Classification & cladistics - classification system

Question 1

What is the largest taxonomic group now known as?

Answer 1

Domain

This reflects the modern understanding of biological classification.

Question 2

How many domains are there in the current taxonomic system?

Answer 2

Three

The three domains are Archaea, Eubacteria, and Eukaryotes.

Question 3

What are the three domains of life?

Answer 3

• Archaea (prokaryotes)
• Eubacteria (prokaryotes)
• Eukaryotes (eukaryotes)

This classification is based on genetic and structural differences.

Question 4

What type of organisms are Archaea?

Answer 4

Single-celled organisms

Archaea can live in a variety of habitats, including extreme environments.

Question 5

What are thermophiles?

Answer 5

Organisms that live in hot springs

Thermophiles are a type of Archaea adapted to extreme heat.

Question 6

What is a key feature of Archaea’s cell walls?

Answer 6

Different material from bacteria

Unlike Eubacteria, Archaea do not have peptidoglycan in their cell walls.

Question 7

What type of ribosomes do Archaea have?

Answer 7

70S with a small subunit similar to eukaryotic ribosomes

This feature distinguishes Archaea from Eubacteria.

Question 8

Fill in the blank: The Archaea were originally classified with the rest of the bacteria in one taxon due to _______.

Answer 8

sharing several features with them

This classification was based on observable similarities.

Question 9

What type of lipids are found in Archaea cell membranes?

Answer 9

Glycerol-ether lipids

This is distinct from the glycerol-ester lipids found in Eubacteria and Eukaryotes.

Question 10

What is the chromosome structure of Archaea?

Answer 10

Circular

This is similar to Eubacteria but differs from the linear chromosomes of Eukaryotes.

Question 11

Do Archaea have histones?

Answer 11

Yes

Histones are proteins that help package DNA in Archaea, similar to Eukaryotes.

Question 12

True or False: Eubacteria have introns.

Answer 12

False

Introns are rarely found in Eubacteria, unlike in Eukaryotes where they are common.

Question 13

What is the primary difference in the cell walls of Eukaryotes compared to Archaea and Eubacteria?

Answer 13

Sometimes present and without peptidoglycan

Eukaryotic cell walls vary; they may not always be present.

Question 14

What significant change occurred in taxonomic thinking due to rRNA analysis?

Answer 14

Recognition of two distinct groups of prokaryotes

This led to the development of the three domain system.