Glossary Flashcards
1
Q
abiotic factors
A
Non living factors
2
Q
Accuired variations
A
are not inherited but are learned or developed during life
3
Q
Active immunity
A
the production of a persons own anitbodies in response to foreign antigens that enter the body
4
Q
Active site
A
the part of an enzyme that combines with the substrate
5
Q
Active transport
A
Energy (in the form of ATP) is used to move molecules, often against a concentration gradient, i.e from low concentrations to high concentrations
6
Q
Adaption
A
any alteration that improves an organisms chances of survival and reproduction
7
Q
Adhesion
A
occurs when different molecules stick together
8
Q
Aerobic respiration
A
the controlled release of energy from food using oxygen
pg133
9
Q
Alleles
A
Different (or alternative) forms of the same gene
pg191
10
Q
All or nothing law
A
states that if the threshold is reached an impulse is carried, but if the threshold is not reached no impulse is carried.
pg378
11
Q
Anabolic reactions
A
use energy to convert smaller molecules into larger molecules
pg24
12
Q
Anaerobic respiration
A
The controlled release of energy from food without the use of oxygen
pg135
13
Q
Antagonistic pair
A
two muscles that have opposite effects to each other
pg415
14
Q
Antibiotics
A
chemicals produced by micro-organisms that stop the growth of, or kill, other micro-organisms without damaging human tissue
pg244
15
Q
Antibody
A
a protein produced by white blood cells(called lymphocytes) in response to a specific antigen
pg423
16
Q
anticodon
A
a sequence of three bases (a triplet) on tRNA that are complementary to a sequence of three bases on mRNA
pg182
17
Q
Antigen
A
A foreign molecule that stimulates the production of antibodies
pg 423
18
Q
Appendicular skeleton
A
composed of the limbs(arms and legs),the pectoral (shoulder) girdle and the pelvic (hip) girdle
pg 409
19
Q
artificial active immunity
A
occurs when a pathogen is medically introduced into the body
pg 424
20
Q
artificial passive immunity
A
occurs when a person is given an injection containing antibodies made by another organism
pg 425
21
Q
Aseptic or asepsis
A
means that measures are taken to exclude unwanted micro-organisms
pg256
22
Q
asexual reproduction
A
involves only one parent
pg14, 438
23
Q
autotrophic (organism)
A
one that makes its own food
pg241
24
Q
axial skeleton
A
consists of the skull,spine,ribs,and sternum (breastbone)
pg408
25
Bacteriophage or phage
a virus that infects bacteria
pg433
26
balanced diet
contains all the necessary food types in the correct proportions
pg239
27
batch culture
the growth of cells in a sealed container (or bioreactor) over a short period of time and under ideal conditions until all the nutrients are used up
pg246
28
biogenesis
living things arise from other living things of the same type. Also called continuity of life
pg11
29
biology
study of all living things
pg2
30
Biomolecules
chemicals that are made inside a living thing
pg16
31
bioprocessing
the use of enzyme controlled reactions to produce a product
pg105
32
bioreactor
a vessel or container in whhich living cells or their products are used to make a product
pg105, 247
33
biosphere
the part of the planet containing living organisms
pg32
34
biotechnology
the use of living things or their components (especially cells and enzymes) to mamufacture useful products or to carry out useful reactions
pg136
35
biotic factors
living factors
pg34
36
birth control
methods taken to limit the number of children that are born
pg482
37
blastocyst or blastula
a hollow ball of cells formed from a morula
pg479
38
Blood pressure
the force exerted by the blood against the walls of the blood vessels (mainly the arteries).
pages 302, 308
39
Bud
a potential growth point that may develop into a shoot, a leaf or a flower.
page 267
40
Bulb
a modified bud.
page 461
41
Cancer
a group of disorders in which certain cells lose their ability to control both the rate of mitosis and the number of times mitosis takes place.
page 160
42
Carnivores
animals that feed mainly on animals.
Examples are dogs, cats and ladybirds.
page 320
43
Carpels
the female parts of the flower.
page 439
44
Catabolic reactions
release energy when a complex molecule is broken down to a simpler form.
page 24
45
Catalyst
a substance that speeds up a reaction, without itself being used up in the reaction.
page 103
46
Cell continuity
all cells develop from pre-existing cells.
page 155
47
Cell cycle
the changes that take place in a cell during the period between one cell division and the next.
page 157
48
Cellular energy
the energy stored in the bonds of biomolecules.
page 102
49
Centromere
the point at which the chromosomes are attached in a double-stranded chromosome.
page 162
50
Characteristics
characteristics traits or features that are inherited genetically.
page 170
51
Chemosynthesis
the production of food using energy released from chemical reactions.
page 241
52
chemotropism
a change in growth of a plant in response to chemicals.
page 365
53
Chromatin
the name given to chromosomes when they are elongated and not dividing,
page 87
54
Chromosomes
coiled threads of DNA (which forms genes) and protein that become visible in the nucleus at cell division.
page 155
55
Chromosome mutation
a large change in the structure or number of one or more chromosomes.
page 215
56
Classification
placing objects into groups based on similar characteristics.
page 212
57
Climatic factors
refer to weather over a long period of time.
page 34
58
Cloning
the production of identical copies of the bacterium (containing the target gene).
page 226
59
Closed circulatory system
blood remains in a continuous system of blood vessels.
page 300
60
Codon or Triplet
) a sequence of three bases in
DNA (or RNA) that act as a code for an amino acid.
page 172
61
Cohesion
the sticking of similar molecules to each other.
page 285
62
Community
all the different populations in an area.
page 33
63
Competition
occurs when organisms actively struggle for a resource that is in short supply.
page 51
64
Conclusion
a summary of the results of an experiment.
page 3
65
Conservation
the wise management of the existing natural resources in an ecosystem, in order to maintain a wide range of habitats and prevent the death and extinction of organisms.
page 42
66
Consumers
organisms that take in food from another organism.
page 36
67
Contest competition
an active physical contest between two individual organisms.
page 52
68
Continuity of life/biogenesis
living things arise from other living things of the same type. This is also called biogenesis.
page 11
69
Continous flow
(food processing) the growth of cells in an open container (or bioreactor), where nutrients are added and the end products are removed all the time at a rate that maintains the volume of liquid and the number of cells.
page 247
70
Contraception
the deliberate prevention of fertilisation or pregnancy.
page 482
71
Control
used to provide a comparison (or standard) against which the actual experiment can be judged.
page 5
72
Copulation
the act of sexual intercourse.
page 475
73
Cotyledon
a seed leaf.
pages 272, 445
74
cross-pollination
the transfer of pollen from an anther to a stigma on a different plant.
page 443
75
Cutting
a portion of a plant that is removed from the parent plant and grown into a new, independent plant.
page 462
76
Cytoplasm
the living material in a cell outside the nucleus.
page 85
77
Data
the measurements, observations or information gathered from experiments.
page 3
78
Decomposers
organisms that feed on dead organic matter
pg 36
79
Denatured enxzyme
one that has lost its shape and can no longer carry out its function.
pages 104, 115
80
Denitrification
the conversion of nitrates to nitrogen gas.
page 40
81
Detrius feeders
organisms that feed on small pieces of dead organic matter.
page 36
82
Diastole
when the heart chambers relax.
page 307
83
Diffusion
the spreading out of molecules from a region of high concentration to a region of low concentration.
page 147
84
Dihybrid cross
dihybrid cross involves the study of two characteristics.
page 197
85
Diploid cell
one that has two sets of chromosomes, i.e. it has two of each type of chromosome in the nucleus.
page 156
86
Dispersal
the transfer of a seed or fruit away from the parent plant.
page 447
87
DNA profile
DNA profile (also called a DNA or genetic fingerprint) a method of making a unique pattern of bands from the DNA of a person, which can then be used to compare with the DNA profile of another person.
page 174
88
Dominant
the allele that prevents the recessive allele from being expressed.
page 191
89
Dormancy
a resting period when seeds undergo no growth and have reduced cell activity or metabolism.
page 449
90
Double blind
both the investigator and the participant are unaware of the nature of the treatment the participant is receiving. page 6
91
Ecological niche
(of an organism) the functional role it plays in the community.
page 38
92
Ecology
the study of the interactions between living things (organisms) and between organisms and their environment.
page 32
93
Ecosystem
a group of clearly distinguished organisms that interact with their environment as a unit.
page 32
94
Ectotherms
gain or lose heat from or to their external environment.
page 349
95
Edaphic factors
edaphic factors relate to soil.
page 34
96
Ejaculation
the release of semen from the penis.
page 475
97
Endocrine gland
a ductless gland that produces hormones, which are released directly into the bloodstream.
page 398
98
Endospermic seed
contains some endosperm when fully formed.
page 445
99
Endotherms
generate their own heat from metabolic reactions.
page 349
100
Enzymes
proteins that speed up a reaction without being used up in the reaction.
page 103
101
Enzyme specificity
each enzyme will react with only one particular substrate.
page 115
102
Ethics
Relate to whether conduct is right or wrong
103
Eukaryotic cells
eukaryotic cells have a nucleus and cell organelles, all of which are enclosed by membranes.
page 89
104
Evolution
the way in which living things change genetically to produce new forms of life over long periods of time.
page 216
105
Excretion
the removal of waste products of metabolism from the body.
page 13
106
Exhalation
breathing out.
page 342
107
Exocrine glands
release their product into ducts or tubes.
page 398
108
Experiment
a test for a hypothesis.
pages 3, 4
109
Expression
expression the formation of the product by the organism with the recombinant DNA.
page 226
110
Facultative parasite
facultative parasite can get its food from a live or a dead host.
page 251
111
Fauna
fauna all the animals in an ecosystem. page 36
112
Fermentation
fermentation another name for anaerobic respiration.
page 135
113
Fertilisation
the union of the male and female gametes to form a diploid zygote.
pages 190, 444, 475
114
Filtration
water and small molecules pass (under high pressure) from the blood into the nephron.
page 355
115
Flora
all the plants in an ecosystem.
page 36
116
Food chain, Grazing food chain
) a sequence of organisms in which each one is eaten by the next member in the chain.
page 36
117
Food web
food web two or more interlinked food chains.
page 37
118
Forensic medicine
the way in which medical knowledge is used in legal situations.
page 175
119
Fossil
the remains of something that lived a long time ago (or some indication of something that lived a long time ago).
page 218
120
Frequency
the chance of finding a named species with any one throw of a quadrat.
page 73
121
Fruit
a developed ovary. page 446
122
Gametes
haploid cells capable of fusion.
pages 190,
439
123
Ganglion (plural ganglia)
(plural: ganglia) a group of cell bodies located outside the CNS.
page 377
124
Gene
a section of DNA that contains the instructions for the formation of a protein.
pages 156, 169
125
Gene expression
the way in which the genetic information in a gene is decoded in the cell and used to make a protein.
page 169
126
Gene or Point Mutation
a change in a single gene.
page 215
127
General Defence systen
acts as a barrier to all pathogens attempting to gain entry to the human body.
page 420
128
Genetic Code
the sequence of bases in DNA that provide the instruction for a cell (using RNA) to form a protein.
page 172
129
Genetic engineering
the artificial manipulation or alteration of genes.
page 223
130
Genetic screening
testing DNA for the presence or absence of a particular gene or an altered gene.
page 177
131
Genotype
the genetic make-up of an organism, i.e. the genes that are present
page 191
132
Geotropism
(or gravitropism) the change in growth of a plant in response to gravity.
page 365
133
Germination
the regrowth of the embryo, after a period of dormancy, if the environmental conditions are suitable.
page 449
134
Germ Layers
basic layers of cells in the blastocyst from which all adult tissues and organs will form.
page 479
135
Gestation
the length of time spent in the uterus from fertilisation to birth.
page 480
136
Glycolisis
the conversion of glucose into two molecules of pyruvic acid.
page 138
137
Gonad
an organ that produces sex cells in animals.
page 467
138
Grafting
the joining and uniting of part of one plant with a second plant.
page 462
139
Growth inhibitor
a chemical that causes a reduction in growth of plants.
page 367
140
Growth plate
the area between the epiphysis and the diaphysis in a long bone within which bone growth occurs.
page 411
141
Growth Promoter
a chemical that causes increased growth in plants.
page 366
142
Growth regulator
a chemical that controls the growth of a plant.
page 365
143
Habitat
the place where a plant or an animal lives (and is also the local area of study).
pages 33, 65
144
Haploid cell
one that has one set of chromosomes, i.e. it has only one of each type of chromosome in the nucleus.
page 156
145
Helper T cells
stimulate B cells and killer T cells.
page 427
146
Herbaceous plants
herbaceous plants do not contain wood (or lignin).
page 267
147
Herbivores
animals that feed mainly on plants.
Examples are sheep, cattle and rabbits. page 320
148
Hereditary
the passing on of features from parents to offspring by means of genes.
page 169
149
Heterotrophic organism
one that takes in food made by other organisms.
page 241
150
Heterozygous
the alleles are different.
page 192
151
Homeostasis
the ability of an organism to maintain a constant internal environment.
page 334
152
Homolougous pair
two chromosomes of similar size with the same sequence of genes.
page 156
153
Homozygous
two alleles that are identical.
page 192
154
Hormone
a chemical messenger produced by an endocrine gland and carried by the bloodstream to another part of the body, where it has a specific effect.
page 399
155
Hydrotropism
a change in growth of a plant in response to water.
page 365
156
Hypha
hypha a tube or filament in a fungus.
page 251
157
Hypothesis
an educated guess based on observations. page 3
158
Immobilized enzymes
are attached, or fixed, to each other, or to an inert material. page 105
159
Immunisation
occurs when we produce or are injected with antibodies against a pathogen.
page 425
160
Immunity
the ability to resist infection.
page 420
161
Implantation
the embedding of the fertilised egg into the lining of the uterus.
page 476
162
Incomplete dominance
neither allele is dominant or recessive with respect to the other. Both alleles are equally expressed in the heterozygous genotype to produce an intermediate phenotype.
page 193
163
Induced immunity
the ability to resist disease caused by specific pathogens by the production of antibodies.
page 424
164
Infertility
the inability to produce offspring.
page 469
165
Inhalation
breathing in. page 341
166
Inherited variations
inherited variations are controlled by genes.
page 213
167
Insemination
the release of semen into the vagina, just outside the cervix.
page 475
168
Interneuron/intermediate relay/association neuron
interneuron (also called an intermediate, relay or association neuron)
carries information between sensory and motor neurons.
page 377
169
Internode
the region on a stem between two nodes.
page 267
170
Interphase
the phase in the cell cycle when the cell is not dividing.
page 157
171
Inter-specific competition
inter-specific competition occurs between members of different species. page 51
172
Intra-specific competition
intra-specific competition occurs between members of the same species. page 51
173
In-vitro fertilisation (IVF)
removing eggs from an ovary and fertilising them outside the body.
page 477
174
Isolation
the removal of the chromosome (containing the target gene) from the human cell and the plasmid DNA from the bacterium.
page 225
175
Joint
where two or more bones meet.
page
413
176
Key
a means of naming organisms by answering a series of questions with alternative answers.
page 69
177
Killer T cells
killer T cells destroy abnormal human body cells.
page 427
178
Lactation
the secretion of milk by the mammary glands (breasts) of the female.
page 482
179
Larynx
the voice box. page 339
180
Law or Principle
arises from a theory that has been shown to be valid when fully tested over a long period of time.
page 4
181
law of independent assortment states that:
when gametes are formed either of a pair of alleles is equally likely to combine with either of another pair of alleles. page 197
182
Law of Segregation (Mendels first law) states that:
• Inherited characteristics are controlled by pairs of alleles.
• These alleles segregate (or separate) from each other at gamete formation, with only one member of the pair being found in each gamete.
page 196
183
Layering
the growth of a new plant from a stem that is still attached to the parent plant.
page 463
184
Lenticels
openings in the stems of plants that allow gas exchange.
pages 267, 284
185
LIFE
the possession of all the following characteristics:
organised,
requiring nutrition and excretion,
capable of responding
and reproducing.
page 12
186
Ligaments
strong, fibrous, slightly elastic tissues that connect bone to bone.
page 414
187
Ligation
the joining of two sections of DNA to form a single strand.
page 225
188
Lignin
a strengthening material found in some plant cell walls.
page 270
189
Linkage genes
linkage genes are located on the same chromosome.
page 200
190
Locus (of a gene)
its position on a chromosome.
page 191
191
Meiosis
a form of nuclear division in which the four daughter nuclei contain half the chromosome number of the parent nucleus.
page 161
192
Memory B cells
memory B cells survive for years after the infection is eliminated and can make the specific antibody if the same infection later enters the body.
page 427
193
Memory T cells
memory T cells survive for years after the infection is eliminated and can stimulate the specific B cells and killer T cells if the same infection later enters the body.
page 428
194
Menopause
when ovulation and menstruation stop happening in a female.
page 471
195
Menstrual cycle
a series of events that occurs every 28 days on average in the female if fertilisation has not taken place.
page 471
196
Menstruation
the discharge of the lining of the uterus (the endometrium) and the unfertilised egg.
page 472
197
Meristem
meristem a plant tissue capable of mitosis.
page 266
198
Metabolism
the sum of all the chemical reactions in an organism.
page 11
199
Micro-organisms
small living things. page 237
200
Micropropogation
the growth of plants from small pieces of tissue under sterile conditions on a specially selected medium.
page 463
201
Mitosis
a form of nuclear division in which one nucleus divides to form two nuclei, each containing the same number of chromosomes with identical genes.
page 157
202
Monohybrid Cross
involves the study of a single characteristic.
page 197
203
Morula
a solid ball of cells formed from a zygote by mitosis.
page 478
204
Motor/Efferent Neuron
motor (or efferent) neuron takes a message from the CNS to a muscle or a gland.
page 376
205
Mutagens
agents that cause mutations.
page 214
206
Mutation
mutation a spontaneous (or sudden) change in the amount or structure of DNA.
page 214
207
Mycelium
a (usually) visible mass of hyphae.
page 251
208
Natural Active Immunity
occurs when a pathogen enters the body in the normal way (i.e. when you get an infection).
page 424
209
Natural passive Immunity
natural passive immunity occurs when a child gets antibodies from its mother. page 425
210
Natural selection
the process by which those organisms with genetically controlled characteristics that allow them to be well adapted to their environments will survive and reproduce to pass on their genes to following generations.
page 217
211
Natural Vegetatuve Propogation
natural vegetative propagation involves forming new plants from a stem, root, leaf or bud.
page 460
212
Negative Tropism
negative tropism occurs when the growth is away from the stimulus.
page 364
213
Neuron
neuron (or neurone) a nerve cell.
page 376
214
Nitrification
the conversion of ammonia and ammonium (NH *) compounds to nitrite and then to nitrate.
page 40
215
Nitrogen fixation
the conversion of nitrogen gas into ammonia (NH), ammonium (NH, *) or nitrate (NO,).
page 40
216
Node
the point on a stem at which a leaf is attached. page 267
217
Non endospermic seed
non-endospermic seed has no endosperm when fully formed.
page 445
218
Nutrient recycling
the way in which elements (such as carbon and nitrogen) are exchanged between the living and non-living components of an ecosystem.
page 38
219
Nutrition
the way organisms obtain and use food.
page 12
220
Obligate Parasite
obligate parasite can only take its food from a live host.
page 251
221
Observation
observation when something is noticed. page 3
222
Omnivores
animals that feed on plants and animals.
Examples are humans, badgers and hedgehogs.
page 320
223
Open circulatory system
blood leaves blood vessels and flows around the cells of the animal's body before re-entering blood vessels again.
page 300
224
Optimum pH
the pH value at which the enzyme works best. page 115
225
Organ
a structure composed of a number of tissues that work together to carry out one or more functions.
page 98
226
Organisation
living things are composed of cells, tissues, organs and organ systems.
page 12
227
Organism
organism a living thing.
page 11
228
Organ system
a number of organs working together to carry out one or more functions,
page 99
229
Orgasm
the physical and emotional sensations experienced at the peak of sexual excitement.
page 475
230
Osmosis
the movement of water molecules across a semi-permeable membrane from a region of high water concentration to a region of low water concentration.
page 148
231
osteoblast
a bone-forming cell.
page 411
232
osteoclast
a bone-digesting cell. page 412
233
ovulation
the release of an egg from the ovary.
page 470
234
parasites
organisms that take in food from a live host and usually cause harm.
page 242
235
Parasitism
when two organisms of different species live in close association and one organism (the parasite) obtains its food from, and to the disadvantage of, the second organism (the host).
page 53
236
Passive immunity
passive immunity occurs when individuals are given antibodies that were formed by another organism.
page 425
237
pathogen
pathogen an organism that causes disease.
page 420
238
pathogenic bacteria
bacteria that cause disease.
page 244
239
pectoral girdle
pectoral girdle consists of the collarbone (or clavicle and the shoulder blade (or scapula).
page 409
240
pedigree
a diagram showing the genetic history of a group of related individuals.
page 194
241
pelvic girdle
composed of two halves of the hip joined to the sacrum.
page 409
242
percentage cover
an estimate of the amount of ground in a quadrat covered by each species.
page 72
243
peristalsis
a wave of muscular action in the walls of the alimentary canal that moves the contents along
page 323
244
pharynx
pharynx the throat. page 339
245
phenotype
the physical make-up, or appearance, of an organism.
page 191
246
phospholipids
fat-like substances in which one of the fatty acids is replaced by a phosphate group or has a phosphate group added to it.
page 19
247
photolysis
the splitting of water by light. page 125
248
phototropism
the change in growth of a plant in response to light, usually from one direction (i.e. unidirectional light),
page 364
249
plasma
the liquid part of blood. page 292
250
Plasma B cells
produce antibodies. page 426
251
plumule
the part of the plant embryo that develops into the shoot.
page 445
252
pollination
the transfer of pollen from an anther to a stigma of a flower from the same species.
page 443
253
pollutants
harmful additions to the environment. page 41
254
pollution
any harmful addition to the environment.
page 41
255
population
all the members of the same species living in an area. page 33
256
portal system
a blood pathway that begins and ends in capillaries.
page 305
257
positive tropism
occurs when the growth is towards the stimulus.
page 364
258
predation
the catching, killing and eating of another organism.
page 53
259
predator
an organism that catches, kills and eats another organism.
page 53
260
prey
the organism that is eaten by a predator.
page 53
261
principle(or law)
principle (or law) arises from a theory that has been shown to be valid when fully tested over a long period of time. page 4
262
producers
organisms that carry out photosynthesis.
page 36
263
product
the substance(s) formed by an enzyme. page 103
264
progency
offspring that are produced. page 192
265
prokaryotic cells
do not have a nucleus or membrane-enclosed organelles.
page 89
266
protoplasm
all the living parts of a cell. page 85
267
puberty
the beginning of sexual maturity. page 469
268
pulse
the alternate expansion and contraction of the arteries. page 308
269
punnett square
a grid used to show the ratio of the genotypes of the progeny in a genetic cross.
page 192
270
Purines
(double-ring molecules) adenine (A) and guanine (G).
page 180
271
pyramid of numbers
represents the numbers of organisms at each trophic level (or stage) in a food chain.
page 38
272
pyrimidines
(single-ring molecules) thymine (T)
and cytosine (C).
page 180
273
qualitative study
records the presence or absence of organisms
274
quantitative study
records the numbers of organisms that are present. page 66
275
radicle
part of the plant embryo that develops into a root
276
re absorption
molecules pass from the nephron back into the blood. page 355
277
rcessive
the allele is prevented from being expressed by a dominant allele.
page 191
278
reflex action
an automatic, involuntary, unthinking response to a stimulus.
page 384
279
reflex arc
the pathway taken by a nerve impulse in a reflex action.
page 384
280
refractory period
a short time span after a neuron has carried an impulse during which a stimulus fails to cause a response.
page 378
281
replicate
a repeat of an experiment.
page 6
282
reproduction
the production of new individuals.
page 14
283
response
the activity of a cell or organism as a result of a stimulus.
page 363
284
root tuber
a swollen, underground root that remains dormant during winter and from which new plants may grow.
page 460
285
runners
horizontal stems that run (or grow) above ground and from which new plants grow.
page 460
286
sacrophytes
organisms that take in food from dead organic matter.
page 241
287
scientific method
a process of investigation in which problems are identified and their suggested explanations are tested by carrying out experiments
page 3
288
scramble competition
all of the competing individuals get some of the resource. page 52
289
secondary sexual characteristics
those features that distinguish males from females, apart from the sex organs themselves.
page 469
290
secretion
some substances pass from the blood into the nephron.
page 356
291
selectively permeable membrane
allows some but not all molecules to pass through.
page 147
292
self-pollination
the transfer of pollen from an anther to a stigma on the same plant.
page 443
293
semen
a fluid containing sperm and seminal fluid.
page 468
294
sensory or afferent neuron
takes a message from a sense organ to the CNS.
page 376
295
serum
plasma from which the clotting proteins have been removed.
page 293
296
sex linkage
a characteristic is controlled by a gene on a sex (or X) chromosome.
page 202
297
sexual reproduction
the union of two sex cells or gametes. pages 14, 439
298
Solar energy
energy from the Sun. page 102
299
Speculation
the production of new species as a result of evolution.
page 217
300
Species
a group of similar organisms that are capable of naturally interbreeding with each other to produce fertile offspring. page 212
301
Specific Defence System
attacks particular (or specific) pathogens. page 422
302
Sporulation
the process of making spores.
page 253
303
Stamens
the male parts of the flower.
page 439
304
Sterile
all micro-organisms are destroyed, i.e. there is nothing living.
page 256
305
Stimulus/ plural=Stimuli
) anything that causes a reaction in an organism or in any of its parts.
page 363
306
Substrate
the substance with which an enzyme reacts.
page 103
307
Suppresor T cells
inhibit the immune response.
page 428
308
Symbiosis
occurs when two organisms of different species live (and have to live) in close association and at least one of them benefits.
page 54
309
Synapse
a region where two neurons come into close contact.
page 379
310
Snyaptic Cleft
the tiny gap between the two neurons at a synapse.
page 379
311
Systole
when the heart chambers contract.
page 307
312
Taxonomy
the science of classifying organisms.
page 212
313
Tendons
strong, flexible, inelastic fibres that connect muscle to bone.
page 414
314
Theory
a hypothesis that has been supported by many different experiments.
page 4
315
Thigmotropism
a change in growth of a plant in response to touch.
page 365
316
Threshold
the minimum stimulus needed to cause an impulse to be carried in a neuron. page 377
317
Tissue Culture
the growth of cells in or on a sterile nutrient medium outside an organism. page 97
318
Tissue
a group of similar cells that are modified (or adapted) to carry out the same function (s).
page 95
319
Transcription
the copying of a sequence of genetic bases from DNA onto messenger RNA (mRNA).
page 178
320
Transformation
the uptake of DNA into a cell.
page 226
321
Translation
the conversion of a sequence of genetic bases on messenger RNA into a sequence of amino acids.
page 179
322
Transpiration
the loss (by evaporation) of water vapour from the leaves and other aerial parts of a plant.
page 279
323
Triplet (or codon)
a sequence of three bases in
DNA (or RNA) that act as a code for an amino acid.
page 172
324
Trophic Level
a feeding stage in a food chain.
page 36
325
Tropism
a change in the growth of a plant in response to an external stimulus.
page 364
326
Turgor (or turgor pressure)
the outward pressure of the cytoplasm and vacuole against the cell wall of a plant.
page 149
327
Ultrastructure
the detail of a structure as seen using an electron microscope.
page 85
328
Vaccination
the administration (usually by injection) of a non-disease-causing dose of a pathogen (or its toxin) to stimulate the production of antibodies.
page 425
329
Vaccine
a non disease-causing dose of a pathogen (or its toxin), which triggers the production of antibodies.
page 424
330
Valves
valves control the direction of blood flow.
page 302
331
Variable
a factor that may change in an experiment.
page 4
332
Variation (within a species)
in a group of successfully interbreeding organisms the individual members show different characteristics.
page 213
333
Vegetative propagation /Vegetative reproduction
asexual reproduction in plants.
page 460
334
Venation
the pattern of veins in a leaf.
page 268
335
Woody Plants
contain wood (or lignin). page 267
336
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