Science - Biology - Inheritance, Variation and Evolution - B6 Flashcards
1
Q
what does DNA stand for ?
A
deoxyribonucleic acid
2
Q
what is DNA ?
A
the chemical that all of the genetic material in a cell is made up from
3
Q
what does DNA do ?
A
have all of the information to put an organism together and make it work
4
Q
what does DNA determine ?
A
what inherited characteristics you have
5
Q
where is DNA found ?
A
in the nucleus
6
Q
what really long structures are DNA found in ?
A
chromosomes
7
Q
what does DNA form in a chromosome ?
A
the arms of a chromosome
8
Q
what number do chromosomes come in ?
A
pairs
9
Q
DNA is a polymer - what does this mean ?
A
it is made up of a large molecule built from a chain of smaller molecules
10
Q
what shape do the 2 strands of DNA form ?
A
double helix
11
Q
what is a gene ?
A
a small section of DNA found on a chromosome
12
Q
what does a gene do ?
A
tell cells what order to put the amino acids together
13
Q
what do amino acids form ?
A
proteins
14
Q
how many types amino acids are used in DNA ?
A
20
15
Q
does DNA determine what proteins the cell produces, and therefore determines what cell is produced ?
A
yes
16
Q
what is a genome ?
A
the entire set of genetic material in an organism
17
Q
what does understanding the human genome tell scientists ?
A
- it helps them identify genes in the genome which are linked to different types of disease
- knowing which genes are linked to inherited diseases helps us understand them better and could help us develop treatment
- genomes can trace the migration of certain populations around the world - scientists can work out when and where populations went
18
Q
how did the human genome change ?
A
it is mostly identical in all humans
but as different populations migrated away from Africa they developed tiny differences in their genomes
19
Q
what are nucleotides ?
A
strands of polymers made up of lots of repeating units which help form DNA
20
Q
what does a nucleotide consist of ?
A
- a sugar
- a phosphate group
- one of 4 different bases
21
Q
how many types of nucleotides are there ?
A
4
22
Q
what are the 4 different bases ?
A
A
T
C
G
23
Q
what do the 4 different bases join to ?
A
a sugar
24
Q
what forms the backbone to the DNA strands ?
A
the sugars and phosphate groups in the nucleotides
25
what does the order of bases determine ?
the order of amino acids in a protein
26
how many bases is each amino acid coded by ?
3
27
what do amino acids join together to make up ?
proteins
28
what does the base A always pair up with ?
T
29
what does the base C always pair up with ?
G
30
what do the non - coding parts of DNA do ?
switch genes on and off
control whether or not a gene is used
31
where are proteins made ?
in the ribosomes in the cytoplasm
32
what do ribosomes do to make up proteins ?
- use the code in DNA
33
how does the cell get the code needed to make up proteins from DNA in the nucleus to the ribosomes ?
mRNA
34
why can't DNA move out of the cell nucleus ?
it is too big
35
what is mRNA ?
a molecule which acts as a messenger between the DNA and the ribosome by carrying the code between the 2 and by acting as a template
36
what do carrier molecules do in mRNA ?
bring the correct amino acids to the ribosomes in the correct order
37
what do amino acids do when they have been assembled ?
folds into a unique shape which allows the protein to perform the task it is meant to do
38
what are proteins used for ?
- enzymes
- hormones
- structural proteins
39
what is a mutation ?
a random change in an organisms DNA
they can sometimes be inherited
40
how do mutations occur ?
- continuously
- randomly
- when a chromosome isn't replicated properly
41
how can the chances of a mutation be increased ?
- when exposed to some types of radiation
- when exposed to certain substances
42
what do mutations do ?
change the sequence of the DNA bases in the gene which produces a genetic variant
as the sequence of DNA bases codes for the sequences of amino acids which make up proteins, mutations can lead to cell changes
43
what is a genetic variant ?
a different form of the gene
44
do mutations have an effect on the protein ?
most of the time no
45
what could happen if a mutation changes a proteins shape ?
- if an enzyme's active site is changed its substrate may not be able to bind to it
- structural proteins like collagen could lose their strength if their shape has changed
46
what are the 3 ways DNA can change the DNA base sequence ?
- insertions
- deletions
- substitutions
47
what are insertions ?
where a base is inserted into the DNA base sequence where it shouldn't be
48
what can insertions cause ?
amino acids to change, as they have a knock-on effect so the bases further on in the sequence can be altered
49
what are deletions ?
where a random base is deleted from the DNA base sequence
50
what are substitutions ?
where a random base in the DNA sequence is changed to a different base
51
what is sexual reproduction ?
where genetic information from 2 organisms is combined to produced offspring which are genetically different to either parent
52
what are gametes ?
things produced by the mother and father in sex
53
what is the female gamete ?
egg
54
what is the male gamete ?
sperm
55
how many chromosome does each gamete contain in humans ?
23
56
what happens during fertilisation ?
the egg and sperm cell fuse together to form a cell with the full number of chromosomes
57
what is the fusion of gametes known as ?
fertilisation
58
why does the offspring inherit features from both parents ?
it recieves a mixture of chromosomes from its mum and dad which causes variation
59
what does sexual reproduction involve the fusion of ?
female and male gametes
60
what is the sperm version of a gamete in a flowering plant ?
pollen
61
how does asexual production happen ?
mitosis
62
what is asexual reproduction ?
there is only 1 parent, no fusion of gametes and no genetic variation between the parent and offspring
63
the offspring and the parent are identical in asexual reproduction - what are they ?
clones
64
how do you make gametes ?
meiosis
65
how many cell divisions does meiosis involve ?
2
66
where does meiosis happen in humans ?
reproductive organs
67
describe the steps of meiosis ?
1. before cell divides it duplicates its genetic information, forming 2 armed chromosomes which are identical, after replication chromosomes arrange themselves into pairs
2. in the first division pairs line up in the centre of the cell
3. the pairs are then pulled apart so each cell has 1 copy of each chromosome - some of the fathers - some of the mothers
4. in the 2nd division chromosomes line up again in the centre of the cell - arms of the chromosomes are pulled apart
5. you get 4 sets of gametes with only 1 set of chromosomes in it
68
why are the gametes produced genetically different from the others ?
the chromosomes get shuffled up during meiosis and each gamete only gets 1 of them - at random
69
what happens to the cells when the embryo starts to develop ?
they differentiate into different types of specialised cell that make up a whole organism
70
what are the advantages of sexual reproduction ?
- offspring will have a mixture of 2 sets of chromosomes - the organism inherits genes from both parents giving variation
71
what are the advantages of variation ?
it increases the chance of species surviving a change in environment as some of the varied organisms may be able to survive in the new environment whilst others are killed off
72
what is natural selection ?
individuals with characteristics which make them better adapted to the environment are more likely to breed successfully and pass the genes for the characteristics on
73
what is used to speed up natural selection ?
selective breeding
74
what is selective breeding ?
where individuals with a desirable characteristic are bred to produce more offspring that also have the desired characteristic
75
why can we use selective breeding to increase food production ?
- breeding animals that have lots of meat
- breeding cows which have a high milk yield
76
what are the advantages of asexual reproduction ?
- needs 1 parent so it uses less energy because organisms don't have to find a mate
- identical offspring can be produced in favourable conditions
77
give an example of how asexual production can be used successfully ?
- dandelion plants can grow quicker and spread faster if grown in a good environment and because all offspring have the same genes as the parent they're all likely to survive in these conditions
78
give examples of when organisms can reproduces both asexually and sexually ?
- malaria = reproduces sexually when in mosquito and asexually when it is in human host
- fungus = spores
- plants = runners, bulbs
79
how many pairs of chromosomes are in every human body cell ?
23
80
how are the 23rd pair of chromosomes labelled ?
xx
xy
81
what do the 23rd pair of chromosomes determine ?
your sex
82
what sex has xy characteristics ?
male
83
what sex has xx characteristics ?
females
84
what chromosome causes male characteristics ?
y
85
what is the % chance of a sperm cell getting a y chromosome ?
50 %
86
what is the % chance of the eggs getting an x chromosome ?
100 %
87
what depends on whether the individual is male or female ?
the sex chromosomes it recieves - its sex inheritance
88
what can genetic diagrams be used to show ?
sex inheritance
89
what are genetic diagrams ?
models that are used to show all the possible genetic outcomes when you cross together different genes or chromosomes
90
what is probability ?
the measure of how likely something is to happen
91
what are alleles ?
an alternative version of a gene
92
how many alleles to gametes have ?
1
93
how many alleles do all the other cells in an organism - apart from gametes have ?
2
94
why do all cells except for gametes get 2 alleles?
we inherit half our alleles from our mother and half from our father
95
what represents alleles in genetic diagrams ?
letters
96
what does homozygous mean ?
if an organism has 2 alleles that are the same for a particular gene
97
what does heterozygous mean ?
if an organism has 2 alleles that are different for a particular gene
98
what is a dominant allele ?
the allele for the characteristic that is shown
99
what is the recessive allele ?
the allele for the characteristic which isn't shown
100
how can an organism display a recessive characteristic ?
both its alleles must be recessive
101
how can an organism display a dominant characteristic ?
whenever a dominant allele is present as it overrules the recessive one if the organism is heterozygous
102
what is a genotype ?
the combination of alleles you have
103
give an example of a genotype ?
you could have the genotype Bb for hair colour
104
what is a phenotype ?
the characteristics you have
105
how can you study characteristics that are determined by a single gene ?
using monohybrid crosses
106
what are monohybrid crosses ?
where you cross 2 parents to look at just one charactersistic
107
why do we need genetic diagrams ?
to predict and explain the outcomes of single gene crosses between individuals and lots of different combinations of alleles
108
how are the outcomes of genetic diagrams shown ?
ratios to work out the probability of having offspring with a certain characteristic
109
what are inherited disorders ?
disorders that are caused by a faulty allele which can be passed onto an individuals offspring
110
give examples of 2 inherited disorders ?
- cystic fibrosis
- polydacyly
111
what is cystic fibrosis ?
an inherited disorder of the cell membranes which results the body in producing a lot of sticky mucus in the air passages and in the pancreas
112
what are the problems of cystic fibrosis ?
it makes breathing difficult
113
what kind of allele causes cystic fibrosis ?
recessive allele
114
why people who have the recessive allele for cystic fibrosis but don't actually have cystic fibrosis known as carriers ?
because it is recessive people with 1 copy of the allele won't have the disorder - they carry the faulty allele but do not have any symptoms
115
how can a child get cystic fibrosis ?
both parents must either be carriers or have the disorder themselves
116
what are the chances of a child having a disorder if both of the parents are carriers ?
1/4
117
what is polydactyly ?
an inherited disorder where a baby is born with extra fingers or toes
118
is polydactyly dangerous ?
no
119
how polydactyly caused ?
a dominant allele so can be inherited if 1 parent carries the defective allele
120
will the parent of the offspring that has polydactyly have the disorder ?
yes
121
what are the chances of a child getting polydactyly if 1 parent has the polydactyly allele ?
50 %
122
what is a family tree ?
a diagram that shows how a characteristic is inherited in a group of related people
123
what is embryonic screening ?
a way of detecting inherited disorders
124
what are the 2 ways of embryonic screening ?
- pre-implantation genetic diagnosis
-chorionic villus sampling
125
what is pre implantation genetic diagnosis - step by step ?
- during IVF embryos are fertilised in a laboratory then implanted into a mothers womb
- before being implanted you can remove a cell from each embryo and analyse its genes - embryos with healthy alleles would be implanted into the mother, the faulty ones destroyed
126
what is chronic villus sampling - step by step ?
- carried out between 10-13 weeks of pregnancy
- involves taking sample cells from part of the placenta and analysing their genes
- the part of the placenta that's taken and the embryo develops from the same cell with the same genes
- if the embryo is found to have an inherited disorder the parents can decide whether to end the pregnancy
127
what are the arguments for embryo screening ?
- helps people stop suffering from inherited disorders
- treating the disorders is costly
- during IVF embryos are destroyed anyway PGD just ensures the chosen ones are healthy
- if an inherited disorder is diagnosed through CVS parents have a choice whether to terminate or not
128
what are the arguments against embryo screening ?
- there may be a time everyone wants to screen their embryos so they can pick the most desirable one
- it implies people with genetic problems are undesirable
- after PGD rejected embryos are destroyed - unethical
- risk that CVS could cause miscarriage
- after CVS and a disorder is highlighted an abortion may happen
- expensive
129
who was Gregor Mendel ?
an Austrian monk who trained in mathematics and natural history
130
what did Mendel do ?
at his garden plot he noticed how characteristics of plants were passed on from 1 generation to the next - his research became the foundation of modern genetics
131
what experiments did Mendel carry out ?
he crossed 2 pea plants of different heights - a tall and dwarf pea plant - the offspring produced were all tall pea plants
132
what did Mendels results show ?
the height characteristics in his pea plants were determined by separately inherited 'hereditary units' passed on from each parent
133
what are the suggested alleles of the pea plants after Mendel's experiment ?
tall plants were dominant over the herditary unit for dwarf plants
134
what were Mendel's conclusions from his experiment ?
- characteristics in plants are determined by 'hereditary units'
- hereditary units are passed on to offspring unchanged from both parents - 1 unit from each parent
- hereditary units can be dominant or recessive
135
what is the timeline of studies about DNA after Mendel's death ?
1866 - Mendel published his research
1884 - Mendel died
Late 19th C - Scientists became familiar with chromosomes and observed how they behaved during cell division
Early 20th C - scientists discovered a similarity between the way chromosomes and Mendels units acted showing these units were found in chromosomes - units are now known as genes
Mid 20th C - structure of DNA was determined so scientists discovered exactly how genes worked
136
what is variation within a species ?
where organisms of the same species look slightly different
137
what are the 2 types of variation ?
- genetic variation
- environmental variation
138
what is an organisms characteristics determined by ?
the genes inherited from their parents
139
what causes genetic variation ?
the combining of genes from 2 parents so no species are genetically identical
140
give examples of characteristics determined by genes ?
- violet flower colour
- eye colour
- blood group
- inherited disorders
141
what is environmental variation ?
the environment in which an organism lives and grows in causes differences between members of the same species
142
what causes environmental variation ?
a difference caused by the conditions something lives in
143
give an example of environmental variation ?
suntans
a plant grown in a sunny area would grow green and luscious
144
give examples of characteristics which are caused by both genetic and environmental variation
height
intelligence
health
145
give examples of when a gene mutation has no effect ?
- it may produce a genetic variant that codes for the same sequence of amino acids so the same protein is produced
- mutation may cause a change of 1 amino acid in a protein but doesn't have an effect on the proteins function
146
give an example of when a gene mutation slightly changes someones characteristics ?
a mutation in a gene may cause the eye colour to change slightly
147
give an example of when a gene mutation causes a dramatic change on a species ?
cystic fibrosis
148
how can a mutation make something better suited to survive its environment ?
the new phenotype might make an individual more suited to the environment which can cause an overall change in the species via natural selection
149
what is the theory of evolution ?
all of today's species have evolved from simple life forms that first started to develop over 3 billion years ago
150
what did Charles Darwin do ?
make up a very important theory about evolution by making observations and experiments
151
How does Darwins theory work ?
1- all of the individuals within a species show a wide range of variation for a particular characteristic
2- because of this range in variation some of these individuals will be better suited to the environment than others
3- these individuals are more suited to the environment so will be more likely to survive and breed more successfully
4- this useful characteristic is passed onto the offspring
152
why was Darwin's theory not fully accepted ?
the relevant scientific knowledge wasn't available at the time so he couldn't give a good explanation as to why his theory worked
153
how do we now know Darwins theory works ?
we know the phenotype is controlled by genes
new genetic variants happen to phenotypes that are suited to the environment
beneficial genetic variants are passed on to the future generations in the DNA that parents contribute to their offspring
154
why do individuals within a species show wide variation in their characteristics ?
there is a mix of genetic variants present in the population
155
why do some genetic variants give rise to characteristics that are better suited to the environment ?
they have a better chance of survival so are more likely to breed successfully
156
what is evolution ?
the changing of inherited characteristics of a population over time
157
who's theory for evolution is now the accepted hypothesis ?
Darwins
158
where is there evidence for Darwins theory ?
looking at fossils of different ages allows you can see organisms changes developing over time
bacteria becoming resistant to antibiotics
159
what is speciation ?
the phenotypes of organisms change so much because of natural selection, a new species is formed
160
what is extinction ?
when no living individuals of a species remains
161
give an example of a species which became extinct ?
dinosaurs
dodos
162
why do species become extinct ?
- environment changes too quickly
- a new predator kills them
- a new disease kills them
-they can't compete with another species for food
- a catastrophic event happens which kills them all
163
what book did Darwin publish ?
on the origin of species
164
why was Darwins book and theories not accepted when he first published them ?
- it went against religious beliefs because some people believe God creates earth
- Darwin couldn't explain why these new characteristics appeared as he didn't know anything about genes or mutations
- lack of evidence
165
what was Lamarcks theory about evolution ?
he said changes in the organism happens during its lifetime will be passed onto its offspring - he thought if a characteristic was used a lot by an organism it would become more developed during its lifetime #dumb #loser
166
why may scientists develop different hypothesis's about evolution ?
- religious beliefs
- influenced by different people
- they think differently
167
why was Lamarcks theory rejected ?
his experiments didn't support his hypothesis
168
what is selective breeding ?
when humans artificially select the plants or animals that are going to breed so that the genes for particular characteristics remain in the population
169
what are organisms selectively bred ?
- animals produce more milk/meat
- crops with disease resistance
- dogs with good, gentle behaviours
- decorative plants
170
what is the step by step process of selective breeding ?
1- from the existing stock select the organisms with the desired characteristics
2- breed them with each other
3- select the best offspring, breed them together
4- continue this process over many generations and the desirable trait gets stronger until all the offspring has that characteristic
171
give an example on how farmers use selective breeding to improve meat yields ?
they breed the cows and bulls with the best characteristics for producing meat
172
what is inbreeding ?
when farmers breed the best animals and plants which are closely related
173
what is the issues with selective breeding ?
it reduces the gene pool
174
what is the issue with inbreeding ?
it reduces the gene pool
175
what is a gene pool ?
the number of different alleles (forms of gene) in a population
176
what can inbreeding cause ?
- health problems because there's more of a chance of the organisms inheriting harmful genetic defects
177
how can inbreeding be a problem when a new disease shows up
there isn't as much variation in the species so if all the stock are closely related and one of them is killed by a disease all of them probably will be too
178
give a diagram of the problems associated with reducing the gene pool ?
selective breeding -
reduction of number of alleles-
less chance of any resistant alleles being present in the population
179
what is genetic engineering ?
transferring a gene responsible for a desirable characteristic from 1 organism's genome into another organism so it has the desired characteristic
180
explain how genetic engineering works - step by step ?
1 - useful gene is cut from one organisms genome using enzymes and is inserted into a vector
2- the vector is usually a virus or bacterial plasmid
3- when the vector is introduced to target the organism, the useful gene is inserted into its cells
181
show how the human insulin gene is inserted into bacteria to produce human insulin ?
1 - insulin gene is cut out of human DNA using enzymes
2- same enzymes are then used to cut the bacterial DNA and different enzymes are used to insert the human insulin gene
3- the bacteria are then allowed to multiply and the insulin they produce while they grow is purified and used by people with diabetes
182
what is genetic engineering used for ?
- bacteria is genetically modified to produce human insulin and treat diabetes
- genetically modified crops have their genes modified to improve the size and quality of plants
- sheep have been genetically modified to produce substances in their milk which can help treat diseases
- treats inherited disorders
183
what are the issues with genetic engineering ?
- long term effects are unknown
- unplanned problems may occur which can get passed down to future generations
184
what are the benefits of genetically modified crops ?
- they can increase yield - making more food
- they can contain missing nutrients which people in developed countries lack
185
what are the issues with genetically modified crops ?
- affects number of wild flowers - reducing biodiversity
- may not be safe/ effects are unknown
- transplanted genes may get out into the natural environment, spread
186
what is cloning ?
making an exact copy of an organism
187
how do organisms naturally clone themselves ?
asexual reproduction
188
what are the 2 ways of cloning ?
tissue culture
cuttings
189
what is tissue culture ?
plant cells are put in a growth medium with hormones
they grow into new plants - clones from the parent
190
what are the benefits of tissue culture ?
- quick
- uses little space
- grown all year
191
why is tissue culture used ?
to preserve rare plants which are hard to reproduce naturally
192
what are cuttings ?
gardeners take cutting from good plants
they plant them to produce genetically identical copies
193
what are the advantages of taking cuttings ?
- reproduce quickly
- cheap
194
how do you clone animals ?
embryo transplants
195
how do farmers clone cows using embryo transplants ?
1- sperm cells are taken from a prize bull and eggs are taken from a prize cow, the sperm are used to artificially fertilise an egg cell
2- embryos developed splits many times before any cells become specialised
3- cloned embryos are implanted into other cows
4- theys cows grow into calves identical to each other
196
what is adult cell cloning used for ?
making animal clones
197
what does adult cell cloning involve - step by step ?
1- an unfertilised egg cell is removed from its nucleus
2- the nucleus is removed from the adult body cell and inserted into the empty egg cell
3- egg cell is stimulated by an electric shock making it divide
4- when the embryo is a ball of cells it is implanted into the uterus of the mother
5- embryo grows into a clone of the original adult cell
198
give an example of when adult cell cloning was used
dolly the sheep
199
what are the benefits of cloning ?
- gives you ideal offspring
- leads to a greater understanding of the development of the embryo
- helps preserves endangered species
200
what are the issues with cloning ?
- reduced gene pool
- they may not be as healthy as normal organisms in the population
- people worry humans may be cloned, which could lead to unsuccessful attempts and many humans with disabilities are born
201
what are fossils ?
the remains of organisms from many years ago
202
where are fossils found ?
in rocks
203
what do fossils show ?
evidence that organisms lived many years ago - how much or little organisms have changed - development of species
204
how do fossils form ?
gradual replacement by minerals
from casts and impressions
preservations in places where no decay happens
205
how are fossils shown from gradual replacements from minerals ?
things like teeth and bones which don't decay as easily are replaced by minerals forming a rock like substance shaped like the original hard part
206
how are fossils formed from cast and impressions ?
when an organism is buried in a soft material like clay the material can harden around it and the organisms decays leaving a cast of itself
207
what can be preserved as casts ?
an animals burrow
rootlet traces
footprints
208
how are fossils made by preservation in places where no decay happens ?
- microbes in decay need the right conditions to breakdown a material
- if the conditions aren't right decay can't happen and organisms are preserved
209
what are the conditions microbes need to decay ?
oxygen
moisture
the right temperature and pH
210
why can't the hypothesis's of the origins of life on earth be supported or disproved ?
there's lack of valid evidence
211
why is there a lack of evidence of the origins of life on earth ?
- scientists believed many early organisms were soft bodied and soft bodies decay quickly leaving few traces
- fossils from many years ago may have been destroyed due to geological activity
212
what does an incomplete fossil record mean ?
we do not have the fossils of every organisms or every type of organism that has ever existed
213
what is isolation ?
where populations of species is separated
214
why does isolation happen ?
- physical barrier = floods/earthquakes
215
how does variation happen to populations of species which have been isolated ?
1- each population shows genetic variation as they have a wide range of alleles
2- in each population individuals with characteristics that make them better adapted to their environment have a better chance of survival so breed more successfully
3- alleles that control the beneficial characteristics are more likely to be passed onto the next generation
4- eventually individuals from populations will have differentiated so much they cannot breed together so they are a separate species
216
what did Russel Wallace do ?
worked on the ideas of speciation
217
what did Wallace investigate ?
ideas about natural selection with Darwin, prompted Darwin to publish 'on the origin of species'
218
when travelling the world to investigate speciation, what did Wallace find ?
warning colours are used by some species to deter predators from eating them which was an example of a beneficial characteristic evolved by natural selection
219
what is antibiotic resistant bacteria ?
a mutation which leads to bacteria being unaffected by antibiotics
220
why is antibiotic bacteria really bad ?
bacteria spreads very quickly
221
how can a resistant bacteria survive ?
it can survive even in a host who is being treated to get rid of the infection so it will live longer and reproduce
222
why is antibiotic resistant bacteria bad for infected people ?
they aren't immune to the new strain and there is no effective treatment so it can easily spread between people
223
give examples of anti biotic resistant bacterium
MRSA
Multi drug resistant TB
224
why is it important for you to take the anti-biotics doctors prescribe you ?
it decreases the chances of antibiotic resistant bacteria emerging - it makes sure the full bacteria is destroyed and there is none left to mutate
225
why are antibiotics given to animas ?
so they grow faster
prevents them becoming ill
226
why can giving antibiotics to animals be a concern ?
it can lead to antibiotic resistant bacteria in the animals which can spread to humans during meat preparation and consumption
227
what has increasing concern about overuse of antibiotics lead to ?
some countries restricting their use
228
why is the problems of antibiotic resistance getting worse ?
overuse and inappropriate use of antibiotics
229
give examples of when antibiotics are over-used ?
- doctors prescribing antibiotics for non-serious conditions
- doctors prescribing antibiotics for infections caused by viruses
230
what actually causes antibiotic resistance ?
the antibiotics cause a situation where naturally resistant bacteria have an advantage and so an increase in numbers
231
what has the increase in antibiotic resistance caused ?
drug companies to work on developing new antibiotics that are effective against the strains
232
what is the annoying things about creating new antibiotics to overcome strains ?
- rate of development is slow
- costly
- can't keep up with spread of demand for new drugs and antibiotic strains
233
what does classification mean ?
sorting things into groups
234
what is the Linnaean system ?
where living things are divided into kingdoms which are then subdivided into smaller and smaller groups
235
when did Carl Linnaeus create the Linnaean system ?
1700s
236
what is the order of classification ?
- kingdom
- phylum
- class
- order
- family
- genus
- species
237
what did Carl Woese propose as a classification species in 1990 ?
the 3 domain system
238
how did Woese come up with the 3 domain system ?
he used evidence from the new chemical analysis techniques such as RNA
239
what are the 3 domains ?
- archaea
- bacteria
- eukaryota
240
what is the archaea domain ?
organisms which were once thought to be primitive bacteria but are now a type of prokaryotic cell - found in hot springs and salt lakes = extreme conditions
241
where are species in the Archaea domain found ?
extreme conditions - salt lakes, hot springs
242
what is the bacteria domain ?
contains bacteria
243
what is the eukaryota domain ?
included organisms such as fungi, plants, animals, protists
244
what are the 3 domain groups divided into ?
kingdom
phylum
class
order
family
genus
species
245
what is the binomal system ?
means scientists in different countries and speak different languages can all refer to the same species using the same name
246
what language does the binomal system use ?
latin
247
what are humans known as in the binomal system ?
homo sapiens
248
what do evolutionary trees show ?
how scientists this different organisms are related to each other
249
what do evolutionary trees do ?
show common ancestors and relationships between species - the more recent the ancestor, the more closely they are related and the more characteristics they share
250
how do scientists work out evolutionary relationships in living things ?
using DNA analysis
structural similarities
classification data
251
how do scientists work out evolutionary relationships in extinct things ?
information from fossil records
