IGCSE Biology - Pearson Edexcel - GLOSSARY DEFINITIONS ONLY - COMPLETED Flashcards
FLASHCARDS MADE MYSELF WITH AID OF SOURCE BOOK: BIOLOGY PEARSON EDEXCEL INTERNATIONAL GCSE (9-1) STUDENT BOOK BY PHIL BRADFIELD AND STEVE POTTER
What is an abiotic factor?
A physical or chemical factor affecting an ecosystem (e.g. light intensity or temperature).
Name 2 examples of abiotic factors:
- Light intensity
- Temperature
What is accommodation?
Accommodation refers to the changes taking place in the eye which allow it to focus on objects at different distances.
What is the ACCURACY of experimental results?
The closeness of an experimental result to its true value.
What is acid rain?
Rain with a pH of less than 5.5, caused by pollutant gases such as sulphur dioxide and nitrogen oxides.
What is the active site?
The area on the surface of an enzyme where the substrate attaches and products are formed.
What is active transport?
The net movement of molecules or ions against a concentration gradient (from an area of low concentration to an area of high concentration), using energy from respiration.
What is an adaptation (of an organism)?
Feature of an organism that suits its structure to its function.
What does ATP stand for?
Adenosine Triphosphate
What is adenosine triphosphate (ATP)?
A chemical present in all cells which acts as an energy ‘currency’. ATP is made by respiration and used up by any process that needs a supply of energy.
What are the adrenal glands?
A pair of endocrine glands situated above the kidneys which secrete adrenaline.
What is adrenaline?
Adrenaline is a hormone secreted by the adrenal glands. It stimulates several organs in the ‘fight or flight’ response.
What is aerobic respiration?
A reaction that releases energy from food. It uses oxygen and produces carbon dioxide and water.
What is agar?
A jelly-like substance used as a culture medium for growing microorganisms.
What are algae?
Photosynthetic protocists. Mostly unicellular, some multicellular lifeforms (such as seaweed).
What is algal bloom?
A rapid increase in numbers of algal cells in an aquatic habitat. It is often caused by eutrophication.
What are alleles?
Alleles are different forms of a gene.
What is the singular form of alveoli?
Alveolus
What is the plural form of alveolus?
Alveoli
What is an amino acid?
One of about 20 different molecules that form the building blocks of proteins.
What is the amnion?
The membrane enclosing the embryo during pregnancy.
What is amniotic fluid?
Fluid secreted by the amnion that protects the embryo by acting as a shock absorber.
What is amylase?
An enzyme that digests starch into maltose.
What is anaerobic respiration?
A reaction that releases energy from food, without using oxygen. It produces lactate in mammals, and produces carbon dioxide and ethanol in yeast.
What is the anther?
The part of the stamen where pollen grains are produced.
What are antibodies?
Proteins produced by lymphocytes that bind with foreign antigens as part of the immune response.
What is an anticodon?
A group of 3 bases on a tRNA molecule that are complimentary to a codon on the mRNA.
What does ADH stand for?
Antidiuretic Hormone
What is an antidiuretic hormone (ADH)?
A hormone released from the pituary gland. It controls the water content of the blood by increasing reabsorption of water from the collecting ducts of the kidney into the blood.
What is an antigen?
A chemical ‘marker’ on the surface of a cell that identifies the cell as ‘self’ or ‘non-self’.
What is the anus?
The outlet of the gut where faeces is expelled from the body.
What is an arteriole?
An arteriole is a small artery.
What is an artery?
A blood vessel with a thick muscular wall and a narrow lumen, which carries blood away from the heart.
What does AI stand for in biology?
Artificial Insemination
What is artificial insemination (AI)?
A method of selective breeding, where semen is used to make an animal pregnant without sexual intercourse (e.g. using semen from prize bulls to inseminate cows).
What is asexual reproduction?
Reproduction that does not involve fusion of gametes. New organisms are produced by part of an organism separating from a single parent.
What is assimilation in cells?
Manufacture of new substances in cells using the products of digestion.
What is the singular form of atria?
Atrium
What is the plural form of atrium?
Atria
What are the atria?
The two upper chambers of the heart where blood enters the heart. Blood enters the right atrium via the vena cava, and the left atrium via the pulmonary vein.
What is auxin?
A plant hormone involved in tropisms and other growth responses.
What is an axon?
A long extension of a neurone that carries nerve impulses in a direction away from the cell body.
What is the singular form of bacteria?
Bacterium
What is the singular form of bacteria?
Bacterium
What is the plural form of bacterium?
Bacteria
What are bacteria?
Small single-celled organisms with no nucleus.
What is bacteriophage?
A virus that infects bacteria which is used as a vector in genetic engineering.
What is a balanced diet?
A diet containing all the necessary food types in the correct amounts and proportions to keep the body healthy.
What is a base (in DNA)?
One of four nitrogen-containing groups in the DNA molecule - adenine (A), thymine (T), cytosine (C) and guanine (G). The bases form complementary pairs linking the chains of the double helix structure (A pairs with T, C pairs with G).
What is the basement membrane in Bowman’s capsule?
The membrane in the wall of the Bowman’s capsule that acts as a molecular filter during ultrafiltration in the kidney.
What is beri-beri?
A cluster of symptoms caused primarily by thiamine (vitamin B1) deficiency.
What is the bicuspid valve?
The valve in the heart between the left atrium and the left ventricle. It prevents backflow of blood when the ventricle contracts.
What is bile?
A green liquid made by the liver and stored in the gall bladder. It causes lipids in the gut to form an emulsion, increasing their surface area and thus speeding up digestion by enzymes.
What is the bile duct?
The tube carrying bile from the gall bladder to the duodenum.
What is bioaccumulation?
The build-up of pollutants such as insecticides in the fatty tissues of an organism.
What is biodiversity?
The amount of variation shown by organisms in an ecosystem. Biodiversity is a measure of both numbers of species and abundance of each species.
What is biological control?
Use of another organism to control the numbers of a pest species.
What is biomagnification?
The increase in concentration of bioaccumulated substances along a food chain.
What is biomass?
Total mass of organisms, e.g. an ecosystem.
What is biotechnology?
The use of microorganisms to make useful products.
What is a biotic factor?
A biological factor affecting an ecosystem.
Name 2 examples of biotic factors:
- Food supply
- Predation
What is the bladder?
A muscular bag that stores urine before its removal from the body.
What is the blind spot in the eye?
The area of the retina where the optic nerve leaves the eye. It contains no light-sensitive cells so an image can not be detected.
What is a Bowman’s capsule?
A structure consisting of a hollow cup of cells at the start of a kidney tubule. It is the site of ultrafiltration.
What is the bronchial tree?
The branching network of air passages in the lungs.
What are the bronchioles?
Small air passages leading from the bronchi to the alveoli.
What is bronchitis?
A lung disease caused by irritation of the bronchial tree and infection by bacteria, resulting in breathing difficulties.
What is the plural form of bronchus?
Bronchi
What is the singular form of bronchi?
Bronchus
What are the bronchi?
The tubes leading from the trachea to the lungs.
What is a capillary?
A microscopic blood vessel that carries blood through organs and allows exchange of substances between the blood and the cells of the organ.
What is a capsule (as relevant to bacteria)?
A slime layer covering some bacterial cells. Protects the bacterium and stops it drying out.
What is carbohydrase?
An enzyme which digests carbohydrates
What is a carbohydrate?
An organic compound composed of one or more sugar molecules.
What is carbon monoxide?
The toxic gas present in car exhaust fumes and cigarette smoke.
What is carboxyhaemoglobin?
The substance formed when carbon monoxide combines with haemoglobin, displacing oxygen from the haemoglobin.
What is a carcinogen?
Something which causes cancer, e.g. a chemical or radiation.
What is the cardiac centre?
The region in the medulla of the brain that controls heart rate.
What is the cardiac cycle?
A sequence of events taking place in the heart during one heartbeat.
What is cardiac muscle?
Specialised muscle making up the heart wall. It is able to contract rhythmically and without fatiguing.
What is a carnivore?
An animal that feeds on other animals.
What is cartilage?
Tough tissue present in several places in the body, such as rings in the trachea and between the bones at a joint.
What is a catalyst?
A chemical that increases the rate of a reaction but remains unchanged at the end of the reaction.
What is a cell?
The basic structural unit of living organisms.
What is the cell membrane?
A thin surface layer around the cytoplasm of a cell. It forms a partially permeable barrier between the cell contents and the outside of the cell.
What is cellulose?
Polysaccharide of glucose that forms plant cell walls.
What is the CNS made up of?
The brain and the spinal cord.
What does CNS stand for?
Central Nervous System
What is the cervix?
The ‘neck’ of the uterus.
What does CHD stand for?
Coronary Heart Disease
What is chitin?
A substance that makes up the cell wall of fungi and the outside skeleton of insects.
What is chlorophyll?
The green pigment present in chloroplasts, which absorbs light energy during photosynthesis.
What is a chloroplast?
An organelle found in some plant cells. Chloroplasts are the site of the reactions of photosynthesis.
What is cholesterol?
A lipid substance present in the blood which is linked to coronary heart disease.
What is the choroid?
The dark layer of tissue below the sclera of the eye which contains blood vessels and pigment cells.
What is a chromatid?
One of two thread-like strands of a replicated chromosome. Each chromatid contains an exact copy of the double helix of DNA. Chromatids become visible at the start of mitosis and meiosis.
What is a chromosome?
A thread-like structure found in the nucleus of a cell, made of DNA and protein. Chromosomes contain the genetic information (genes).
What is the singular form of cilia?
Cilium
What is the plural form of cilium?
Cilia
What are cilia?
Cilia are microscopic hair-like projections from the surface of some animal cells, such as those lining the trachea and bronchi. Beating of cilia moves mucus and trapped particles towards the mouth.
What is the ciliary muscle?
The ring of muscle around the lens of the eye that alters the shape of the lens during accommodation.
What is a clone?
A group of cells, or organisms, that are genetically identical.
What is the cell wall?
A non-living layer outside the cell membrane of certain types of cell. It is made of cellulose in plants and algae, chitin in fungi and peptidoglycan in bacteria.
What is codominance?
A pattern of inheritance where neither allele of a gene is dominant over the allele so that both alleles are expressed in the phenotype.
What is a codon?
A triplet of bases on the mRNA molecule. Different triplets code for different amino acids in a protein.
What is a coleoptile?
A protective sheath covering the first few leaves of a cereal seedling which is used in tropism experiments.
What is the collecting duct?
The last part of a kidney tubule, where water is reabsorbed before the final urine is produced.
What is the colon?
The first part of the large intestine, where water is absorbed from the waste material in the gut.
What is a community?
All organisms of a certain species found in a particular area at a certain time.
What is a companion cell?
A specialised cell lying next to a sieve tube in the phloem and controlling its activities.
What is a cone cell?
A cell in the retina of the eye that is sensitive to different wavelengths of light and results in colour vision.
What is control in an experiment?
Part of an experiment which is set up to show that other variables are not having an effect on the outcome of the experiment.
What are controlled variables?
Variables in an experiment other than the independent variable, which are kept constant by the person carrying out the experiment so that they do not affect the results.
What is a consumer?
An organism that eats other organisms.
What is the cornea?
The transparent ‘window’ at the front of the eye that allows light to enter the eye. It also (along with the lens) refracts the light as it enters the eye.
What are the coronary arteries?
Small arteries which supply blood to the heart muscle.
What is coronary heart disease?
It is a disease cause by the blockage of the coronary arteries due to a build-up of fatty material. It can cut off blood supply to the heart and result in a heart attack.
What are the coronary veins?
Small veins which carry blood away from the heart muscle.
What is corpus luteum?
The remains of an ovarian follicle after ovulation which secretes progesterone.
What is the cortex (of the kidney)?
The outer part of the kidney, containing kidney tubules and blood vessels.
What are cotyledons?
Seed leaves - these may act as food store in seed.
What is cross-pollination?
The transfer of pollen from an anther of one plant to a stigma of a different plant of the same species.
What is the cuticle?
A thin layer of waxy material covering the epidermis cells of a plant.
What is cutting (in terms of producing new plants)?
Cutting is a method of producing new plants by taking a piece of a shoot and planting it in compost - this is an example of asexual reproduction.
What is the cytoplasm?
A jelly-like material that makes up most of the cell.
What is decomposition?
The breakdown of the dead remains of other organisms, helping to recycle nutrients.
What is a decomposer?
An organism that feeds by breaking down the dead remains of other organisms, e.g. some bacteria and fungi.
What is denaturing?
The process where the structure of a protein is damaged by high temperatures (becomes denatured). If the protein is an enzyme, it will no longer catalyse its reaction.
What are dendrites?
Fine extensions of the dendrons of a neurone.
What is a dendron?
An extension of the cytoplasm of a neurone that carries impulses towards the cell body.
What is denitrifying bacteria?
The type of bacteria in the nitrogen cycle that converts nitrates into nitrogen gas.
What does DNA stand for?
Deoxyribonucleic Acid
What is deoxyribonucleic acid (DNA)?
The chemical of which genes are made. It is a double helix structure composed of deoxyribose sugar, phosphates and four bases (adenine, thymine, guanine and cytosine).
What is the dermis?
The middle layer of the skin containing many sensory receptors.
What is diabetes?
A disease where the blood glucose concentration cannot be properly controlled. It is caused by a lack of insulin.
What is the diaphragm?
The muscular sheet separating the thorax from the abdomen. It is involved in the mechanism that ventilates the lungs.
What is a dicot (dicotyledonous plant)?
A plant with two seed leaves.
What is differentiation?
The process taking place during the development of the embryo, where cells become specialised to carry out particular functions.
What is diffusion?
The net movement of ions or molecules down a concentration gradient (from an area of high concentration to an area of low concentration).
What is digestion?
The process by which food is broken down into simpler molecules that can be absorbed.
What does diploid refer to (number)?
The number of chromosomes found in body cells. Diploid cells contain both chromosomes of each homologous pair.
What is a disaccharide?
A sugar made up of two monosaccharides, e.g. sucrose, which is a disaccharide of glucose and fructose.
What is the dominant allele?
The allele of a gene that is expressed in the heterozygote.
What is the dorsal root ganglion?
A swelling in the spinal nerve that contains the cell bodies of sensory neurones.
What is the double circulatory system?
The blood circulatory system in mammals, where the blood passes through the heart to the lungs and returns to the heart before passing to the rest of the body.
What is dietary fibre?
Indigestible plant material, mainly cellulose, in the diet. It helps to prevent constipation and bowel diseases.
What is the duodenum?
The first part of the small intestine following the stomach.
What is a dorsal root?
Part of a spinal nerve that emerges from the dorsal (back) side of the spinal cord.
What is an ecosystem?
A community of living organisms together with their non-living environment.
What is an effector?
An organ that brings about a response (a muscle or gland).
What is the epidermis (in plants)?
The outer layer of cells of a leaf or other non-woody parts of a plant.
What is the epidermis (in skin)?
The outer layer of skin, consisting of dead cells.
What is an erythrocyte?
A red blood cell
What is an endocrine gland?
A gland secreting a hormone into the blood stream.
What are eukaryotic cells?
Cells that have a nucleus (the cells of all living organisms except for bacteria).
What is emphysema?
Lung disease where the walls of the alveoli break down and fuse together again, forming air spaces with a reduced surface area. It results in breathing difficulties.
What is ejaculation?
Release of semen during sexual intercourse.
What is an enzyme?
A protein that acts as a biological catalyst.
What is an embryo?
A multicellular structure formed by division of a zygote.
What is eutrophication?
The process where an aquatic habitat receives large amounts of minerals, either naturally or as a result of pollution by sewage or fertilisers.
What is evolution?
Change in form of organisms over the course of time. It is the process by which species develop from earlier forms during the history of the Earth.
What is excretion?
The removal from the body of the waste products of metabolism.
What is an exocrine gland?
A gland secreting a product through a duct.
What is an explant?
A small piece of plant tissue used in micropropagation.
What is faeces?
Semi-solid indigestible waste that passes out of the gut via the anus.
What is the F1 generation?
Offspring formed from breeding the parent organisms.
What is the F2 generation?
Offspring formed from the breeding of individuals from the F1 generation.
What is a fatty acid?
A type of molecule that, with glycerol, is one of the building blocks of lipids.
What is fermentation?
Using the respiration of microorganisms to produce useful products.
What is fibrin?
A protein formed from fibrinogen during blood clotting.
What is a fermenter?
A vessel used to grow microorganisms.
What is fertilisation?
The fusion of male and female gametes to form a zygote.
What is a fetus?
Unborn offspring of a mammal, in particular an unborn human embryo more than two months after fertilisation, when it shows recognisably human features.
What is fibrin?
A protein formed from fibrinogen during blood clotting.
What is fibrinogen?
A protein in blood plasma that forms insoluble fibres of fibrin during blood clotting.
What is a flaccid cell?
A condition in a plant cell which has lost internal pressure, so that the cytoplasm no longer pushes against the cell wall.
What is the plural form of flagellum?
Flagella
What is the singular form of flagella?
Flagellum
What is the flagellum?
IN ANIMAL CELLS SUCH AS SPERM: Tail-like structure that beats from side-to-side, producing movement.
IN SOME BACTERIA: Structure with similar function but much smaller and quite different structure.
What does FSH stand for?
Follicle-stimulating Hormone
What is a food chain?
A flow diagram showing the feeding relationships in an organism.
What is a food web?
A diagram showing the way in which several food chains are linked together in an ecosystem.
What is fructose?
Monosaccharide sugar found in fruits.
What are gametes?
Male and female sex cells, formed by meiosis.
What is a gene?
A gene is part of a chromosome, the basic unit of inheritance. It is a length of DNA that controls a characteristic of an organism by coding for the production of a specific protein.
What is genetic engineering?
Techniques used to transfer genes from the cells of a donor organism to those of a recipient.
What is the follicle (in ovary)?
The structure in the mammalian ovary that contains a single developing egg cell.
What is the fovea?
The region at the centre of the retina of the eye where there is a high concentration of light-sensitive receptor cells.
What is a fruit?
A structure containing a seed or several seeds. Formed from the ovary following fertilisation.
What is a genome?
The entire DNA of an organism (the amount present in a diploid cell).
What is the gall bladder?
The organ that stores bile from the liver.
What is a follicle-stimulating hormone?
The hormone made by the pituitary gland which stimulates the maturation of eggs in the ovary and sperm production in the testes.
What is the genotype?
The alleles an organism has for a certain characteristic.
What is geotropism?
The growth movement of a plant in response to the directional stimulus of gravity.
What is germination?
A sequence of events taking place when the embryo in a seed begins to develop into a young plant.
What is glomerular filtrate?
Fluid that passes through the Bowman’s capsule at the start of a kidney tubule.
What is a glomerulus?
A ball of capillaries surrounded by the Bowman’s capsule at the start of a kidney tubule.
What is glucagon?
A hormone released by the pancreas. Action of glucagon causes an increase in the concentration of glucose in the blood.