Abiotic components
Components of an ecosystem that are non living
Abiotic factors
Non living components of an ecosystem that effect other living organisms
Acetycholine
Chemical that acts as a transmitter that diffuses across synaptic cleft
Acetycholinesterase
Enzyme in synaptic cleft that breaks down acetycholine. After it has triggered an action potential in the post synaptic neurone, acetycholine must be broken down otherwise it would remain in the synaptic cleft and continue to open sodium ion channels in the post synaptic membrane causing action potentials
Acinus (plural acini)
Small group of exocrine cells in a sac like structure. in the pancreas these surround a tubule and secrete into the tubule
Action potential
A brief reversal of teh potential across the membrane of a neurone causing a peak of +40mV compared to the resting potential of -60mV
Adenyl cyclase
An intracellular enzyme that converts ATP to cyclic AMP (CAMP)
ADP
Adenosine diphosphate
Adrenal cortex
Outer layer of the adrenal gland
Adrenal gland
One of the pair of glands lying above kidneys, which release adrenaline and a number of hormones known as corticoids (or corticosteroids) such as aldosterone
Adrenaline
Hormone released from medulla of adrenal glands which stimulates body to prepare for fight or flight
Adrenal medulla
Inner layer of adrenal gland
Adrenocorticotropic hormone (ACTH)
Hormone released by pituitary gland which stimulates adrenal cortex to produce corticosteroid hormones
Actin and myosin
Proteins involved in muscular contraction
Agar
Polysacharide of galactose obtained from seaweed which is used to thicken a medium into a gel.
Agarose
Type of sugar that can incorporated into a type of agar gel
Alkaloids
Organic nitrogen containing bases that have important physiological effects on animals, includes nicotine, quinine, strychnine and morphine
Allele
Version of a gene
Allele frequency
Propotion of a particular allele within the gene pool
Allopatric speciation
Formation of 2 different species from one original one due to geographic isolation
Alpha cells
Cells found in islets of langerhans that secrete glucagon
Ammonification
Production of ammonia by bacterial action in the decay of nitrgenous organic matter
AMP
Adeonside monophosphate
Aneuploidy
Abnormal chromosome number
Antagonist
Something that works against the other in opposite pairs, such as in the muscles that are arranged in opposing pairs, so one contracts and the other elongates
ADH (antidiuretic hormone)
Hormone made in hypothalamus, stored and released from pituitary gland, that controls permeability of collecting duct in walls of kidneys
Apical dominance
Inhibition of lateral buds fruther down shoot by chemicals produced by apicial bud at tip of plant shoot.
Apoptosis
Programmed cell death
Artificial selection
Selective breeding of organisms to produce desired phenotypes
Ascending limb
Part of loop of Henle that carries fluid back into distal tubule in cortex
ATP
Adenosine triphosphate
Autoimmune response
Response in which body's immune system attacks and destroys some of its own cells.
Autonomic nervous stsrem
Part of nervous system responsible for controlling involuntary motor activities of body
Autoradiograms
Photographs made when photographic film is exposed to molecules labelled with radioactivity
Autosomal linkage
Gene loci present on the same autosome (non sex chromosome) are often inherited together
Autosome
Chromosome not concerned with sex determination
Autotrophic nutrition
Nutrition where organic molecules are synthesised from inorganic molecules, i.e carbon dioxide and water. I.e photosynthesis where sunlight energy converted to chemical energy to synthesise large organic molecules from smaller inorganic ones. Chemosynthesis uses energy derived from chemical reactions (e.g nitrifying bacteria in soil)
Auxins
E.g IAA (indole 3 acetic acid)
Promotes cell elongation
Inhibits leaf abcission
Inhibits growth of side shoots- maintains apical dominance
Involved in tropisms
Stimulates release of ethene
Involved in food ripening
Cytokines
Promotes cell division
Leaf expansion
Delays leaf senescense
Overcomes apicial dominance
Ethene
Promotes food ripening
Promotes abscission in deciduous trees
Abscisic acid
Causes stomatal clouse when plant is streed by low water availabliity
Inhbits seed germination and growth
Stimulates cold protective responses I.e production of antifreeze
Gibberelins
Promotes seed germination and growth of stems
Triggers mobilisation of food stores in seed at germination
Stimulates pollen tube growth in fertilisation
Belt transcer
Continous belt or series of quadtrats used to estimate distribtion of organisms across a certain area such as a meadow or seashore.
Beta cells
Found in islets of langerhans in pancreas and release insulin
Bioinformatics
Branch of biology that deals with storing, displaying and using large quantities of complex data
Biomass transfer
Transfer of biomass from one trophic level to another
Biotechnology
Use of living ogrnaisms or part of living organisms in industrial processes. Could be to produce food, drugs or other products
Biotic compoentns
Living components of an ecoystsem
Biotic factors
Environemtnal factors associaed with living organisms in an ecosystem that affect each other, e.g predation, disease, competition and food availiability
Blunt ends
Cut ends of DNA where there are no staggered cut and no exposed unpaired bases
Cardiac muscle
Muscle found in heart walls
Cardiovascular centre
Part of medulla oblonata in brain that controls heart rate and other aspects of circulation
Carotid sinus
Small swelling in cartoid artery with stretch receptors in its walls
carrying capacity
Maximum population size that can be maintained over a period of time in a particular habittat
Caesin
Protein in milk
Cell signalling
Way in which cells communicate with each other
CNS
Central part of nervous system composed of brain and spinal cord
Cerebellum
Region of brain coordinating balance and fine control of movement
Cerebral cortex
Outer layer of cellebrum
Cerebrum
Region of brain dealing with higher thought processes such as conscious thought, divided into 2 cerebral hemispheres
Chemoautotrophic bacteria
Bacteria that derive energy from oxidation of certain inorganic compounds
Chemoreceptors
Sensory receptors that detect changes in cocnentration of chemical, e.g in blood. They transduce a chemical signal into an electrical signal.
Chemotropism
Directional growth response, in plants, to chemicals
Chi- squared test
Statistical test to find out if difference between observed and expected data is significant or due to chance
Cholinergic synapse
Synapse that uses acetycholine as neurotransmitter
Climax community
Final stable community that arises after process of succession.
Codominance
Where both alleles present in genotype of heterozygous invididual contributes to individuals phenotype
Coenzymes
Organic non protein molecules that act as cofactors which aid in catalysing biochemical reactions
Community
Populations of different species living in same place and time that can interact with each other
Conservation
Maintenance of biodiversity including genetic, speicies and habitat divserity
Conserved
Has remained in all descendent species throughout evolutionary history
Consumers
Any of heterophobic organisms in food chain or web; primary consumers feed on plants, eaten be secondary consumers which are eaten by tertiary consumers
Continuous variation
Variation that produces phenotypic variation where quantitative traits vary by very small amounts between one group and next
Coppicing
Cutting tree trunk close to ground to encourage new growth
Corneal reflex
Protective blinking response resulting from physiological stimulation of cornea
Corpus callosum
Nerve tract that connects cerebral hemispheres of brain
Corticotropin releasing hormone (CRH)
Known as cotricotropin releasing factor, hormone that causes release of adrencotricotropic hormone from pituitary gland
Cranial reflex
Reflex mediated by neurones that pass into brain
Creatine phosphate
Organic compound in muscle that acts as a store of phosphates and can supply phosphates to make ATP rapidly within mucle cells
Cristae
Inner folded mitochondrial membrane
Cyclic AMP (cAMP)
Secondary messenger released inside cells to activate a response
Cyclic changes
Rhythmic changes, such as tides, day length, and fluctuations in predator and prey species
Dark band
In stritated muscle also known as the A band which shows the length of the mysoin filaments; there is some overlap with the actin filaments within this band.
Death phase
Population size is decreasing as cells are dying faster than new ones are formed
Decomposers
Living organisms that feed on waste or dead organic matter
Deflected succession
When succession is stopped or interfered with such as by grazing or when a lawn is mowed