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OCR A-Level Biology > Chap 10 - Classification & Evolution > Flashcards

Chap 10 - Classification & Evolution Flashcards

1
Q

Define classification

A

process of sorting living organisms into groups

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2
Q

Define taxonomy

A

study of naming and classifying groups of biological organisms based on shared characteristics

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3
Q

Define taxonomic group

A

hierarchical group of classification

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4
Q

Define phylogeny

A

evolutionary relationships between organisms

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5
Q

List the taxonomic groups from broadest to smallest

A

domain
kingdom
phylum
class
order
family
genus
species

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6
Q

State 3 reasons why scientists classify organisms

A
  • to identify species
  • to predict characteristics - if several members have a specific characteristic, likely that another species in the group has the same one
  • to find evolutionary links - same group probably share characteristics bc they share a common ancestor
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7
Q

Define species

A

group of organisms with similar features that are able to breed together to produce fertile offspring

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8
Q

Explain why horses and donkeys are separate species and why mules are not given a scientific name and are not a separate species.

A
  • horses and donkeys can interbreed but the offspring (mule) is not fertile - they are separate species by definition.
  • mules are not a separate species because they are infertile (odd number of chromosomes so meiosis cannot happen)
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9
Q

Define binomial nomenclature

A

system of naming species by giving each a name composed of two parts:
- first word - genus
- second word - species (specific name)

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10
Q

State the conventions when writing scientific names

A
  • first word is capitalised
  • if typed - italics
  • if handwritten - underline
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11
Q

Explain the value of the binomial nomenclature system of the scientific community

A
  • allows for identification and comparison of organisms based on characteristics
  • allows all organisms to be named according to a globally recognised scheme
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12
Q

Name the 5 kingdoms and give examples of the organisms they contain

A
  • prokaryotae (E. coli)
  • protoctista (Plasmodium)
  • fungi (Yeast)
  • plantae (Wheat)
  • animalia (Lion)
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13
Q

Describe the characteristics of prokaryotae

A
  • unicellular
  • no nucleus or any membrane-bound oragnelles
  • small ribosomes
  • no visible feeding mechanism - nutrients absorbed through cell wall or produced by photosynthesis
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14
Q

Describe the characteristics of protoctista

A
  • mainly unicellular
  • cucleus and membrane-bound organelles
  • some have chloroplasts
  • some sessile, some move by cillia, flagella or ameboid mechanisms
  • autotrophs, heterotrophs or both, some parasitic
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15
Q

Describe the characteristics of fungi

A
  • uni or multicellular
  • nucleus and membrane-bound organelles
  • chitin cell wall
  • no chloroplasts or chlorophyll
  • no mechanism for locomotion
  • body or mycelium made of threads or hyphae
  • saprophytic feeders (absorb externally digested nutrients), some parasitic
  • food storage as glycogen
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16
Q

Describe the characteristics of plantae

A
  • multicellular
  • nucleus and membrane-bound oragnelles
  • cellulose cell wall
  • all contain chlorophyll
  • generally dont move
  • autotrophic (photosynthetic)
  • food storage as starch
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17
Q

Describe the characteristics of animalia

A
  • multicellular
  • nucleus and membrane-bound organelles
  • no cell wall
  • no chloroplasts
  • move using cillia/flagella/contractile proteins (muscle)
  • nutrients ingested - heterotrophic
  • food storage as glycogen
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18
Q

State the 3 domains of life and 6 kingdoms that this system uses.

A

3 domains:
- bacteria
- archaea
- eukarya

6 kingdoms:
- eubacteria
- archaebacteria
- protoctista
- fungi
- plantae
- animalia

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19
Q

Describe the characteristics of eukarya (domain)

A
  • 80s ribosomes
  • RNA polymerase contains 12 proteins
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20
Q

Describe the characteristics of archaea (domain)

A
  • 70s ribosomes
  • RNA polymerase contains 8-10 proteins
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21
Q

Describe the characteristics of bacteria (domain)

A
  • 70s ribosomes
  • RNA polymerase contains 5 proteins
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22
Q

Describe the evidence used to create the three domain system

A
  • eubacteria are chemically different to archaebacteria (they have peptidoglycan cell wall)
  • archaebacteria live in extreme conditions (hot, anaerobic, highly acidic)
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23
Q

Define phylogenetic tree

A

diagram used to represent the evolutionary links between organisms (and how closely related they are)

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24
Q

Define sister group

A

two descendents that split from the same node

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25
Q

Define node

A

point on an phylogenetic tree

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26
Q

Describe the advantages of using phylogenetic trees as a form of classification as opposed to just using taxonomic groupings.

A
  • species can have similar characteristics (dolphins and fish) but phylogeny confirms they come from different ancestors
  • phylogeny produces continuous tree, classification requires discrete taxonomical groups (not forced to put organisms in groups they dont quite fit)
  • classification implies different groups within the same rank are equivalent (cats and orchids both families but orchids 70mil years older)
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27
Q

State 3 sources of evidence for evolution

A
  • palaeontology - study of fossils
  • comparative anatomy - study of similarities and differences between organisms anatomy
  • comparative biochemistry - similarities and differences between the chemical makeup of organisms
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28
Q

Explain how the age of fossils can be determined

A
  • over period of time, sediment deposit forms different layers (strata) of rock which correspond to different geological eras
  • within different strata - fossils different so sequence from oldest to youngest can be established
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29
Q

Explain how the fossil record provides evidence for evolution.

A
  • fossils of simplest organisms in oldest rocks, complex organisms in more recent rocks - supports theory that simple organisms gradually evolved into complex ones
  • sequence in which organisms found matches their evolutionary links to each other (plants appear before animals - animals require plants to survive)
  • analysis of anatomy of fossils studied to show how closely related organisms have evolved from same ancestor
  • allows relationships between extinct and living organisms to be investigated
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30
Q

Explain how comparative anatomy provides evidence for evolution

A
  • study of similarities and differences in anatomy of different living species
  • example: vertebrate limbs structures very similar - same bones adapted to carry out range of different functions
  • led to theory that all vertebrates evolved from common ancestor
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31
Q

Define homologous structures

A

structure that appears superficially different but has same underlying structure

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32
Q

Define divergent evoluton

A

process where groups from same common ancestor evolve and accumulate differences - forms new species

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33
Q

Define comparative biochemistry

A

study of similarities and differences in the proteins and other molecules that control life processes

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34
Q

Explain how comparative biochemistry provides evidence for evolution

A
  • cytochrome c and rRNA studied
  • they remain almost unchanged amont species throughout time
  • slight changes that occur can help identify evolutionary links
  • species with most similar structures - more closely related than those w different structures
  • to check how closely related - compare molecular sequences of a particular molecule (order of DNA bases or amino acid sequence) - can estimate the point at which the species last shared common ancestor
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35
Q

Summarise how Darwin and Wallace formulated the theory of evolution by natural selection.

A
  • darwin carried out observations on finches in Galapagos islands - different islands had different finches which were similar, tf closely related but beaks and claws different
  • darwin realised that beak structure was linked to food available on island
  • conclusion - bird born with more suitable beak will survive longer, have more offspring and pass on the characteristic until all have it
  • wallace independently worked on his theory of evolution, ideas so similar they did joint presentation
  • darwin published On the Origin of Species, detailing the theory of evolution by natural selection - very controversial and influential
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36
Q

Define variation

A

differences in characteristics between organisms

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37
Q

Define interspecific variation

A

variation between members of different species

38
Q

Define intraspecific variation

A

differences between organisms within a species

39
Q

Name and describe two causes of variation

A
  • an organism’s genetic material - differences in genetic material an organism inherits form parents - genetic variation
  • environment - causes environmental variation
40
Q

Describe 5 causes of genetic variation between individuals within a population.

A
  • alleles - genes have different alleles, individuals may inherit different alleles
  • mutations - changes to DNA sequence can lead to change in proteins coded, if occurred in gamete it can be passed on
  • meiosis - indepednent assortment and crossing over leads to gametes showing variation
  • sexual reproduction - offspring inherits alleles from each parent - each individual is different to parent
  • chance - many different gametes produced from parental genome, result of chance which two combine so offpsring differ from their siblings
41
Q

State 3 characteristics that are solely genetically-determined

A

blood group, hair color, eye color

42
Q

State 3 characteristics that are solely environmentally-determined

A

scars, hair length, muscle strength

43
Q

State 3 characteristics that are a combination of genetics and the environment.

A

height, skin color, intelligence

44
Q

Explain what continuous variation is

A

characteristics that can take any value within range
- eg. mass, intelligence, height, weight

45
Q

Explain what discontinuous variation is

A

characteristics that can only result in certain values
- eg. distinct features, blood group

46
Q

Describe the causes of variation that result in discontinuous variation.

A

purely genetic

47
Q

Define polygenic

A

characteristics that are controlled by number of genes
- usually show continuous variation

48
Q

Define multifactorial

A

characteristic caused by many factors, can be both genetic and environmental

49
Q

Describe the causes of variation that result in continuous variation

A

multiple genes (polygenic) & influenced by environmental factors

50
Q

State the types of graph used to represent continuous and discontinuous variation within population.

A

continuous: line graph
discontinuous: bar chart

51
Q

Define mean

A

average value in a data set

52
Q

Define mode

A

most common number in data set

53
Q

Define median

A

middle value in data set

54
Q

Give the 4 characteristics of a normal distribution

A
  • mean, mode median are the same
  • bell shape distribution, symmetrical about mean
  • 50% of values are less than mean, 50% greater than mean
  • most values lie close to mean value, number of individuals at extremes is low
55
Q

Define range

A

difference between largest value and smallest value

56
Q

Define standard deviation

A

the measure of how spread out the data is

57
Q

Describe the usefulness of standard deviation over range

A

range uses only the extreme values whereas SD uses all the values in the set

58
Q

What is the formula for standard deviation

A
59
Q

State the type of graph used to show whether there is a correlation between two variables.

A

scatter graph

60
Q

Define correlation

A

the statistical relationship between two variables

61
Q

Explain why there can be correlation between two variables without there being a direct causal link.

A

there could be a missing third variable that links the two

62
Q

Explain why statistical tests are important and what they are used for.

A

statistical tests used to determine significance of data collected

63
Q

Define null hypothesis

A

prediction that there is no significant difference between specified populations
- represents “status quo belief”, such as absence of a characteristic or lack of an effect
- eg: there will be no difference in the length of leaves growing in light vs in the shade

64
Q

Explain what a test statistic is

A

random sample from population
- used to decide whether or not to reject the null hypothesis

65
Q

Explain what a p-value is

A

probability of obtaining test results at least as extreme as the test statistic, under the assumption that the null hypothesis is correct

66
Q

Explain what interpretation can be drawn from the p-value

A
  • if less than significance level, reject null hypothesis
  • if greater than significance level, do not reject null hypothesis
67
Q

Describe when a Student’s t-test would be used.

A

used to compare the means of data values of two populations
- eg - determining whether there is statistical significance between length of ivy grown in light vs in shade

68
Q

Describe when a Spearman’s rank correlation test would be used.

A
  • used to consider the relationship between two sets of data
  • possible outcomes are: no correlation, +ve correlation and -ve correlation
69
Q

Describe when to use paired or unpaired t-test when analysing data

A
  • paired - determine if significant difference between means of two codependent samples
  • unpaired - determine if significant difference between means of two independent samples
70
Q

Describe when to use paired or unpaired t-test when analysing data

A
  • paired - determine if significant difference between means of two codependent samples
  • unpaired - determine if significant difference between means of two independent samples
71
Q

Define adaptations

A

characteristics that increase an organism’s chance of survival and reproduction in its environment

72
Q

State the 3 types of adaptations

A
  • anatomical
  • behavioral
  • physiological
73
Q

Define anatomical adaptation

A

physical features (internal/external)

74
Q

Define behavioural adaptation

A

the way an organism acts
- can be inherited or learned

75
Q

Define physiological adaptation

A

processes that take place inside an organism

76
Q

Give 4 examples of anatomical adaptations.

A
  • body covering - hair/scales/feathers/shells, can help fly/stay warm/provide protection
  • camouflage - harder for predators to spot
  • teeth - shape and type related to diet
  • mimicry - allows harmless organisms to scare predators away by appeearing poisonous/dangerous
77
Q

Give 4 examples of behavioural adaptations

A
  • survival behaviors - opossum plays dead/rabit freezes
  • courtship - scorpions “dance” to attract partner, increasing chance of reproducing
  • migration - moving from one region to another when environmental conditions are more favorable
  • hibernation - inactivity to reduce requirement for food during winter
78
Q

Give 3 examples of physiological adaptations

A
  • poison production - to kill prey or protect themselves
  • antibiotic production - some bacteria use antibodies to kill other species and outcompete them
  • water holding - species of frog can store water in its body, allowing for longterm survival without access tow ater
79
Q

Define analogous structures

A

adapted to perform the same function but have different genetic origin

80
Q

Define convergent evolution

A

unrelated species begin to share similar traits
- due to organisms adapting to similar environments

81
Q

Compare the features of the marsupial mole and the placental mole

A
  • resemble each other bc adapted to fill similar niches
  • both embryos start life in uterus
  • in placental - placenta connects embryo to mother’s circulatory system in uterus, nourishing embryo and reaching high maturity before birth
  • in marsupial - embryo leaves and enters marsupium where they complete development with milk
82
Q

Define evolution

A

gradual change that takes place over many generations where organisms slowly change their physical characteristics as a result of natural selection

83
Q

Define natural selection

A

process by which organisms best suited to their environemnt survive and reproduce, passing on their characteristics to their offpsring through their genes

84
Q

Define gene pool

A

sum of all the genes in a population at a given time

85
Q

Define allele frequency

A

relative frequency of a particular allele in a population at a given time

86
Q

Define selection pressure

A

factors that affect an organism’s chance of survival or reproductive success

87
Q

Define selectively neutral allele

A

does not alter fitness of individual to survive and reproduce

88
Q

Describe the steps in the process of adaptations evolving by natural selection

A
  • organisms within species show variation in their characteristics caused by differences in their genes. New alleles can arise by mutation
  • those with characteristics that are best adapted to a selection pressure have increased chance of survival and successfully reproducing - ‘survival of the fittest’
  • successful organisms pass on the allele encoding the advantageous characteristic into offspring.
  • process repeated for many generations, over time proportion of individuals with adv. adaptation increases -> frequency of adv. allele increases in gene pool
  • over very long period of time, can lead to evolution of a new species
89
Q

Explain how natural selection has resulted in the change in frequency of dark and pale moths in populations of the peppered moth near industrial towns and cities over time.

A
  • before industrial revolution, most were pale - camo against tree bark, dark ones were easily spotted and eaten
  • during industrial revolution, trees became darker bc covered in soot and loss of lichen cover - dark moths were better adapted bc more highly camouflaged
  • more and more of them survived and reproduced, increasing frequency of ‘dark’ allele
  • over time their number became much higher than pale due to natural selection where dark color was the advantageous characteristic
  • after clean air act, trees became paler and number of pale moths increased again
90
Q

Describe how human activity has resulted in evolution in populations of Staphylococcus aureus.

A
  • bacteria reproduce rapidly and evolve in short time
  • a mutation arose in S. aureus that allowed resistance to methicillin
  • when bacteria exposed to antibiotic, resistant individuals survived and reproduced, passing the allele for resistance onto offspring
  • non-resistant individuals died
  • over time number of resistant individuals increased - establishing MRSA as species
91
Q

Describe how human activity has resulted in evolution in populations of Flavobacterium.

A
  • live in waste water of factories that produce nylon 6
  • they have evolved to digest nylon - beneficial for cleaning up factory waste
  • no other strain of Flavobacterium has nylonases
  • it is thought that gene duplication + frameshift mutation led to tis adaptation, it was advantageous and therefore naturally selected bc it provides them with another source of nutrients
92
Q

Define how human activity has resulted in evolution in populations of the Sheep blowfly

A
  • they cause fatal condition for sheep - flystrike
  • in 1950s, used diazinon pesticide to kill them and prevent the condition
  • within 6 years, they developed resistance to diazinon - individual insects with resistance survived and passed on their advantageous characteristics through their alleles, allowing resistant population to evolve

OCR A-Level Biology (16 decks)

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