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Abiotic condition
A non-living feature of an ecosystem
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Abundance
The number of individuals of one species in a particular area (i.e. population size)
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Accurate result
A result that is really close to the true answer
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Acetylation
Attachment of an acetyl group to something (e.g. histones)
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Acetylcholine (ACh)
A type of neurotransmitter that binds to cholinergic receptors
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Acetyl coenzyme A (Acetyl CoA)
A type of coenzyme involved in respiration. It transfers acetate from one molecule to another.
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Acquired Mutation
A mutation developed during life.
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Actin
The thin myofilament protein in muscle fibres.
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Actin-myosin cross bridge.
The bond formed when a myosin head binds to an actin filament.
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Activator
A transription factor that increases the rate of transcription.
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Active Transport
Movement of molecules and ions across plasma membranes usually against a concentration gradient. Requires energy.
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Adaptation
A feature that increases an individual's chance of survival and reproduction.
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ADP (Adenosine diphosphate)
A molecule made up of adenine a ribose sugar and two phosphate groups. A nucleotide derivative. ADP becomes ATP when it is phosphorylated.
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Adrenaline
A hormone secreted from the adrenal glands that has many effects - including increasing blood glucose concentration.
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Allele
A specific version of a gene (blood group, eye colour etc.)
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Allele Frequency
How often and allele crops up in a population.
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Allopatric speciation
Speciation caused by geographic separation.
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Ammonification
The process by which nitrogen compounds from dead organisms or waste material are turned into ammonium compounds by saprobionts.
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Anomalous result
A measurement that falls outside of the range of values you expected, based on the pattern of results you have seen.
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Antidiuretic hormone (ADH)
A hormone that regulates the water potential of the blood by controlling the permeability of the cells of the distal convoluted tubule and the collecting duct of the kidney.
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ATP (Adenosine triphosphate)
A molecule made up of adenine and ribose sugar (a nucleotide derivative) with three phosphates attached. The source of energy in the cell.
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ATP hydrolase
Enzyme catalyses breakdown ATP-ADP + Pi
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ATP-Phosphocreatine system
A system that generates ATP very quickly by phosphorylating ADP using a phosphate group from phosphocreatine.
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ATP Synthase
An enzyme that generates ATP from ADP + Pi (usually during respiration).
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Atrioventricular Node (AVN)
A group of cells in the heart wall that is responsible for passing waves of electrical impulses from the SAN to theĀ bundle of His.
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Autonomic nervous system
A division of the peripheral nervous system that controls unconscious activities - such as heart rate.
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Autosomal linkage
When two genes are located on the same autosome and are inherited together.
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Autosome
Non-sex chromosome.
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Benign tumour
A non-cancerous tumour (growth)
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Bias
When someone intentionally (or not) favours a particular result.
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Biomass
The mass of living material in an organism/population/ecosystem.
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Biotic condition
A living feature of an ecosystem (competition, availability of prey, predators, potential reproductive partners or any other biotic interaction).
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Bundle of His
A group of muscle fibres in the heart responsible for conducting waves of electrical impulses from the AVN to the Purkyne fibres.
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Cardiomyocyte
A heart muscle cell.
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Carrier
A person carrying an allele that is no expressed in their phenotype, but can still be passed on.
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Carrying Capacity
The maximum stable population size of a species that an ecosystem can support.
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Causal relationship
Where a change in one variable causes a change in the other.
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cDNA (complementary DNA)
A DNA copy of mRNA made using reverse transcriptase.
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Chemical mediator
A chemical messenger that acts locally (i.e. on nearby cells).
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Chemiosmosis
The process of electrons flowing down the electron transport chain and creating a proton gradient across a membrane to drive ATP synthesis.
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Chlorophyll
A photosynthetic pigment found in Chloroplasts. There are different types of this pigment - given letters (a, b).
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Choice chamber
A container with different compartments that can be used to investigate how animals respond to different environmental conditions.
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Cholinergic synapse
A synapse that uses the neurotransmitter acetylcholine.
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Climax community
The final stage in succession - for example Oak Woodland in Western Europe, or Tropical hardwood forest in central America. The point at which carrying capacity is all used up.
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Codominant allele
An allele whose character together with another allele in the phenotype because neither is recessive.
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Codon
3 nucleotides = 1 amino acid.
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Coenzyme
A molecule that aids the function of an enzyme. They work by transferring one chemical group to another.
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Community
All the populations of different species in a habitat.
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Compensation point
The point at which the rate of photosynthesis in a plant exactly matches matches its rate of respiration.
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Cone (eye)
A photoreceptor cell found in the eye that is colour sensitive.
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Conservation
The protection and management of species and habitats in a sustainable way.
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Continuous data
Data that can take any value in the range (height, mass, age) as opposed to things such as handedness, or blood type.
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Control group
A group in a study that is treated in exactly the same way as the experimental group apart from the factor you are investigating.
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Control variable
A variable which is kept the same each time an experiment is repeated.
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Coordinator (nervous)
Part of the nervous system (CNS etc.) which formulates the response to a stimulus before sending impulses to an effector.
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Correlation
A relationship between two variables.
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Dehydrogenase
An enzyme that transfers hydrogen and electrons from one molecule to another.
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Denitrification
The process by which nitrates in the soil are converted into nitrogen gas by denitrifying bacteria.
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Dependent variable
The variable you measure in an experiment.
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Depolarisation
A decrease in the potential difference across a cell's membrane making it less negative (i.e. more positive) than the resting potential.
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Diabetes mellitus (type 1)
A condition in which blood glucose concentration can't be controlled properly because the body doesn't produce insulin.
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Diabetes mellitus (type 2)
A condition in which blood glucose concentration can't be controlled because the body doesn't produce enough insulin or cells don't respond to insulin in the blood.
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Dihybrid inheritance
The inheritance of two characters controlled by different genes. (dihybrid crosses etc)
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Directional selection
Where individuals with alleles for a single extreme phenotype are more likely to survive and pass on genes - shifting the average towards those features over several generations.
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Discrete data
Numerical data that can only take certain values in a range (number of limbs/leaves/eyes/elephants in a herd).
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Disruptive selection
Where individuals with alleles for various extreme features at the limits of the phenotype are more likely to survive - possibly leading to sympatric speciation.
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Distribution
The spread of a particular species across an area. Often associated with other factors - light, salinity, prey availability/presence of predators.
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DNA polymerase
An enzyme that joins together the nucleotides on a new strand of DNA after complementary base pairing has linked them to the original template strand.
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DNA Probe
A short single strand of DNA that has a base sequence complementary to a target gene.
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DNA Sequencing
A technique used to determine the order of bases in a sequence of DNA.
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Dominant allele
An allele who characteristic appears in the phenotype whenever it is present.
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Ecosystem
All the living and non living aspects of a habitat.
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Effector
Does things - muscles/glands (usually)
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Electrochemical gradient
A concentration gradient of ions.
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Electron transport chain
A chain of proteins down which excited electrons flow.
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Epigenetic control of gene expression
The attachment and removal of chemical groups to DNA/histones which determines whether genes are 'switched on' or 'switched off'.
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Epistasis
When the expression of an allele masks the expression of others. For example. A man with a widows peak (an allele for this exists) would not express it if he also had the allele for baldness - the first allele would be rendered invisible.
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Evolution
The change in the allele frequency in a population over time.
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Exocytosis
The process whereby a cell secretes/excretes substances using vesicles.
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Exon
The part of DNA that codes for amino acids
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Extracellular digestion
When food is broken down using enzymes outside the cell, and absorbed. Saprobionts use extracelluar digestion.
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Facilitated diffusion
The diffusion of particles through the cell membrane using carrier proteins or protein channels.
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FAD
A coenzyme involved in respiration. It transfers hydrogen from one molecule to another.
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Fast twitch (muscle fibre)
A muscle fibre that contracts very quickly - but also gets tired very quickly.
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Frameshift mutation
A mutation caused by a deletion or addition (which changes the number of bases in the genome). This shifts all the triplets which come after it - meaning they are read differently.
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Gel electrophoresis
A technique that allows DNA fragments to be separated on a gel plate according to size (using electric current to move the fragments).
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Gene
A section of DNA that codes for a protein and results in a characteristic.
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Gene Expression
The transcription of a gene into mRNA and translation of the gene into a protein.
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Gene Pool
The complete range of alleles present in a population.
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Generator potential
The change in potential difference across a cell membrane due to a stimulus (in sensory receptor cells usually).
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Gene technology
Techniques that allow the study of genes and alteration of their functions.
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Gene Therapy
Altering genes inside cells to treat cancer or genetic illnesses.
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Genetic code
The sequence of codons in a nucleic acid (DNA/mRNA) that codes for amino acids.
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Genetic disorder
An inherited disorder caused by an abnormal gene or chromosome.
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Genetic drift
The process whereby an allele changes in frequency in a population due to chance.
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Genetic engineering
AKA recombinant DNA technology. When DNA from different organisms is joined together by isolating a fragment from a donor organism and inserting it into the DNA of a host.
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Genetic fingerprint
A DNA gel that shows the number of times repetitive non-coding base sequences occur at different loci in an individual.
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Genetic pedigree diagram
A diagram that shows how an inherited characteristic runs through a group of related individuals.
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Genome
All the genetic material in an organism.
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Genotype
The genetic constitution of an organism (the specific alleles of an individual). So a Brown eyed person may have a Bb genotype or a BB genotype.
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