IB biology: topic 5: classification of biodiversity

how do you write

genus is written first and is capitalised (e.g. Homo),

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

what are the 3 domains?

eukarya,

archaea,

eubacteria

what are eukarya?

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

what are archaea ?

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

what is eubacteria?

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

what is taxonomy?

classifying groups of organisms on the basis of shared characteristics

what is the hierarchy of taxa?

kingdom, phylum, class, order, family, genus, species

what are the four eukarya kingdoms?

protists, plants, fungi, animals

what is artificial classification?

arbitrarily selecting unifying characteristics first and then grouping organisms accordingly

what is the advantage of artificial classification?

easy to develop and relatively stable (unlikely to change)

what is the disadvantage of artificial classification?

they do not generally show evolutionary relationships and for this reason are not commonly used

what is natural classification?

grouping organisms based on similarities first and then identifying shared characteristics

what is the advantage of natural classification?

can be used to predict characteristics shared by species within a group

what is the disadvantage of natural classification?

they are highly mutable and tend to change as new information is discovered

what is phylogenetic classification?

grouping organisms based on genetics - organisms who share a greater level of homology in their DNA or amino acid sequences are expected to be more closely related

fish

• covered in scales made out of bony plates

• reproduce via external fertilisation

• breathe through gills that

• does not maintain a constant internal body temperature (ectothermic)

amphibian

• moist skin,

• reproduce via external fertilisation

• 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

• 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

• 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

• maintain a constant internal body temperature (endothermic)

what is a dichotomous key?

a method of identification whereby groups of organisms are divided into two categories repeatedly