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Glossary

amino small from which are A built abiotic factor physical or non-living conditions a digestive () that that affect the distribution of a in an breaks down , such as , , pH anaerobic respiration without using absorption the process by which soluble products of move into the from the antibacterial chemicals chemicals produced by as a defence ; the amount abstinence method of contraception whereby the produced will increase if the is under attack couple refrains from intercourse, particularly when an might be in the e.g. ; that inside the to kill bacterial accommodation ability of the eyes to change focus normally present in the body rain which is made more acidic by or produced in response to an , which it pollutant neutralises, thus producing an the place on an enzyme where the resistance (AMR) an increasing binds problem in the twenty-first century whereby in active transport, cells use have evolved to develop resistance against to transport substances through membranes due to their overuse against a gradient antiretroviral drugs used to treat HIV features that have to help ; they stop the entering the lymph them survive in their environment nodes ADH (antidiuretic ) a hormone released antiseptic substance that prevents the growth of by the pituitary , which acts on the bacteria in response to changes in the concentration of the antitoxins chemicals produced by white blood cells blood plasma () that neutralise to make a safe a hormone released quickly from the chemical adrenal during a ‘ or fight’ situation antivirals drugs used to treat viral infections; they part of the that are specific to the virus but can only slow down viral produces the hormone adrenaline development cell a of cloning where an artery that carries oxygenated blood from the is produced from an adult body cell. The left to tissues around the body embryo is then implanted into a or with no predators, they used for therapeutic reasons, (e.g. process was are at the top of the chain used to created Dolly the ) (greenfly) -causing small that adult stem cells rare, unspecialised cells found in reproduce rapidly; infestation causes reduced some tissues in that can differentiate only into growth, , wilting and the cell where they are found, e.g. blood cells primitive bacteria that usually live in aerobic respiration respiration that involves the use extreme conditions of oxygen artificial a temporary heart used to plate plastic dish, with a lid, containing a keep patients alive while they are waiting for a gel upon which bacteria are grown in a lab transplant inherited characteristics are carried as pairs of artificial pacemaker a device fitted under the alleles on pairs of . Different forms of a that sends out electrical impulses to control the are different alleles heartbeat alveolus (plural: alveoli) air sacs; the site of gaseous exchange in the

378 AQA GCSE Biology: Student Book

16771_P378_390.indd 378 21/01/17 6:06 PM arteries blood vessels with thick elastic walls that binomial system the scientific way of naming an carry oxygenated blood away from the heart under whereby each organism has a high pressure and a name; e.g. sapiens aseptic technique measures taken to reduce range of different plant and animal when preparing bacterial cultures, species living in an ecosystem e.g. working with a flame energy released when bacteria break down asexual reproduction involving only , which can be used as a cheap fuel source one biomass the dry mass of organisms painkiller derived from bark Biuret chemical indicator used to for ATP molecule used to store energy in the body the presence of protein in a sample atrium (plural: atria) the upper chambers of the blood level the amount of in the heart that receive blood from the body or lungs blood (controlled by the , and ) hot oven in which contaminated materials used in are sterilised biological catalysts – molecules in the body that speed up chemical reactions a type of produced at the tips of plant and using living organisms to make products to improve quality of B body mass index (BMI) measure of someone’s weight in relation to their height bacteria single-celled which can either be free-living organisms or parasites (they breed new form of animal created with particular sometimes invade the body and disease) characteristics, created through bacterial bell-shaped curve that (plural: bronchi) branches of the shows how bacteria in culture increase in number – one going to each exponentially until a build-up of toxins in the culture causes them to die off C barrier methods of contraception; where a condom calibrate the process of checking the accuracy a or diaphragm is used to prevent reaching piece of equipment using standard an egg a method of avoiding detection used by metabolic rate the level at which chemical prey to avoid predators and by predators to surprise reactions take place in the body at rest prey behaviour adapt their movement and capillaries small blood vessels that are one cell thick feeding patterns according to the conditions of their and permeable for of gases; join arteries environment to veins Benedict’s test a test for sugar in which Benedict’s capillary network tree of capillaries surrounding reagent turns orange-red in the presence of sugar alveoli that are adapted for efficient gaseous benign tumour slow-growing, harmless mass of cells exchange that can usually be easily removed carbohydrase enzyme that breaks down bias when a data set is inaccurate or into simple unrepresentative; it contains systematic carbohydrates one of the main groups of ; bile an alkaline substance made by the and e.g. glucose, starch stored in the gall bladder, which emulsifies to aid a natural cycle through which digestion carbon moves by respiration, and biotic factor factors caused by living organisms, such , in the form of as food availability and between species ‘stores’ of carbon dioxide in or binary the process by which a bacterium forests divides and doubles its numbers, approximately substance or virus that increases the risk every 20 minutes of , e.g. ionising

Glossary 379

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carrier someone who is heterozygous for a disease- combined contraceptive pill a hormonal method causing gene so that they do not have the condition of contraception, taken orally, which contains but ‘carry’ the defective , which they could pass synthetic forms of oestrogen and on to their children communicable disease infectious condition caused causal mechanism where a direct link has been by a virus, , bacteria or fungi; e.g. measles, HIV made between a risk factor and a disease; e.g. all the plants and animals living in an smoking and lung cancer ecosystem, e.g. a garden cell lines cells grown in a lab that are used to study a companion cells found next to cells, certain condition companion cells control the activities of the phloem layer around a cell which helps to compare to examine your data set next to a known control substances entering and leaving the cell set of results a of three stages during which a cell competition when different species in an ecosystem divides compete for the same of glucose; strengthening complementary describes how each DNA strand in a component of walls double pairs with the opposite strand through central (CNS) collectively, the base pairs (A-T and G-C) and complex conditions that are caused by a cerebellum area at the base of the brain that combination of genetic and environmental factors coordinates muscular activity dead and decaying plant material cerebral cortex highly folded outer layer of the condom rubber sheath that covers the erect brain that controls , intelligence, and prevents sperm reaching the egg; a barrier form memory and language of contraception the neck of the womb cones light-sensitive cells in the that who proposed the allow us to see in colour of by conservation a way of protecting a species or found in plants which is used in environment photosynthesis (gives green plants their colour) cooling the body loses through sweating a cell found in green plants coordination centre region of the body that receives that contains chlorophyll and processes information from receptors, e.g. brain, chlorosis when a plant develops yellow leaves due to a lack of cornea transparent region at the front of the eye chromosomes thread-like in the cell through which light refracts when it enters the eye nucleus that contain DNA coronary artery vessel that provides the heart cilia tiny -like structures found throughout the muscle with oxygen and glucose for respiration that beat together to move coronary heart disease a condition caused by build- out of the lungs up of fatty deposits in the coronary artery, leading classify to organise and present data in a logical to reduced blood flow and less oxygen and glucose , e.g. in a table reaching the heart , which can cause a heart attack clinical trial process during which a new is tested on patients and healthy correlation relationship between two sets of results clone in , the culture the growing of cells in a lab produced are identical to the parent (clones) culture medium the (nutrient broth) or gel collision theory an explanation of enzyme action; (agar) in which bacteria are grown in a lab enzymes cause more collisions between reactants culture with known amounts thereby increasing the rate of reaction until of specific in which plants are grown to reactants are used up investigate deficiencies a spot containing millions of bacteria growing cycle predator–prey relationships follow a cyclical on an pattern whereby the numbers of prey rise and fall

380 AQA GCSE Biology: Student Book

16771_P378_390.indd 380 21/01/17 6:06 PM over a of , and the numbers of predators the level of classification group above follow the same pattern , first suggested by cystic fibrosis disorder of cell membranes that is dominant an allele that is expressed when one or caused by a recessive allele two copies are present; represented by a capital letter D dominant hand the hand a person uses most often for single-handed tasks, e.g. writing daughter cells cells produced during that are identical to the parent cell donor refers to the person or organism where donated cells or tissue come from the removal of amino groups, as , from excess amino acids, in the liver dormant describes that have not germinated; they can be sprayed with the plant hormone an organism that breaks down carbon gibberellins, which induces them to germinate in dead animals and plants dose amount of a drug given to a patient deforestation removal of large of trees to provide land for or growing double-blind trial a drugs trial where neither doctors nor patients know whether the patient has result of the body losing too much received the test drug or the placebo water double where the blood is demographic describes the structure of a population pumped to the lungs then returned to the heart denatured an enzyme is denatured if its shape before being pumped round the body changes so that the substrate cannot fit into the double helix the shape of DNA – two strands of active site that around each other like a depression a mental condition twisted ladder dialysis process by which the blood is filtered by a dredging the process of digging up sea beds; an dialysis machine, in someone with example of environmental change induced by diarrhoea a symptom of food ; frequent dual bar chart bar graph on which two data sets are passing of liquid stools plotted at each point differentiation when cells gain certain features needed for their ; they become specialised E a heart drug extracted from foxgloves Ebola a deadly virus that kills 50–90% of people infected directly proportional describes a relationship between two variables on a graph where the line of ecosystem the interaction of a community of best fit through 0,0 living organisms with the non-living parts of their surroundings disc-diffusion technique used to test effectiveness of antibiotics or on plates of cultured muscle or gland that brings about a bacteria using discs soaked in the test response to a substance and measuring the size of clear area efficacy how effective a drug is at preventing or around the discs curing the disease disease resistance plants that are not affected embryonic stem cells unspecialised cells found in by certain diseases and can therefore be cloned in the early embryo that can differentiate into almost large numbers for farmers any cell type in the body distribution how living organisms are dispersed/ embryo screening the process whereby a few cells spread out over an ecosystem are taken from an embryo produced by IVF are DNA (deoxyribonucleic acid) found as chromosomes checked for any defective in the nucleus – its sequence determines how our embryo transplants form of cloning where cells are bodies are made, and gives each one of us a unique taken from a developing embryo from a pregnant genetic animal, separated and grown in culture then DNA bases four chemicals that are found in DNA, implanted into mothers they make up the base sequence and are given the emulsify the process by which are broken into letters A, T, G and C smaller droplets by bile

Glossary 381

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part of the body that releases in which chemical messengers, or hormones, directly into the heat is given out bloodstream the elimination of all members of a a in the body species; there have been five mass over that communicates using chemical messengers, or geological hormones, to produce slow but long-lasting responses referring to when food endothermic reaction chemical reaction which is broken down outside an organism, e.g. bacteria takes in heat secrete enzymes to breakdown dead material environmental change a shift in the external organisms that can survive very conditions caused by activity or a natural extreme environments, e.g. high temperature or event high environmental variation differences between individuals that arise during development; e.g. F wearing glasses factory farming a form of intensive farming where enzymes biological catalysts that increase the speed animals are reared in sheds or cages under controlled of a chemical reaction conditions an outbreak of a disease that spreads tree a diagram used to show how a condition quickly to many people is passed down through a family epidermal tissues layers of cells that cover the top anaerobic respiration in cells; surface of a ; they let light penetrate produces and carbon dioxide epiphyte plant that is adapted to grow fertiliser chemical containing minerals (, above ground level (e.g. on trees) , and magnesium) put on soil to improve plant growth estimate a guess based on prior knowledge drug combination of hormones given ethanol of anaerobic respiration in plant to a with low FSH levels to stimulate egg and yeast cells; used in the manufacture of alcoholic production of view the area of a sample visible under a ethene a plant hormone released as a that speeds up filtrate dissolved substances that cross into the ethical whether a process is considered to be right or kidney after the blood has been filtered wrong, based on moral considerations flaccid floppy refers to the notion of improving a population by selecting certain desirable follicle the sac left once an egg is released in the characteristics ; it produces the hormone progesterone eukaryotic cells cells that contain a true nucleus in food security when all people have access to a the ; e.g. plant and animal cells consistent supply of food to meet their needs when waterways become too rich the remains of organisms that lived millions of with nutrients (from fertilisers), allowing to years ago grow wildly and subsequently decay, resulting in the oxygen being used up fossil record an incomplete account of organisms that lived millions of years ago the process by which the body loses heat through sweating fraction (in ) the number of people affected by a recessive condition expressed as a fraction could evolution the gradual change in organisms over be 1/4 millions of years caused by random and natural selection FSH (follicle stimulating hormone) a reproductive hormone that causes to mature in the evolutionary tree a diagram created by that shows how animals are believed to have evolved functional adaptation an adaptation involving how from common ancestors the body operates, e.g. camels don’t sweat to avoid water loss exchange surfaces specialised areas with large surface area to volume ratios for efficient diffusion chemical used to kill fungi

382 AQA GCSE Biology: Student Book

16771_P378_390.indd 382 21/01/17 6:06 PM global warming the increase in the ’s G temperature due to increases in carbon dioxide levels the male and female cells (sperm and glucagon hormone released by the pancreas that, eggs) along with insulin, controls blood glucose levels gel derived from silicone, the material that contact glucose tolerance test a way of testing for diabetes lenses are made from by measuring how the body responds to glucose gene of DNA that contains the instructions GM crops varieties of crops that have had their for a particular characteristic modified by the insertion of genes from a whether genes are switched on or plant or other organism off, which is regulated by non-coding DNA goblet cells cells in the epithelium that produce generator large tanks full of rotting organic , mucus to trap used for biogas production golden rice that has been genetically modified gene theory dogma developed in the twentieth to contain β - carotene, which converts to A century that brought together the work of many gonorrhoea a sexually transmitted disease caused by scientists on inheritance, DNA structure and the bacteria, resulting in pain when urinating and a thick discharge from the or penis gene medical procedure where a virus is gradient the steepness of a line plotted on a graph used to ‘carry’ a gene into the nucleus of a cell (this is a new treatment for genetic diseases) graticule piece of glass or plastic onto which a has been drawn, which is used with a microscope genetic code a sequence of three DNA bases that for a single Austrian monk who established the of genetics through his work on pea plants genetic cross a way of working out the probability of the of the offspring produced from the guard cells cells surrounding the stomata that ’ genotype for a particular characteristic, e.g. open and close the pore to control the exchange of using a gases and water loss genetic transfer of specific genes from one organism to another H genetic a gene inserted into a the place where an organism in an modified organism alongside the required gene; ecosystem; e.g. the worm’s habitat is the soil the marker gene is often resistant to an antibiotic, haemocytometer device used for counting the so that when cultures of cells are treated with that number of cells, e.g. under a microscope antibiotic, cells that do not contain the marker gene will be killed haemodialysis filtering of the blood by a machine in patients with kidney failure; takes four hours, three genetic variation the product of , mutations a week and , which all to changes in our haemoglobin chemical found in red blood cells which binds to oxygen to transport it around the genome the entire genetic material of an organism body genome editing an experimental method of health a state of compete mental and physical detecting and correcting defective genes in an wellbeing heterozygous a person who has two different alleles the science of studying the for a characteristic, e.g. someone with blond hair to increase our understanding of human DNA may also carry the allele for red hair genotype the alleles present for a particular gene HIV (human immunodeficiency virus) virus make up the organism’s genotype transmitted through sexual contact that attacks the geotropism a plant’s growth response to (also called gravitropism) the regulation of internal conditions, gibberellins plant hormones that speed up such as temperature, in the body homozygous a person who has two alleles that are gills a surface found in and the same for a characteristic, e.g. a blue-eyed person tadpoles will have two ‘blue’ alleles for eye colour

Glossary 383

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hormone chemical messenger that acts on target inverse square law (in terms of light intensity and organs in the body photosynthesis) the intensity of light is proportional to 1/d2 (where d = distance from the light source); infertile organism created through for example, if the distance is doubled, the light interbreeding organisms from two different species intensity is quartered hybridoma cells cells made from combining absorb take in or soak up, for example energy from in-vitro (IVF) a fertility treatment, tumour cells with lymphocytes, to give cells that can sound whereby an egg is fertilised with sperm outside the produce and divide (for the production of body, in a monoclonal antibodies) an orange solution used to test for a compound composed of the starch (turns blue-black when starch is present) elements and carbon part of the eye that has sets of muscles that growing plants in mineral solutions control the size of the pupil and regulate the light without the need for soil reaching the retina hyperopia long-sightedness; where people can see IUD (intrauterine device) a device containing hormones objects far away but not close up that is placed in the to prevent a fertilised egg a scientific explanation formed based on from implanting; a hormonal method of contraception prior knowledge that can be tested in an IVF cycle the process of IVF from stimulation of the ovaries to implantation of an embryo; if I unsuccessful, another cycle can be attempted after about two months immune system the body’s defence against pathogens K when the body is protected from a as it has already encountered it and can kingdom the level of classification above and therefore produce antibodies against it, rapidly below domain of living organisms inbreeding breeding closely related animals L incubation period of time a culture of bacteria is left at a certain temperature in order for the bacteria to grow product of anaerobic respiration in muscles indicator species organisms used to measure the larva immature but active form of an that’s level of in water or the air created from an egg and turns into a inoculating loop length of wire with a ring at the laser a technique used to correct eye end used for transferring bacteria to an agar plate defects by changing the shape of the cornea insulin hormone made by the pancreas that controls LH (luteinising hormone) a hormone the level of glucose in the blood that stimulates an egg to be released from an ovary interbreeding organisms of the same species can slow-growing plant that grows up trees interbreed to give fertile offspring substance found in some plant cell walls that intercept the point where the line on a graph crosses gives them strength and rigidity the y-axis factors such as light, temperature interdependence plants need animals for carbon and carbon dioxide, which affect the rate of dioxide and seed dispersal; animals need plants for photosynthesis food and oxygen; i.e. they depend on each other for enzymes that digest fats into fatty acids and survival interspecific competition competition between lock and key theory to explain how enzymes work; two different species of organism the substrate is the ‘key’ and the active site is the ‘lock’ intraspecific competition competition among the central part of a vessel organisms from the same species lymphatic system network of vessels containing a a cause of extinction as a result of colourless fluid into which fatty acids and glycerol a new species of organism being introduced into a are absorbed population, which may bring disease, be a predator or compete with native organisms lymphocytes white blood cells that produce antibodies and antitoxins to destroy pathogens

384 AQA GCSE Biology: Student Book

16771_P378_390.indd 384 21/01/17 6:06 PM mineral deficiency when a plant cannot get enough M of an essential mineral from the soil magnetic resonance imaging (MRI) scanning mineral substances found in the soil that are technique that uses strong magnetic fields to essential for a plant’s survival; e.g. plants need produce detailed images of the body; used to magnesium ions to make chlorophyll diagnose nervous system disorders missing links evidence for evolution found as magnification the factor by which an object is intermediate forms between different organisms, as enlarged by a microscope; calculated as: size of they evolved image/size of real object mitochondria structures in a cell where respiration condition characterised by recurring , takes place which is spread by mosquitoes and can be fatal mitosis cell that results in genetically malignant tumour abnormal cancerous mass of cells identical diploid cells that grows quickly and can spread to other parts of the body mixed population plants bred from two different varieties for their desirable traits an independent method used to show that Mendelian genetics is consistent with mode the most frequently occurring number in a set evolution of values median the middle number in a set of values when monoclonal antibodies antibodies made from they are arranged in order from lowest to highest cells that are cloned from one cell that are specific to one on an antigen. They are used in medulla region at the base of the brain that controls to treat cancer, and in unconscious activities, such as monocultures where only one crop is grown in an mean average value calculated by adding up all the area values in a data set then dividing by the number of values motor neurone cell carrying information from the to muscles meiosis that results in gametes being produced, with half the number of chromosomes as MRSA bacteria that are resistant to the antibiotic, the parent cell methicillin melanism darkening of appearance – a form of mulch compost or decaying leaves put around colour variation in animals, e.g. melanic moths bushes in the spring to prevent rose black spot reaching the stems name given to single-gene disorders, such as cystic fibrosis where the DNA within cells has been altered (this happens in cancer) menstrual cycle monthly cycle in which is controlled by reproductive hormones mycoprotein a protein-rich food made from microorganisms in fermentation vats mental health a feeling of well-being, having a positive frame of sheath a fatty insulating layer that surrounds neurones and speeds up nerve regions at tips of roots and shoots where cell division takes place myopia short-sightedness; when people can see objects at short distances but not far away the sum of all reactions in a cell or the body N micrograph image captured using a microscope natural selection process by which advantageous microorganisms tiny organisms that can only be characteristics that can be passed on in genes viewed with a microscope – also known as microbes become more common in a population over many migration patterns historical movements of humans across the world, which have been deduced through negative a regulatory process in the body studying genomes whereby changes in the body can be reversed once mechanical defence mechanism where a they have happened plant uses features to trick animals into not feeding nervous system a control system in the body that or not laying eggs uses electrical impulses to communicate rapidly and precisely

Glossary 385

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neurone a nerve cell that is specialised to transmit oxygen debt the amount of oxygen that the body electrical signals needs to breakdown lactic acid after muscles undergo anaerobic respiration nitrates nutrients found in fertilisers and the soil that plants need for protein synthesis, and therefore oxyhaemoglobin bright red substance formed when growth oxygen binds to haemoglobin in red blood cells; this is how oxygen is transported to tissues non-coding DNA sections of DNA that do not code for genes but genes on or off instead; they regulate gene expression P

non-communicable disease conditions caused by pacemaker a group of cells in the right atrium that environmental or genetic factors that are not spread controls the among people; e.g. cancer, cardiovascular disease palaeontologists scientists who study non-invasive describes brain mapping techniques, such as MRI scans, that can be carried out without palisade mesophyll tightly packed together cells the need for surgery found on the upper side of a leaf that carry out photosynthesis nuclear transfer type of cloning that involves taking a nucleus from a body cell and placing it into an pandemic when an outbreak of a disease becomes global group of complex molecules found in living organisms including DNA and various types of a relationship between two organisms RNA where one benefits and the other is harmed, e.g. tapeworms in humans a sugar and group with a chemical base (A, T, C, G) attached to the sugar partially permeable membrane a membrane that allows some small molecules to pass through but not nutrient broth liquid used for growing bacteria larger molecules pathogen harmful that invades the O body and causes infectious disease oestrogen the main female reproductive hormone peatlands areas of peat bog formed in marshlands; produced by the ovaries peat is partially decomposed leaf matter that is used as fuel and cheap compost opiates a group of painkillers found in poppies scientific findings are scrutinised by optic nerve nerve found at the back of the eye that independent experts before they can be published carries impulses from the retina to the brain penicillin an antibiotic, isolated from Penicillum optimum the conditions, in terms of temperature mould, which was discovered by Alexander Flemming and pH, at which an enzyme works best percentage a number or amount expressed per optimum dose the amount of a new drug needed to be hundred effective, determined in a trial by starting at low doses peripheral nervous system (PNS) network of order a level of classification below but above leading to and from the spinal cord family; e.g. and moths are orders of the insect family the movement of food through the digestive system by order of magnitude in , the difference between sizes of cells, calculated in factors of 10 peritoneal dialysis a type of dialysis where fluid is pumped into the abdomen and waste products group of tissues that carries out a specific diffuse into it across a membrane in the body called function the peritoneum arrangement of organs in the body plate, with a lid, used for growing bacteria according to function; e.g. respiratory system in a lab the diffusion of water molecules through phagocyte a type of white that enters a partially permeable membrane, from a dilute tissues and engulfs pathogens then ingests them solution to a concentrated solution process by which a white blood cell out of phase refers to the cycle of a predator (phagocyte) engulfs a pathogen lagging behind that of its prey indicator a pink solution (at pH 10) release of an egg from the ovary that turns colourless when fatty acids are added

386 AQA GCSE Biology: Student Book

16771_P378_390.indd 386 21/01/17 6:06 PM the characteristic that is shown or progesterone reproductive hormone that causes the expressed lining of the uterus to be maintained phloem specialised transporting cells which form -only pill (or mini pill or POP) tubules in plants to carry sugars from leaves to other contraceptive pill that only contains progesterone parts of the plant (not oestrogen), which may be more suitable (than the combined pill) for women who are older or have phosphates nutrients found in soil and fertilisers high that plants need for respiration and growth Prokaryota group of single-celled organisms photosynthesis process carried out by green plants including bacteria and Archaeans where , carbon dioxide and water are used to produce glucose and oxygen prokaryotic cells single cells of bacteria and Archaeans with DNA found in a loop not enclosed in a plant’s growth response to light a nucleus pituitary gland known as the ‘master gland’ as it proportion (in genetics) the number of people controls other endocrine glands, such as the affected by a condition expressed in relation to the gland total population placebo a treatment that does not contain a drug digestive enzymes that break down organ that forms during that proteins into amino acids provides the foetus with oxygen and nutrients protist a type of single-celled organism, for example plant cuttings in plant cloning, a leaf and stem are the pathogen that causes malaria cut off a plant and then dipped in hormone powder pruning snipping the tops off plant shoots in the to encourage rooting, a new plant then grows spring, a treatment for rose black spot plant organ system roots, stems and leaves, which pulmonary artery vessel that carries deoxygenated collectively form a plant’s transport system blood from the right ventricle to the lungs plasma straw-coloured liquid part of blood pulmonary vein vessel that carries oxygenated small ring of DNA found in prokaryotic cells blood from the lungs to the left atrium plasmolysis/plasmolysed the shrinking of a plant Punnett square a grid used to determine possible cell due to loss of water, the cell membrane pulls outcomes of a genetic cross away from the pyramid of biomass table of dry weight of platelets cell fragments which help in blood clotting organisms at different trophic levels in an ecosystem, which forms a pyramid shape polydactyl condition caused by a dominant allele in which the sufferer has extra fingers or toes Q polymer a molecule, such as DNA, made up of repeating units qualitative chemicals used to test for the presence of a substance in a sample population the total number of one species in an ecosystem R potometer piece of equipment used to measure water uptake by plants radiometric method of determining the absolute age of rocks preclinical testing testing of a new drug in a lab using cells, tissues or live animals range a measure of spread; the difference between the biggest and smallest values in a set prey animals that are eaten by a predator range bar line drawn on a graph to show the range primary organism in a that of a set of values gets its energy from eating food (producers) rate the speed at which an event is occurring over probability the likelihood of an event happening; time; can be calculated using the gradient on a e.g. there is a 1 in 4 chance of a couple who are both graph heterozygous for cystic fibrosis having a child with cystic fibrosis rate of photosynthesis is affected by temperature, light intensity, carbon dioxide concentration and producers organisms in a food chain that make food amount of chlorophyll using sunlight

Glossary 387

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ratio the relationship between two variables, expressed as 1:4, for example S reaction time the time it takes the body to respond a type of bacteria that causes food to an event poisoning receptors cells in the body that detect changes in the sampling techniques methods used to choose a environment small, representative number of individuals from a large population recessive two copies of a recessive allele must be present for the characteristic to be expressed; scale bar a line drawn on a micrograph used to represented by lowercase letters measure the actual size of the object red blood cells blood cells with a concave shape scanning microscope (SEM) works by which are adapted to carry oxygen from the lungs to bouncing off the surface of a specimen body cells that has had an ultrathin coating of a heavy metal, usually gold, applied. Used to view surface shape of action rapid automatic responses to a stimulus cells or small organisms reflex arc pathway taken by nerve impulses through sclera tough outer layer of the eye the spinal cord during a reflex action secondary consumer organism in a food chain that refraction the bending of light rays as they travel gets its energy from eating primary consumers from one medium to another, e.g. as they enter the eye secondary sex characteristics features that develop during , as a result of sex hormones restoration (of a habitat) being released, such as a deep voice and hair growth in boys, and in girls relay neurone neurone found in the spinal cord that transmits impulses from the sensory to the motor secondary tumour abnormal growth of cells that neurone forms from a malignant tumour elsewhere in the body repeatability consistent data with a narrow secrete to produce a substance; e.g. range has a high repeatability; it is likely that the secrete enzymes to help break down food conclusions drawn from such a data set are valid selective breeding process of breeding organisms resolving power the ability of a microscope to with the desired characteristics (also known as distinguish between two points; the resolving power artificial selection) of electron is higher than that of light microscopes selective reabsorption in the kidney, useful substances, such as glucose and amino acids, are respiration the process used by all organisms to absorbed back into the blood after release the energy they need from food selective weedkiller preparations of synthetic plant retina area at the back of the eye where light- hormones that only kill with broad leaves, for sensitive receptor cells are found example, and leave grasses and crops unharmed structures in a cell where protein synthesis self-supporting ecosystem all can takes place support themselves; i.e. everything organisms need for growth and survival is present risk factor a lifestyle or genetic factor that increases the chance of developing a disease sensory neurone nerve cell carrying information from receptors to central nervous system rods light-sensitive receptor cells in the retina that allow us to see in dim light waste water and excrement, a form of pollution hair cells specialised cells in plant roots that are adapted for efficient uptake of water by osmosis and sex chromosomes a pair of chromosomes that mineral ions by active transport determines gender; XX in females, XY in males rose black spot fungal disease that affects plant sex determination whether a fertilised egg growth; can be treated with fungicide or by develops into a male (XY) or female (XX) depends on destroying the leaves the 23rd pair of chromosomes run-off when fertilisers from a farmer’s field sexual reproduction form of reproduction involving are washed off into rivers or lakes (can lead to two parents, which introduces variation eutrophication) sexually transmitted disease (STD) disease spread rusts type of plant disease caused by fungi through sexual contact; e.g. HIV

388 AQA GCSE Biology: Student Book

16771_P378_390.indd 388 21/01/17 6:06 PM sieve plates the end walls of phloem cells that suspensory ligaments ligaments in the eye that are contain many small pores attached to the ciliary muscle and hold the in place species basic category of biological classification, composed of individuals that resemble one another, sustainable long-lasting; something that can be can breed among themselves, but cannot breed with maintained for future generations members of another species sustainable measures to improve fish specialised when cells or tissues become adapted to stocks, which were declining due to over-fishing, to carry out their specific function include controls on net size and fishing quotas formation of a new species over a the gap between two neurones long period of time, through separation of a systematic mistakes made during data population collection that give false outcomes spermicide a cream that is toxic to sperm; it is used alongside other contraceptive techniques, e.g. T condoms the site where a hormone has its effect sphere shape that has the smallest surface area target organ compared with its volume male sex hormone produced by the testes that stimulates sperm production spiracles tiny holes along the side of an insect’s body used in gas exchange therapeutic cloning the process of creating stem cells with the same genes as the patient, through spongy mesophyll layer of cells found in the middle of a leaf with an irregular shape and large air nuclear transfer between them for diffusion of gases thermoregulatory centre a region in the brain that detects changes in body temperature spores small seed-like particles released by a to help it spread three-domain system developed by Carl Woese, a classification system where organisms are divided stacked bar chart bar graph where two data sets are stacked on top of each other for each group/bar into Archaea, Bacteria and Eukaryota (animals, fungi and plants) standard form way of writing very large or small numbers using powers of ten; e.g. 1.0 × 10–3 thyroid gland gland at the base of the neck that makes the hormone thyroxine starch a complex found in animals and plants thyroxine hormone produced by the thyroid gland that increases the body’s metabolism drugs that stop the liver producing so much tissue group of cells that work together, with a particular function stem cells unspecialised body cells (found in marrow) that can develop into other, specialised, process that uses small sections of cells that the body needs, e.g. blood cells tissue to clone plants pathogen that causes stents a treatment for heart disease; a catheter with tobacco virus (TMV) a balloon attached is inserted to open up a narrowed mosaic pattern of discolouration on leaves and coronary artery affects growth of plant windpipe, through which air travels sterilise the process of removing contaminated trachea (lungs) material (e.g. from an agar plate) to the lungs small tubes in insects containing stomata (singular ) small holes in the trachea (insects) surface of leaves which allow gases in and out water, through which gases diffuse into body cells of leaves transect line across an area to sample organisms structural adaptation a physical adaption to a body translocation the movement of sugars through a part of an animal, e.g. have larger ears to plant maximise heat loss transmission (TEM) uses an surface area to volume ratio the relationship electron beam to view thin sections of cells at high between the surface area of an organism or resolution structure and its volume; SA:V ratios are large in single-celled organisms for efficient diffusion the movement of water up through a plant and its loss from the leaves

Glossary 389

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trend a pattern in a data set in warm conditions, the diameter of small blood vessels near the surface of the body feeding positions in a food chain increases, which increases blood flow tropism the response of a plant by growing towards a carrier, usually a plasmid, used to transfer or away from a stimulus a gene into an organism to be genetically modified; tundra regions in the Arctic where few plants grow also, mosquitoes are vectors – they spread malaria as the subsoil is permanently frozen but don’t cause it themselves turgid plant cells which are full of water with their veins blood vessels with thin walls and valves to walls bowed out and pushing against neighbouring prevent backflow, that carry blood at low pressure cells back to the heart a condition where the pancreas vena cava vein that carries deoxygenated blood from cannot produce enough, or any, insulin the body to the right atrium type 2 diabetes a condition where the body cells no ventilate the movement of air into and out of the longer respond to insulin produced by the pancreas lungs ventricles the lower chambers of the heart that U pump blood around the body (left) or back to the lungs (right) umbilical cord joins the foetus to the mother during pregnancy and is a source of stem cells W uncertainty a measure of the range about the mean, calculated by the range divided by two Wallace (Alfred Russel) scientist that proposed the theory of evolution through natural selection, waste products formed by breakdown of excess independently from Darwin proteins, excreted in warning colouration bright colours or patterns V found on animals, used to deter predators injection of a small quantity of inactive X pathogen to protect us from developing the disease caused by the pathogen X-chromosomes sex present in males (XY) and females (XX) preparation of an inactive or dead form of a pathogen given by injection or nasal spray cells specialised for transporting water through a plant; xylem cells have thick walls, no valid refers to results that are accurate, cytoplasm and are dead, their end walls break down representative and repeatable and they form a continuous tube valves flaps of tissue that prevent the backflow of blood in the heart and in veins Y variation the differences between individuals Y-chromosomes found only in males brought about by both genetic and environmental influences yield the amount (of crop) produced vascular bundle (veins) group of xylem and phloem cells that transport water and glucose around the Z plant zones of inhibition areas of no bacterial growth on in cold conditions, the diameter an agar plate around an antibiotic disc of small blood vessels near the surface of the body a fertilised egg cell decreases, which reduces blood flow

390 AQA GCSE Biology: Student Book

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