Reaction centre		The early stages of population growth, in which little or no growth is evident, as the organisms adjust to a new environment
Phenylketonuria		The maximum size of a population that can be supported sustainably (that is over a ling time period) in a particular habitat
Independent Assortment		Two chromosomes that carry the same genes in the same positions (loci)
Pioneer Plant		A process in which enrichment of water with nutrients leads to an increase in algae and bacteria, and a reduction in oxygen content
Link Reaction		Cutting down trees or shrubs very close to the ground, leaving only a short trunk or stems called a coppice stool; the plant will regrow from this stool and can be coppiced again in several years' time
Meiosis		A sausage-Shaped epidermal cell found in pairs bounding a stoma and controlling its opening or closure
Lamina		The final community in a succession
Homologous Chromosomes		the synthesis of ATP from ADP and Pi using light energy in photosynthesis
Krebs Cycle		The succession that occurs on an area where no living things were originally present
Guard Cell		A closed pathway of reactions in aerobic respiration in a mitochondrion in which hydrogens pass to hydrogen carriers for subesquent ATP syntehsis and some ATP is synthesized directly
Electron Transport Chain		A graph of the absorbance of different wavelengths of light by a compound such as a photosynthetic pigment
Lactose Permease		All the living organisms in a particular habitat
Absorption Spectrum		The existence of three or more alleles of a gene, as, for example, in the determination of A,B,O blood groups
Multiple Alleles		Anaerobic Respiration in which glucose is converted to ethanol
Biotic Factor		Part of an operon to which a repressor protein can bind , so preventing the expression of the structural gene in that operon
Climax Community		An enzyme secreted by some bacteria, such as E.Coli, which enables the cells to absorb lactose
Respiratory Quotient		The part of an operon to which RNA polymerase must bind before transcription of the structural genes can begi
Oxidative Phosphorylation		Cutting down all the trees in an area of woodland
Chemiosmosis		The blade of a leaf
Niche		A random and unpredicatable change in the structure or number of chromosomes in a cell.
Mutagen		The way in which different alleles of genes on different chromosomes may end up in any combination in gametes, resulting from the random alighment of bivalents on the equator during meiosis I
Secondary Succession		All the chromosomes except the X and Y (sex) chromosomes
Population		Part of a DNA molecule that codes for a protein that controls the expression of another gene
Alcoholic Fermentation		The transfer of a phosphate group to an organic compound
Clear Felling		A graph of the rate of photosynthesis at different wavelengths of light
Allele		A plant growth regulator that causes closure of stomata in dry conditions, and inhibits seed germination
Autosomes		a protein that can bind to part of a DNA molecules, preventing expression of a nearby gene
Accessory Pigment		A length of DNA containing genes coding for one or more proteins, plus other regions which control whether or not these genes will be expressed
Action Spectrum		a gene that is carried on an X chromosome but not on a Y chromosome
Primary Succession		the type of cell division that results in a halving of chromosome number and a reshuffling of alleles; in humans it occurs in the formation of gametes
Crossing Over		the ratio of the volume of carbon dioxide given out in respiration to that of oxygen used
Operon		A pigment that is not essential to photosynthesis but which absorbs light of different wavelengths and passes the energy to chlorophyll a
Repressor		decarboxylation and dehydrogenation of pyruvate and formation of acetyl coenzyme A, linking glycolysis with the krebs cycle
Respirometer		Growing different crops in a field in successive years
Crista		A fold of the inner membrane of the mitochondrial envelope on which are found stalked particles of ATP synthase
Abiotic Factor		Chain of adjacently arranged carrier molecules in the inner mitochondrial membrane along which electrons pass by redox reactions
Chromosome Mutation		A cluster of light harvesting accesory pigments surroundig a primary pigment or reaction centre.
Coppicing		The apparatus for measuring the rate of oxygen consumption in respiration or for finding the RQ
Community		The synthesis of ATP using energy stored as a difference in hydrogen ion concentration across a membrane in a chloroplast or mitochondrion
Photosystem		Synthesis of ATP from ADP and Pi using energy released by the electron transport chain in aerobic respiration
Sex linked Gene		A particular variety of a gene
Photophosphorylation		A factor which affects a population or a process, that is caused by other living organisms; examples include competition, predation and parasitism
Biochemical Oxygen Demand		the stage in the lifetime of a population in which no growth or decrease takes place; the rate of production of new individuals exactly matches the rate of death
Operator		A genetic disease resulting from a mutation in a gene that codes for an enzyme involved in the metabolism of phenylalanine
Eutrophication		The conversion of gaseous nitrogen, N2, into a more reactive form such as nitrate or ammonia
Abscisic Acid		The physical characteristics of a habitat, such as temperature, light intensity and soil pH. Non-Living
Log phase		The rate at which oxygen is used up in a sample of water; a high one indicates a rapid rate of aerobic respiration by bacteria
Crop Rotation		A substance that can cause mutation
Stationary Phase		A plant which can colonise newly cleared or disturbed ground
Ecosystem		the particular role played by a species in an ecosystem
Fixation		The succession taking place in an area where some vegetation was already present
Carrying Capacity		The internal tissue of a leaf blade with chloroplasts for photosynthesis and consisting of an upper layer of palisade cells(main photosynthetic tissue) and a lower layer of spongy mesophyll with large air spaces for gas exchange
Lag phase		A molecule of chlorophyll a that recieves energy from the light absorbed by surrouding accessory pigments in a photosystem
Promoter		All of the living organisms of all species, and all of the non-living components, that are found together in a defined area and that interact with each other
Regulator Gene		The stage of population growth that follows the lag phase, during which the population repeatedly doubles per unit time
Phosphorylation		An event that occurs during meiosis I, when chromatids of two homologous chromosomes break and rejoin so that a part of one chromatid swaps places with the same part of the other
Mesophyll		All the individuals of a species living in an area at the same time and that can interbreed with one another