6.
One of the main products of photosynthesis in plants.
glycerol = alcohol found in triglycerides.
glycogen = a branched polysaccharide formed from alpha glucose
molecules. A chemical energy store in animal cells.
glycolipids = cell-surface membrane lipids with attached
carbohydrate molecules of varying lengths and shapes.
glycoproteins = extrinsic membrane proteins with attached
carbohydrate molecules of varying lengths and shapes.
glycosidic bond = a covalent bond between two monosaccharides.
goblet cells = differentiated cells specialised to secrete mucus.
Golgi apparatus = organelle in most eukaryotic cells formed from an
interconnected network of flattened, membrane-enclosed sacs, or
cisternae. Play a role in modifying and packaging proteins into
vesicles.
Gram negative bacteria = bacteria with cell walls that stain red with
Gram stain.
Gram positive bacteria = bacteria with cell walls that stain purple-blue
with Gram stain.
granum (plural grana) = a structure inside chloroplasts composed of a
stack of several thylakoids. Contains chlorophyll pigments, where
light reactions occur during photosynthesis.
guard cells = cells that can open and close the stomatal pores,
controlling gaseous exchange and water loss in plants.
habitat = biodiversity the number of different habitats found within an
area.
haemoglobin = the red, oxygen-carrying pigment of red blood cells.
haemoglobinic acid = the compound formed when haemoglobin
accepts free hydrogen ions in its role as a buffer in the blood.
haemolymph = the transport medium or 'blood' in insects
haploid = half the normal chromosome number; one chromosome of
each type.
heterotrophic = organisms that acquire nutrients by the ingestion of
other organisms.
hexose monosaccharide = a monosaccharide composed of six
carbons.
histamines = chemicals produced by mast cells in damaged tissues
that make the blood vessels dilate (causing redness and heat) and the
blood vessel walls leaky (causing swelling and pain).
histones = proteins that form a complex with DNA called chromatin.
homologous chromosomes = matching pair of chromosomes, one
inherited from each parent.
homologous structure = a structure which appears superficially
different but has the same underlying structure.
hydrolysis = reaction the breakdown of a molecule into two smaller
molecules requiring the addition of a water molecule. The opposite
reaction to a condensation reaction.
hydrophilic = the physical property of a molecule that is attracted to
water.
hydrophobic = the physical property of a molecule that is repelled by
water.
hydrophytes = plants with adaptations that enable them to survive in
very wet habitats or submerged or at the surface of water.
hydrostatic pressure = the pressure created by water in an enclosed
system.
immune response = a biological response that protects the body by
recognising and responding to antigens and by destroying substances
carrying non-self antigens.
immunoglobulins = Y-shaped glycoproteins that form antibodies.
in situ conservation = conservation methods within the natural habitat.
independent assortment = the arrangement of each homologous
chromosome pair (bivalent) in metaphase 1 and metaphase 2 of
meiosis is independent of each other and results in genetic variation.
induced-fit hypothesis = modified lock and key explanation for
enzyme action; the active site of the enzyme is modified in shape by
binding to the substrate.
inflammation = biological response of vascular tissues to pathogens,
damaged cells, or irritants, resulting in pain, heat, redness and
swelling.
inhibitor = a factor that prevents or reduces the rate of an
enzyme-catalysed reaction.
inspiratory reserve volume = the maximum volume of air that can be
breathed in over and above a normal inhalation (tidal volume).
insulin = a globular protein hormone involved in the regulation of
blood glucose concentration.
intercostal muscles = the muscles between the ribs that pull the ribs
upwards during inhalation (internal intercostal muscles) and
downwards during forced exhalation (external intercostal muscles)
interleukins = a type of cytokine produced by T helper cells.
interphase = growth period of the cell cycle, between cell divisions
(mitotic phase). Consists of stages G1, S and G2.
interspecific variation = the differences between organisms of
different species.
intraspecific variation = the differences between organisms of the
same species.
iodine test = chemical test for the presence of starch using a
potassium iodide solution. A colour change to purple/black indicates a
positive result.
ion = an atom or molecule with an overall electric charge because the
total number of electrons is not equal to the total number of protons.
See anion and cation.
ionic bond = a chemical bond that involves the donating of an
electron from one atom to another, forming positive and negative ions
held together by the attraction of the opposite charges.
keystone species = species which are essential for maintaining
biodiversity − they have a disproportionately large effect on their
environment relative to their abundance.
kingdom = the second biggest and broadest taxonomic group.
lactose = a disaccharide made up of a galactose and glucose
monosaccharide.
laser scanning confocal microscope = a microscope that employs a
beam of fluorescence and a pin-hole aperture to produce an image
with a very high resolution.
light microscope = an instrument that uses visible light and glass
lenses to enable the user to see objects magnified many times.
line transect = a line is marked along the ground and samples are
taken at specified points.
lipids = non-polar macromolecules containing the elements carbon,
hydrogen and oxygen. Commonly known as fats (solid at room
temperature) and oils (liquid at room temperature).
lung surfactant = chemical mixture containing phospholipids and both
hydrophilic and hydrophobic proteins, which coats the surfaces of the
alveoli and prevents them collapsing after every breath.
lymph = modified tissue fluid that is collected in the lymph system.
lymphocytes = white blood cells that make up the specific immune
system.
lysosomes = specialised vesicles containin hydrolytic enzymes for the
breakdown of waste materials within a cell.
macromolecules = large complex molecules with a large molecular
weight.
maltose = two glucose molecules linked by a 1, 4 glycosidic bond.
mass transport system = a transport system where substances are
transported in a mass of fluid.
meiosis = form of cell division where the nucleus divides twice
(meiosis I and meiosis II) resulting in a halving of the chromosome
number and producing four haploid cells from one diploid cell.
membrane = a selectively-permeable barrier surrounding all cells and
forming compartments within eukaryotic cells.
membrane proteins = protein components of cell-surface membranes.
meristematic tissue (meristems) = tissue found at regions of growth in
plants. Contains stem cells.
messenger (m)RNA = short strand of RNA produced by transcription
from the DNA template strand. It has a base sequence complementary
to the DNA from which it is transcribed, except it has uracil (U) in
place of thymine (T).
metaphase = second stage of mitosis when chromosomes line up at
the metaphase plate.
mitochondrial DNA = DNA present within the matrix of
mitochondria.
mitosis = nuclear division stage in the mitotic phase of the cell cycle.
mitotic phase = period of cell division of the cell cycle. Consists of
the stages mitosis and cytokinesis.
monoculture = the cultivation of a single crop in a given area.
monomers = individual molecules that make up a polymer.
monosaccharide = a single sugar molecule. mRNA see messenger
(m)RNA.
MRSA (methicillin-resistant Staphylococcus aureus) = a mutated
strain of the bacterium Staphylococcus aureus that is resistant to the
antibiotic, methicillin.
mucous membranes = membranous linings of body tracts that secrete
a sticky mucus.
multipotent = a stem cell that can only differentiate into a range of
cell types within a certain type of tissue.
mutation = a change in the genetic material which may affect the
phenotype of the organism.
myogenic = muscle which has its own intrinsic rhythm.
natural active immunity = immunity which results from the response
of the body to the invasion of a pathogen.
natural passive immunity = the immunity given to an infant mammal
by the mother through the placenta and the colostrum.
natural selection = the process by which organisms best suited to their
environment survive and reproduce, passing on their characteristics to
their offspring through their genes.
non-competitive inhibitor = an inhibitor that binds to an enzyme at an
allosteric site.
non-random sampling = an alternative sampling method to random
sampling, where the sample is not chosen at random. It can be
opportunistic, stratified or systematic.
normal distribution curve = the bell-shaped curve that results from
plotting continuous variation data on a graph.
nucleic acids = large polymers formed from nucleotides. Contain the
elements carbon, hydrogen, nitrogen , phosphorus, and oxygen.
nucleotides = the monomers used to form nucleic acids. Made up of a
pentose monosaccharide,a phosphate group and a nitrogenous base.
oncotic pressure = the pressure created by the osmotic effect of the
solutes in a solution
open circulatory system = a circulatory system with a heart but few
vessels to contain the transport medium.
operculum = the bony flap covering the gills of bony fish. Part of the
mechanism that maintains a constant flow of water over the gas
exchange surfaces.
opportunistic sampling = sampling using the organisms that are
conveniently available. The weakest form of sampling as it may not
be representative of the population.
opsonins = chemicals that bind to pathogens and tag them so they are
recognised more easily by phagocytes, e.g. antibodies.
organelle = membrane-bound compartments with varying functions
inside eukaryotic cells.
osmosis = diffusion of water through a partially permeable membrane
down a water potential gradient. A passive process.
oxygen = dissociation curve graph showing the relationship between
oxygen and haemoglobin at different partial pressures of oxygen.
oxygenated blood = blood that has passed through the gas exchange
organs (e.g. lungs) and is high in oxygen.
pandemic = when a communicable disease spreads rapidly to a lot of
people across a number of countries.
partially permeable = membrane that allows some substances to cross
but not others.
passive transport = transport that is a passive process (does not
require energy) and does not use energy from cellular respiration.
pathogens = microorganisms that cause disease.
penicillin = the first widely used, safe antibiotic, derived from a
mould, Penicillium notatum.
pentose monosaccharide = a monosaccharide composed of five
carbons.
peptide bond = bond formed between two amino acids.
peptides = chains of two or more amino acid molecules.
phagocytosis = process by which white blood cells called phagocytes
recognise non-self cells, engulf them digest them within a vesicle
called a phagolysosome.
phagosome = the vesicle in which a pathogen or damaged cell is
engulfed by a phagocyte.
phloem = plant transport tissue that carries the products of
photosynthesis (assimilates) to all cells of the plant.
phosphodiester bonds = covalent bonds formed between the
phosphate group of one nucleotide and the hydroxyl (OH) group of
another.
phospholipid bilayer = arrangement of phospholipids found in cell
membranes; the hydrophilic phosphate heads form both the inner and
outer surface of a membrane, sandwiching the fatty acid tails to form
a hydrophobic core.
phospholipids = modified triglycerides, where one fatty acid has been
replaced with a phosphate group.
phylogeny = the evolutionary relationships between organisms.
pinocytosis = endocytosis of liquid materials.
plasma = the main component of blood, a yellow fluid containing
many dissolved substances and carrying the blood cells.
plasma cells = B lymphocytes that produce about 2000 antibodies to a
particular antigen every second and release them into the circulation.
plasma membrane = all the membranes of cells, which have the same
basic structure described by the fluid-mosaic model.
pluripotent = a stem cell that can differentiate into any type of cell,
but not form a whole organism.
polymers = long-chain molecules composed of linked (bonded)
multiple individual molecules (monomers) in a repeating pattern.
polypeptide = chains of three or more amino acids.
polysaccharide = a polymer made up of many sugar monomers
(monosaccharides).
primary immune response = the relatively slow production of a small
number of the correct antibodies the first time a pathogen is
encountered.
prokaryotes = single-celled prokaryotic organisms from the kingdom
Prokaryotae.
prokaryotic cells = cells with no membrane-bound nucleus or
organelles.
prophase = first stage of mitosis when chromatin condenses to form
visible chromosomes and the nuclear envelope breaks down.
prosthetic group = non-protein component of a conjugated protein.
proteases = enzymes that catalyse the breakdown of proteins and
peptides into amino acids.
Proteins = one or more polypeptides arranged as a complex
macromolecule.
Protista = biological kingdom containing unicellular eukaryotes.
Purines = double-ringed, nitrogenous bases that form part of a
nucleotide.
Purkyne fibres = tissue that conducts the wave of excitation to the
apex of the heart.
Pyrimidines = single-ringed, nitrogenous bases that form part of a
nucleotide.
quaternary structure = the association of two or more protein subunits.
random sampling = sampling where each individual in the population
has an equal likelihood of selection.
receptors = extrinsic glycoproteins that bind chemical signals,
triggering a response by the cell.
recombinant chromatids = chromatids with a combination of DNA
from both homologous chromosomes, formed by crossing over and
chiasmata in meiosis.
reducing sugars = saccharides (sugars) that donate electrons resulting
in the reduction (gain of electrons) of another molecule.
reduction division = cell division resulting in the production of
haploid cells from a diploid cell; meiosis.
residual volume = the volume of air that is left in the lungs after
forced exhalation. It cannot be measured directly
resolution = the shortest distance between two objects that are still
seen as separate objects.
R-groups = variable groups on amino acids.
ribonucleic acid (RNA) = molecules involved in the copying and
transfer of genetic information from DNA. Polynucleotides consisting
of a ribose sugar and one of four bases; uracil (U), cytosine (C),
adenine (A), and guanine (G).
ribose = the pentose monosaccharide present in RNA molecules.
ribosomal (r)RNA = form of RNA that makes up the ribosome.
RNA polymerase = enzyme that catalyses the formation of
phosphodiester bonds between adjacent RNA nucleotides.
root hair cells = cells found just behind the growing tip of a plant root
that have long hairlike extensions that greatly increase the surface
area available for the absorption of water and minerals from the soil.
root pressure = the active pumping of minerals into the xylem by root
cells that produces a movement of water into the xylem by osmosis.
Saprophytic = organisms that acquire nutrients by absorption −
mainly of decaying material.
scanning electron microscopy = an electron microscope in which a
beam of electrons is sent across the surface of a specimen and the
reflected electrons are focused to produce a three dimensional image
of the specimen surface.
secondary immune response = the relatively fast production of very
large quantities of the correct antibodies the second time a pathogen is
encountered as a result of immunological memory − the second stage
of a specific immune response.
seed bank = a store of genetic material from plants in the form of
seeds.
selection pressure = factors that affect an organism's chance of
survival or reproductive success.
selective toxicity = the ability to interfere with the metabolism of a
pathogen without affecting the cells of the host.
selectively permeable = plasma membrane with protein channels that
allows specific substances to cross only.
semi-conservative replication = DNA replication results in one old
strand and one new strand present in each daughter DNA molecule.
sense strand = the strand of DNA that runs 5' to 3' and contains the
genetic code for a protein.
sieve plates = areas between the cells of the phloem where the walls
become perforated giving many gaps and a sieve-like appearance that
allows the phloem contents to flow through.
sieve tube elements = the main cells of the phloem that have a greatly
reduced living content and sieve plates between the cells.
Simpson's Index of Diversity (D) = a measure of biodiversity that
takes into account both species richness and species evenness.
single circulatory system = a circulatory system where the blood
flows through the heart and is pumped out to travel all around the
body before returning to the heart.
sinks (in plants) = regions of a plant that require assimilates to supply
their metabolic needs, e.g. roots, fruits.
sino-atrial node (SAN) = region of the heart that initiates a wave of
excitation that triggers the contraction of the heart.
smooth endoplasmic reticulum = endoplasmic reticulum lacking
ribosomes; the site of lipid and carbohydrate synthesis, and storage.
sources (in plants) = regions of a plant that produce assimilates (e.g.
glucose) by photosynthesis or from storage materials, e.g. leaves,
storage organs.
Specialised = having particular structure to serve a specific function.
Species = the smallest and most specific taxonomic group. a group of
organisms that can freely interbreed to produce fertile offspring
specific immunity = also known as active immunity or acquired
immunity − the immune system 'remembers' an antigen after an initial
response leading to an enhanced response to subsequent encounters.
Spiracles = small openings along the thorax and abdomen of an insect
that open and close to control the amount of air moving in and out of
the gas exchange system and the level of water loss from the
exchange surfaces.
stage graticule = a slide with a scale in micrometres (μm) etched into
it. Used to measure the size of a sample under a light microscope.
stains (staining) = dyes used in microscopy sample preparation to
increase contrast or identify specific components.
Starch = a polysaccharide formed from alpha glucose molecules
either joined to form amylose or amylopectin.
stem cells = undifferentiated cells with the potential to differentiate
into any of the specialised cell types of the organism.
Stomata = pores in the surface of a leaf or stem that may be opened
and closed by guard cells. That allow gaseous exchange
stratified sampling = sampling where populations are divided into
sub-groups (strata) based on a particular characteristic. A random
sample is then taken from each of these strata proportional to its size.
Stroma = fluid interior of chloroplasts.
Student's t test = statistical test used to compare the means of data
values of two populations.
Substrate = a substance used, or acted on, by another process or
substance. For example a reactant in an enzyme-catalysed reaction.
Succession = the progressive replacement of one dominant type of
species or community by another in an ecosystem, until a stable
climax community is established
Sucrose = a disaccharide made up of a fructose and glucose
monosaccharides.
sustainable development = economic development that meets the
needs of people today, without limiting the ability of future
generations to meet their needs.
Symplast = the continuous cytoplasm of living plant cells connected
through the plasmodesmata.
symplast route = phloem loading through the cytoplasm of the cells
via plasmodesmata by diffusion (passive).
systematic sampling = different areas of a habitat are identified and
sampled separately. Often carried out using a line or belt transect.
Systole = the stage of the cardiac cycle in which the atria contract,
followed by the ventricles, forcing blood out of the right side of the
heart to the lungs and the left side of the heart to the body.
T helper cells = T lymphocytes with CD4 receptors on their
cell-surface membranes, which bind to antigens on antigen-presenting
cells and produce interleukins, a type of cytokine.
T killer cells = T lymphocytes that destroy pathogens carrying a
specific antigen with perforin.
T lymphocytes = lymphocytes which mature in the thymus gland and
that both stimulate the B lymphocytes and directly kill pathogens.
T memory cells = T lymphocytes that live a long time and are part of
the immunological memory.
T regulator cells = T lymphocytes that suppress and control the
immune system, stopping the response once a pathogen has been
destroyed and preventing an autoimmune response.
Tachycardia = a fast heart rhythm of over 100 beats per minute at rest.
taxonomic group = the hierarchical groups of classification - domain,
kingdom, phylum, class, order, family, genus, species
telophase = fourth stage of mitosis when chromosomes assemble at
the poles and the nuclear envelope reforms.
temperature coefficient (Q10) = a measure of how much the rate of a
reaction increases with a 10 °C temperature increase.
template strand = the antisense strand of DNA that acts as template
during transcription so that the complementary RNA strand formed
carries the same code for a protein as the DNA sense strand.
tertiary structure = further folding of the secondary structure of
proteins involving interactions between R-groups, to form hydrogen
bonds, disulfide bridges, ionic bonds and hydrophobic interactions
tidal volume = the volume of air which moves into and out of the
lungs with each resting breath.
Tissue = a collection of differentiated cells that have a specialised
function or functions in an organism.
tissue fluid = the solution surrounding the cells of multicellular
animals.
Tonoplast = membrane forming a vacuole in a plant cell.
total lung capacity = the sum of the vital capacity and the residual
volume.
Totipotent = a stem cell that can differentiate into any type of cell and
form a whole organism.
Trachea = the main airway, supported by incomplete rings of
cartilage, which carries warm moist air down from the nasal cavity
into the chest.
tracheal fluid = fluid found at the ends of the tracheoles in insects that
helps control the surface area available for gas exchange and water
loss.
Transcription = the process of copying sections of DNA base
sequence to produce smaller molecules of mRNA, which can be
transported out of the nucleus via the nuclear pores to the site of
protein synthesis.
transfer (t)RNA = form of RNA that carries an amino acid specific to
its anticodon to the correct position along mRNA during translation.
Translation = the process by which the complementary code carried
by mRNA is decoded by tRNA into a sequence of amino acids. This
occurs at a ribosome.
Translocation = the movement of organic solutes (assimilates) around
a plant in the phloem.
transmission electron microscopy (TEM) = an electron microscope in
which a beam of electrons is transmitted through a specimen and
focused to produce an image.
transpiration = the loss of water vapour from the stems and leaves of a
plant as a result of evaporation from cell surfaces inside the leaf and
diffusion down a concentration gradient out through the stomata.
(aerial parts of the plant)
transpiration stream = the movement of water through a plant from
the roots until it is lost by evaporation from the leaves.
transport system = the system that transports required substances
around the body of an organism.
Triglyceride = a lipid composed of one glycerol molecule and three
fatty acids.
triplet code = the genetic code is a sequence of three nucleic acid
bases, called a codon. Each codon codes for one amino acid.
Turgor = the pressure exerted by the cell-surface membrane against
the cell wall in a plant cell.
Ultrastructure = the ultrastructure of a cell is those features which can
be seen by using an electron microscope. (structure within a cell)
Undifferentiated = an unspecialised cell originating from mitosis or
meiosis.
Vaccine = a safe form of an antigen, which is injected into the
bloodstream to provide artificial active immunity against a pathogen
bearing the antigen. (stimulates an immune response)
Vacuoles = membranous sacs used to transport materials in the cell.
vascular bundle = the vascular system of herbaceous dicots, made up
of xylem and phloem tissue.
vascular system = a system of transport vessels in animals or plants.
Vector = a living or non-living factor that transmits a pathogen from
one organism to another, e.g. malaria mosquito.
Ventilation rate = is the total volume of air inhaled in one minute.
Ventilation rate = tidal volume × breathing rate (per minute).
vital capacity = volume of air that can be breathed in when the
strongest possible exhalation is followed by the deepest possible
intake of breath.
Vmax = maximum initial velocity or rate of an enzyme-catalysed
reaction.
water potential (Ψ) = measure of the quantity of water compared to
solutes, measured as the pressure created by the water molecules in
kilopascals (kPa). The tendency of the water molecules to diffuse
from one region to another.
Xerophytes = plants with adaptations that enable them to survive in
dry habitats or habitats where water is in short supply in the
environment.
Xylem = plant transport tissue that carries water and minerals from
the roots to the other parts of the plant as a result of physical forces.
Zygote = the initial diploid cell formed when two gametes are joined
by means of sexual reproduction. Earliest stage of embryonic
development.
Xylem vessels = the tube which carry water up the plant
water vapour potential gradient = a difference in the concentration of
water vapour molecules inside the leaf compared to the outside
waxy cuticle = these prevent water collecting on the cell surfaces.
Since pathogens collect in the water and need water to survive, it's a
passive defence
wildlife reserves = areas set aside for the conservation of species or
habitats
vascular pathway = the route taken by water as is passes from cell to
cell via the cytoplasm and vacuoles
viable = capable of surviving or living successfully, especially under
particular conditions
venules = small blood vessels that collect blood from the capillaries
and lead into the veins
ventricles = the lower chambers in the heart, their walls create
pressure to to pump the blood out of the heart and into the arteries
venom = a harmful secretion injected into a victim by a venomous
organism such as a snake or a spider
ventilation = the refreshing of air in the lungs, so that there is a higher
concentration of O2 than in the blood, and a lower C02 concentration
veins = vessels that carry blood back to the heart
variation = the presence of variety
vasodilation = an increase in the diameter of the lumen of arterioles
allowing and increased blood flow to specific region of the body
vena cava = a large vein carrying deoxygenated blood into the heart
validity = if an investigation provides the answer to the research
question it is valid
unsaturated fatty acid = there are double double carbon bonds, giving
the hydrocarbon chain kinks
urinary system = consists of two kidneys, ureters, the bladder, and the
urethra. Each kidney consists of millions of nephrons, these systems
deal with the removal of nitrogenous waste and with osmoregulation
tendinous cords = cord like tendons in heart ventricles that connect
the papillary muscles in the ventricle walls to the tricuspid/bicuspid
valves in the heart to prevent the valves from turning inside out
toxin = a substance that is poisonous to living cells/organisms
tracheal system = a system of air filled tubes in insects
transect = a line across a habitat
transmission = passing a pathogen from an infected individual to an
uninfected individual
transverse section = a section cut crossways
turgid = a swollen state of plant cells that have taken in water by
osmosis and reached their maximum state of swelling.
tylose = an outgrowth from parenchyma into the xylem vessels which
can block the vessel
systemic circulation = the part of the cardiovascular system which
carries oxygenated blood away from the heart to the body, and returns
deoxygenated blood back to the heart
systematic error = errors that may be inherent in the equipment and
are repeated at every replicate. However if the percentage error is
known , a calculation can be made to find the margin of error
synthetic biology = the re-engineering of biology, this could be the
production of new molecules that mimic natural processes or the use
of natural molecules to produce new biological systems that do not
exist in nature
synthesis = making large molecules from small ones
symbiosis = the relationship where two organisms coexist for their
mutual benefit
surface area to volume ratio = the surface area of an organism divided
by its volume, expressed as a ratio
succulent = a plant that stores water in its stem which becomes fleshy
and swollen
student's t-test = a test used to compare two means
standard deviation = a measure of the spread around a mean
squamous epithelial cells = flattened epithelial cells arranged in a
layer
spirometer = a device that can measure the movement of air into and
out of the lungs
spherocytosis = cells being more spherical in shape than they usually
are
species richness = a measure of how many different species are
present
species evenness = a measure of how evenly represented the species
are
soil depletion = the loss of soil fertility caused by removal of minerals
by continuous cropping
smooth muscle = involuntary muscle that contracts without the need
for conscious thought
sister chromatid = when a chromosome has replicated the resulting
two identical chromatids produce are sister chromatids
significant figures = the digits of the number that have a meaning and
contribute to the numbers precisions
septum = the walls that separated two chambers
semilunar valves = valves that prevent blood re-entering that hear
from the arteries
selective breeding = the selection of specific traits in plants or animals
through breeding programmes
secondary structure = the coiling or folding of an amino acid chain,
which arises often as a result of hydrogen bond formation between
different parts of the chain. The main forms of secondary structure are
the helix and the pleated sheet
sampling techniques = techniques used to collect samples, for
example random sampling, systematic and stratified sampling
sarcomere = the smallest contractile unit of muscle
sclerenchyma cells = plant cells that have lignified walls and are used
to strengthen stems and leaf midribs
secondary defences = defences which attack pathogens that have
entered the body
risk = the level of exposure to a hazard
risk assessment = a way of managing risks by reducing exposure to
hazards
random error = statistical fluctuations in the measured data sure to the
precision limitations of the measurement device
regenerative medicine = stem cells may be used to populate a
bioscaffold of an organ, and then directed to develop and grow into
specific organs for transplanting
reproductive system = a collection of organs that work together for
the purpose of producing a new organism including gonads (ovaries
and testes) and uterus
respiration = a process in living organisms involving the release of
energy from food; aerobic respiration occurs in the presence of
oxygen and involves the release of carbon dioxide; anaerobic
respiration occurs in the absence of oxygen and may involve the
production of carbon dioxide and ethanol or the production of lactic
acid, both aerobic and anaerobic respiration involve the oxidation of
complex organic substances, such as glucose or fatty acids
respiratory system = a biological system consisting of specific organs
and structures used for the process of breathing gaseous exchange and
respiration in an organism
ribosome = a small organelle consisting of RNA and associated
proteins found in large numbers in the cytoplasm of prokaryotic and
eukaryotic cells and on the rough endoplasmic reticulum of
eukaryotic cells. Each ribosome consists of two subunits. Amino
acids are assembled into polypeptides at ribosomes, during a process
called translation, where the ribosome moves along and reads
instructions from a length of messenger RNA
ring vaccination = used when a new case of disease is reported, All
people who have been in contact with/live close to the patient are
vaccinated
palisade cells = closely packed photosynthetic cells within leaves
partial pressure = the concentration of oxygen is measured by the
relative pressure that it contributes to a mixture of gases. This is
called that partial pressure of oxygen or pO2
parenchyma = a packing tissue in plants which fills spaces between
other tissues. In roots parenchyma cells may store starch, In leaves
some (called chlorenchyma) have chloroplasts and can
photosynthesis. In aquatic plants aerenchyma tissue is parenchyma
with air spaces to keep the plant buoyant
passive immunity = immunity achieved when antibodies are passed to
the individual though breast feeding or injection
pepsin = an enzyme that digests protein in the stomach of mammals
pericycle = a thin layer of meristem tissue between the endodermis
and the phloem in plant roots
peristalsis = the involuntary contraction and relaxation of the muscle
layer of the intestine or another canal within the body, creating wave
like movements which push the contents of the canal forward
personalised medicine = the development of designer medicines for
individuals
phospholipid = molecule consisting of one glycerol, two fatty acids
and one phosphate group
photomicrograph = a photograph of an image seen using an optical
microscope
phylum = a major subdivision of the kingdom. A phylum contains all
the groups of organisms that have the same body plan
physiological adaptations = affect the way that processes work
plasmodesmata = gaps in the cell wall containing cytoplasm that
connects two cells
plasmolysed = plant cell where the contents have shrunk due to loss
of water by osmosis and the plasma membrane has separated from the
cell wall
plasmolysis = the process in which the protoplast of a plant cell
shrinks as a result of water loss and the plasma membrane detaches
from the cell wall
platelets = small colorless disc shaped cell fragments without a
nucleus, found in large numbers in blood and involved in clotting
polar = where the change is not evenly distributed across the particle
polymorphic gene locus = a locus that has more than two alleles
polynucleotide = a large molecule consisting of many nucleotides
polysaccharides = polymers of monosaccharides that are made of
hundreds or thousands of monosaccharides monomers bonded
together
potometer = a device that can measure the rate of water uptake as a
leafy stem transpires
precision = the closeness of agreement between measured values
obtained by repeated measurements
primary defence = those that prevent pathogens entering the body
primary structure = the sequence of amino acids found in a protein
molecule
product = molecule produced from substrate molecules by an enzyme
catalyzed reaction
pulmonary artery = the artery carrying blood from the right ventricle
of the heart to the lungs for oxygenation
pulmonary vein = the vein carrying oxygenated blood from the lungs
to the left atrium
order = taxonomic group, a subdivision of the class using additional
information about the organism
organ = collection of tissues working together to perform a function
organ system = a number of organs working together to perform a
specific function
ossification = process of changing cartilage to bone by depositing
calcium phosphate
ostia = pores in the heart of an insect that allow blood from the body
to enter the heart
ovalocytosis = cells being more oval in shape that they usually are
oxygen tension = measured in units of pressure (kPa). See partial
pressure
oxygen uptake = the volume of oxygen absorbed by the lungs in one
minute
oxyhaemoglobin = a molecule of haemoglobin with oxygen
molecules loosely bound to it. When haemoglobin takes up oxygen, it
becomes oxyhaemoglobin