Key Definitions Flashcards
1
Q
a-glucose
A
glucose in which the hydrogen atom on carbon atom number one projects above the plane of the ring,
2
Q
ab initio protein modelling
A
a model is built based on the physical and electrical properties of the atoms in each amino acid in the sequence
3
Q
accuracy
A
how close a measured or calculated value is to the true value
4
Q
active immunity
A
where the immune system is activated and manufactures its own antibodies
5
Q
active site
A
an indented area on the surface of an enzyme molecule, with a shape that is complementary to the shape of the substrate molecule
6
Q
active transport
A
the movement of substances against their concentration gradient, from low to high concentration of these substances across a cell membrane, using ATP and protein carriers.
7
Q
adaptation
A
a characteristic that enhances survival in the habitat
8
Q
adhesion
A
the attraction between water molecules and the walls of the xylem vessel
9
Q
affinity
A
a strong attraction
10
Q
agglutination
A
the clumping of insoluble antigen molecules caused by crosslinking by antibodies that have a number of binding sites
11
Q
agglutinins
A
antibodies that cause pathogens to stick togther
12
Q
allele
A
a version of a gene, also called genetic variant
13
Q
alveoli
A
tiny folds of the lung epithelium to increase the surface area
14
Q
amino acids
A
monomers of all proteins, and all amino acids have the same basic structure
15
Q
amphiphilic
A
attracted to both water and fat- containing hydrophobic/lipophilic and hydrophilic/lipophobic parts
16
Q
amylopectin molecule
A
a molecule of polysaccharide with glycosidic bonds between carbon 1 and 4, and branches formed by glycosidic bonds between carbon 1 and 6. It is a constituent of starch
17
Q
amylose molecule
A
a molecule of polysaccharide with long straight chains of between 100 to 1000 a-glucose molecules. It is a constituent of starch. Like maltose, it has glycosidic bonds between carbon 1 and 4
18
Q
anatomy
A
the branch of science concerned with studying the bodily structure of living organisms
19
Q
angina pectoris
A
a condition marked by severe pain in the chest, resulting from an inadequate blood supply, and therefore the lack of oxygen, to the heart muscle that causes the coronary arteries to spasm (tighten)
20
Q
anion
A
a negatively charged ion
21
Q
anomaly
A
a result that does not fit the expected trend or pattern
22
Q
antibiotic
A
a chemical which prevents the growth of microorganisms. Antibiotics can be antibacterial or antifungal
23
Q
antibodies
A
specific proteins released by plasma cells that can attach to pathogenic antigens
24
Q
antigen-presenting cell
A
a cell that isolated the antigen from a pathogen and places it one the plasma membrane so that it can be recognized by other cells in the immune system
25
antigen
a membrane-bound molecules used to recognise pathogens
26
anti-toxins
antibodies that render toxins harmless
27
aorta
the main artery of the body in mammals
28
apoplast pathway
route by which water travels through the cell walls and in spaces between cells of plant tissue when travelling from roots to xylem and from xylem to leaves.
29
apoptosis
the death of cells which happens as a normal part of an organisms growth and development
30
archaea
prokaryotic microorganisms of similar size to bacteria but having some differences of metabolism
31
arithmetic mean
the average value of numbers in a collection, found by dividing the sum of all the values by the number of vale in the collection
32
arteries
vessels that carry blood away from the heart
33
arterioles
small blood vessels that distribute the blood from an artery to the capillaries
34
artificial classification
a classification based on just one or a few characteristics
35
artificial immunity
immunity that is achieved as a result of medical intervention
36
artificial insemination
The medical or veterinary procedure of injecting semen, collected from a male animal, into the vagina or uterus of a female of the same species.
37
asexual reproduction
some multicellular organisms and single-called protoctists such as Ameoba and Paramecium divide by mitosis to produce new individuals. They are genetically identical to the parent.
38
assimilates
substances that have become part of the plant
39
asymptomatic
not having symptoms
40
atria
thin-walled chambers of the heart that receives the blood from the veins and then pass into the ventricles.
41
atrio-ventricular nose (AVN)
a patch of tissue in the heart at the top of the septum that conducts the excitation wave from the atria to the ventricles
42
atrio-ventricular valves
valves between the atria and the ventricles, which ensure that blood flows in the correct direction
43
B-glucose
glucose in which the hydrogen atom on carbon atom number one projects below the plane of the ring.
44
B memory cells
cells that remain in the blood for a long time, providing long-term immunity
45
bacterium
a member of a large group of unicellular microorganisms that have cell walls made of murein but lack membrane-bound organelles and a nucleus. Their DNA floats free in the cytoplasm
46
behavioural adaptations
the ways that behaviour is modified for survival
47
binary fission
a type of division found in prokaryotic cells and organelles such as chloroplasts and mitochondria
48
binomial system
a system that uses the genus name and the species name to avoid confusion when naming organisms
49
biodiversity
a measure of the variation found in the living world
50
blood
the fluid used to transport materials around the body
51
Bohr effect
the effect that extra carbon dioxide has on the haemoglobin, explaining the release of more oxygen
52
bordered pits
the part of the plant cell walls which allow the exchange of fluids between tracheids or vessel elements
53
bradycardia
a slow heart rhythm
54
breathing rate
the number of breaths per minute
55
bronchi and bronchioles
smaller airways leading into the lungs
56
buccal cavity
the mouth
57
buffer
a solution that resists changes in pH, so keeps the pH stable
58
callose
a large polysaccharide deposit that blocks old or damaged phloem sieve tubes
59
canker
a sunken lesion in tree bark caused by necrosis
60
capillaries
very small vessels with very thin walls
61
carbaminohemoglobin
a compound of Haemoglobin and carbon dioxide, and is one of the forms in which carbon dioxide exists in the blood, within red blood cells. 10% of carbon dioxide is carried in blood this way
62
carbohydrates
a group of molecules containing carbon, oxygen and hydrogen
63
carbonic acid
a very weak acid formed when carbon dioxide reacts with water
64
carbonic anhydrase
the enzyme that cataylses the combination of carbon dioxide and water
65
cardiac cycle
the sequence of events in one full beat of the mammalian heart
66
cardiac muscle
specialised muscle found in the walls of the heart chambers
67
cartilage
a form of connective tissue
68
casparian strip
an impermeable, waterproof substance (suberin) in the walls of the endodermal cells of plant roots. It creates a water tight seal between the cells, preventing water entering the xylem via the apoplast pathway
69
catalyst
a chemical that speeds up the rate of a reaction and remains unchanged and reusable at the end of the reaction
70
cation
a positively charged ion
71
chloride shift
the movement of chloride ions into the erythrocytes to balance the charge as hydrogencarbonate ions leave the cell
72
chromatids
replicate the chromosomes
73
chromotography
a technique for the separation of a mixture by passing it in solution or suspension through a medium in which the components of the mixture move at different rates
74
circulatory system
| single
one in which the blood flows through the heart once for each circuit of the body
75
circulatory system
| double
one in which the blood flows through the heart twice for each circuit of the body
76
ciliated epithelium
a layer of cells that have many hair-like extensions called cilia
77
CITES
Convention on International Trade in Endangered Species
78
class
a taxonomic group of organisms that all poses the same general traits e.g. the same number of legs
79
classification
the process of placing living things into groups
80
climate change
significant, long-lasting changes in weather patterns
81
clonal expansion
an increase in the number of cells by mitotic cell division
82
clonal selection
selection of specific B or T cell that is specific to the antigen
83
closed circulatory system
one in which the blood is held in the vessels
84
coenzymes
small organic non-protein molecules that bind temporarily to the active site of enzyme molecules, either just before or at the same time that the substrate binds
85
cofactor
a substance that has to be present to ensure that an enzyme-catalysed reaction takes place at an appropriate rate. Some cofactors (prosthetic groups) are part of the enzyme structure, and others (mineral ion cofactors and organic coenzymes) form temporary associations with the enzyme
86
cohesion
the attraction between water molecules caused by hydrogen bonds
87
collenchyma cells
cells that have thick cellulose walls and strengthen vascular bundles and outer parts of the stems, whilst also allowing some flexibility in these regions
88
colorimeter
an instrument for measuring the absorbance of different wavelengths of the light in a solution
89
common anscestor
the most recent individual from which a set of organisms in a group are directly descended
90
companion cells
plant cells that help to load sucrose into the sieve tubes
91
comparative protein modelling
one approach is protein threading, which scans the amino acid sequence against a database of solved structures and produces a set of possible models which would match that sequence
92
competitive inhibition
inhibition of an enzyme, where the inhibitor molecule has a similar shape to that of the substrate molecule and competes with the substrate for the enzyme's active site. It blocks the active site and prevents formation of enzyme-substrate complexes.
93
computer modelling
a model of a process which is created on a computer, often used for processes that can need the increased calculation speed
94
concentration
the abundance of molecules per unit volume
95
concentration gradient
a measurement of how the concentration of a substrate changes from one place to another, often across a membrane
96
conformational change
a change in the shape of a macromolecule
97
conjugated protein
a protein associated with a non-protein component
98
connective tissue
a widely distributed animal/mammalian tissue consisting of cells in an extracellular matrix of protein and polysaccharide; includes bone, cartilage and blood
99
conservation ex situ
carrying out active management to maintain the biodiversity in the natural environment
100
continuous variation
variation where there are two extremes and a full range of values in between
101
convergent evolution
the process whereby organisms not closely related independently evolve similar traits as a result of being adapted to similar environments or ecological niches
102
coronary arteries
arteries supplying blood to the heart muscle
103
correlation coefficent
a measure of how closely two sets of data are correlated. A value of 1 means a perfect correlation.
104
cotransport
transport across a cell membrane, using a carrier or channel protein, of two substances, both moving in the same direction - for example, both moving into the cell.
105
countercurrent flow
where two fluids flow in opposite directions
106
Countryside Stewardship Scheme
a scheme to encourage farmers and other land owners to manage parts of their land in a way that promotes conservation
107
covalent bonds
formed when electrons are shared between atoms. These bonds are very strong
108
crenated
a shriveled animal cell that has lost water by osmosis
109
cytochrome c
a type of cytochrome, an iron-containing protein found within the inner mitochondrial membranes and that forms a part of the electron transport chain
110
cytokines
hormone-like molecules used in cell signalling to stimulate the immune response
111
cytokinesis
cytoplasmic division following nuclear division, resulting in two new daughter cells
112
cytolysis
the process in animal cells where, if a lot of water molecules enter, the cell will swell and burst as the plasma membrane breaks
113
cytology
the study of cell structures and function
114
cytoskeletal motor proteins
molecular motors such as myosins, kinesins and dyneins
115
datalogger
an electronic device that records data over time or in relation to location either with a built-in instrument or sensor or via external instruments and sensors
116
denaturation
a process in which proteins lose their tertiary structure of proteins; caused by high temperatures or extremes of pH
117
denatured
the irreversible change of shape/loss of tertiary structure of proteins; caused by high temperatures or extremes of pH
118
deoxyribose
a five-carbon sugar derived from the five-carbon sugar ribose by replacement of a hydroxyl group by hydrogen, at carbon 2 atom.
119
diaphragm
a layer of muscle beneath the lungs
120
dicotyledonous plants
plants with two seed leaves and a branching pattern of veins in the leaf
121
diastole
the relaxing phase of the cardiac (heartbeat) cycle
122
differential staining
stains that bind to specific cell structures, staining each structure differently so the structures can be easily identified within a single preparation
123
differentiation
process by which stem cells become specialised into different types of cells
124
diffusion
movement of molecules from an area of high concentration of that molecule to an area of low concentration, it may or not be across a membrane; it does not involve metabolic energy (ATP)
125
digestive system
the organs and glands in the body that are responsible for digestion beginning at the mouth and extending through the oesophagus, stomach, small intestine and large intestine, ending with the rectum and anus
126
dilate
to make or become wider, larger, or more open
127
diploid
cell in which the nucleus has two complete sets of chromosomes
128
direct transmission
passing a pathogen from host to new host, with no intermediary
129
disaccharides
any of a class of sugars whose molecules contain two monosaccharide residues joined by a condensation reaction
130
discontinuous variation
where there are distinct categories and nothing in between
131
dissection
to cut apart tissues, organs or organisms for visual or microscopic study of their structure
132
dissociation
releasing the oxygen from oxyhaemoglobin
133
disulfide links
also called disulfide bridges or disulfide bonds, strong covalent bonds (where electrons are shared) between two sulfur atoms, within a (protein) molecule. These bonds are not broken by heat but can be broken by reducing agents
134
DNA polymerase
enzyme that catalyzes formation of DNA from activated deoxyribose nucleotides, using single-stranded DNA as a template
135
domain
the highest taxonomic rank. There are three domains: Archaea, Eubacteria and Eukaryotae
136
double helix
shape of DNA molecule, due to coiling of the two sugar-phosphate backbone strands into a right-handed spiral configuration
137
ecosystem
a community of interacting organisms and their physical environment
138
ectopic heartbeat
an extra or early beat of the ventricles
139
elastic fibres
protein fibres that can deform and then recoil to their original size
140
elastin
a type of protein made by cross-linking a polypeptide called tropoelastin. Tropoelastin has a coiled structure. The cross-linking and coiling make elastin a strong and extensible protein. It is found in structures in living organisms, such as elastic cartilage and ligaments , where they need to stretch or adapt their shape as part of life processes.
141
electrocardiogram
a trace that records the electrical activity of the heart
142
electron micrograph
a trace that records the electrical activity of the heart
143
elliptocytosis
cells being more elliptical in shape than they usually are
144
electrophoresis
the movement of charged particles/molecules in a fluid or gel under the influence of an elastic field
145
embryo-transfer
a step in the process of assisted reproduction in which embryos are placed into the uterus of a female with the intent to establish a pregnancy
146
endemicity
refers to the degree of a condition being endemic- always present in an area/community
147
endocytosis
bulk transport of molecules, too large to pass through a cell membrane even via channel or carrier proteins, into the cell
148
endothelium
the inner layer or lining of blood vessels, made of a single layer of cells
149
environmental variation
variation caused by a response to environmental factors such as light intensity
150
endodermis
a layer of cells surrounding the vascular tissue in the root of a plant
151
enzyme cascade
a sequence of successive activation reactions involving enzymes, which is characterized by a series of amplifications stemming from an initial stimulus. The product of each preceding reaction cataylses the next reaction
152
enzyme-product complex
enzyme molecule with product molecules in its active site. The two are joined temporarily by non-covalent forces
153
enzyme-substrate complex
enzyme molecule with substrate molecules in its active site. The two are joined temporarily by non-covalent forces
154
epidemic
a rapid spread of disease through a high proportion of the population
155
epidermal tissue
tissue consisting of epidermal cells- cells that form the outer layer of cells of a multicellular organism. Usually has a protective function
156
epithelial cells
cells that constitute lining tissue in animals
157
epithelial tissue
lining or covering tissue, consisting of epithelial cells
158
erythrocyte
a red blood cell
159
ester bond
a bond formed by a condensation reaction between the -OH group of a carboxylic acid and the -OH group of an alcohol, to produce an ester
160
eubacteria
taxonomic domain consisting of organisms that have eukaryotic cells
161
eukaryotae
taxonomic domain consisting of organisms that have eukaryotic cells
162
eukaryotic
cells having a true nucleus/organism with eukaryotic cells
163
eukaryotic cell cycle
series of events in a eukaryotic cell leading to its replication to produce two daughter cells; consists of interphase, mitosis and cytokinesis
164
evaporation
the change of state of a liquid into a vapour at a temperature below the liquids boiling point. Evaporation occurs at the surface of a liquid where some molecules of liquid with high kinetic energy escape
165
evolution
the gradual process by which the present diversity of living organisms has developed from earlier forms during the last 3000 million years of the history of the earth
166
exocytosis
the bulk transport of molecules, too large to pass through a cell membrane even via channel or carrier proteins, out of a cell
167
extant
still in existence; surviving
168
extinction
when the last living member of a species dies and the species ceases to exist
169
extracellular
outside the cell
170
eyepiece graticule
a measuring device. It is placed in the eyepiece of a microscope and acts as a ruler when you view an object under the microscope
171
facilitated diffusion
movement of molecules from an area of high concentration of that molecule to an area of low concentration, across a partially permeable membrane via protein channels or carriers; it does not involve metabolic energy (ATP)
172
family
a group of closely related genera e.g. within the order Carnivora we might recognise the 'dog' family and the 'cat' family
173
fatty acids
have a carboxyl group (-COOH) at one end, attached to a hydrocarbon tail, made of only carbon and hydrogen atoms. This may be anything from 2 to 20 carbons long
174
fertilisation
the fusion of male and female gamete nuclei
175
fetal haemoglobin
the type of haemoglobin usually found only in the fetus
176
fibrillation
uncoordinated contraction of the atria and ventricles
177
fibrous proteins
has a relatively long, thin structure, is insoluble in water and metabolically inactive, often having a structural role within an organism
178
filaments
slender branches of tissue that make up the gill. They are often called the primary lamellae
179
flaccid
plant tissue where there is no turgor- the tissue is soft
180
fluid mosaic model
theory of cell membrane structure with proteins embedded in a sea of phospholipids
181
gamete
sex cell e.g. ovum/ spermatozoon
182
gene
a length of DNA, that codes for a polypeptide or for a length of RNA that is involved in regulating gene expression
183
genetic erosion
a process whereby an already limited gene pool of an endangered species of plant or animal diminishes even more when individuals from the surviving population die off without getting a chance to meet and breed with others in their endangered low population
184
genetic variation
variation caused by possessing a different combination of alleles
185
genome
the total DNA content of a cell or an individual
186
genus
a group of closely related species
187
gill filaments
slender branches of tissue that make up the gill of a fish. They are often called the primary lamellae
188
glucose
a 6-carbon monosaccharide sugar
189
glycerol
has three carbon atoms. It is an alcohol, which means it has free -OH groups
190
globular proteins
has molecules of a relatively spherical shape, which are soluble in water, and often have metabolic roles within the organism
191
glycocalyx
all the carbohydrates molecules on the exterior of a cell surface membrane
192
glycogen molecule
the energy store in humans; large polysaccharide molecule made of many glucose residues joined by condensation reactions and like amylopectin, has glycosidic bonds between carbons 1 and 4, and branches formed by glycosidic bonds between carbon atoms 1 and 6.
193
glycolipid
lipid/phospholipid with a chain of carbohydrate molecule attached
194
glycoprotein
protein with a chain of carbohydrate molecules attached
195
glycosidic bonds
a bond formed between two monosaccharides by a hydrolysis reaction
196
growth factors
a substance, such as a vitamin, hormone or cytokinin, which is required for the stimulation of growth in living cells
197
goblet cells
cells that secrete mucus
198
guard cell
in leaf epidermis, two of these cells surround stomata
199
habitat
where an organism lives
200
haemoglobin
the red pigment used to transport oxygen in the blood
201
haemoglobinic acid
the compound formed by the buffering action of haemoglobin as it combines with excess hydrogen ions
202
haemolysis
lysis of animal cells, in this case it is referring to lysis of red blood cells
203
haemolytic anemia
anemia with chronic premature destruction of red blood cells
204
haploid
having only one set of chromosomes; represented by the symbol 'n'
205
helicase
enzyme that cataylses the breaking of hydrogen bonds between the nitrogenous base pairs of bases in a DNA molecule
206
hazard
a factor that has the potential to cause harm
207
herd vaccination
using a vaccine to provide immunity to all or almost all of the population at risk
208
heterotopic ossification
overgrowth of bone, often in the wrong place e.g. muscle tissue
209
high-power drawing
a drawing showing detail of some individual cells
210
histamine
a compound which is released by mast cells in response to injury and in allergic and inflammatory reactions, causing contraction of smooth muscle and dilation of capillaries
211
homologous chromosomes
matching chromosomes, containing the same genes at the same place (loci). They may contain different alleles for some or all of the genes
212
homozygosity
in a diploid cells or organism the state where both copies of a given gene are the same allele
213
hormone
a chemical produced in glands and that travels to its target cells via the blood. Later broken down in the liver. Involved with communication and control
214
hydathodes
structures in plants that can release water droplets which may then evaporate from the leaf surface
215
hydrocarbon
a compound consisting of only hydrogen and carbon
216
hydrogen bond
a weak interaction that can occur wherever molecules contain a slightly negatively charged atom bonded to a slightly positively charged hydrogen
217
Hydrogencarbonate ion
HCO3-
218
Hydrolysis reaction
reaction that occurs when a molecule is split into two smaller molecules with the addition of water
219
hydrophilic
attracted to water
220
hydrophobic
repelled by water
221
hydrophyte
a plant adapted to living in water or where the ground is very wet
222
hydrostatic pressure
the pressure that a fluid exerts when pushing against the side of the vessel or the container
223
hypertension
long term high blood pressure
224
hyphae
each of the branching filaments that make up the mycelium of a fungus
225
immune response
the reaction of the cells and fluids of the body to the presence of a substance which is not recognised as a constituent of the body itself
226
immune system
the organs and processes of the body that provide resistance to infection and toxins. Organs include the thymus, bone marrow and lymph nodes
227
in vitro fertilisation
a process where an egg is surgically removed from the ovaries and fertilised with sperm in a laboratory
228
indirect transmission
passing a pathogen from host to new host, via a vector
229
inflammation
swelling and redness of tissue caused by infection
230
inhibitor
a substance that reduces or stops a reaction
231
inorganic ions
charged particles of inorganic (not carbon-based) substances e.g. Mg2+ and Ca2+
232
integumentary system
the organ system that protects the body from various kinds of damage, such as loss of water or abrasion from outside. The system comprises the skin and its appendages (including hair, scales, feathers, hooves and nails)
233
intercalated discs
gap junctions between muscle cells in the heart muscle. They enable the heart muscle cells to fit tightly together and help to facilitate synchronized contraction of the heart muscle
234
intercostal muscles
muscles between the ribs. Contraction of the external intercostal muscles raises the rib cage
235
interleukins
signalling molecules that are used to communicate between different white blood cells
236
interphase
phase of cell cycle where the cell is not dividing, it is subdivided into growth and synthesis phases
237
interspecific variation
the differences between species
238
intracellular
inside the cell
239
intraspecific variation
the variation between members of the same species
240
ionic bond
a type of chemical bond that involves the electrostatic attraction between oppositely charged ions
241
karyotype
a photomicrograph of chromosomes in a cell
242
keratin
a fibrous protein forming the main structural constituent of hair, feathers, hooves, nails, claws and horns
243
keratinocytes
an epidermal cell that produces keratin
244
keystone species
one that has a disproportionate effect upon its environment relative to its abundance
245
kinetic energy
the energy of motion
246
kingdom
taxonomic group; traditionally there are five main kingdoms: Plantae, Animalia, Fungi and Protoctista are all Eukarya whose cells posses a nucleus. All those single celled organisms that do not posses a nucleus are grouped into the kingdom Prokaryota.
247
lamellae
folds of the filament to increase the surface area. They are also called secondary lamellae or gill plates
248
leucocyte
a white blood cell
249
lignification
the deposition of lignin in the walls of xylem vessels
250
lignin
the waterproof substance that impregnates the walls of xylem vessels. When plant xylem vessels are lignified they are woody
251
limiting factor
an environmental factor that limits the rate of a biological process. When a process is controlled by a number of factors, the factor that is in least supply will limit the process. If this factor is increased then the process with proceed at a faster rate. If it is decreased the process will proceed at a slower rate.
252
lipids
a group of substances that are soluble in alcohol rather than water. They include triglycerides, phospholipids, glycolipids and cholesterol
253
lipophilic
attracted to fat
254
lipophobic
repelled by fat
255
locus
the position of a gene on a chromosome
256
longitudinal section
a section cut lengthways
257
low-power plan
a drawing showing distribution of cells but no individual cells shown
258
lymph
the fluid held in the lymphatic system, which is a system of tubes that return excess tissue fluid to the blood system
259
lymphatic system
a network of vessels and organs that help maintain the internal fluid environment of the body; also transports fat and proteins and makes some blood cells. Receives tissue fluid that has passed out of blood capillaries and bathed cells. Lymph drains into blood vessels in the neck region. Lymph organs include the tonsils, thymus, spleen and lymph nodes.
260
macromolecule
a very large, organic molecule
261
macrophages
large phagocytic cells that ingest and digest pathogens and present the pathogens antigens to other ells of the immune system
262
magnification
the number of times larger an image appears, compared to the size of the object
263
marine conservation zones
areas of the sea set aside to conserve the diversity of species and habitats
264
median
the number that separates a data set into two halves; half the set is above the median value and the other half is blow the median value. In a sample there may be no specimen that actually has the median value
265
meiosis
type of nuclear division that results in the formation of cells containing half the number of chromosomes of the parent cell
266
meristem
an area of unspecialised cells, in plants, that can divide and differentiate into other cell types
267
mesenchyme
connective tissue
268
mesoderm
the middle of the three layers in the early embryo; gives rises to connective tissue, muscles and part of the gonads (ovaries and testes)
269
mesophyll
a type of cell found in plant leaves
270
metabolic/metabolism
the chemical reactions that take place inside living cells or organisms
271
micrometer
a precise measuring device and not a unit of measurement. It is a small scale on a microscope slide that can be viewed under a microscope and used to calibrate the value of eyepiece divisions at different magnifications
272
micrometre
equal to one millionth (10-6) of a metre. It is the standard unit for measuring cell dimensions.
273
microscopy
the use of the microscope to study small objects or organisms
274
mitosis
a type of nuclear division that produces daughter cells genetically identical to each other and to the parent cell
275
mode
the most common value amongst a group or data set
276
monoculture
a crop consisting of one strain of one species
277
monocytes
the largest white blood cells, usually have a large kidney-shaped nucleus
278
monomer
a small molecule which binds to many other identical molecules to form a polymer
279
monosaccharide
any of the class of sugars (e.g. glucose) that cannot be hydrolysed to give a simpler sugar
280
mucous membrane
specialised epithelial tissue that is covered by mucus
281
muscle tissue
highly cellular, well vasculised (has many blood vessels) tissue responsible for most types of body movement. Muscle cells are called fibres, contain the proteins actin and myosin, and can contract. Three types of muscle tissue: smooth, skeletal and cardiac
282
musculo-skeletal system
the combination of the skeletal muscles and skeleton working together; includes the bones, muscles, tendons and ligaments of the body
283
mutation
a change to the genetic material of an organism, either to a gene or to a chromosome. The changing of the structure of a gene, resulting in a variant allele that may be transmitted to subsequent generations, caused by the alterations of single base units in DNA, or the deletion, insertion, or rearrangement of larger sections of genes or chromosomes. May involves loss of a portion of a chromosomes, or an abnormal chromosome number.
284
mycelium
the vegetative part of a fungus, consisting of a network of fine white filaments called hyphae
285
myocardial infarction
a heart attack
286
myofibrils
microscopic fibres that make up the larger fibres of skeletal (striated) muscle
287
myogenic muscle
muscle that can initiate its own contraction
288
nanometre
one thousandth (10-3) of a micrometre. It is therefore one thousand millionth (10-9) of a metre. It is a useful unit for measuring the sizes of small organelles within cells and for measuring the size of large molecules
289
natural classification
the term used to explain how features of the environment apply a selective force on the reproduction of individuals in a population
290
natural immunity
immunity achieved through normal life processes
291
natural selection
the term used to explain how features of the environment apply a selective force on the reproduction of individuals of a population
292
necrosis
cell death caused by disease or injury; it may subsequently limit the spread of a pathogen
293
nervous system
the central nervous system (brain and spinal cord) and the peripheral nervous system- the network of nerve cells (neurons) that transmit nerve impulses between parts of the body and the central nervous system. Fast acting control system to detect stimuli and to bring about responses in muscles and glands
294
nervous tissue
the main component of the nervous system. Consists of neurones and supporting cells
295
neutrophil
a type of white blood cell that engulfs foreign matter and traps it in a larger vacuole (phagosome), which fuses with lysosomes to digest the foreign matter
296
non-competitive inhibition
the inhibition of an enzyme where the competitor molecule attaches to a part of the enzyme molecule but not to the active site. It changes the shape of the active site and prevents ES complexes forming as the enzyme active site is no longer complementary in shape to the substrate molecule
297
nucleotide
molecule consisting of a five-carbon sugar, a phosphate group and a nitrogenous base
298
oncotic pressure
the pressure created by the osmotic effects of the solutes in a solution
299
open circulatory system
one in which the blood is not held in the vessels
300
operculum
a bony flap that covers and protects the gills
301
opsonins
proteins that bind to the antigen on a pathogen and then allow the phagocytes to bind
302
optimum pH
the pH at which an enzyme works best, as its fastest rate
303
order
taxonomic group; a subdivision of the class using additional information about the organisms e.g. the class Mammalia is divided into meat-eating animals (order Carnivora) and vegetation-eating mammals ( order Herbivora)
304
organ
collection of tissues working together to perform a function or related functions
305
organ system
a number of organs working together to carry out an overall life function
306
organelles
small structures within cells, each of which carries out a specific function
307
osmosis
passage of water molecules down their water potential gradient, across a partially permeable membrane
308
ossification
process of changing cartilage to bone by depositing calcium phosphate
309
ostia
pores in the heart of an insect that allow blood from the body to enter the heart
310
ovalocytosis
cells being more oval in shape than they usually are
311
oxygen tension
measured in units of pressure (kPa)
312
oxygen uptake
the volume of oxygen absorbed by the lungs in one minute
313
oxyhaemoglobin
a molecule of haemoglobin with oxygen molecules loosely bound to it. When haemoglobin takes up oxygen, it becomes oxyhaemoglobin
314
palisade cells
closely-packed photosynthetic cells within leaves
315
pandemic
an infectious disease which spreads rapidly across continents
