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A-level Biology > 4.10 - Classification and evolution > Flashcards

4.10 - Classification and evolution Flashcards

1
Q

Why do scientists classify organisms?

A
  • to identify species
  • to predict characteristics
  • to find evolutionary links
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2
Q

What are the eight taxonomic groups

A
  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
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3
Q

Simple definition of species

A

A group of organisms that can reproduce to produce fertile offspring

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4
Q

What are the drawbacks to the simple definition of species

A

‘A group of organisms that can reproduce to produce fertile offspring’
- hybrids cannot be classified into any groups
- some species reproduce asexually
- hybrids can sometimes be fertile

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5
Q

Carl Linnaeus

A

18th century biologist that was first to devise a hierarchal classification system (often known as Linnaean classification)
- ‘Father of modern taxonomy’

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6
Q

What are the three domains

A

(Eu)bacteria:
- True bacteria
e.g. E. Coli, Staphylococcus
- Not bound to particular environments
- Some are pathogens
- Prokaryotic (single-celled, no nucleus)
- Biochemically distinct from Archaea
- Peptidoglycan cell wall
- 70S ribosomes
- RNA polymerase contains 5 proteins

Archaea
- Primitive bacteria
e.g. thermophiles
- Found in extreme environments (hot springs, salt lakes, hydrothermal vents)
- Prokaryotic (single-celled, no nucleus)
- Oldest organisms on Earth
- Cell walls lack peptidoglycan
- 70S ribosomes
- RNA polymerase contains 5-10 proteins

Eukarya:
- Range of organisms
e.g. fungi, plants, animals, protists
- Eukaryotic (contain a membrane-bound nucleus)
- Cells contain DNA instead of RNA
- May be multicellular or unicellular
- Most flexible organisms in terms of habitats
- 80S ribosomes
- RNA polymerase contains 12 proteins

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7
Q

What are the 5 kingdoms

A
  • plantae
  • fungi
  • animalia
  • protocista
  • prokaryota
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8
Q

Plantae kingdom

A
  • multicellular
  • membrane bound organelles e.g. nucleus
  • chloroplasts and chlorophyll
  • cellulose cell wall
  • most do not move
  • nutrients acquired by photosynthesis (autotrophic)
  • store food as starch
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9
Q

Fungi kingdom

A
  • yeasts, mushrooms, mould etc
  • unicellular or multicellular
  • membrane bound organelles e.g. nucleus
  • chitin cell wall
  • no chloroplasts or chlorophyll
  • no mechanisms for locomotion
  • most have a body or mycelium made of threads or hyphae
  • nutrients acquired mainly through absorption of decaying material (saprophytic or parasitic)
  • most store their food as glycogen
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10
Q

Animalia kingdom

A
  • e.g. fish, birds, mammals, insects
  • multicellular
  • membrane bound organelles e.g. nucleus
  • no cell walls or chloroplasts/chlorophyll
  • move with aid of cilia, flagella or contractile proteins (muscular organs)
  • nutrients acquired by ingestion (heterotrophic)
  • food stored as glycogen
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11
Q

Protoctista kingdom

A
  • e.g. amoeba, paramecium
  • mainly unicellular
  • membrane bound organelles e.g. nucleus
  • some have chloroplasts
  • some are immobile but others move with flagella or amoeboid mechanisms
  • either autotrophic, heterotrophic or parasitic
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12
Q

Prokaryota kingdom

A
  • e.g. bacteria
  • unicellular
  • no membrane bound organelles, rings of DNA
  • no visible feeding mechanism, nutrients are absorbed through cell wall or produced internally by photosynthesis
  • archaebacteria and eubacteria (sometimes 6 kingdoms)
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13
Q

binomial nomenclature system

A
  • developed by Carl Linnaeus
  • first word is organism’s genus
  • second word in organism’s species (italics or underlined)
  • ensures scientists all over the world are discussing the same organism, as common names differ
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14
Q

Phylogeny

A

The evolutionary relationships between organisms. The study of the evolutionary history between groups in phylogenetics

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15
Q

How are phylogenetic trees produced

A

Looking at similarities and differences in species’ physical characteristics and genetic makeup to find the evolutionary relationships between organisms. Often evidence is gained from fossils

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16
Q

Advantages of phylogenetic classification (over Linnaean system)

A
  • phylogeny can be done without reference to Linnaean classification, but classification uses knowledge of phylogeny to confirm classification groups are correct
  • Phylogeny produces a continuous tree whereas classification requires discrete taxonomic groups. Scientists are not forces to put organisms into a specific group where they do not quite fit
  • hierarchal nature of Linnaean classification can be misleading as it implies two groups within same rank are equivalent when one may have a longer history and more diversity
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17
Q

James Hutton and Charles Lyell (uniformitarianism)

A

The idea that in the past, the Earth was shaped by forces that you can still see today such as sedimentation, wind erosion and deposition of ash and lava from volcanoes. Challenged the claims of earlier geologists that the Earth was shaped by biblical events. Influenced Charles Darwin to think of evolution as a long, slow continuous process.

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18
Q

Charles Darwin and the theory of evolution

A
  • in 1831, the common belief was creationism
  • Darwin boarded 5 year trip on HMS Beagle as Geologist and Naturalist
  • began to notice differences in species living in different habitats
  • on Galapagos Islands, Darwin observed that finches on different islands had different shaped beaks depending on the food source available on the island
  • developed the theory of evolution
  • stated that those who were fittest would survive and their characteristics would be inherited by their offspring
19
Q

How paleontology provides evidence for evolution

A
  • study of fossils
  • fossils of simplest organisms found in oldest rocks
  • plant fossils appear before animal fossils, as animals require plants to survive
  • allows relationships between extinct and living animals to be investigated
  • studying similarities in anatomy of fossilised organisms, scientists can show how closely related orgaisms have evolved from the same ancestor
20
Q

How comparative anatomy has provided evidence for evolution

A
  • the study of similarities and differences in the anatomy of different living species
  • a homologous structure is a structure that appears superficially different (and may perform different functions) in different organisms but have the same underlying structure. For example, the pentadactyl limb of vertebrates:
  • vertebrate limbs can be used for running, jumping, swimming and flying
  • the basic bone structure of all vertebrate limbs are very similar
  • an explanation is that all vertebrates have evolved from a common ancestor
  • provides evidence for divergent evolution
21
Q

Convergent evolution

A

describes how, from a common ancestor, different species have evolved, each with a different set of adaptive features. This occurs when closely related species diversify to adapt to new habitats as a result of migration or loss of habitat

22
Q

How comparative biochemistry has provided evidence for evolution

A

The study of similarities and differences in the proteins and other molecules that control life processes.
- some molecules are highly conserved across species
- slight changes that occur in these molecules can help identify evolutionary links e.g. cytochrome c and rRNA
- neutral evolution = most of the variability in the structure of a molecule does not affect its function
- to discover how closely two species are related, the molecular sequence of a particular molecule is compared
- scientists compare differences to rate of substitution (e.g. in rRNA) to estimate when organisms last shared a common ancestor

23
Q

Intraspecific variation

A

differences between organisms within a species

24
Q

Interspecific variation

A

differences between members of different species

25
Q

What two factors cause variation

A
  • an organism’s genetic material = genetic variation from differences in the genetic material an organism inherits from its parents
  • the environment in which the organism lives causes environmental variation
26
Q

Genetic causes of variation

A

Alleles:
- individuals in a species population may inherit different alleles of a gene
- different alleles produce different effects
Mutations:
- changes to the DNA sequence and therefore to genes can lead to changes in the proteins that are coded for
- can affect physical and metabolic characteristics
- only passed on to offspring if mutation is in gametes
Meiosis:
- each gamete produces half the genetic content of a parent cell
- before cytokinesis, the maternal and paternal genetic material is mixed through independent assortment and crossing over
- leads to gametes of an individual showing variation

(Sexual reproduction
Chance during sexual reproduction )

27
Q

Discontinuous/discrete variation

A
  • a characteristic that can only result in certain values
  • there can be no intermediate values
  • purely genetic variation
  • usually represented using bar chart or pie chart
  • e.g. biological sex, bacteria shape, human blood groups
28
Q

Continuous variation

A
  • a characteristic that can take any value within a range
  • there is a graduation from one extreme to the other
  • controlled by a number of genes and often influenced by environmental factors
  • collected into a frequency table and plotted as a histogram to show the trend
29
Q

normal distribution curves

A
  • when continuous variation data are plotted on a graph, the usually result in the production of a bell-shaped curve known as anormal distribution curve
  • mean, median and mode are the same
  • graph is symmetrical about the mean
    (50% of values are less than the mean and 50% are greater)
  • most values lie close to the mean value, the number of individuals at the extremes are low
  • when you calculate the standard deviation you will generally find that 68% of values are within 1 standard deviation of the mean (95% =2, 99.7%=3)
30
Q

Student’s t-test

A
  • used to compare the means of data values of two populations
  • to use this the data collected must be normally distributed and enough data must be collected to calculate a reliable mean
  • different sample sizes may be used
31
Q

Spearman’s rank correlation coefficient

A
  • used to consider the relationship between two set of data
  • find if the data has no correlation, positive correlation or negative correlation
32
Q

Adaptations

A

characteristics that increase an organism’s chance of survival and reproduction in its environment
- anatomical adaptations
- behavioural adaptations
- physiological adaptations

33
Q

Anatomical adaptations

A
  • body covering (e.g. to stay warm or provide protection)
  • camouflage, making it harder for predators or prey to spot it
  • teeth, the shape and type relate to its diet
  • mimicry, copying another animal’s appearance or sounds fools predators into thinking it is dangerous
34
Q

Adaptations of marram grass

A

Adapted to reduce rate of transpiration:
- curled leaves
- hairs on inside surface of leaves
- sunken stomata
- thick waxy cuticle

35
Q

Behavioural adaptations

A
  • survival behaviours such as freezing or playing dead
  • courtship behaviours to attract a mate
  • seasonal behaviours such as migration (moving to a region where environmental conditions are more favourable) and hibernation (temperature, breathing and heart rate slow to conserve energy when there is little food)
36
Q

Behavioural adaptations fall into two categories

A
  • innate/ instinctive (ability to do it is inherited through genes such as spiders building webs)
  • learned behaviour (learnt from experience or observing other animals such as the use of tools)
37
Q

Physiological adaptations

A
  • poison production (reptiles producing venom to kill prey or plants producing poisonous leaves to protect from herbivory)
  • antibiotic production (some bacteria to kill other competition)
  • water holding (frog, cacti holding water so they can survive without regular access to water)
38
Q

Anatomical adaptations providing evidence for convergent evolution

A

Convergent evolution = when unrelated species share similar traits, because both organisms are adapting to similar environments or other selection pressures
Analogous structures = different structures that have adapted to form the same function, but have a different genetic origin

39
Q

Examples of convergent evolution

A

Marsupial and placental mice:
- both ere small, agile climbers that live in dense ground cover and forage at night
- very similar in size and body shape
- marsupial mice are in Australia and have a marsupium pouch
Flying phalangers and flying squirrels:
- both are gliders that eat insects and plants
Marsupial and placental moles:
- both burrow to find worms and grubs and have streamlined shape and modified forelimbs for digging
- differ in fur colour
Aloe and agave:
- both adapted to survive in desert and have a similar appearance
- aloe evolved in Sub-Saharan Africa
- agave evolved in Mexico

40
Q

process of natural selection

A
  1. organisms within a species show variation in their characteristics that are caused by genetic variation. For example they may have different alleles of a gene for a articular characteristic (sometimes created by genetic mutation)
  2. ‘survival or the fittest’
    organisms whose characteristics are best adapted to a selection pressure such as predation, competition or disease have an increased chance of surviving and successfully reproducing. Less well adapted organisms die or fail to reproduce
  3. successful organisms pass the allele encoding the advantageous characteristic to their offspring.
  4. this process is repeated every generation. Over time, the proportion of individuals with the advantageous adaptation increases. Therefore the frequency of the allele that codes for this particular characteristic increases in the population’s gene pool
  5. Over very long periods of time, many generations and often involving multiple genes, this process can lead to the evolution of a new species
41
Q

Antibiotic resistant bacteria

A
  • MRSA (methicillin resistant S. aureus) is resistant to many antibiotics
  • bacteria reproduce very rapidly, so can evolve over a short period of time
  • when bacteria replicate, their DNA can be altered
  • this lead to a mutation in some S. aureus that provided resistance to methicillin
  • when the bacteria was exposed to methicillin, only the bacteria with the mutation survived, passing on the resistant allele to their offspring
  • over time the number of resistant individuals in the population increased
42
Q

modern evolution of peppered moths

A
  • most peppered moths before the industrial revolution were pale coloured (due to a different allele)
  • this provided camouflage against light-coloured tree bark, increasing chances of survival
  • the industrial revolution in the 19th century caused dramatic changes in the moth’s environment, as trees got darker from soot and the loss of lichen
  • the dark moths were now better adapted to be camouflaged
  • more dark coloured moths survived and reproduced, increasing the proportion of dark moths and the dark coloured allele in the population, especially near industrial towns and cities
  • deindustrialisation and the clean air act means that not there is a higher proportion of light coloured moths
43
Q

modern evolution of sheep blowflies

A
  • lay their eggs in fecal matter around a sheep’s tail
  • larvae hatch and cause sores known as ‘flystrike’ which is usually fatal
  • 1950s Australia, pesticide diazinon was used to kill blowflies
  • within six years, blowflies developed a high level of resistance to diazinon
  • pre-adaptation (when an organism’s existing trait is advantageous to a new situation) contributed to the development of diazinon resistance, as the flies had pre-existing resistance to a similar pesticide
44
Q

Modern evolution of flavobacterium

A
  • scientists found a new strain of flavobacterium living in waste water from factories that produce nylon 6
  • strain of bacteria had evolved to digest nylon 6, therefore being beneficial to humans as they help to clear up factory waste
  • bacteria uses enzymes called nylonases, providing them with another source of nutrients
  • nylonases are unlike any other enzymes found in flavobacterium, so scientists believe that a gene mutation occurred to produce these enzymes (gene duplication combined with frame shift mutation)

A-level Biology (24 decks)

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