Classification

Question 1

Features of Bryophyta (4)

Answer 1

• 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

Question 2

Features of Filicinophyta (ferns) (3)

Answer 2

• 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

Question 3

Features of Coniferophyta (conifers) (3)

Answer 3

• 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

Question 4

Features of Angiospermophyta (flowering plants) (3)

Answer 4

• 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

Question 5

Features of Monocots (3)

Answer 5

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

Question 6

Feature of Dicots (3)

Answer 6

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

Question 7

Features of phylum Porifera (7)

Answer 7

• 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

Question 8

Features of phylum Cnidaria (5)

Answer 8

• 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

Question 9

Features of phylum Platyhelminthes (4)

Answer 9

• 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

Question 10

Features of phylum Annelida (5)

Answer 10

• 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

Question 11

Features of phylum Arthropoda (7)

Answer 11

• 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

Question 12

Features of phylum Mollusca (6)

Answer 12

• 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)

Question 13

Features of phylum Echinodermata (8)

Answer 13

• 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

Question 14

Features of phylum Chordata (5)

Answer 14

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

Question 15

Features of sub-phylum Vertebrata (4)

Answer 15

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

Question 16

Features of lass Chondrichthyes (3)

Answer 16

• skeleton of cartillage
• no swim bladder
• all aquatic

Question 17

Features of Osteichthyes (3)

Answer 17

• swim bladder present
• all aquatic
• bony endoskeleton

Question 18

Features of class Amphibia (4)

Answer 18

• 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)

Question 19

Features of class Reptilia (4)

Answer 19

• 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)

Question 20

Features of class Aves (4)

Answer 20

• 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)

Question 21

Feature of class Mammalia (4)

Answer 21

• 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)

Question 22

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

Answer 22

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

Question 23

WHo developed the binomial system?

Answer 23

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

Question 24

Is the binomial system updated?

Answer 24

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

Question 25

What are the 4 benefits of the binomial system?

Answer 25

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

Question 26

How is an organism named due to the binomial system?

Answer 26

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

Question 27

What are the three domains?

Answer 27

eukarya archaea eubacteria

Question 28

What are eukarya?

Answer 28

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

Question 29

What are archaea?

Answer 29

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

Question 30

What are eubacteria?

Answer 30

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

Question 31

What is the key development in the 3 domains?

Answer 31

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

Question 32

What is taxonomy?

Answer 32

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

Question 33

What are organisms grouped according to?

Answer 33

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

Question 34

What is the hierarchy of taxa?

Answer 34

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

Question 35

What domain do animal and plants belong to?

Answer 35

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

Question 36

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

Answer 36

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

Question 37

What is the similarity between the two classification systems?

Answer 37

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

Question 38

What is artificial classification?

Answer 38

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

Question 39

What is the advantage of artificial classification?

Answer 39

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

Question 40

What is a disadvantage of artificial classification?

Answer 40

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

Question 41

Give examples of disadvantages of artificial classifications?

Answer 41

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

Question 42

What is natural classification?

Answer 42

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

Question 43

How would something be classified according to natural classification?

Answer 43

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

Question 44

What are natural classification systems used to predict?

Answer 44

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

Question 45

What is a disadvantage of natural classification?

Answer 45

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

Question 46

What is a third type of classification?

Answer 46

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

Question 47

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

Answer 47

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

Question 48

What is an advantage of natural classification?

Answer 48

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

Question 49

Therefore what type of relationships does natural selection show?

Answer 49

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

Question 50

What does each taxonomic level include?

Answer 50

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

Question 51

What species have a common genus ancestor?

Answer 51

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

Question 52

Therefore what must organisms with a lower taxa share?

Answer 52

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)

Question 53

What is a disadvantage of natural classifications?

Answer 53

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

Question 54

when do taxonomists rearrange classification systems?

Answer 54

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

Question 55

How may new species be separated?

Answer 55

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

Question 56

what is an example of reclassification?

Answer 56

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

Question 57

How may species be grouped into a common taxon?

Answer 57

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

Question 58

Why was the homininae sub-family created?

Answer 58

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)

Question 59

what is a dichotomous key?

Answer 59

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

Question 60

what does each sequential division lead to?

Answer 60

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

Question 61

when can an organism be identified in a dichotomous key?

Answer 61

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

Question 62

what features are used to identify a specimens

Answer 62

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

Question 63

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

Answer 63

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

Question 64

what are better classification systems?

Answer 64

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

Question 65

in what two ways are dichotomous keys represented?

Answer 65

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)