Changing the way you learn

Question	Answer
α-helix	A protein secondary structure - a right-handed spiral held in place by hydrogen bonds between adjacent C=O and NH groups.
Abundance	The frequency of occurrence of plants in a sampled area such as a quadrat.
Activation energy	The level of energy required to enable a reaction to take place. Enzymes reduce the amount of energy required to allow a reaction to proceed.
Active immunity	Immunity that is acquired by activation of immune system.
Active site	The area on an enzyme molecule to which the substrate binds.
Active transport	Movement of substances across membranes against their concentration gradient requiring the use of energy in the form of ATP. Active transport usually involves the use of transport proteins.
Adaptation	Feature of a living organism that increases its chances of survival for example thick fur on an animal that lives in a cold habitat.
Adenine	A nitrogen-containing organic base found in nucleic acids. It pairs with thymine in DNA and with uracil in RNA.
Adhesion	Force of attraction between molecules of two different substances.
Adipose	Describes tissue consisting of cells that store fat/lipid.
Affinity	An attractive force between substances or particles.
Allele	A version of a gene.
Allopatric	Speciation due to organisms of a species being separated by geographical barriers so that over time members of the two populations become so different that they cannot interbreed and are considered to be two different species.
Alveoli	Small air sacs in the lungs.
Amino acid	An organic compound that contains both an amino group (NH2) and a carboxyl group (COOH). Amino acids are the monomers of protein molecules.
Amylase	An enzyme that catalyses the hydrolysis of starch to maltose.
Amylose	Part of a starch molecule consisting of many thousands of glucose residues bonded together.
Anaphase	In mitosis the stage when the newly separated chromatids are pulled towards opposite poles of the nuclear spindle.
Anomalous	Describes a result/data point that does not appear to fit the pattern of the other results. It may be assumed to be anomalous if the experimenter has made an error or if the apparatus used is not suitable for the measurements being taken.
Antibiotics	Molecules produced by microorganisms that kill or limit the growth of other microorganisms
Antibodies	Protein molecules released by the immune system in response to an antigen which are capable of neutralising the effects of the antigen.
Antigen	A foreign molecule (which may be protein or glycoprotein) that can provoke an immune response. Organisms have antigens on their plasma (cell surface) membranes.
Antigen-presenting cell	A macrophage that has ingested a pathogen and displays the pathogens antigens on its cell surface membrane.
Apoplast pathway	The route taken by water between the cells or through the cell walls in a plant.
Arteriosclerosis	Hardening of the artery walls and loss of elasticity caused by atherosclerosis or by deposition of calcium.
Artificial immunity	Immunity acquired as a result of deliberate exposure to antigens or by the injection of antibodies.
Artificial selection	Also called selective breeding the process of improving a variety of crop plant or domesticated animal by breeding from selected individuals with desired characteristics.
Asexual reproduction	The production of genetically identical new organisms by a single parent organism.
Assay	The use of comparative studies or samples to determine the concentration or quantity of a substance in a sample.
Assimilation	Incorporation. Usually applied to the process of incorporating simple molecules of food produced by digestion into the living cells of an animal for use in metabolism. In plants refers to the incorporation of carbon from carbon dioxide into organic substances during photosynthesis. The newly formed compounds may be referred to as assimilates.
Atherosclerosis / atheroma	The process of deposition of fatty substances in the lining of arteries to form atheroma which may eventually lead to arteriosclerosis (hardening of the arteries).
ATP	Adenosine triphosphate a molecule used to store energy temporarily in organisms. The molecule is broken down to adenosine diphosphate + phosphate to release energy to drive metabolic processes.
Atrioventricular node (AVN)	A patch of tissue in the septum of the heart that conducts the electrical stimulus from the atria in the heart through to the Purkyne fibres.
Atrioventricular valves	Valves between the atria and ventricles that prevent backflow of blood.
Atrium	One of the upper chambers in the heart.
Autotroph	An organism that makes its own food from simple inorganic molecules such as carbon dioxide and water. Some (photoautotrophs) e.g. plants use light as the source of energy. Some (chemoautotrophs) e.g. some bacteria use chemical energy. Autotrophs are the producers in a food chain.
Base-pairing rules	Complementary base-pairing between nitrogenous bases in nucleic acids. Adenine pairs with thymine (or uracil). Guanine pairs with cytosine.
Benedicts test	Test for reducing sugars. The substance is heated to 80?şC with Benedicts reagent. If a reducing sugar is present the Benedicts reagent changes from blue to red/red precipitate.
Binary fission	Method of cell division in bacteria. The DNA replicates and the cell divides into two each having the same DNA as the parent cell. It does not involve mitosis.
Binomial system	A system of naming living things using two Latin words the genus name and the specific name.
Biodiversity	The number and variety of living things to be found in the world in an ecosystem or in a habitat.
Biuret test	A biochemical test for the presence of proteins.
Body mass index	Numerical value found by dividing an individuals mass in kg by the (height in m)2 and used to assess if the individual is underweight acceptable weight overweight or obese.
Bohr shift / Bohr effect	The effect of carbon dioxide concentration on the affinity of haemoglobin for oxygen.
Bronchi	Airways in the lungs that lead from the trachea to the bronchioles.
Bronchioles	Airways in the lungs that lead from the bronchi to the alveoli.
Buffer	A chemical system that resists changes in pH by maintaining a constant level of hydrogen ions in solution. Certain chemicals dissolved in the solution are responsible for this.
Calibration	To determine the quantity of a substance in a solution by taking readings from solutions containing known amounts of the solution (e.g. by colorimetry) and constructing a calibration curve on a graph. This can then be used to determine the amount of that substance in solutions of unknown concentration. Also to determine the value of intervals of a scale on an instrument such as a thermometer.
Cambium	Plant tissue in the stem and root that contains dividing cells.
Carbaminohaemoglobin	The molecule resulting from combination of carbon dioxide and haemoglobin.
Carbohydrate	A class of biological molecules with the general formula Cx(H2O)y. It includes sugars starches glycogen and cellulose.
Carcinogen	A substance that causes cancer.
Cardiac cycle	The sequence of events making up one heartbeat.
Cardiac muscle	The muscle found in the heart. It has its own intrinsic heartbeat (it is myogenic).
Carnivore	An animal that eats meat.
Carrier protein	A protein found in membranes which is capable of carrying a specific molecule or ion through the membrane by active transport.
Cartilage	A flexible slightly elastic connective tissue.
Cartilage ring	A flexible ring of cartilage that holds the airways open.
Casparian strip	A strip of waterproof material (suberin) in the cell walls of root endodermis cells. It blocks the apoplast pathway.
Catalyst	A substance that increases the rate of a reaction but does not take part in the reaction and so is re-usable.
Cell signalling	Processes that lead to communication and coordination between cells. Hormones binding to their receptors on the cell surface membrane are an example.
Cell surface membrane	See Plasma membrane.
Cellulose	A carbohydrate polymer (of ?-glucose) that forms plant cell walls.
Centriole	An organelle from which the spindle fibres develop during cell division in animal cells.
Centromere	The region of a chromosome where two sister chromatids are joined together and where the spindle fibre attaches during cell division.
Channel protein	A protein pore that spans a membrane through which very small ions and water soluble molecules may pass.
Chemotaxis	The movement of cells or organisms towards or away from a particular chemical.
Chloride shift	The movement of chloride ions into red blood cells to balance the loss of hydrogencarbonate ions.
Chlorophyll	Pigments found in chloroplasts of plant (and some protoctist) cells. Each molecule consists of a hydrocarbon tail and a porphyrin ring head with a magnesium atom. Chlorophyll absorbs red and blue light trapping the energy and reflects green light.
Chloroplast	An organelle found in plants which contains chlorophyll and is responsible for photosynthetic activity in the plant.
Cholesterol	A lipid molecule (not a triglyceride) found in all cell membranes and involved in the synthesis of steroid hormones.
Chromatid	A replicated chromosome appears as two strands in early stages of cell division. Each strand is a chromatid.
Chromatin	Material staining dark red in the nucleus during interphase of mitosis and meiosis. It consists of nucleic acids and proteins. Chromatin condenses into chromosomes during prophase of nucler division.
Chromosome	A linear DNA molecule wrapped around histone proteins found in the nucleus. Chromosomes become visible in prophase of cell division.
Cilia	Short extensions of eukaryotic cells typically 210 ľm long and 0.03 ľm in diameter. They may be used for locomotion or to move fluids or mucus over a surface for example in the mammalian respiratory tract.
Ciliated epithelium	Epithelial cells that have cilia on their cell surface.
Class	Taxonomic group used in classification of living organisms. Members of the same class share some characteristics. Within each class are orders consisting of families genera and species. Similar classes are grouped into a phylum.
Classification	The organisation of living organisms (or other items) into groups according to their shared similarities.
Clonal expansion	The division of selected cells by mitosis to increase their numbers.
Clonal selection	The selection of cells (of the immune system) with a specific receptor site. These cells will undergo clonal expansion as part of the immune response.
Clones	Genetically identical cells or individuals.
Coenzyme	An organic non-protein molecule that binds temporarily with substrate to an enzyme active site. It is essential for enzyme activity.
Cofactor	A molecule or ion that helps an enzyme to work. It may be an inorganic ion or an enzyme.
Cohesion	The attraction between water molecules due to hydrogen bonding.
Collagen	A structural fibrous protein found in connective tissue bones skin and cartilage. It accounts for 30% of body protein.
Companion cell	A cell in the phloem involved in actively loading sucrose into the sieve tube elements. The companion cell is closely associated with a phloem sieve element to which it is linked by many plasmodesmata.
Competitive inhibitor	A substance that reduces the rate of an enzyme-controlled reaction by binding to the enzymes active site.
Complementary (base / structure)	Refers to structures that fit together because their shapes and/or charges match up. For example adenine and cytosine are complementary bases in DNA.
Concentration gradient	The difference in concentration of a substance between two regions.
Condensation	A type of chemical reaction in which two molecules are joined together by means of a covalent bond to form a larger molecule and at the same time a water molecule is released.
Connective tissue	A type of tissue that consists of separate cells held together by a ground substance (matrix).
Conservation ex situ	Conservation in areas other than the natural habitat.
Conservation in situ	Conservation in the natural habitat.
Constrict	To make narrow. For example vasoconstriction is the narrowing of blood vessels.
Continuous variation	Variation between living organisms where there is a range of intermediates such as height hair colour and intelligence in humans. These characteristics are determined by many genes that interact. The expression of these genes is also influenced by the environment.
Control	Part of an experimental investigation set up to show that the variable being investigated is responsible for the change observed.
Coronary arteries	Arteries that carry blood to the heart muscle.
Cortex	Tissue in plant roots and stems between epidermis and vascular tissue.
Cotransporter protein	A protein in a cell membrane that allows movement of one molecule when linked to the movement of another molecule in the same direction by active transport.
Covalent bond	A chemical bond formed by the sharing of one or more electrons between two atoms.
Crenation	State of animal cells when they have been immersed in a solution of lower water potential and have lost water by osmosis. They become shrivelled.
Cristae	The folds found in the inner membrane of a mitochondrion. Stalked particles containing ATP synthase are found on cristae.
Cytokines	Hormone-like proteins produced by vertebrate (including mammalian) cells which are used for communication between cells allowing some cells to regulate the activities of others.
Cytokinesis	The division of the cell following nuclear division to form two new cells.
Cytosine	A nitrogen-containing organic base found in nucleic acids. It pairs with guanine in DNA.
Cytoskeleton	The network of protein fibres and microtubules found within the cell that gives structure to the cell and is responsible for the movement of many materials within it.
Deamination	Removal of amine (NH2) group from an amino acid
Denaturation	An irreversible change in the tertiary structure of a protein molecule. It leads to loss of function in most proteins.
Deoxygenated	Blood with haemoglobin that carries no or little oxygen.
Deoxyribose	The 5-carbon sugar in DNA nucleotides.
Diaphragm	A sheet of muscular and fibrous tissue separating the chest cavity from the abdominal cavity.
Diastole	The period when the heart muscle in the ventricles is relaxing and blood pressure is at its lowest.
Differentiation	The development and changes seen in cells as they mature to form specialised cells.
Diffusion	The net movement of molecules or ions in a gas or liquid from an area of high concentration to an area where they are less concentrated.
Diffusion gradient	The gradient in molecular concentration (the difference in concentrations) that allows diffusion to occur.
Dilate	To make wider. For example vasodilation is when the lumens of blood vessels become wider.
Dipeptide	A molecule consisting of two amino acids joined by a peptide bond.
Diploid	Cells or organisms that have two copies of each chromosome in their nuclei.
Disaccharide	A molecule consisting of two monosaccharide sugars joined by a glycosidic bond.
Discontinuous variation	Variation between living organisms within a species where there are discrete categories and no intermediates e.g. blood grops A B AB or O in humans. This type of variation is determined by one gene.
Disease	A departure from full health.
Dissociation	The breakdown of a molecule into two molecules atoms or ions. For example the release of oxygen from oxyhaemoglobin.
Dissociation curve (oxyhaemoglobin)	The curve on a graph showing the proportion of haemoglobin that is saturated with oxygen at different oxygen tensions.
Diversity	Being diverse usually used in the context of biodiversity where there are many different types of organisms present or genetic diversity within a population of organisms that have genetic variation.
Division of labour	Any system where different parts perform specialised functions each contributing to the functioning of the whole.
DNA	Deoxyribonucleic acid a polymer of nucleotide molecules that form the instructions for the synthesis of proteins found within organisms. These nucleotides contain the 5-carbon sugar deoxyribose.
Domain	Classification group. Carl Woeses three-domain classification system divides the Kingdom prokaryotae into two domains and places all Eukaryotes in the third domain.
Double circulatory system	A transport system in which blood travels twice through the heart for each complete circulation of the body.
Double helix	Describes the structure of DNA a twisted helix of two strands with bases joining the strands.
Ecosystem	All the living organisms and all the non-living components in a specific area and their interactions.
Elastic fibres	Long fibres of the protein elastin that have the ability to stretch and recoil.
Elastic tissue	Tissue containing the protein elastin which is able to stretch and recoil.
Electrocardiogram	Trace (graph) showing the electrical activity of the heart muscle (atria and ventricles) during a cycle.
Emulsion	A suspension of one material in another as droplets because it does not dissolve. For example fat droplets dispersed in water.
Endemic	Describes a disease that is always present in an area. May also mean a species that is found only in a particular area and nowhere else.
Endocytosis	The process of taking materials into a cell by surrounding them with part of the plasma membrane which then pinches off to form a vesicle inside the cell. This is an active process requiring ATP.
Endodermis	A ring of cells between the cortex of a root and the area housing the xylem and phloem.
Endoplasmic reticulum (ER)	A series of membrane-bound flattened sacs extending from the outer nuclear membrane through the cytoplasm. It may appear rough (rough ER) when ribosomes are attached to the outer surface and it is involved with synthesis of proteins. It may appear smooth (smooth ER) when ribosomes are not attached and it is involved with lipid metabolism or membrane formation.
Endothelium	A tissue that lines the inside of a structure such as a blood vessel.
Endotherm	An animal that produces heat within its cells from respiration to maintain a constant body temperature.
End-product inhibition	The regulation of metabolic pathways where the last product in a sequence of enzyme-controlled reactions becomes an inhibitor of one of the enzymes earlier in the sequence.
Environmental impact assessment	An assessment of the damage that may be caused to the (local) environment by a proposed development.
Enzyme	A protein molecule that acts as a biological catalyst.
Enzymeproduct complex	The intermediate structure in which product molecules are bound to an enzyme molecule.
Enzymesubstrate complex	The intermediate structure formed when a substrate molecule binds to an enzyme molecule.
Epidemic	Describes a disease that spreads to many people quickly and affects a large proportion of the population.
Epidemiology	The study of patterns of disease and the factors that influence their spread.
Epidermis	Outer layer(s) of cells of a multicellular organism. Plants have a single layer surrounding the tissues of roots stems and leaves. Invertebrates have an epidermis made of a single layer of cells that secrete a cuticle. Vertebrate (including mammals) epidermis consists of several layers the outer layer being made of dead cells.
Epithelium	A tissue that covers the outside of a structure.
Erythrocytes	Red blood cells.
Ester bond	The bond formed when fatty acid molecules are joined to glycerol molecules in condensation reactions.
Ethanol emulsion test	A biochemical test for the presence of lipids.
Eukaryote	An organism having cells with a nucleus and membrane-bound organelles.
Eukaryotic cell	Cells that have a nucleus inside a nuclear envelope and other membrane-bound organelles.
Evolution	Gradual process by which the present diversity of living organisms arose from simple primitive organisms that were present about 4000 million years ago. New species have arisen by natural selection.
Evolutionary distance	A measure of how far apart two organisms are on the evolutionary scale. Closely related species will be a short distance apart while distant relatives will be further apart.
Exchange surface	A specialised area adapted to make it easier for molecules to cross from one side of the surface to the other.
Exocytosis	The process of removing materials from the cell by fusing vesicles containing the material with the plasma membrane (cell surface membrane).
Extinction	The death of the last individual in a species.
Extracellular	Outside the cell. Extracellular enzymes/digestion work outside the cell.
Facilitated diffusion	The passive movement of molecules across membranes down their concentration gradient which is aided by transport (carrier) protein molecules. No metabolic energy is required.
Family	Taxonomic group used in the classification of living organisms. Related genera are placed in the same family.
Fat	Mixture of lipids mainly triglycerides with saturated fatty acids that is solid at body temperature. In living organisms they act as an energy store insulation waterproofing the outer layer and may give buoyancy.
Fatty acid	A molecule consisting of a fatty (hydrocarbon) chain and an acid (carboxylic acid ?COOH) group.
Fermenter	A vessel used to grow microorganisms in large numbers.
Fertiliser	A substance added to soil to enhance the growth of plants.
Fibrillation	A state in which the chambers in the heart contract out of rhythm.
Fibrous protein	A protein with a relatively long thin structure which is insoluble in water and metabolically inactive often having a structural role within the organism.
Flaccid	A term used to describe plant tissue where the cells have lost turgor and are not firm.
Fluid mosaic (model)	The model of cell membrane structure proposed by Singer and Nicholson a phospholipid bilayer with proteins floating in it.
Food tests	Simple tests that show the presence of various biological molecules in samples or structures.
Gamete	Sex cells usually haploid (one set of chromosomes). Male and female gametes can fuse during sexual reproduction to form zygotes (diploid).
Gaseous exchange	The movement of gases by diffusion across a barrier such as the atreous wall.
Gated channels	Protein channels found in cell membranes which can be opened or closed in response to cell signals.
Gene	A length of DNA that carries the code for the synthesis of one (or more) specific polypeptide.
Gene pool	The sum total and variety of all the genes in a population or species at a given time.
Genetic erosion	The loss of genetic variation due to (artificial) selection.
Genome	All the genetic material inside an organism (or cell).
Genus	Taxonomical group used in the classification of living organisms. Species that are similar are placed in the same genus.
Globular proteins	Proteins with relatively spherical molecules soluble in water often having metabolic roles in organisms.
Glucose	A 6-carbon monosaccharide sugar.
Glycerol	A 3-carbon (alcohol) molecule. It forms the basis of lipids when fatty acids are bonded to it.
Glycogen	A polysaccharide found in animal cells. Formed from the bonding together of many glucose molecules used as a store of glucose.
Glycolipid	A lipid with carbohydrate molecules attached.
Glycoprotein	A protein with carbohydrate molecules attached.
Glycosidic bond	The covalent bond formed when carbohydrate molecules are joined together in condensation reactions.
Goblet cells	Mucus-secreting cells in epithelial tissue.
Golgi body	Membrane-bound organelle in eukaryote cells. Its functions are: to modify proteins made at the rough endoplasmic reticulum into glycoproteins; to package proteins for secretions outside the cell; to make lysosomes; in plant cells to secrete carbohydrates that make up the cell walls.
Guanine	A nitrogen-containing organic base found in nucleic acids. It pairs with cytosine.
Guard cells	In pairs these form the stomatal pore in the epidermis plants. They control the opening and closing of the pore by changes in their turgidity.
Habitat	The place where an organism or population lives. It includes the climatic topographic and edaphic factors as well as the plants and animals that live there.
Haem	The iron-containing prosthetic group found in haemoglobin.
Haemoglobin	The protein that carries oxygen in the red blood cells.
Haemoglobinic acid	The acid produced when haemoglobin takes up hydrogen ions.
Haemolysis	(First observed in red blood cells.) The rupturing of animal cell surface membranes and subsequent release of their contents when animal cells are placed in a solution of higher water potential and water enters by osmosis.
Haploid	A cell or organism that has one set of chromosomes/one copy of each chromosome.
Health	Complete mental physical and social wellbeing.
Herbivore	An animal that eats plant material.
Heterotroph	Organism that has heterotrophic nutrition it gains nutrients from complex organic molecules. These molecules are digested by enzymes to simple soluble molecules and then built up into the complex molecules that the organism requires. Heterotrophs are consumers or decomposers in a food chain.

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	Created by Cameron Rogers over 6 years ago