classification and evolution Flashcards
1
Q
What is classification?
A
The process by which living organisms are sorted into groups. The organisms within each group share similar features
2
Q
What are taxonomic groups?
A
Hierarchical groups of classification:
domain, kingdom, phylum, class,
order, family, genus, species
3
Q
Why do scientists classify organisms?
A
To identify species - by using a clearly defined system of classification, the species an organism belongs to can be easily identified • To predict characteristics - if several members in a group have a specific characteristic, it’s likely that so will another species in the group • To find evolutionary links - species in the same group probably share characteristic because they have evolved from a common ancestor
4
Q
What is a species?
A
The smallest and most specific taxonomic group. A species is defined as a group of organisms that are able to reproduce to produce fertile offspring.
5
Q
What is the classification of humans?
A
Domain: Eukarya Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Primates Family: Homindae Genus: Homo Species: Sapiens
6
Q
What is binomial nomenclature?
A
The scientific naming of a species with a Latin name made of two parts - the first indicating the genus, and the second the species. No two species have the same generic (genus) and specific (species) name The name should be written underlined with only the first letter of the genus capital e.g. Felus catus
7
Q
What are the five kingdoms?
A
- Prokaryotae (bacteria)
- Protoctista (unicellular eukaryotes)
- Fungi (yeasts,moulds, mushrooms)
- Plantae (plants)
- Animalia (animals)
8
Q
What are the features of Prokaryotae?
A
• Unicellular • No nucleus or other membranebound organelles - a ring of ‘naked’ DNA - small ribosomes • No visible feeding mechanisms - nutrients are absorbed through the cell wall, or produces internally by photosynthesis • e.g. bacteria E.coli, Staphylococcus aureus
9
Q
What are the features of protoctista?
A
• (mainly) unicellular • A nucleus and other membranebound organelles • Some have chloroplasts • e.g. Paramecium, Amoeba • Some are sessile, but others moveably cilia, flagella, or amoeboid mechanisms • Nutrient are acquired by photosynthesis (autotrophic feeders), ingestion of other organisms (heterotrophic feeders), or both - some are parasitic
10
Q
What are the features of fungi?
A
• Unicellular or multicellular • A nucleus, other membrane-bound organelles, and chitin cell wall • No chloroplasts or chlorophyll • No mechanisms for locomotion • Most have a body or mycelium made of threads or hyphae • Nutrients are acquired by absorption - mainly from decaying material - they are prophetic feeders, and some are parasitic • Most store their food as glycogen
11
Q
What are the features of plantae?
A
• Multicellular • A nucleus and other membranebound organelles including chloroplasts, and cellulose cell wall • All contain chlorophyll • Most don’t move, although gametes of some plants move using cilia or flagella • Nutrient acquired by photosynthesis (autotrophic feeders) • Store food as starch
12
Q
What are the features animalia?
A
• Multicellular • A nucleus and other membranebound organelles (no cell walls) • No chloroplasts • Move with the aid of cilia, flagella, or contractive proteins, sometimes in the form of muscular organs • Nutrients are acquired by ingestion - they are heterotrophic feeders • Food stored as glycogen
13
Q
Why have there been changes to classification systems?
A
• Originally, classification systems were based on observable features • Through the study of genetics and other biological molecules, scientist can now study the evolutionary relationships between between organisms, and theses links can be used to classify organisms
14
Q
What happens when organisms evolve?
A
Their internal and external features change, as does their DNA, because the DNA determines the proteins made, which in turn determines the organisms characteristics
15
Q
What distinguishes the three domains?
A
The organisms in the different
domains contain a unique form of
rRNA and different ribosomes
16
Q
Describe the characteristics of the 3 domains
A
Eukarya • 80s ribosomes • RNA polymerase contains 12 proteins Archaea • 70s ribosomes • RNA polymerase of different organisms contains between 8 and 10 proteins and is very similar to eukaryotic ribosome Bacteria • 70s ribosomes • RNA polymerase contains 5 proteins
17
Q
Describe the three domain, six
kingdom classification system
A
18
Q
What is the difference between archaebacteria and
eubacteria?
A
Both are single-celled prokaryotes, but they have different chemical makeups • Eubacteria contain peptidoglycan in their cell walls whereas Archaebacteria do not
19
Q
Describe archaebacteria
A
• aka ancient bacteria • Can live in extreme environments e.g. thermal vents, anaerobic conditions, and highly acidic environments • e.g. methanogens live in anaerobic environments such as sewage treatment plants and make methane
20
Q
Describe eubacteria
A
- aka true bacteria
- Most bacteria
- Found in all environments
21
Q
What is phylogeny?
A
The evolutionary relationships between organisms • Reveals which group a particular organism is related to, and how closely related these organisms are
22
Q
What is a phylogenetic tree?
A
• aka evolutionary tree • Diagram used to represent the evolutionary relationships between organisms • Show that different species have evolved from a common ancestor • Earliest species found at the base of the tree, and the most recent species found at the tips of the branches
23
Q
What are the advantages of phylogenetic classification?
A
• Can be done without reference to Linnaean classification • Produces a continuous tree, whereas classification requires discrete taxonomical groups. Scientists are not forced to put organisms into a specific group that they don’t fit • Hierarchal nature Linnaean classification can be misleading as it implies different group within the same rank are equivalent
24
Q
What is evolution?
A
The theory that describes the way in
which organisms evolve, or change,
over many many years as a result of
natural selection
25
Who was James Hutton?
```
• Scottish geologist who proposed
the concept of uniformitarianism
• The idea that in the past, the earth
was shaped by forces that still
exist today e.g. sedimentation in
rivers, wind erosion, and
deposition of ash and lava
• Prompted Darwin to think of
evolution as a slow process
```
26
Who was Charles Lyell?
```
• Scottish geologist who
popularised the principle of
uniformitarianism
• Wrote ‘Principles of Geology’
which Darwin read
• Suggested the fossils were
evidence of animals that had lived
millions of years ago
```
27
What was Darwin’s observation
of finches on the Galapagos
Islands?
```
• Noticed that different islands had
different finches that were similar
but had different beaks and claws
suited to the food available on the
island
• The best suited finches would
have more offspring, passing on
its characteristic
• Over time the finch population on
that island would all share this
characteristic
```
28
Who was Alfred Wallace?
```
• Was working on his own theory of
evolution in Borneo at the same
time as Darwin
• Sent his ideas to Darwin for peer
review in 1858
• In 1859, Darwin independently
published ‘On the Origin of
Species’, and named the theory
that he and Wallace had presented
as ‘the theory of evolution by
natural selection’
```
29
What is the evidence of evolution?
```
• Palaeontology - the study of
fossils and the fossil record
• Comparative anatomy - the study
of similarities and differences
between organisms’ anatomy
• Comparative biochemistry -
similarities and differences
between the chemical makeup of
organisms
```
30
What are fossils?
```
The remains or impression of a
prehistoric pant or animal preserved
in rock
• Over long periods of time,
sediment is deposited o the earth
to form layers (strata) of rock
• Different layers correspond to
different geological eras, the most
recent layer being found on top
```
31
What evidence does the fossil
| record provide?
```
Simple life forms evolve over a long
time period into more complex ones
• Fossils of simplest organisms e.g.
bacteria are found in oldest rock
• Fossils of more complex
organisms e.g. vertebrates are
found in more recent rocks
Animals require plants to survive
• Sequence in which the organisms
are found matches their ecological
links to each other
• Plant fossils appear before animal
fossils
• By studying similarities in the
anatomy of fossil organisms,
scientists can show how closely
related organisms have evolved
from the same ancestor
• Fossils allow relationships
between extinct and living (extant)
organisms to be investigated
```
32
Why is the fossil record not complete?
```
• Many organisms are soft-bodied
and decompose quickly before
they have a chance to fossilise
• The condition needed for fossils to
form are not often present
• Many other fossils have been
destroyed by the Earth’s
movements, e.g. volcanoes, or
haven’t been discovered yet
```
33
What are homologous structures (comparative
| anatomy)?
```
A structure which appears
superficially different (and may
perform different functions) , but has
the same underlying structure
• e.g. the pentadactyl limb of
vertebrates
• An explanation is that all
vertebrates have evolved from a
common ancestor, therefore
vertebrate limbs have all evolved
from the same structure
```
34
What does the presence of homologous structures provide evidence for?
```
Divergent evolution
• Species diverge over time into two
different species, resulting in a
new species becoming less like
the original one
• This type of evolution will occur
when closely related species
diversify to adapt to new habitats
as a result of migration or loss of
habitat
```
35
How does comparative biochemistry work?
```
Although the molecules that
control life processes change over
time, some important molecules
are highly conserved among
species
• Slight changes that occur in
theses molecules can help identify
evolutionary links
• Two of the most common
molecules are cytochrome c
(protein involved in respiration) and
ribosomal RNA
```
36
What is the hypothesis neutral evolution?
```
Most of the variability in the
structure of a molecules does not
affect its function
• This is because most of the
variability occurs outside of the
molecule’s functional regions
• Changes that don’t affect a
molecule’s function are called
‘neutral’, and their accumulation is
not affected by natural selection
```
37
Using comparative biochemistry, how do you see
| how closely two species are related?
```
Compare the molecular sequence of
a particular molecule by looking at
the order of DNA bases, or at the
order of amino acids in a proteins
• Number of difference that exist are
plotted against the rate the
molecule undergoes neutral base
substitutions
• From this, scientists can estimate
the point at which tow species last
shared a common ancestor
• Species that are closely related
have more similar DNA and
proteins
```
38
What is variation?
The differences in characteristics
| between organisms
39
What are the different types of variation?
```
Interspecific variation - the
differences between organisms
different species
Intraspecific variation - the
differences between organisms of
the same species
```
40
What are the two causes of variation?
```
• An organism’s genetic material -
differences in the genetic material
an organism inherits from its
parents leads to genetic variation
• The environment in which the
organism lives - this causes
environmental variation
```
41
What are the genetic causes of variation?
```
Genetic variation is due to the genes
( and alleles) an individual
possesses. The causes for this are:
• Alleles (variants)
• Mutations
• Meiosis
• Sexual reproduction
• Chance
e.g. blood group is determined
purely by genetic variation
```
42
How do alleles cause genetic variation?
```
• Genes have alleles
• Different alleles produce different
effects
• Depending on the parental
combination of these alleles,
different genes can be produced
• Individuals in a species population
may inherit different alleles of a
gene
```
43
How do mutations cause genetic variation?
```
• Changes to the DNA sequence
and therefore to genes can lead to
changes in the proteins that are
coded for
• These protein changes can affect
physical and metabolic
characteristics
• If a mutation occurs in the somatic
cells, only the individual is affected
• If a mutation occurs in the
gametes, it may be passed onto
the organism’s offspring
```
44
How does meiosis cause genetic variation?
```
• Gametes are produced by the
process of meiosis in organisms
that reproduce sexually
• Each gamete receives half the
genetic content of a parent cell
• The genetic material inherited by
the parents is ‘mixed up’ by
independent assortment and
crossing over
• Leads to the gametes of an
individual showing variation
```
45
How does sexual reproduction cause genetic variation?
```
The offspring produced from two
individuals inherits genes (alleles)
from each of the parents
• Each individual produced is
therefore different from the parents
```
46
How does chance cause genetic variation?
```
• Many different gametes are
produced from the parental
genome
• During sexual reproduction, it is a
result of chance as to which two
combine (random fertilisation)
• Individuals produced therefore
also differ from their siblings as
each contains a unique
combination of genetic material
```
47
Why is there greater variation in organisms that reproduce sexually than asexually?
```
• Meiosis, sexual reproduction and
chance are all aspects of sexual
reproduction
• Asexual reproduction results in the
production of clones; genetic
variation can only be increased in
these organisms as a result of
mutation
```
48
Why are plants affected by
environmental variation to a
greater degree than animals?
```
• Due to their lack of mobility
• As the plant cannot move to gain
sunlight, it is more affected by the
environment than an animal, which
could move to another area to look
for food or shelter
```
49
Give an example of a characteristic that is determined purely by environmental variation
```
The presence (or absence) of any
scars on your body. They will have
occurred as a result of an accident
or disease and have no genetic
origin. Scars cannot be inherited
from a parent
```
50
Give examples of variation with environmental and genetic causes
```
Height
• If you have tall parents, you most
like inherit the genes to grow to a
tall height
• If you eat a very poor diet or suffer
from disease, you may not reach
this height
Skin colour
• Your skin colour at birth is
determined purely by genetics
• When you expose your skin to
sunlight, you produce more
melanin to protect your skin from
harmful UV rays, resulting in your
skin turning darker
```
51
What is discontinuous variation?
```
A characteristic that can only result
in certain discrete values e.g. blood
type. Normally represented using a
bar chart or pie chart
• Determined purely by genetic
factors
• Mostly characteristics controlled
by a single gene
• E.g. shape of bacteria: spherical
(cocci), rods (bacilli), spiral
(spirilla), comma (vibrios), or
corkscrew shaped (spirochaetes)
```
52
What is continuous variation?
```
A characteristic that can take any
value within a range
• e.g. height
• Not controlled by a single gene but
by a number of genes (polygenes)
• Also often influenced by
environmental factors
• Data are collected in a frequency
table. These data are then plotted
onto a histogram. Normally a
curve is then draw onto the graph
```
53
What are the 3 groups of adaptations?
```
• Anatomical adaptations - physical
features (internal and external)
• Behavioural adaptations - the way
an organisms acts. These can be
inherited or learnt from their
parents
• Physiological adaptations -
processes that take place inside
an organism
```
54
What are some types of anatomical adaptations?
* Body covering
* Camouflage
* Teeth
* Mimicry
55
How is body covering an adaptation?
```
• Feathers on birds help them to fly
• Thick hair on polar bears help to
keep warm
• Snail’s shell provides protection
• Thick waxy cuticle on plants
prevent water loss; spikes deter
herbivores and protect the tissue
from sun damage
```
56
How is camouflage an adaptation?
```
• The outer colour of an animal
allows it to blend into its
environment, making it harder for
predators to spot it
• Snowshoe hare is white in winter
to match the snow, and turn brown
in summer to blend in with the soil
and rock environment in which it
lives
```
57
How are teeth adaptations?
```
• The shape and type of teeth
present in an animal’s jaw are
related to its diet
• Herbivores, e.g. sheep, have
continuously growing molars for
chewing tough grass and plants
• Carnivores, e.g. tigers, have sharp
large canines to kill prey and tear
meat
```
58
How is mimicry an adaptation?
```
• Copying another animal’s
appearance or sounds allows a
harmless organism to fool
predators into thinking it’s
poisonous or dangerous
• e.g. harmless hoverfly mimics the
markings of a wasp to deter
predators
```
59
What are the adaptations of marram grass?
```
It is a xerophyte, so has adaptations
that reduce the rate of transpiration
• Curled leaves to minimise the
surface area of moist tissue
exposed to the air, and protect the
leaves from the wind
• Hairs on the inside surface of
leaves to trap moist air close to
the leaf, reducing the diffusion
gradient
• Stomata sunk into pits, which
makes them less likely to open
and lose water
• A thick waxy cuticle on leaves and
stems, reducing water loss
through evaporation
```
60
What are some types of behavioural adaptations?
* Survival behaviours
* Courtship
* Season behaviours
61
What are survival behaviours?
e.g. an opossum plays dead and a
rabbit freezes when they think they
have been seen
62
What are courtship behaviours?
```
• Many animals exhibit elaborate
courtship behaviours to attract a
mate
• e.g. scorpions perform a dance to
attract a partner
• This increases the organism’s
chance of reproducing
```
63
What are seasonal behaviours?
```
Adaptations that enable organisms
to cope with changes in their
environment
• Migration - animals move from
one region to another, then back
again when environmental
conditions are more favourable.
This may be for a better climate or
a source of food
• Hibernation - period of inactivity in
which an animal’s body
temperature, heart rate and
breathing rate slow down to
conserve energy, reducing the
animal’s requirement for food. e.g.
brown bears hibernate during
winter
```
64
What are the two main categories of behavioural
| adaptations?
```
Innate (or instinctive) behaviour
• Ability to do this is inherited
through genes
• e.g. behaviour of spiders to build
webs and woodlice to avoid light
• Allows the organism to survive in
the habitat in which it lives
Learned behaviour
• Learnt form experience or from
observing other animals
• e.g. the use of tools, such as sea
otters which use stones to
hammer the shells off rocks, then
to crack the hard shells open
```
65
What are some examples of physiological adaptations?
```
Poison production
• Many reptiles produce venom to
kill their prey
• Many plants produce poisons in
their leaves to protect themselves
from being eaten
Antibiotic production
• Some bacteria produce antibiotics
to kill other species of bacteria in
the surrounding area
Water holding
• The water-holding frog can store
water in tis body, so can survive in
the desert for more than a year
without access to water
• Many cacti and other desert plants
can hold large amounts of water in
their tissues
Reflexes, blinking, temperature
regulation
```
66
What are analogous structures?
Structures that have adapted to perform the same function, but have a different origin
67
What is convergent evolution?
```
Organisms evolve similarities
because the organisms adapt to
similar environments or other
selection pressures
• Takes place when unrelated
species begin to share similar
traits
```
68
What do anatomical adaptations provide evidence
| for?
```
Convergent evolution
• e.g. Marsupials in Australia and
placental mammals in the North
America
• In placental mammals, placenta
connects the embryo to mother’s
circulatory system in the uterus.
This nourishes the embryo,
allowing it to reach a high level of
maturity before birth
• Marsupials start life in the uterus,
then leave and enter the
marsupium (pouch) while they are
still embryos, then complete
development here by suckling milk
• Produced varieties of species that
bear a strong resemblance in
shape, type of locomotion and
feeding techniques, because they
have adapted to similar climates
and feeding techniques
```
69
Give examples of species displaying convergent
| evolution
```
• Marsupial and placental mice
• Flying phalangers and flying
squirrels
• Marsupial moles and placental
moles
```
70
What is natural selection?
```
The process by which organisms
best suited to their environment
survive and reproduce, passing on
their characteristics to their offspring
through their genes
```
71
What are selection pressures?
```
Factors that affect an organism’s
chance of survival or reproductive
success
• Predation
• Competition (for mates and
resources)
• Disease
```
72
What are the steps involved in
| natural selection?
```
1. Organisms within a species
show genetic variation, e.g. they
may have different alleles of a
gene for a characteristic. New
alleles can arise by mutation
2. Organisms whose characteristics
are best adapted to a selection
pressure have an increased
chance of surviving and
successfully reproducing. This
process is known as ‘survival of
the fittest’
3. Successful organisms pass the
allele encoding the
advantageous characteristic
onto their offspring. Organisms
that have the non-advantageous
allele are less likely to
successfully pass it on
4. This process is repeated every
generation, and over time, the
proportion of individuals with the
advantageous adaption
increases, and so the frequency
of the allele that codes for this
characteristic increases in the
population’s gene pool
5. Over long periods of time, many
generations and involving
multiple genes, this process can
lead to the evolution of a new
species
```
73
What are modern examples of
| evolution?
* Antibiotic-resistant bacteria
* Peppered moths
* Sheep blowflies
* Flavobacterium
74
How have antibiotic-resistant
| bacteria evolved?
```
• Bacteria reproduce rapidly and so
evolve in a relatively short time
• When bacteria replicate, their DNA
can be altered, often resulting in
the bacteria dying
• When bacteria are exposed to
antibiotics, resistant individuals
survive and reproduce, passing on
allele for resistance to offspring
• Non-resistant individuals died
• Over time the number of resistant
individuals in the population
increased
• e.g. Methicillin-resistant
Staphylococcus aureus (MRSA)
has developed resistance to many
antibiotics
```
75
How have peppered moths
| evolved?
```
• Before industrial revolution, most
were pale, which provided
camouflage against the lightcoloured
tree bark
• During industrial revolution, trees
became darker due to being
covered in soot and loss of lichen
cover, so dark moths were
increased in population
• Since Clean Air Act of 1956, vast
majority of trees are lighter
coloured, so frequency of pale
moths has increased
```
76
How have sheep blowflies evolved?
```
• Sheep blowflies lay their eggs in
faecal matter around a sheep’s tail,
the larvae hatch and cause sores.
This condition is known as
‘flystrike’ is normally fatal if left
untreated
• In 1950s Australia, the pesticide
diazinon was used to kill blowflies
and prevent the condition
• Individual insects with resistance
survived exposure to the
insecticide and passed on this
characteristic through their alleles,
allowing a resistant population to
evolve
• Pre-adaptation contributed to the
development of diazinonresistance
```
77
What is pre-adaptation?
```
When an organism’s existing trait is
advantageous for a new situation
• e.g. the alteration in the DNA that
caused the pre-existing resistance
allowed the flies to rapidly develop
resistance to organophosphate
chemicals in general
```
78
How have Flavobacterium
| evolved?
```
• New strain of Flavobacterium
found living in waste water from
factories that produce nylon 6,
have evolved to digest nylon
• Use enzymes known as nylonases,
which are unlike enzymes found in
other strains of Flavobacterium,
and don’t help the bacteria to
digest any other known material
• Genetic mutation here = Gene
duplication combined with a
frameshift mutation
```
