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IB Bio > 5.3 > Flashcards

5.3 Flashcards

1
Q

what is the binomial system of nomenclature

A

the formal system by which all living species are classified (taxonomy)
- originally grouped all organisms into two kingdoms – vegetable (plants) and animal

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2
Q

who invented the binomial system of nomenclature

A

developed by a Swedish botanist named Carolus Linnaeus in 1735

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3
Q

what is the value of the binomial naming system

A
  • It allows for the identification and comparison of organisms based on recognised characteristics
  • It allows all organisms to be named according to a globally recognised scheme
  • It can show how closely related organisms are, allowing for the prediction of evolutionary links
  • It makes it easier to collect, sort and group information about organisms
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4
Q

how to write binomial names

A

Genus is written first and is capitalised (e.g. Homo)

Species follows and is written in lower case (e.g. Homo sapiens)

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5
Q

binomial writing conventions

A
  • When typing the scientific name, it should be presented in italics
  • When hand writing the scientific name, it is customary to underline
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6
Q

three domains

A

Eukarya, Archaea, Eubacteria

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7
Q

Eukarya

A

eukaryotic organisms that contain a membrane-bound nucleus (includes protist, plants, fungi and animals)

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8
Q

Archaea

A

prokaryotic cells lacking a nucleus and consist of the extremophiles (e.g. methanogens, thermophiles, etc.)

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9
Q

Eubacteria

A

prokaryotic cells lacking a nucleus and consist of the common pathogenic forms (e.g. E. coli, S. aureus, etc.)

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10
Q

taxonomy

A

Taxonomy is the science involved with classifying groups of organisms on the basis of shared characteristics

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11
Q

hierarchy of taxa

A

Organisms are grouped according to a series of hierarchical taxa – the more taxa organisms share, the more similar they are
The taxa used are kingdom, phylum, class, order, family, genus and species (genus + species = scientific name)

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12
Q

taxa mnemonic

A 
(domain)
King -- kingdom
Philip -- phylum
Came -- class
Over -- order
For -- family
Grape -- genus
Soda -- species
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13
Q

Eukarya

A

All plant and animal species belong to the same domain (Eukarya) as they are composed of eukaryotic cells

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14
Q

Eukarya kingdoms

A

Beyond this point plants and animals differ in their classification as they belong to different kingdoms (Plantae vs Animalia)

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15
Q

classification schemes

A

artificial classification, natural classification and phylogenic classification

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16
Q

Artificial classification

A

involves arbitrarily selecting unifying characteristics first and then grouping organisms accordingly

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17
Q

Artificial classification advantage

A

The advantage of artificial classification is that such schemes are easy to develop and relatively stable (unlikely to change)

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18
Q

Artificial classification disadvantage

A

The disadvantage is that they do not generally show evolutionary relationships and for this reason are not commonly used

  • For example, if organisms were classified according to the presence of fins then whales would be grouped with fish
  • If organisms were classified based on the presence of shells then snails would be grouped with turtles and not with squid
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19
Q

Natural classification

A

involves grouping organisms based on similarities first and then identifying shared characteristics

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20
Q

Natural classification advantage

A
  • According to a natural classification system, all members of a particular group would have shared a common ancestor
  • This means that natural classification schemes can be used to predict characteristics shared by species within a group
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21
Q

Natural classification disadvantage

A

A disadvantage of such schemes is that they are highly mutable and tend to change as new information is discovered
- Taxonomists will reclassify groups of species when new evidence arises to compromise the traditional classification scheme

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22
Q

phylogenetic classification

A

is now being used to differentiate organisms based on genetics

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23
Q

phylogenetic classification explanation

A

Organisms who share a greater level of homology in their DNA or amino acid sequences are expected to be more closely related

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24
Q

taxonomic levels according to natural selection

A

According to natural classification, each taxonomic level includes all species that would have evolved from a common ancestor

  • Species of the same genus would have a common genus ancestor and be more closely related than species of the same order
  • Hence, organisms that share a lower taxa must share all higher taxa (e.g. if the same order then must also be the same class)
25
Q

why different species may be separated

A

Groups of species may be separated into different genera if new evidence suggests they evolved from different ancestral species

26
Q

example of species being separated

A

Species originally classified as figworts have been reclassified into different genera based on DNA sequence comparisons

27
Q

why different species may be grouped

A

Alternatively, different species may be grouped into a shared taxon if new evidence suggests more recent common ancestry

28
Q

example of species being grouped

A

The Homininae sub-family was created to include gorillas and chimpanzees when it was deduced that they share more common ancestry with humans than with other great apes (e.g. orang-utan)

29
Q

phyla in the kingdom Plantae (4 main)

A

The kingdom Plantae contains 12 phyla – which includes bryophytes, filicinophytes, coniferophytes and angiospermophytes

30
Q

Bryophytes

A
  • Has no vascularisation (i.e. lacks xylem and phloem)
  • Has no ‘true’ leaves, roots or stems (are anchored by a root-like structure called a rhizoid)
  • Reproduce by releasing spores from sporangia (reproductive stalks)
31
Q

Filicinophytes

A
  • Has vascularisation (i.e xylem and phloem)
  • Have leaves, roots and stems (leaves are pinnate – consisting of large fronds divided into leaflets)
  • Reproduce by releasing spores from clusters called sori on the underside of the leaves
32
Q

Coniferophytes

A
  • Has vascularisation
  • Have leaves, roots and stems (stems are woody and leaves are waxy and needle-like)
  • Reproduce by non-motile gametes (seeds) which are found in cones
33
Q

Angiospermophytes

A
  • Has vascularisation
  • Have leaves, roots and stems (individual species may be highly variable in structure)
  • Reproduce by seeds produced in ovules within flowers (seeds may develop in fruits)
34
Q

Bryophytes example

A

Examples include mosses and liverworts

35
Q

Filicinophytes example

A

Examples include ferns

36
Q

Coniferophytes example

A

Examples include pine trees and conifers

37
Q

Angiospermophytes example

A

Examples include all flowering plants and grasses

38
Q

kingdom Animalia two main groups

A

invertebrates (no backbone) and vertebrates (most chordata)

39
Q

Animalia phyla

A

porifera, cnidaria, platyhelmintha, annelida, mollusca, arthropoda and chordata

40
Q

Porifera

A
  • No body symmetry (asymmetrical)
  • No mouth or anus (have pores to facilitate the circulation of material)
  • May have silica or calcium carbonate based spicules for structural support
    Examples include sea sponges
41
Q

Cnidaria

A
  • Have radial symmetry
  • Have a mouth but no anus (single entrance body cavity)
  • May have tentacles with stinging cells for capturing and disabling prey
    Examples include jellyfish, sea anemones and coral
42
Q

Platyhelmintha

A
  • Have bilateral symmetry
  • Have a mouth but no anus (single entrance body cavity)
  • Have a flattened body shape to increase SA:Vol ratio and may be parasitic
    Examples include tapeworms and planaria
43
Q

Annelida

A
  • Have bilateral symmetry
  • Have a separate mouth and anus
  • Body composed of ringed segments with specialisation of segments
    Examples include earthworms and leeches
44
Q

Mollusca

A
  • Have bilaterial symmetry
  • Have a separate mouth and anus
  • Body composed of a visceral mass, a muscular foot and a mantle (may produce shell)
    Examples include snails, slugs, octopi, squid and bivalves (e.g. clams)
45
Q

Arthropoda

A
  • Have bilateral symmetry
  • Have a separate mouth and anus
  • Have jointed body sections / appendages and have a hard exoskeleton (chitin)
    Examples include insects, crustaceans, spiders, scorpions and centipedes
46
Q

Chordata

A
  • Have bilateral symmetry
  • Have a separate mouth and anus
  • Have a notochord and a hollow, dorsal nerve tube for at least some period of their life cycle
    Examples include mammals, birds, reptiles, amphibians and fish (also invertebrate sea squirts)
47
Q

Vertebrate Classes

A

birds, mammals, amphibians, reptiles and fish

48
Q

Chordates

A

animals that possess certain key features in an embryonic state that may persist into adulthood
- These features include a notochord, hollow dorsal neural tube, pharyngeal slits and a post-anal tail

49
Q

Fish

A
  • Covered in scales made out of bony plates in the skin
  • Reproduce via external fertilisation (egg and sperm released into the environment)
  • Breathe through gills that are covered with an operculum
  • Does not maintain a constant internal body temperature (ectothermic)
50
Q

Amphibian

A
  • Moist skin, permeable to gases and water
  • Reproduce via external fertilisation (usually spend larval state in water, adult state on land)
  • Can breathe through skin but also possess simple lungs
  • Do not maintain a constant internal body temperature (ectothermic)
51
Q

Reptiles

A
  • Covered in scales made out of keratin
  • Reproduce via internal fertilisation and females lay eggs with soft shells
  • Breathe through lungs that have extensive folding (increases SA:Vol ratio)
  • Do not maintain a constant internal body temperature (ectothermic)
52
Q

Birds

A
  • Covered in feathers (made out of keratin)
  • Reproduce via internal fertilisation and females lay eggs with hard shells
  • Breathe through lungs with parabronchial tubes
  • Maintain a constant internal body temperature (endothermic)
53
Q

Mammals

A
  • Skin has follicles which produce hair made out of keratin
  • Reproduce via internal fertilisation and females feed young with milk from mammary glands
  • Breathe through lungs with alveoli
  • Maintain a constant internal body temperature (endothermic)
54
Q

dichotomous key

A

A dichotomous key is a method of identification whereby groups of organisms are divided into two categories repeatedly

55
Q

how dichotomous keys are represented

A
  • As a branching flowchart (diagrammatic representation)

- As a series of paired statements laid out in a numbered sequence (descriptive representation)

56
Q

archea and eukaryotes

A

The archaeal cells were found to possess certain features that were more in common with eukaryotic cells than eubacteria

  • This included certain structural features (e.g. cell wall composition) and the presence of histone-like proteins in DNA
  • Based on these discoveries it was concluded that eukaryotes and archaea share more recent common ancestry than eubacteria
57
Q

Animal Classification

A 
Red Fox (Vulpes vulpes)
D: Eukarya
K: Animalia
P: Chordata
C: Mammalia
O: Carnivora
F: Canidae
G: Vulpes
S: Vulpes vulpes
58
Q

Plant Classification

A 
Common Sunflower (Helianthus annuus)
D: Eukaryote
K: Plantae
P: Magnoliophyta
C: Magnoliopsida
O: Asterales
F: Asteraceae
G: Helianthus
S: Helianthus annuus

IB Bio (18 decks)

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