CCEA GCSE Biology - Denmour Boyd, James Napier 2017


Abiotic factor A physical (non-living) factor which affects an organism

Absorption The ability of cells to take in substances through their cell membrane

Active immunity A type of immunity produced by the body producing antibodies

Active site The part of an enzyme molecule into which the substrate molecule fits because they have complementary shapes

Active uptake (transport) A process which uses energy released by respiration to move substances from a low concentration to a high concentration

Aerobic A chemical process which requires oxygen

Algal bloom The excessive growth of green algae on the surface of lakes and rivers

Allele One of two possible versions of a particular gene

Alveolus A single bubble-shaped air space in the lungs

Amino acids A group of twenty molecules which join together to form proteins

Amniocentesis A process in which foetal cells are obtained from the amniotic fluid and then examined for the presence of genetic abnormalities

Amnion The lining that contains the amniotic fluid

Amniotic fluid The fluid within the amnion, which cushions the foetus

Anaerobic A chemical process which can take place in the absence of oxygen

Angioplasty The process in which dye is injected into the blood to allow examination of (diseased) blood vessels

Antibiotic A chemical produced by fungi that kills bacteria

Antibiotic-resistance An antibiotic-resistant bacterium cannot be killed by (at least one type of) antibiotic

Antibody A structure produced by lymphocytes that has a complementary shape (and can attach to) the antigens on a particular microorganism

Antidiuretic hormone A chemical messenger molecule, produced in the brain which controls the amount of water reabsorbed by the kidneys

Antigen A distinctive marker on a microorganism that leads to the body producing specific antibodies

Aorta The blood vessel that carries oxygenated blood from the heart to the body

Apical Refers to the tip of a plant shoot or root

Artery A blood vessel that carries blood under high pressure away from the heart

Aseptic technique The procedures used to prevent contamination when culturing microorganisms in the laboratory

Auxin A plant hormone which controls the growth of plant cells

Axon The extension of the neurone that gives a neurone its long length (and its ability to transmit nerve impulses over a long distance)

Bacteria A group of microorganisms which have a cell wall without cellulose and no nucleus

Base triplet A sequence of three bases in DNA that codes for a particular amino acid

Belt transect A method of sampling used when a habitat changes from one side to the other

Benign tumour A tumour that is surrounded by a capsule and does not spread around the body

Biodiversity The variety of living organisms in an area

Biotic factor A factor caused by the living organisms in an area

Blood pressure The force exerted by blood in the heart and the circulatory system

Booster vaccination A second (additional) vaccination that is given in a vaccination programme to combat a particular disease

Breathing rate The number of breaths per unit time

Bronchitis The narrowing of the airways in the lungs, usually caused by smoking tobacco

Cancer Uncontrolled cell division

Capillary A very thin blood vessel through which the exchange of material between blood and cells takes place

Carbohydrate A type of food molecule, including sugars, starch and cellulose, that are made up of only carbon, hydrogen and oxygen and are the main source of energy in the diet

Carbon cycle The cycling of carbon-containing substances in the environment

Cardiac output The volume (amount) of blood the heart pumps per minute

Catalyst Something which speeds up the rate of a reaction but is unchanged by the reaction

Cell The basic building block in the structure and function of living things

Cell lysis The bursting of a cell due to too much water being taken in by osmosis

Cell membrane The membrane bounding the outside of living cells controlling the substances entering and leaving the cell

Cell sap The liquid found in cell vacuoles

Cellulose A complex carbohydrate molecule found in plant cell walls

Cell wall A stiff layer outside the cell membrane of plant, bacterial and fungal cells which provides support

Central Nervous System The term referring to the coordinator in the nervous system, i.e. the brain and the spinal cord

Cervix The opening of the uterus

Chemotherapy A form of cancer treatment in which drugs are used to kill cancer cells

Chlorophyll A green coloured chemical in chloroplasts which contains magnesium and is responsible for absorbing light energy during photosynthesis

Chloroplast A structure in the cytoplasm of plant cells which contains chlorophyll and carries out photosynthesis

Chromosomes Genetic structures usually occurring in functional pairs in the nucleus of cells (except gametes and bacteria)

Circulatory system The body system that includes the heart and blood vessels

Clinical trials The stages involved in testing drugs and medicines that use human volunteers

Cloning A laboratory process which uses a single cell to grow a group of genetically identical cells or organisms

Communicable disease A disease that can be passed from one organism (person) to another

Community All the species normally found in a habitat

Compensation point Occurs in a plant when the environmental conditions [temperature, light intensity and carbon dioxide concentration] cause the rate of photosynthesis to equal the rate of respiration, resulting in no net gas exchange

Competition The interaction between two or more organisms as they try to get sufficient resources to survive

Complementary Shapes which fit into each other as in an enzyme and its substrate

Concentration gradient The difference in the concentration of a molecule or ion present in one area compared to another area

Condom A barrier contraceptive method

Consumer An animal that gains its food from consuming other organisms

Continuous variation The type of variation characterised by gradual change in a characteristic across a population

Contraception A method used to try to avoid pregnancy

Contraceptive pill A contraceptive tablet containing hormones and prevents pregnancy by affecting hormone levels thereby preventing eggs being released

Coordinator A part of the nervous system (i.e. brain or spinal cord) that links receptors and effectors

Coronary artery The very narrow arteries that supply the heart tissue with glucose and oxygen

Cuticle A waxy layer on the outer surface of a plant epidermis cell, allowing light through while reducing water loss

Cystic fibrosis A genetic condition caused by having two recessive alleles of a particular gene

Cytoplasm The contents of a cell between the cell membrane and the nucleus where chemical reactions take place

Decomposers An organism which breaks down the tissues of dead organisms and excretory products

Deforestation The cutting down of trees

Denaturation An irreversible change in the shape of an enzyme which means it is no longer complementary to the substrate and cannot catalyse the reaction

Denitrification A process carried out by bacteria in anaerobic conditions which changes nitrates into nitrogen gas

Destarch A procedure which removes stored starch from plants

Diabetes (type 2) A disease that develops in older people, associated with poor diet and obesity, in which they have difficulty controlling the concentration of their blood glucose because the insulin they produce does not work effectively

Diaphragm A muscular sheet between the thorax and abdomen which helps bring about breathing

Differentiate The ability of a cell to change into a specialised cell with adaptations to a particular function

Diffusion The movement of molecules or ions from where they are in high concentration to where they are in a lower concentration

Digestion Enzymes breaking down large, complex food molecules into small, simple soluble ones which can be absorbed

Diploid The normal chromosome number

Discontinuous variation The type of variation in which all the individuals can be clearly divided into two or more groups and there are no intermediate states

DNA The molecule that forms genes and chromosomes

Dominant In the heterozygous condition, the dominant allele will override the recessive allele

Double circulation The type of circulation in humans in which blood travels through the heart twice for each complete circulation of the body

Double helix The structure of DNA

Downstreaming The term used to describe the extraction, purification and packaging of insulin during genetic engineering

Down’s Syndrome A genetic condition in humans caused by having one extra (47) chromosome

Ecosystem An area in which a community of organisms interact with each other and their physical surroundings

Effector An organ (a muscle or gland) which responds to a stimulus by causing a change

Egested The removal of faeces

Egg (ovum) A female gamete

Electron microscope A microscope which uses a beam of electrons instead of light and allows much greater detail of cells to be visible

Emphysema Damage to the gas exchange surfaces in the lungs, usually caused by cigarette smoke

Endothermic A chemical reaction that absorbs heat

Energy flow The transfer of energy between the trophic levels in food chains and food webs

Environment The conditions which surround and effect an organism in their habitat

Enzyme specificity The ability of an enzyme to catalyse only one type of substrate

Epidermis An outer layer of cells

Eutrophication The process occurring in areas of fresh water which have too many nitrates, leading to the death of animal species

Evolution The change in a species over time—evolution also leads to the formation of new species

Excretory system An organ system which removes wastes from the body

Exothermic A chemical reaction which releases heat

Extinction A species is extinct if there are no living members of that species left

Fatty acids Long chain molecules which join to glycerol to form fats and oils (lipids)

Female sterilisation The cutting of the oviducts to prevent pregnancy

Fertilisation The fusion (joining) of a haploid sperm cell and a haploid egg cell to form a diploid zygote

Fertiliser A substance, either a waste product from animals (natural fertiliser) or produced by the chemical industry (artificial fertiliser), which provides plants with the chemicals they need to grow

Field of view The circle of light visible in a light microscope

Flagellum The tail of a sperm used for movement

Food chain A sequence of organisms which feed off each other, passing nutrients and energy

Food web A number of interlinked food chains

Fossil The remains of a living organism that has been preserved (usually in rocks) for millions of years

Gamete Sex cell that contains only one chromosome from each pair

Gas exchange The movements of gases between an organism and its surroundings

Gene Short section of DNA (chromosome) that codes for a particular characteristic

Genetic condition A condition caused by problems in genes or chromosomes

Genetic engineering The deliberate modification of the genome (DNA) in an organism to introduce desirable effects

Genetic screening A process used to test people for the presence of particular harmful alleles or other genetic abnormalities

Genome The entire genetic material (all the DNA) in an organism

Genotype The genetic make-up of an organism represented by symbols (letters), e.g. tt

Global warming The rise in the Earth’s temperature

Glycerol A molecule which makes up part of all fats (lipids)

Glycogen A complex carbohydrate molecule used for storage in animals

Habitat The place where an organism or population is normally found

Haemoglobin A molecule containing iron that is found in red blood cells

Haemophilia A sex-linked conditions that is almost exclusively found in males

Haploid A cell or nucleus with half the normal number of chromosomes

Heart disease Any disease which prevents the heart from functioning normally

Heart valve A structure in the heart that prevents the backflow of blood

Heterozygous The two alleles of a gene are different (one dominant and one recessive allele)

Homeostasis The ability of the body to maintain an almost constant internal environment

Homozygous The two alleles of a gene are the same

Huntington’s disease A genetic condition caused by the presence of a dominant allele of a particular gene

Ileum The longest part of the small intestine

Immunity Freedom from disease

Immunotherapy A form of treatment of cancer in which antibodies are injected into the patient. The antibodies attach to cancer cells and help the body’s immune system destroy the cancer cells

Implantation The term describing the attachment of the ball of cells (embryo) following fertilisation to the uterus lining

Independent assortment A process that takes place during meiosis, in which chromosomes are reassorted in the formation of gametes

Indicator species A species which can be used to monitor the level of pollution in a habitat

Infertility The inability of someone to have children

Inhibitor A molecule which fits into the active site of an enzyme and stops the normal substrate entering so reducing the reaction rate of the enzyme

Intercellular space A space between cells as in a leaf

Intercostal muscles The muscles in the chest wall that contract and cause the ribs to move out thereby increasing the volume of the thorax during breathing

In-vitro fertilisation Fertilisation outside the body

In-vitro testing Testing of medicines and drugs in the laboratory

Kinetic energy The energy of movement

Left atrium The heart chamber that receives blood from the lungs

Left ventricle The heart chamber that pumps blood around the body

Legume A group of plants including peas, beans and clover

Lethargy Tiredness, a total lack of energy

Leukaemia A type of cancer in which some types of blood cells increase out of control

Limiting factors Any factor which affects a chemical process such as photosynthesis and is at a level less than optimum will slow or limit the process

Lipid A fat or oil molecule

Lock and key model Model used to explain how an enzyme reacts with its substrate

Lymphocyte A type of white blood cell that produces antibodies

Lysis The process that describes the rupturing of an animal cell when it takes in too much water by osmosis

Magnification The number of times the length of an image is larger than the actual length of the object

Male sterilisation The cutting of the sperm tubes (vasectomy) to prevent pregnancy

Malignant tumour A tumour that is not surrounded by a capsule and capable of spreading around the body

Meiosis A type of cell division that produces cells (gametes) that have half the normal chromosome number (haploid cells)

Memory lymphocyte A special type of lymphocyte that can remain in the body for many years and produce antibodies quickly when required

Menstrual cycle The monthly cycle in females of reproductive age that prepares the body for pregnancy

Meristem Cells at the tip (apex) of a plant stem or root which constantly divide to form new cells

Mesophytic Land plants which grow in temperate climates

Mitochondria Structures in the cytoplasm where the reactions of respiration occur

Mitosis A type of cell division that produces cells genetically identical to the parent cell and to each other

MRSA A type of bacterium that is resistant to most antibiotics

Multi-celled An organism made up of many cells

Mutation Random change in the number of chromosomes or type of gene

Myelin sheath A fatty layer around the axon that both acts as an insulator and speeds up nerve impulses

Natural selection The process in which the better adapted individuals survive (at the expense of the less well adapted individuals) and pass on their genes to their offspring

Negative feedback A process involved in homeostasis which, by constant monitoring of an internal factor in the body, causes any change to be reversed, bringing the factor back to normal values

Nerve impulses Small electrical charges that pass along neurones

Neurones The cells (also called nerve cells) of the nervous system

Nicotine The addictive substance in tobacco smoke, which also affects heart rate

Nitrifying bacteria Bacteria that convert ammonium compounds to nitrates in the nitrogen cycle

Nitrogen fixation A process which allows bacteria to change nitrogen gas into nitrates

Nuclear membrane The membrane surrounding the nucleus

Nucleus The large structure in a cell containing chromosomes

Nutrient cycle The cycling of substances (e.g. nutrients and elements) in the environment

Obesity Being extremely overweight

Oestrogen The female sex hormone produced by the ovaries, which both causes the repair and build-up of the uterus lining following menstruation and stimulates ovulation

Optimum The value of a factor which allows a reaction to happen at its fastest rate

Optimum dosage The best amount or concentration of a drug or medicine to use when treating patients

Osmoregulation The ability to control the amount of water in the body

Osmosis The diffusion of water molecules from a dilute solution to a more concentrated solution through a selectively permeable membrane

Ovary The female organ that produces eggs (ova)

Oviduct The structure that carries eggs (ova) from the ovary to the uterus

Ovulation The release of an egg by an ovary

Palisade mesophyll The upper of the two layers of mesophyll cells in the centre of a leaf, closely packed end on to the upper surface and containing many chloroplasts. They are the main site of photosynthesis

Passive immunity A type of immunity produced by injecting antibodies

Pedigree diagram A diagram that shows how a particular condition is inherited through the different generations in a family

Peer review A process of validation in which other scientists in the same field review research and provide feedback and/or suggest refinements

Penicillin The first antibiotic developed

Penis Organ that introduces sperm into the vagina

Percentage cover A method of estimating the amount of a plant species in a quardat

Phagocyte A type of white blood cell that destroys microorganisms by engulfing them and digesting them (phagocytosis)

Phenotype The outward appearance of an individual, e.g. tall

Photosynthesis The chemical process in green plants which uses light energy to convert carbon dioxide and water into sugars and oxygen

Phototropism A growth movement in plants in response to light

Placenta The structure that links the uterus wall to the foetus via the umbilical cord. It is here that exchange of materials takes place between the mother and the foetus

Plasma The liquid part of the blood that functions as a transport medium

Plasmid A small circular ring of DNA in a bacterium

Plasmolysis A plant cell is plasmolysed when it has lost water by osmosis and its membrane separates from the cell wall

Platelets Blood components that help convert fibrinogen to fibrin in the processes of blood clotting and scab formation

Pleural membranes These membranes line the outside of the lungs and the inside of the chest wall

Population A group of organisms of the same species living in an area

Potometer A piece of apparatus that can be used to compare rates of transpiration in different conditions and to investigate the factors affecting the rate of water uptake by a plant

Preclinical trials The stages involved in testing drugs and medicines that occur before testing on human volunteers

Primary response The response of the immune system to the first exposure of a particular type of microorganism / antigen

Producer An organism that produces food, a plant, which is at the start of a food chain

Product A molecule produced during a chemical reaction

Progesterone The female hormone that maintains the build-up of the uterus lining and prepares the uterus for pregnancy

Prostate gland The male gland that adds fluid to nourish the sperm

Protein A type of food molecule, made up of carbon, hydrogen, oxygen and nitrogen, formed by long chains of amino acids that are important in the structure and functioning of cells

Pulmonary artery The blood vessel that carries deoxygenated blood from the heart to the lungs

Pulmonary vein The blood vessel that carries oxygenated blood from the lungs to the heart

Punnett square A grid (table) used to work out the offspring in a genetic cross

Putrefying bacteria Decomposing bacteria

Pyramid of biomass A diagram showing the mass of living tissue, biomass, at each stage of a food chain

Pyramid of number A diagram showing the numbers of organisms at each stage of a food chain

Quadrat An apparatus, usually a square frame, used to sample an area

Radiotherapy The use of high energy X-rays in the treatment of cancer

Random sampling A method of sampling in which the position of each sample does not depend on the position of the previous sample and the overall sample of the area being studied is unbiased, representative

Reagent A chemical used as a test for the presence of a particular substance

Receptor A structure which can detect a change (stimulus) in the environment

Recessive An allele that will only show a characteristic if both alleles are present (and there is no dominant allele present)

Recovery rate The time taken for the breathing or heart rate to return to normal after exercise

Red blood cells Blood cells that carry oxygen around the body

Reflex action A very fast response to a stimulus by means of a nervous pathway involving a small number of nerve cells

Reliable results Results which, when repeated, are consistent

Representative sample A sample which has all the same characteristics as the whole population

Resolution The ability of a microscope to distinguish detail in an image

Respiration Respiration is the release of energy from food

Response The action of an effector

Restriction enzymes Enzymes used in genetic engineering that cut DNA at particular positions

Right atrium The heart chamber that receives blood from the vena cava

Right ventricle The heart chamber that pumps blood to the lungs

Sample A small part of an area or population

Saprophyte A bacterium or fungus which decomposes material by releasing enzymes onto the surface and absorbing the breakdown products

Scale bar A line drawn on or near a magnified image showing a given length magnified by the same amount

Scrotum Sac that holds and protects the testes

Secondary response The rapid immune response upon a second (or additional) infection by a particular microorganism

Selective breeding The selection and subsequent breeding of organisms chosen by man for their desirable characteristics

Selectively permeable The ability of a membrane to allow some substances to pass through while preventing others

Sex chromosome One of the two chromosomes that determines the sex of an individual

Sex linkage The way in which certain genetic conditions are more likely to affect a particular sex

Side effects An unwanted or unplanned effect of a drug on a person

SI units The International System of units based on the metre, kilogram and second

Specialised A cell that has adaptations to a particular function

Sperm A male gamete (sex cell) formed by meiosis

Sperm tubes The structures that carry sperm from the testes to the penis

Spongy mesophyll The lower of the two layers of mesophyll cells in the centre of a leaf, loosely arranged with airspaces. They are the main site of gas exchange

Stain A chemical which, when added to cells, colours some parts of the cells more than others making the structures more noticeable

Stem cells Simple cells in animals and plants that can continue to divide to produce more stem cells which in turn can change into one or several types of specialised cells

Stent A small mesh-like structure that is inserted into a blood vessel to keep the lumen open

Sticky end The term used to describe the overlapping (and non-paired) strand that is left when DNA is cut by a restriction enzyme

Stimulus A feature of the environment that stimulates a receptor in the nervous system

Stomata The small pores in the surface of plant leaves

Stroke A type of cardiovascular disease that affects the brain

Substrate A molecule that is acted upon by an enzyme

Superbug A type of bacterium that is resistant to a number of antibiotics

Surface area A measure of the external boundary of an object, a cell or an organism that is exposed to the environment

Surface epithelium cells A single layer of cells covering the outer surface of multi-celled organisms

Sustainable woodlands Woodlands harvested at a rate which allows them to continue growing without damaging the environment

Synapse The small junction (gap) between adjacent neurones

Transmitter substance A chemical which diffuses across a synapse

Testes The structure that produces sperm in males

Testosterone The male sex hormone produced by the testes

Thermostable enzymes Enzymes which are able to function over a wide range of temperatures without being broken down

Thorax The area between the lungs and the chest wall

Transpiration The evaporation of water from mesophyll cells followed by diffusion through air spaces and stomata

Trophic level The level at which an organism feeds in a food chain or web

Turgid (turgor) The state of a plant cell when it has gained enough water by osmosis for the cell membrane to push against the cell wall making the cell firm. Turgor provides support in plants

Umbilical cord The structure containing blood vessels that links the placenta to the foetus

Urethra The tube through which the sperm leaves the penis

Uterus The female organ in which the foetus will develop if pregnancy occurs

Vaccination The injection of dead or modified pathogens (disease-causing microorganisms) with the purpose of raising antibody and memory lymphocyte levels in the blood

Vacuole A liquid filled space in the cytoplasm of a cell which is large and permanent in plant cells

Vagina The part of the female reproductive system into which sperm is deposited during sexual intercourse

Validity The validity of experimental results depends on whether the methods used are actually testing the question asked

Vasectomy (Male sterilisation) A contraceptive method in which the sperm tubes are cut

Vein A blood vessel that carries blood back to the heart

Vena cava The vein that returns deoxygenated blood to the heart

Villi Small finger-like projections lining the wall of the ileum which increase its surface area for absorption

Volume A measure of the amount of space an object, a cell or organism occupies

Voluntary action A response to a stimulus which involves thinking

White blood cells Blood cells that help defend against disease

Zygote The first cell of the new individual following fertilisation