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IB Biology > Classification > Flashcards

Classification Flashcards

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1
Q

Features of Bryophyta (4)

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)
  • Small and restricted to moist, terrestrial environment

Examples include mosses and liverworts

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2
Q

Features of Filicinophyta (ferns) (3)

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

Examples include ferns

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3
Q

Features of Coniferophyta (conifers) (3)

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

Examples include pine trees and conifers

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4
Q

Features of Angiospermophyta (flowering plants) (3)

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)

Examples include all flowering plants and grasses

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5
Q

Features of Monocots (3)

A
  • flower parts in multiples of 3
  • leaf veins are parallel
  • pollen with single furrow or pore
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6
Q

Feature of Dicots (3)

A
  • flower parts in multiples of 4/5
  • leaf veins are reticulated
  • pollen with 3 furrows or pores
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7
Q

Features of phylum Porifera (7)

A
  • are aquatic
  • reproduce asexually by budding
  • lack organs
  • lack body symmetry
  • no mouth or anus (have pores to facilitate the circulation of material)
  • no nervous system
  • may have silica or calcium carbonate-based spicules for structural support

Examples include sea sponges

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8
Q

Features of phylum Cnidaria (5)

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
  • all aquatic
  • diploblastic (polyp and medusa - may alternate between these life cycles)

Examples include jellyfish, sea anemones and coral

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9
Q

Features of phylum Platyhelminthes (4)

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
  • unsegmented

Examples include tapeworms and planaria

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10
Q

Features of phylum Annelida (5)

A
  • Have bilateral symmetry
  • Have a separate mouth and anus
  • Body composed of ringed segments with a specialisation of segments
  • body has chaetae (bristles)
  • move using hydrostatic skeleton or parapodia

Examples include earthworms and leeches

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11
Q

Features of phylum Arthropoda (7)

A
  • Have bilateral symmetry
  • Have a separate mouth and anus
  • Have jointed body sections/appendages and have a hard exoskeleton (chitin)
  • jointed body sections/appendages
  • hard exoskeleton of chitin
  • open circulation
  • compound eyes

Examples include insects, crustaceans, spiders, scorpions and centipedes

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12
Q

Features of phylum Mollusca (6)

A
  • Have bilateral symmetry
  • Have a separate mouth and anus
  • Body is composed of a visceral mass (organs), a muscular foot and a mantle (may produce shell)
  • soft bodied
  • most have radula (rasping tongue)
  • aquatic (with gills) and terrestrial

Examples include snails, slugs, octopi, squid and bivalves (e.g. clams)

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13
Q

Features of phylum Echinodermata (8)

A
  • tube feet for movement
  • water vascular system
  • rigid body wall
  • internal skeleton made of calcareous plates
  • many possess spines
  • ventral mouth and dorsal anus
  • external fertilisation
  • unsegmented
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14
Q

Features of phylum Chordata (5)

A
  • dorsal and tubular nerve cord
  • post-anal tail at some part of development
  • circulation closed in most
  • pharyngeal slits
  • heart on ventral side
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15
Q

Features of sub-phylum Vertebrata (4)

A
  • internal skeleton of cartillage/bone
  • vertebral column replaces notochord
  • two pairs of appendages attached to girdles
  • have developed nervous system
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16
Q

Features of lass Chondrichthyes (3)

A
  • skeleton of cartillage
  • no swim bladder
  • all aquatic
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17
Q

Features of Osteichthyes (3)

A
  • swim bladder present
  • all aquatic
  • bony endoskeleton
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18
Q

Features of class Amphibia (4)

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)
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19
Q

Features of class Reptilia (4)

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)
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20
Q

Features of class Aves (4)

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)
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21
Q

Feature of class Mammalia (4)

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)
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22
Q

What is the formal system by which all living species are classified?

A

The binomial system of nomenclature is the formal system by which all living species are classified (taxonomy)

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23
Q

WHo developed the binomial system?

A

It was initially developed by a Swedish botanist named Carolus Linnaeus in 1735

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24
Q

Is the binomial system updated?

A

It is periodically assessed and updated at a series of international congresses which occur every 4 years

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25
Q

What are the 4 benefits of the binomial 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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26
Q

How is an organism named due to the binomial system?

A

According to the binomial system of nomenclature, every organism is designated a scientific name with two parts:

Genus is written first and is capitalised (e.g. Homo)
Species follows and is written in lower case (e.g. Homo sapiens)
Some species may occasionally have a sub-species designation (e.g. Homo sapiens sapiens – modern man)

Writing conventions:

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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27
Q

What are the three domains?

A

eukarya
archaea
eubacteria

28
Q

What are eukarya?

A

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

29
Q

What are archaea?

A

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

30
Q

What are eubacteria?

A

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

31
Q

What is the key development in the 3 domains?

A

Originally, the two prokaryotic domains were considered only as a single kingdom (Monera), however biochemical differences were discovered between the two groups which warranted their reclassification into separate domains

32
Q

What is taxonomy?

A

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

33
Q

What are organisms grouped according to?

A

Organisms are grouped according to a series of hierarchical taxa – the more taxa organisms share, the more similar they are

34
Q

What is the hierarchy of taxa?

A

The taxa used are kingdom, phylum, class, order, family, genus and species (genus + species = scientific name)

35
Q

What domain do animal and plants belong to?

A

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

36
Q

What are the two main classification systems used to identify living organisms (historically)?

A

Historically, there have been two main classification schemes used to identify living organisms – artificial and natural classification

37
Q

What is the similarity between the two classification systems?

A

Both use prominent features as the basis for classification, however differ in the way these characteristics are established

38
Q

What is artificial classification?

A

Artificial classification involves arbitrarily selecting unifying characteristics first and then grouping organisms accordingly

39
Q

What is the advantage of artificial classification?

A

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

40
Q

What is a disadvantage of artificial classification?

A

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

41
Q

Give examples of disadvantages of artificial classifications?

A

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

42
Q

What is natural classification?

A

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

43
Q

How would something be classified according to natural classification?

A

According to a natural classification system, all members of a particular group would have shared a common ancestor

44
Q

What are natural classification systems used to predict?

A

his means that natural classification schemes can be used to predict characteristics shared by species within a group

45
Q

What is a disadvantage of natural classification?

A

A disadvantage of such schemes is that they are highly mutable and tend to change as new information is discovered

46
Q

What is a third type of classification?

A

A third type of classification – phylogenetic classification – is now being used to differentiate organisms based on genetics

47
Q

What do organisms have to have in common to be phylogenetically similar?

A

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

48
Q

What is an advantage of natural classification?

A

An advantage of natural classification is that it identifies traits based on groupings, rather than assigning groups based on traits

49
Q

Therefore what type of relationships does natural selection show?

A

This means that it can be used to show evolutionary relationships and predict characteristics shared by species within a group

50
Q

What does each taxonomic level include?

A

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

51
Q

What species have a common genus ancestor?

A

Species of the same genus would have a common genus ancestor and be more closely related than species of the same order

52
Q

Therefore what must organisms with a lower taxa share?

A

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)

53
Q

What is a disadvantage of natural classifications?

A

A disadvantage of natural classifications is that because they predict evolutionary relationships, they change with new information

54
Q

when do taxonomists rearrange classification systems?

A

Taxonomists will reclassify groups of species when new evidence arises to compromise the traditional classification scheme

55
Q

How may new species be separated?

A

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

56
Q

what is an example of reclassification?

A

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

57
Q

How may species be grouped into a common taxon?

A

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

58
Q

Why was the homininae sub-family created?

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)

59
Q

what is a dichotomous key?

A

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

60
Q

what does each sequential division lead to?

A

With each sequential division, more information is revealed about the specific features of a particular organism

61
Q

when can an organism be identified in a dichotomous key?

A

When the organism no longer shares its totality of selected characteristics with any organism, it has been identified

62
Q

what features are used to identify a specimens

A

When using a dichotomous key to identify specimens it is preferable to use immutable features (i.e. features that do not change)

63
Q

why may size, colouration and behavioural patterns not be good classification features?

A

Size, colouration and behavioural patterns may all vary amongst individuals and across lifetimes

64
Q

what are better classification systems?

A

Physical structures (e.g number of limbs) and biological processes (e.g. reproduction methods) make for better characteristics

65
Q

in what two ways are dichotomous keys represented?

A

Dichotomous keys are usually represented in one of two ways:

As a branching flowchart (diagrammatic representation)
As a series of paired statements laid out in a numbered sequence (descriptive representation)

IB Biology (38 decks)

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