Biology IB: classification/taxonomy

Credit to bioninja for many of these definitions! Access the webpage at: https://ib.bioninja.com.au/standard-level/topic-5-evolution-and-biodi/53-classification-of-biodiv/

Domain, Kingdom, Phylum, etc are types of…

Taxa

What are the three domains?

Eukaryota, Bacteria and Archaea

What are the four types of Eukaryota?

Plants, animals, fungi, and protists

What is convergent evolution?

Distantly-related organisms appear more similar than they really are (based on appearances) due to evolution coming up with the same feature independently multiple times

Give an example of convergent evolution

Koalas and most primates have very similar thumbs despite being very distantly related

What is the difference between a homologous structure and an analogous structure?

Homologous structures are similar because species share a common ancestor, analogous structures are similar because evolution has come up with the same ‘idea‘ multiple times

What are the molecular features of bacteria?

Introns are rare or absent, cell walls made of peptidoglycan, DNA is not associated with histones

What are the molecular features of archaea?

Proteins similar to histones are bound to DNA, some introns present, cell walls not made of peptidoglycan

What are the molecular features of eukaryota?

Histones are present, introns are frequent, cell walls (when present) are not made of peptidoglycan

What is a mnemonic that you could use to remember the order of classification?

Does (Domain) Kenneth (Kingdom) Play (Phylum) Classical (Class) Or (Order) Folk (Family) Guitar (Genus) Songs (Species)

What is the name of the flow diagram used to sort organisms?

A dichotomous key

What are some advantages of natural classifications?

• Identification of species is easier

• Prediction of similar characteristics within a group (for example, if a useful chemical is found in one plant species, it is likely to also be found in other species in the same genus)

What phylum do humans belong to?

Chordata (ie. vertebrae, we have a backbone)

Fish

• 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)

Amphibians

• 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)

Reptiles

• 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)

Birds

• 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)

Mammals

• 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)

What is a clade?

A group of organisms that share a common ancestor

What is a cladogram?

A tree diagram showing the similarities and differences between different species

What is a node?

A speciation event when a common ancestor turns into two or more species

Bryophyta (a plant phylum)

• 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)

• Examples include mosses and liverworts

Filicinophyta (a plant phylum)

• 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

• Examples include ferns

Angiospermophyta (a plant phylum)

• 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

Coniferophyta (a plant phylum)

• 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

Porifera (animal phylum)

• 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

Cnidaria (animal phylum)

• 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

Platyhelmintha (animal phylum)

• 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

Annelida (animal phylum)

• Have bilateral symmetry

• Have a separate mouth and anus

• Body composed of ringed segments with specialisation of segments

• Examples include earthworms and leeches

Mollusca (animal phylum)

• 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)

Arthropoda (animal phylum)

• 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

Chordata (animal phylum)

• 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)