Classification - Topic 4 - Paper 1

Question 1

State the 3 parts of Carl Woese’s three-domain system

Answer 1

Archaea
Bacteria
Eukaryota

Both Bacteria and Archaea are prokaryotes but archaea are only really found in extreme environments like hot springs

Question 2

Give the 8 sections of classification

Answer 2

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Woese added domains after realising, from RNA sequencing, that some prokaryotes previously all included in the kingdom “prokaryotes” weren’t as closely related as we’d thought
Dear - Domain
Kate - Kingdom
Please - Phylum
Come - Class
Over - Order
For - Family
Great - Genus
Spaghetti - Species

Question 3

Which two parts of the Linnean classification system are used in the universal binomial naming system?

Answer 3

Genus and species

e.g. Homo sapiens

Question 4

How has genetic analysis lead to the suggestion of 3 domains rather than the 5 kingdoms classification system?

Answer 4

Prokaryotes were previously all grouped together in the 5 kingdom system but Woese, in RNA sequencing with more advanded technology than was available when the 5 kingdom system was proposed, found that some members of the prokaryote kingdom weren’t as closely related as we first thought so split them into Archaea and Bacteria

The 3 domains system was divised by Woese
The kingdom system was devised by Linneus

Question 5

What enabled Woese to discover some prokaryotes weren’t as closely related as originally thought?

Answer 5

RNA sequencing with more advanced technology (e.g. microscopes with higher magnification and resolution)

Resolution is how well a microscope distinguishes between two points that are close together
Magnification is how many times larger a microscope can make a structure appear
Electron microscopes (20th cent.) have both a better magnification and resolution than light microscopes (16th cent.)