Biology- key terms & definitions

?
Abiotic
non-living factor e.g temperature, pH...
1 of 302
Acetylcholine
A neurotransmitter released by neurones & passes an impulse from one neurone to next.
2 of 302
Action potential
change to electrical charge across membrane of an axon when it is stimulated & a nerve impulse passes
3 of 302
Actin
filamentous protein involved in contraction within cells
4 of 302
Activation energy
minimum amount of energy required to bring about a reaction- lowered by presence of enzymes
5 of 302
Active immunity
activities from an individual's own immune system- antigen induces plasma cells to produce antibodies
6 of 302
Active site
group of amino's that make up region of enzyme into which substrate fits in order to catalyse reaction
7 of 302
Active transport
Movement of substance against a concentration gradient, and requires expenditure of metabolic energy
8 of 302
ATP/ Adenosine triphosphate
activated nucleotide found in all living cells & acts as an energy carrier- hydrolysis leads to ADP + Pi + energy
9 of 302
Adrenaline
hormone produced by adrenal glands in times of stress to prep body for emergency
10 of 302
Aerobic
With the presence of oxygen- aerobic respiration= requires oxygen to release energy from glucose
11 of 302
Allele
One of a number of alternative forms of a gene
12 of 302
Allele frequency
number of times an allele occurs within a gene pool
13 of 302
Allergen
harmless substance that causes immune response from immune system
14 of 302
Allergy
response of immune system to an allergen
15 of 302
Anaerobic
Absence of oxygen- anaerobic respiration releases energy from glucose without oxygen
16 of 302
Antibiotic
substance produced by living organisms that can destroy/inhibit growth of micro-organisms
17 of 302
Antibiotic resistance
development in micro-organisms of mechanisms that prevent antibiotics from killing them
18 of 302
Antibody
Protein produced by lymphocytes in response to presence of specific antigen
19 of 302
Anticodon
sequence of 3 adjacent nucleotides on tRNA that is complimentary to codon on mRNA
20 of 302
ADH
Hormone that reduces vol. of water in urine by increasing water reabsorption in the kidneys (secreted by hypothalmus --> posterior pituitary gland)
21 of 302
Antigen
molecule that triggers an immune response by lymphocytes
22 of 302
Antioxidant
Chemical which reduces or prevents oxidation- often used as an additive to prolong shelf-life of foods
23 of 302
Apoplastic pathway
route through cell walls of plants by which water & dissolved substances are transported
24 of 302
Artificial selection
breeding of organisms by human selection of parents/gametes in order to perpetuate certain characteristics and/or to eliminate others
25 of 302
Asthma
= restistance to air flow to alveoli= airways become inflamed due to an allergic response to allergen
26 of 302
Atheroma
Fatty deposits in walls of arteries often associated w/ high cholesterol in blood
27 of 302
Autonomic nervous system
part of nervous system controlling muscles & glands- not under voluntary control
28 of 302
Autosome
Chromosome which is not a sex chromosome
29 of 302
Axon
process extending away from neurone, conducting A.P away from cell body
30 of 302
B-cell/lymphocytes
white blood cell that matures in bone marrow as produces antibodies in their role in immunity
31 of 302
Benedict's test
simple biochemical reaction to detect reducing sugars
32 of 302
Biodiversity
range & variety of genes, species & habitats in a particular region
33 of 302
Biomass
Total mass of living material, normally measured in a specific area over a given period of time
34 of 302
Biotic
living factors e.g competition, predation...
35 of 302
Biosensor
device that uses biological molecules to measure level of certain chemicals
36 of 302
Biuret test
biochemical reaction to test for presence of protein
37 of 302
BMI/ Body Mass Index
body mass in kg divided by their heigh in metres squared
38 of 302
Calvin cycle
Biochemical pathway that forms light-independent reaction of photosynthesis
39 of 302
Cancer
disease from cells that break away from an original tumour to form secondary tumours elsewhere in body
40 of 302
Carcinogens
A chemical, form of radiation, or other cancer causing agent
41 of 302
Cardiac cycle
continuous series of events which make up a single heart beat
42 of 302
Cardiac muscle
Type of muscle found in heart- fewer striations than skeletal muscle & can contract continously thoughout life without nervous stimulation
43 of 302
Cardiac output
total volume of blood the heart can pump each minute
44 of 302
Carrier protein/molecule
protein on surface of cell that helps to transpot molecules & ions across plasma membranes
45 of 302
Casparian *****
distinctive band of suberin around enodermal cells of a plant root= prevent water passing into xylem via cell walls
46 of 302
Centrifugation
process of separating out particles of different sizes and densities by spinning them at high speed in centrifuge
47 of 302
Cholinesterase
enzyme that breaks down & inactivates acetylcholine
48 of 302
Cholesterol
lipid= important component of cell-surface membranes
49 of 302
Chromatid
One of 2 strands of a chromosome joined together by a centromere
50 of 302
Chromatin
material that makes up chromosomes- consists of DNA & histones
51 of 302
Chromosome
structure made of protein & DNA by which hereditary info passed down through generations
52 of 302
Climax community
organisms that make up final stage of ecological succession
53 of 302
Clone
group of genetically identical cells/ organisms formed from single parents as a result of asexual reproduction
54 of 302
Co-dominance
Both alleles for one gene are expressed
55 of 302
Codon
sequence of 3 adjacent molecules in mRNA that code for one amino acid
56 of 302
Cohesion
attraction between molecules of same type e.g water
57 of 302
Collagen
Fibrous protein that is main component of connective tissues e.g cartilage
58 of 302
Community
all living organisms present in an ecosystem at a given time
59 of 302
Complementary DNA
DNA that is made from mRNA in a process that is the reverse of normal transcription
60 of 302
Condensation
combination of 2 molecules to form 1 complex and release of water
61 of 302
Conservation
method of maintaining ecosystems & the living organisms that occupy them
62 of 302
Consumer
any organisms that obtains energy by eating another
63 of 302
Continuous variation
variation in which organisms do not fall into distincy categories but show gradations from one extreme to other
64 of 302
Coronary arteries
arteries that supply blood to cardiac muscle
65 of 302
Coronary heart disease
any condition affecting the coronary arteries that supply cardiac muscle
66 of 302
Correlation
when a change in 1 variable is reflected by a change in another variable
67 of 302
Co-transport
transport of one substance coupled with transport of another substance across a plasms membrane in same direction through same protein carrier
68 of 302
Countercurrent system
flow in opposite directions= increasing efficiency of exchange between 2 substances
69 of 302
Covalent bond
2 atoms share a pair of electrons
70 of 302
Crossing over
Chromatid breaks during meiosis and rejoins to chromatid of its homologous chromosome so that their alleles are exchanged
71 of 302
Cuticle
exposed non-cellular outer layer of certain animals & leaves of plants
72 of 302
Deciduous
term for plants that shed all their leaves together at one season
73 of 302
Denaturation
permanent changes due to unravelling of 3D structure of a protein
74 of 302
Dendrite
branched structure extending from cell body of a neurone which conducts impulses towards the cell body
75 of 302
Denitrifying bactera
bacteria that converts nirtates to nitrogen gas as part of N cycle
76 of 302
Depolarisation
temporary reversal of charges on cell-surface membrane of neurone= takes place when a nerve impulse is transmitted
77 of 302
Diabetes
body unable to regulate level of blood glucose
78 of 302
Diastole
stage in cardiac cycle where cardiac muscle relaxes
79 of 302
Differentiation
process by which cells become specialised for specific functions
80 of 302
Diffusion
movement of molecules/ions down a concentration gradient
81 of 302
Diploid
nucleus contains 2 sets of chromosomes
82 of 302
Dipolar
having a pair of equal and opposite electrical charges
83 of 302
Directional selection
selection that operates towards one extreme in a range of variation
84 of 302
Discontinuous variation
Variation shown when characteristics of organisms fall into distinct categories
85 of 302
DNA helicase
enzyme that acts on specific of DNA molecule to break H-bonds between bases causing strands to separate and expose nucleotide bases in that region
86 of 302
DNA replication
double helix of DNA uwinds and each strand acts as a template on which a new strand is constructed
87 of 302
Dominant allele
term applied to an allele that is always expressed in phenotype or organism
88 of 302
Ecological niche
describes how an oganism fits into its environment, what a species is like, where it occurs, how it behaves & its interactions with other species and its environment
89 of 302
Ecosystem
all biotic & abiotic components of a particular area
90 of 302
Ectothermic
animal that uses environment to regulate its body temp
91 of 302
Effector
organ that responds to stimulation by a nerve impulse resulting in change/response
92 of 302
Electron
negatively charged subatomic particle that orbits protons and neutrons in nucleus
93 of 302
Electron carrier molecule
chain of carrier molecules along which electrons pass, releasing energy in form of ATP as they do
94 of 302
Emphysema
disease= walls of alveoli break down, reducing SA fpr gas exchange= breathlessness
95 of 302
Endocytosis
inward transport of large molecules through cell-surface membrane
96 of 302
Endotherm
animal maintaining its body temp. by physiological mechanisms
97 of 302
Enzyme
protein/RNA that acts as a catalyst & alters speed of biochemical reactions
98 of 302
Epidemiology
study of spread of disease & factors affecting the spread
99 of 302
Eukaryotic cell
cell that has membrane-bound nucleus & chromosomes (animal & plant cells)
100 of 302
Exocytosis
Outward bulk transport of materials through cell-surface membrane
101 of 302
Facilitated diffusion
involves protein carrier molecules to allow passive movement of substance across plasma membranes
102 of 302
Gamete
reproductive cell that fuses with another gamete in fertilisation
103 of 302
Gel electrophoresis
technique used to separate DNA fragments of different lengths by placing them on agar gel & passing a voltage across them
104 of 302
Gene
section of DNA on a chromosome coding for one or more polypeptides
105 of 302
Gene pool
total no. of alleles in a partcular population at a specific time
106 of 302
Gene marker
section of DNA that is used to indicate the location of a gene or other section of DNA
107 of 302
Gene mutation
change to one or more nucleotide bases in DNA resulting in change in genotype which may be inherited
108 of 302
Gene therapy
mechanism by which genetic diseases may be cured by masking the effect of the detective gene by inserting a functional gene
109 of 302
Generator potential
depolarisation of membrane of a receptor cell as a result of stimulation
110 of 302
Geneticically modified organisms
organisms that has had its DNA altered as a result of recombinant DNA tech
111 of 302
Genotype
The genetic composition of an organism
112 of 302
Glomerulus
Cluster of blood capillaries enclosed by Bowman's capsule in the kidney
113 of 302
Glucagon
hormone produced by alpha cells that increase blood glucose levels
114 of 302
Gluconeogenesis
conversion of non-carbohydrate molecules to glucose
115 of 302
Glycogenesis
Conversion of glucose to glycogen
116 of 302
Glycogenolysis
the conversion of glycogen to glucose
117 of 302
Glycolysis
first part of cellular respiration in which glucose is broken down anaerobically in cytoplasm to give two molecules of pyruvate
118 of 302
Glycoprotein
substance made up of carboydhrate molecule and a protein molecule- and makes up parts of cell surface membrane and certain hormones
119 of 302
Granum
stack of thylakoids in a chloroplast, site of light-dependent stage of photosynthesis
120 of 302
Guard cell
one of a pair of cells that surround a stoma in plant leaves and control its opening and closing
121 of 302
Habitat
place where an organism normally lives & which is characterised by physical conditions and the types of other organisms present
122 of 302
Haemoglobin
globular protein in blood that combins with oxygen to transport it around the body
123 of 302
Haploid
cells that contain only a single copy of each chromosome (gametes)
124 of 302
Heterozygous
condition in which alleles of a gene are different
125 of 302
Histones
proteins which DNA wind around to make up chromosomes
126 of 302
Homeostasis
maintenance of constant internal environment
127 of 302
Homologous chromosomes
pair of chromosomes, one maternal & one paternal, that have the same gene loci and determine the same features but not identical as alleles of the same gene vary
128 of 302
Homozygous
condition in which the alleles of a particular gene are identical
129 of 302
Human genome
totality of the DNA sequences on the chromosomes of a single human cell
130 of 302
Human genome project
international scientific project to map entire sequence of all the base pairs of the genes in a single human cell
131 of 302
Hydrogen bond
chemical bond between positive charge on H and negative charge on N,O,F
132 of 302
Hydrolysis
breaking down of large molecules into smaller ones by the addition of water
133 of 302
Hyperthermia
conditions that results from the core body temperature rising above normal
134 of 302
Hypothalamus
region of brain adjoining pituitary gland that acts as control centre for the autonomic nervous system and regulates body temp & fluid balance
135 of 302
Hypothermia
condition resulting in core body temperature falling below normal
136 of 302
Immunity
means by which body protects itself from infection
137 of 302
Insulin
hormone, produced by alpha cells which decreases blood glucose levels by increasing rate of conversion of glucose to glycogen
138 of 302
Intercropping
practise of growing 2+ crops in close proximity to produce a greater yield on a piece of land
139 of 302
Interspecific competition
competition between organisms of different species
140 of 302
Interspecific variation
differences between organisms of different species
141 of 302
Intraspecific competition
competition between organisms of the same species
142 of 302
Intraspecific variation
differences between organisms of the same species
143 of 302
Intrinsic proteins
proteins of the cell-surface membrane that completely span the phospholipid bilayer from one side to another
144 of 302
Introns
portions of DNA within a gene that do not code for a polypeptide
145 of 302
Ion
an atom or group of atoms that have lost/gained electrons giving them a positive or negative charge
146 of 302
Ion channel
passage across cell-surface membrane made up of a protein that spans the membrane and opens and closes to allow ions to pass in and out of the cell
147 of 302
Islets of Langerhans
groups of cells in the pancreas comprising large alpha cells, which produce glucagon and beta cells which produce insulin
148 of 302
Isotope
variations of a chemical element that have same numbr of protons but different number of neutrons
149 of 302
In vitro
experiments carried out outside the living body
150 of 302
In vivo
experiments that are carried out within living bodies
151 of 302
Krebs cycle
series of aerobic biochemical reactions in matrix of mitochondria of most eukaryotic cells by which energy is obtained through the oxidation of acetyl-coA produced from breakdown of glucose
152 of 302
Latent heat of vaporisation
heat taken in by a liquid in order to transform it into a vapour
153 of 302
Ligament
tough, fibrous, connective tissue, rich in collagen that joins bone to bone
154 of 302
Light-dependent reaction
stage of photosynthesis in which light energy required to prduce ATP and reduced NADP
155 of 302
Light-independent reaction
stage of photosynthesis which doesn't require light energy directly but does need products of light-dependent reaction to reduced CO2 and so form carbohydrate
156 of 302
Limiting factor
variable that limits the rate of a chemical reaction
157 of 302
Link reaction
process linking glycolysis with krebs cycle
158 of 302
Locus
position of a gene on a chromosome/DNA molecule
159 of 302
Loop of Henle
portion of the nephron that forms the hairpin loop that extends into the medulla of the kidney
160 of 302
Lumen
hollow cavity inside a tubular structure
161 of 302
Lymph
Slightly milky fluid found in lymph vessels & made up of tissue fluid, fats and lymphocytes
162 of 302
Lymphocytes
types of white blood cell responsible for the immune response
163 of 302
Meiosis
type of nuclear division in which number of chromosomes is halved
164 of 302
Mesophyll
tissue found between 2 layers of epidermis in a plant leaf and compromising an upper layer of palisade cells and a lower layer or spongy cells
165 of 302
Metabolism
all the chemical processes that take palce in living organisms
166 of 302
Microvilli
tiny finger-like projections from cell-surface membrane of some animal cells
167 of 302
Middle lamella
layer made up of pectins and other substances found between the walls of adjacent plant cells
168 of 302
Mitosis
nuclear division that leads to daughter cells with the same number of chromosomes as the parent cell
169 of 302
Monoclonal antibodies
antibody produced by a single clone of cells
170 of 302
Monomer
one of many small molecules that combine to form one larger molecule- a polymer
171 of 302
Mono-unsaturated fatty acid
fatty acid that possesses a carbon chain with a single double bond
172 of 302
Motor neurone
neurone that transmits action potentials from C.N.S to an effector
173 of 302
Multiple alleles
term used to describe a gene that has more than two possible alleles
174 of 302
Mutagen
any agent that induces a mutation
175 of 302
Mutation
sudden change in amount or arrangement of genetic material in the cell
176 of 302
Mutualism
nutritional relationship between two species in which both gain some advantage
177 of 302
Myelin
fatty substance that surrounds axons and dendrites in certain neurones
178 of 302
Myocardial infarction
heart attack, resulting from interruption of blood supply to heart muscle causing damage to an area of the heart & its function
179 of 302
Myosin
thick filamentous protein found in skeletal muscle
180 of 302
NAD
molecule that carries electrons and hydrogen ions during aerobic respiration
181 of 302
NADP
molecule that carries electrons produced in the light-dependent reaction of photosynthesis
182 of 302
Negative feedback
series of changes that result in substance being returned to its normal level- important in homeostasis
183 of 302
Nephron
basic functional unit of kidney responsible for urine formation
184 of 302
Neurone
nerve cell, compromising of cell body, axon and dendrites which is adapted to conduct action potentials
185 of 302
Neuromuscular junction
Synapse that occurs between a neurone and a muscle
186 of 302
Neurotransmitter
One of many chemicals that are involved in communication between adjacent neurones/ nerve cells and muscle cells
187 of 302
Nitrifying bacteria
Microorganisms that convert ammonium compounds to nitrites and nitrates
188 of 302
Nitrogen fixation
Incorporation of atmospheric N into organic N-containing compounds
189 of 302
Normal distribution
bell-shaped curve produced when distribution is plotted on graph
190 of 302
Node of Ranvier
gap in myelin sheath that surrounds the axon of a neuron
191 of 302
Nucleotides
Organic base, sugar and a phosphate- the basic units of which DNA and RNA are made
192 of 302
Oestrus
the period in the oestrous cycle immediately after ovulation when the female is most fertile
193 of 302
Oncogenes
mutated versions of proto-oncogenes that result in increased cell division leading to tumour growth
194 of 302
Oral rehydration solution
means of treating dehydration involving giving a balanced solution of salts and glucose that stimulates gut to reabsorb water
195 of 302
Osmosis
Net movement of water down a water potential gradient through a selectively permeable membrane
196 of 302
Oxidation
Loss of electrons
197 of 302
Oxidation-reduction
Electrons transferred from one substance to another
198 of 302
Oxidative phosporylation
formation of ATP in the electron transport system of aerobic respiration
199 of 302
Palisade cells
long, narrow cells packed with chloroplasts that are found in upper region of a leaf and carry out photosynthesis
200 of 302
Parasite
Organism that lives on or in a host organism- parasite gains a nutritional advantage and host is harmed in some way
201 of 302
Passive immunity
resistance to disease that is acquired from introduction of antibodies from another individual, rather than an individual's own immune system
202 of 302
Pathogen
microorganism that causes disease
203 of 302
Pentose sugar
sugar that possesses give C atoms
204 of 302
Peptide bond
Chemical bond between 2 amino acids during condensation
205 of 302
Phagocytosis
mechanism where cells engulf particles to form a vesicle or vacuole
206 of 302
Phenotype
the (usually) visible characteristics of an organism resulting from its genotype & the environment its in
207 of 302
Phloem
plant tissue that transports products of photosynthesis from leaves to rest of plant
208 of 302
Phospholipid
triglyceride in which 1/3 fatty acids replaced by phosphate- important in structure and function of plasma membranes
209 of 302
Photolysis
splitting of water molecule by light
210 of 302
Photomicrograph
Photograph of an image produced by a microscope
211 of 302
Pioneer species
species that can colonise bare rock or ground
212 of 302
Plasmid
small, circular piece of DNA found in bacterial cells
213 of 302
Plasmodesmata
fine strands of cytoplasm that extrend through pores in adjacent plant cell walls and connect cytoplasm of one cell with another
214 of 302
Plasmolysis
skrinkage of cytoplasm away from cell wall that occurs as a plant cell loses water by osmosis
215 of 302
Polygenes
group of genes that are responsible for controlling a characteristic
216 of 302
Polymer
large molecule made up of repeating monomer units
217 of 302
Polymerase Chain Reaction/ PCR
Process of making many copies of a specific sequence of DNA or part of a gene- used extensively in gene tech and genetic fingerprinting
218 of 302
Polymerases
Enzymes that catalyse formation of polymers from monomers
219 of 302
Polyunsaturated fatty acid
fatty acid that possesses carbon chains with many double bonds
220 of 302
Population
group of individuals of same species that occupy the same habitat at the same time
221 of 302
Positive feedback
Process which results in substance departing further from its normal level
222 of 302
Primary protein structure
sequence of aminos that make up polypeptides of a protein
223 of 302
Primary succession
the progressive colonisation of bare rock or barren terrain by living organisms
224 of 302
Producer
organism that synthesises organic molecules from simple inorganic ones such as carbon dioxide and water- most are photosynthetic and from first trophic level of food chain
225 of 302
Prokaryotic cell
cell of an ogranism characterised by lacking nucleus and membrane-bound organelles (bacteria)
226 of 302
Proton
positively charged sub-atomic particle found in nucleus of an atom
227 of 302
Protoplast
living portion of a plant cell- the nucleus, cytoplasm and the organelles it contains
228 of 302
Quartnerary protein structure
number of polypeptide chains linked together and sometimes associated with non-protein groups to form a protein
229 of 302
Receptor
cell adapted to detect changes in an environment
230 of 302
Recessive allele
condition in which effect of allel is apparent in the phenotype of a diploid organism only in the presence of an identical allele
231 of 302
Recognition site
nucleotide sequence, usually of 4,6, or 8 nucleotides that is recognised by a restriction endonuclease and to which it attatches
232 of 302
recombinant DNA technology
general term that covers processes by which genes are altered/transferred from one organism to another
233 of 302
Reduction
gain of electrons
234 of 302
Reflex arc
nerve pathway in the body taken by an action potential that leads to rapid, involuntary response to a stimulus
235 of 302
Refractory period
Period during which the membrane of the axon of a neurone cannot be depolarised= no new AP can be initiated
236 of 302
Renal capsule
cup shaped portion of start of nephron that encloses the glomerulus
237 of 302
Repolarisation
return to the resting potential in the axon of a neurone after an action potential
238 of 302
Resting potential
difference in electrical charge maintained across the membrane of the axon of a neurone when not stimulated
239 of 302
Restriction endoucleases
group of enzymes that cut DNA molecules at a specific sequence of bases called a recognition sequence
240 of 302
RNA polymerase
enzyme that joins together nucleotides to form mRNA during transcription
241 of 302
Saltatory conduction
propagation of nerve impulse along a myelinated dendron/axon in which action potentials jump between nodes of Ranvier
242 of 302
Saprobiotic microorganism
organisms that obtains its food from dead or decaying remains of other organisms
243 of 302
Sarcomere
section of myofibril between 2 Z-lines that form basic structural unit of skeletal muscle
244 of 302
Saturated fatty acid
no double bonds between carbon atoms
245 of 302
Schwann cell
cell around a neurone who cell-surface membrane wraps around the dendron/axon to form the myelinated sheath
246 of 302
Secondary protein structure
way in which amino's of a polypeptide of a protein are folded
247 of 302
Secondary succession
recolonisation of an area after an earlier community has been removed/destroyed
248 of 302
Selection
process that results in best-adapted individuals in a population to survive and breed to pass on favourable alleles to next generation
249 of 302
Selection pressure
environmental force altering the frequency of alleles in a population
250 of 302
Selective breeding
breeding of organisms by human selection of gametes in order to create certain characteristics/eliminate others
251 of 302
Semi-conservative replication
means by which DNA makes exact copies of itself by unwinding the double helix so that each chain acts as a template= new copies possess one original and one new strand of DNA
252 of 302
Sensory neurone
neurone that transmits action potential from sensory receptor to central nervous system
253 of 302
Serum
clear liquid left after blood has clotted and blood clot is removed /blood plasma without the clotting factors
254 of 302
Sickle-cell anaemia
inherited blood disorder where abnormal haemoglobin leads to red blood cells becoming sickle-shaped and less able to carry oxygen
255 of 302
Sinoatrial node
area of heart muscle that controls and coordinates contraction of the heart
256 of 302
Skeletal muscle
muscle that makes up bulk of body and works under conscious control
257 of 302
Smooth muscle
involuntary/unstriated muscle= found in walls of blood vessels
258 of 302
Sodium-potassium pump
protein channels across cell-surface membranes that use ATP tomove sodium ions out of cell in exchange for potassium ions that move in
259 of 302
Speciation
evolution of two or more species from existing species
260 of 302
Species
group of similar organisms that can breed together to produce fertile offspring
261 of 302
Species diversity
Number of different species and number of individuals of each species in a community
262 of 302
Stabilising selection
Selection that tends to eliminate extremes of the phenotype range within a population- arises when environmental conditions are constant
263 of 302
Stem cells
undifferentiated dividing cells that occur in embryos and in adult animal tissues that require constant replacement
264 of 302
Stimulus
detectable alteration in the internal/external evironment of an organism that produces a change in that organism
265 of 302
Stoma
pore mostly found in lower epidermis of a leaf through which gases diffuse in and out of leaf
266 of 302
Stroke volume
volume of blood pumped out at each ventricular contraction of the heart
267 of 302
Stroma
matrix of chloroplast where light-independent reaction of photosynthesis occurs
268 of 302
Substrate
substance that is acted on or used by another substance or process
269 of 302
Sustrate-level phosphorylation
formation of ATP by direct transfer of a phosphate group from a reactive intermediate to ADP
270 of 302
Supernatant liquid
the liquid portion of a mixture left at the top of the tube in ultracentrifugation
271 of 302
Symplastic pathway
route through cytoplasms of plant cells by which water and dissolved substances are transported
272 of 302
Synapse
junction between neurones in which they dont touch but have synaptic cleft across which neurotransmitter can pass
273 of 302
Systole
Stage in cardiac cycle in which heart muscle contracts
274 of 302
Tendon
tough, flexible, but inelastic, connective tissue that joins muscle to bone
275 of 302
Tertiary protein structure
folding of whole polypeptide chain in precise way determined by amino acids its composed of
276 of 302
Threshold level/value
minimum intensity that a stimulus must reach in order to trigger an action potential in a neurone
277 of 302
Thrombosis
formation of a blood clot within a blood vessel that may lead to a blockage
278 of 302
Thylakoid
series of flattened sacs in chloroplast that contain chlorophyll and the associated molecules needed for the light-dependent reaction
279 of 302
Tidal volume
volume of air breathed in and out during a single breath when at rest
280 of 302
Tissue
group of similar cells organised into a structural unit that serves a particular function
281 of 302
Tissue fluid
fluid that surrounds the cells of body- composition= similar to blood plasma but lacks proteins. It supplies nutrients to cell and removes waste products
282 of 302
T-cell/lymphocytes
type of white blood cell produced in bone marrow but matures in thymus gland. T lymphocytes coordinate the immune response and kill infected cells
283 of 302
Transcription
Formation of mRNA molecules from DNA that makes up a particular gene
284 of 302
Transducer cells
convert a non-electrical signal e.g light into anelectrical signal and vice versa
285 of 302
Transduction
process by wihch one form of energy is converted into another. In microbiology= natural process by which genetic material trasnferred between host cell to another by a virus
286 of 302
Transpiration
evaporation of water from a plant
287 of 302
Triglyceride
lipid molecule: 3 fatty acids + a glycerol
288 of 302
Trophic level
position of an organism in a food chain
289 of 302
Tumour
swelling in an organism made up of cells continually dividing in an abnormal way
290 of 302
Tumour suppressor gene
gene that maintains normal rates of cell division & prevents devt. of tumours
291 of 302
Turgid
plant cell that contains max. vol of water it can- additional entry of water prevented by cell wall stopping further expansion of cell
292 of 302
Ultrafiltration
Filtration assisted by blood pressure e.g in formation of tissue fluid
293 of 302
Unsaturated fatty acid
fatty acid in which there are one or more double bonds between carbon atoms
294 of 302
Vaccination
introduction of vaccine containing appropriate disease antigens into body by njection/mouth to induce artifical immunity
295 of 302
Vasoconstriction
narrowing of internal diameter of blood vessels
296 of 302
Vasodilation
widening of internal diameter of blood vessels
297 of 302
Vector
a carrier- e.g plasmids are vectors which carry DNA into a cell or to an organism that carries a parasite to its host
298 of 302
Voltage-gated channels
protein channel across cell-surface membrane that opens and closes according to changes in electrical potential across membrane
299 of 302
Water potential
pressure created by water molecules & is a measure of the extent to which a solution gives out water
300 of 302
Xerophyte
plant adapted to living in dry conditions
301 of 302
Xylem vessels
dead, hollow, elonogated tubes, with lignified side walls & no end walls that transport water in plants
302 of 302

Other cards in this set

Card 2

Front

A neurotransmitter released by neurones & passes an impulse from one neurone to next.

Back

Acetylcholine

Card 3

Front

change to electrical charge across membrane of an axon when it is stimulated & a nerve impulse passes

Back

Preview of the back of card 3

Card 4

Front

filamentous protein involved in contraction within cells

Back

Preview of the back of card 4

Card 5

Front

minimum amount of energy required to bring about a reaction- lowered by presence of enzymes

Back

Preview of the back of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

Biology
Teacher recommended
See all Biology resources »See all Key terms resources »