Adult stem cells  

stem cells that are found in adults that can differentiate and form a limited number of cells 

Cell cycle  

the three-stage process of cell division in a body cell that involves mitosis and results in the formation of two identical daughter cells 

Cloning  

the production of identical offspring by asexual reproduction 

Differentiate  

the process where cells become specialised for a particular function 

Embryonic stem cells  

stem cells from an early embryo that can differentiate to form the specialised cells of the body 

Mitosis  

part of the cell cycle where one set of new chromosomes is pulled to each end of the cell forming two identical nuclei during cell division 

Stem cells  

undifferentiated cells with the potential to form a wide variety of different cell types 

Therapeutic cloning  

a process where an embryo is produced that is genetically identical to the patient so the cells can then be used in medical treatments 

Zygote  

the single new cell formed by the fusion of gametes in sexual reproduction 

Active site 

the site on an enzyme where the reactants bind 

Amino acids 

molecules made up of carbon, hydrogen, oxygen, and nitrogen that are the building blocks of proteins 

Amylase 

enzyme that speeds up the digestion of starch into sugars 

Bile 

neutralises stomach acid to give a high pH for the enzymes from the pancreas and small intestine to work well. It is not an enzyme 

Carbohydrases 

enzymes that speed up the breakdown of carbohydrates into simple sugars 

Carbohydrates 

molecules that contain only carbon, hydrogen, and oxygen. They provide the energy for the metabolism and are found in foods such as rice, potatoes, and bread 

Catalyst 

a substance that speeds up the rate of another reaction but is not used up or changed itself 

Denatured 

the breakdown of the molecular structure of a protein so it no longer functions 

Differentiate 

the process where cells become specialised for a particular function 

Digestive system 

organ system where food is digested and absorbed 

Enzymes 

Fatty acids 

biological catalysts, usually proteins  

part of the structure of a lipid molecule 

Glycerol 

part of the structure of a lipid molecule 

Lipase 

enzymes that speed up the breakdown of lipids into fatty acids and glycerol 

Lipids 

include fats and oils and are found in foods such as butter, olive oil, and crisps. They are made of carbon, hydrogen and oxygen 

Metabolism 

the sum of all the reactions taking place in a cell or the body of an organism 

Organ 

an aggregation (collection) of different tissues working together to carry out specific functions 

Organ system 

a group of organs that work together to carry out specific functions and form organisms 

Proteases 

enzymes that speed up the breakdown of proteins into amino acids 

Proteins 

molecules that contain carbon, hydrogen, oxygen, and nitrogen and are made of long chains of amino acids. They are used for building the cells and tissues of the body and to form enzymes 

Simple sugars 

small carbohydrate units, for example glucose 

Tissue 

a group of specialised cells with a similar structure and function 

Aorta 

the artery that leaves the heart from the left ventricle and carries oxygenated blood to the body 

Arteries 

blood vessels that carry blood away from the heart. They usually carry oxygenated blood and have a pulse 

Atria 

the upper chambers of the heart 

Capillaries 

the smallest blood vessels. They run between individual cells and have a wall that is only one cell thick 

Coronary arteries 

the blood vessels that supply oxygenated blood to the heart muscle 

Double circulatory system 

the circulation of blood from the heart to the lungs is separate from the circulation of blood from the heart to the rest of the body 

Epidermal 

the name given to cells that make up the epidermis or outer layer of an organism 

Guard cells  

surround the stomata in the leaves of plants and control their opening and closing 

Haemoglobin 

the red pigment that carries oxygen around the body in the red blood cells 

Palisade mesophyll 

the upper layer of the mesophyll tissue in plant leaves made up of closely packed cells that contain many chloroplasts for photosynthesis 

Phloem 

the living transport tissue in plants that carries dissolved food (sugars) around the plant 

Plasma 

the clear yellow-liquid part of the blood that carries dissolved substances and blood cells around the body 

Platelets 

fragments of cells in the blood that play a vital role in the clotting mechanism of the blood 

Pulmonary artery 

the large blood vessel that takes deoxygenated blood from the right ventricle of the heart to the lungs 

Pulmonary vein 

the large blood vessel that carries oxygenated blood from the lungs back to the left atrium of the heart 

Red blood cells 

biconcave cells that contain the red pigment haemoglobin and carry oxygen around the body in the blood 

Spongy mesophyll 

the lower layer of mesophyll tissue in plant leaves that contains some chloroplasts and many large air spaces to give a big surface area for the exchange of gases 

Statins 

drugs used to lower blood cholesterol levels and improve the balance of high- to low-density lipoproteins in the blood 

stent 

a metal mesh placed in a blocked or partially blocked artery. They are used to open up the blood vessel by the inflation of a tiny balloon 

translocation 

the movement of sugars from the leaves to the rest of the plant through the phloem 

transpiration 

the loss of water vapour from the leaves of plants through the stomata when they are opened to allow gas exchange for photosynthesis. It involves evaporation from the surface of the cells and diffusion through the stomata 

urea 

the waste product formed by the breakdown of excess amino acids in the liver 

veins 

blood vessels that carry blood away from the heart. They usually carry deoxygenated blood and have valves to prevent the backflow of blood 

vena cava 

the large vein that brings deoxygenated blood from the body into the heart 

ventricles 

chambers of the heart that contract to force blood out of the heart 

white blood cells 

blood cells involved in the immune system of the body. They engulf pathogens and make antibodies and antitoxins 

xylem 

the non-living transport tissue in plants that transports water from the roots to the leaves and shoots 

agar gel 

widely used solid (gel) culture medium used for growing microorganisms 

aphids 

insects that penetrate the plant phloem and feed on the dissolved food. They act as plant pathogens and are also vectors that carry pathogenic viruses, bacteria, and fungi into healthy plant tissue 

binary fission 

reproduction by simple cell division, for example in bacteria  

chlorosis 

the yellowing seen on the leaves of plants when they cannot make chlorophyll due to a lack of magnesium ions 

communicable (infectious) disease 

disease caused by pathogens that can be passed from one organism to another 

culture medium 

a liquid or gel used to support the growth of microorganisms or other cultures, often containing specific nutrients 

inoculate 

introducing microorganisms to a culture medium, or introducing modified microorganisms into an individual to protect them against disease 

microorganisms 

organisms that are usually single-celled and can only be seen using a microscope . They include bacteria, fungi, viruses and protists 

mutation 

a change in the genetic material of an organism 

non-communicable diseases 

are not infectious and cannot be passed from one organism to another 

pathogens 

microorganisms that cause disease 

sexually transmitted disease (STD) 

transmitted from an infected person to an uninfected person by unprotected sexual contact 

vaccine 

dead or inactive pathogenic material used in vaccination to develop immunity to a disease in a healthy person 

virus 

pathogens that are much smaller than bacteria and can only reproduce inside living cells of other organisms 

clinical trials 

test potential new drugs on healthy and patient volunteers 

hybridomas 

cells created during the production of monoclonal antibodies by the fusion of an antibody-specific lymphocyte and a tumour cell 

placebo 

a medicine that does not contain the active drug being tested, used in clinical trials of new medicines 

preclinical testing 

is carried out on a potential new medicine in a laboratory using cells, tissues, and live animals 

vaccine 

dead or inactive pathogenic material used in vaccination to develop immunity to a disease in a healthy person 

benign tumours  

growths of abnormal cells that are contained in one area, usually within a membrane, and do not invade other tissues 

cancer 

the common name for a malignant tumour, formed as a result of changes in cells that lead to uncontrolled growth and division 

carcinogens 

agents that cause cancer or significantly increase the risk of developing cancer 

causal mechanism 

something that explains how one factor influences another 

correlation 

an apparent link or relationship between two factors 

ionising radiation 

has enough energy to cause ionisation in the materials it passes through, which in turn can make them biologically active and may result in mutation and cancer 

malignant tumours 

invade neighbouring tissues and spread to different parts of the body in the blood where they form secondary tumours. They are also known as cancers 

tumour 

a mass of abnormally growing cells that forms when the cells do not respond to the normal mechanisms that control growth and when control of the cell cycle is lost 

endothermic reaction 

a reaction that requires a transfer of energy from the environment 

glucose 

a simple sugar 

limiting factors 

limit the rate of a reaction, for example photosynthesis  

photosynthesis 

the process by which plants make food using carbon dioxide, water, and light 

aerobic respiration 

an exothermic reaction in which glucose is broken down using oxygen to produce carbon dioxide and water and release energy for the cells 

anaerobic respiration 

an exothermic reaction in which glucose is broken down in the absence of oxygen to produce lactic acid in animals and ethanol and carbon dioxide in plants and yeast. A small amount of energy is transferred for the cells 

endothermic reaction 

a reaction that requires a transfer of energy from the environment 

exothermic reaction 

a reaction that transfers energy to the environment 

glycogen 

carbohydrate store in animals 

lactic acid 

the end product of anaerobic respiration in animal cells 

oxygen debt 

the extra oxygen that must be taken into the body after exercise has stopped to complete the aerobic respiration of lactic acid 

central nervous system (CNS) 

the part of the nervous system where information is processed. It is made up of the brain and spinal cord 

cerebral cortex 

region of the brain associated with consciousness, memory, and language 

cerebellum 

region of the brain concerned with coordinating muscular activity and balance 

ciliary muscles 

muscles that contract and relax to change the shape of the lens of the eye 

coordination centres 

areas that receive and process information from receptors 

effectors 

areas (usually muscles or glands) that bring about responses in the body 

homeostasis 

the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function, in response to internal and external changes  

hyperopia 

long sightedness, where the rays of light from distant objects can be focused clearly on the retina but the rays of light from close objects are not focused and the objects appear blurred 

medulla 

region of the brain concerned with unconscious activities such as controlling the heart rate and breathing rate 

motor neurones 

carry impulses from the central nervous system to the effector organs  

myopia 

short sightedness, where the rays of light from close objects are brought into focus on the retina but distant objects appear blurred as the light is focused in front of the retina  

nerve 

bundle of hundreds or even thousands of neurones 

neurones 

basic cells of the nervous system that carry minute electrical impulses around the body 

receptors 

cells that detect stimuli – changes in the internal or external environment 

reflex arcs 

bring about a reflex action. They involve the sense organ, sensory neurone, relay neurone and motor neurone 

reflexes 

rapid automatic responses of the nervous system that do not involve conscious thought 

sensory neurone 

neurone that carries impulses from the sensory organs to the central nervous system 

stimuli 

changes in the external or internal environment that can be detected by receptors 

suspensory ligaments 

the ligaments that connect the lens of the eye to the ciliary muscles 

ADH 

anti-diuretic hormone helps control the water balance of the body and affects the amount of urine produced by the kidney 

adrenaline 

hormone that prepares the body for flight or fight 

auxin 

a plant hormone that controls the responses of plants to light (phototropism) and gravity (gravitropism) 

contraception 

methods of preventing pregnancy which usually involve preventing the sperm and egg from meeting 

endocrine system 

the glands that produce the hormones that control many aspects of the development and metabolism of the body, and the hormones they produce 

follicle stimulating hormone (FSH) 

causes the eggs to mature in the ovary 

gibberellins 

plant hormones that are important in initiating seed germination 

glucagon 

hormone involved in the control of blood sugar levels 

gravitropism 

the response of a plant to gravity 

hormones 

chemicals produced in one area of the body of an organism that have an effect on the functioning of another area of the body. In animals hormones are produced in glands 

insulin 

hormone involved in the control of blood sugar levels 

oestrogen 

female sex hormone that controls the development of secondary sexual characteristics in girls at puberty, and the build-up and maintenance of the uterus lining during the menstrual cycle 

ovaries 

female sex organs that produce eggs and sex hormones 

ovulation 

the release of a mature egg (ovum) from the ovary 

phototropism 

the response of a plant to light, controlled by auxin 

pituitary gland 

endocrine ‘master gland’ found in the brain that secretes a number of different hormones into the blood in response to different conditions to control other endocrine glands in the body 

testosterone 

the main male sex hormone that controls the male secondary sexual characteristics at puberty and the production of sperm 

tropism 

the responses of plant roots and shoots to environmental stimuli such as light or gravity 

type 1 diabetes 

a disorder where the pancreas fails to produce sufficient insulin 

type 2 diabetes 

a disorder where the body cells no longer respond to the insulin produced by the pancreas 

ADH 

anti-diuretic hormone helps control the water balance of the body and affects the amount of urine produced by the kidney 

dialysis 

the process of cleansing the blood through a dialysis machine when the kidneys fail 

selective reabsorption 

the process in the kidney where the materials needed in the body such as glucose, some mineral ions, and water are reabsorbed back into the blood from the filtrate 

thermoregulatory centre 

the area of the brain that is sensitive to the temperature of the blood 

vasoconstriction 

the constriction or narrowing of the blood vessels 

vasodilation 

the dilation or opening up of the blood vessels 

alleles 

different forms of the same gene sometimes referred to as variants 

asexual reproduction 

involves only one individual and the offspring is identical to the parent. There is no fusion of gametes or mixing of genetic information 

bases (DNA) 

nitrogenous compounds that make up part of the structure of DNA and RNA. They are represented by the letters A, T, C, and G 

carriers 

individuals who are heterozygous for a recessive allele linked to a genetic disorder. Carriers have one healthy allele so are not affected themselves but they can pass on the affected allele to their offspring 

cystic fibrosis 

an inherited disorder that affects the lungs, digestive, and reproductive system and is inherited through a recessive allele 

dominant allele 

the phenotype will be apparent in the offspring even if only one of the alleles is inherited 

genetic engineering 

the process by which scientists can manipulate and change the genotype of an organism 

genotype 

the genetic makeup of an individual for a particular characteristic, for example hair or eye colour 

heterozygote 

individual with different alleles for a characteristic 

homozygote 

individual with two identical alleles for a characteristic 

meiosis 

two stage process of cell division that reduces the chromosome number of daughter cells. It is involved in making gametes for sexual reproduction 

mutation 

a change in the genetic material of an organism 

natural selection 

the process by which evolution takes place. Organisms produce more offspring than the environment can support. Only those that are most suited to their environment will survive to breed and pass on their useful characteristics to their offspring 

nucleotide 

a molecule made up of a sugar, a phosphate group, and one of four different bases. They are key units in the structure of DNA and RNA 

phenotype 

the physical appearance / biochemistry of an individual for a particular characteristic 

polydactyly 

a dominant inherited disorder that results in babies born with extra fingers and/or toes 

Punnett square diagram 

a way of modelling a genetic cross and predicting the outcome using probability 

recessive 

a phenotype that will only show up in the offspring if both of the alleles coding for that characteristic are inherited 

sex chromosomes 

carry the information that determines the sex of an individual 

sexual reproduction 

involves the joining (fusion) of male and female gametes producing genetic variation in the offspring 

mutation 

a change in the genetic material of an organism 

natural selection 

the process by which evolution takes place. Organisms produce more offspring than the environment can support. Only those that are most suited to their environment will survive to breed and pass on their useful characteristics to their offspring 

selective breeding 

speeds up natural selection by selecting animals or plants for breeding that have a required characteristic 

tissue culture 

a modern way of cloning plants that allows thousands of new plants to be created from one piece of plant tissue 

archaea 

one of the three domains, containing primitive forms of bacteria that can live in many of the extreme environments of the world 

classification 

the organisation of living organisms into groups according to their similarities 

domain 

the highest level of classification. There are three domains – Archaea, Bacteria and Eukaryota  

evolutionary trees 

models used to explain the evolutionary links between groups of organisms 

extinction 

the permanent loss of all members of a species from an area or from the world 

speciation 

the process by which two species evolve from a single original species by natural selection 

species 

the smallest group of clearly identified organisms in Linnaeus’s classification system, often described as a group of organisms that can breed together and produce fertile offspring 

abundance  

a measure of how common or rare a particular type of organism is in a given environment 

adaptations 

special features that make an organism particularly well suited to the environment where it lives 

community 

group of interdependent living organisms in an ecosystem 

competition 

the process by which living organisms compete with each other for limited resources such as food, light, or reproductive partners 

distribution 

where particular types of organisms are found within an environment 

extremophile 

an organism that can survive and reproduce in extreme conditions 

interdependence 

the network of relationships between different organisms within a community, for example each species depends on other species for food, shelter, pollination, seed dispersal, etc. 

mean 

the arithmetical average of a series of numbers 

median 

the middle value in a list of numbers  

mode 

the number which occurs most often in a set of data 

quadrat 

a sample area used for measuring the abundance and distribution of organisms in the field 

quantitative sampling  

records the numbers of organisms rather than just the type 

range  

the maximum and minimum values for the independent or dependent variables – important in ensuring that any patterns are detected 

sample size 

the size of a sample in an investigation 

transect 

a measured line or area along which ecological measurements are made 

biomass 

the amount of biological material in an organism 

carbon cycle 

the cycling of carbon through the living and non-living world 

decomposers 

microorganisms that break down waste products and dead bodies 

primary consumer 

animals that eat producers 

producers 

organisms such as plants and algae that can make food from raw materials such as carbon dioxide and water 

secondary consumer 

animals that eat the primary consumers 

acid rain 

rain that has an acidic pH caused by acid gases that have been released into the atmosphere, such as sulfur dioxide and nitrogen oxide. These gases dissolve in rainwater and react with oxygen in the air to for acid 

biodiversity 

a measure of the variety of all the different species of organisms on Earth 

deforestation 

the removal of trees from a large area of land so that the area can be used for other purposes, such as farming or building 

incident energy 

light from the Sun arriving at the surface of the Earth 

trophic level 

feeding levels in an ecosystem