4.2.2 - Classification And Evolution (set A - Classification Systems)

Question 1

What is classification?

Answer 1

The name given to the process by which living organisms are sorted into groups - organisms within each group share similar features

Question 2

Give 3 reasons whys scientists classify organisms?

Answer 2

• to identify species - by using a clearly defined system of classification the species an organism belongs to can easily be identified
• to predict characteristics - if several members in a group have a specific characteristic it is likely that another species in the group will have the same
• to find evolutionary links - species in the same group probably share characteristics because they have evolved from a common ancestor

can allow scientists to share research globally

Question 3

explain how organisms are classified by the classification system?

Answer 3

First separated into 3 domains (Archaea, Bacteria and Eukarya) - moving down the hierarchy there are more groups at each level but fewer organisms in each, organisms in the same group share similar characteristics

• system ends with organisms being classified as individual species

Question 4

what are the 3 domains?

Answer 4

Archaea, Bacteria and Eukarya

Question 5

Define species?

Answer 5

A group of organisms that are able to reproduce to produce fertile offspring

Question 6

Outline the 7 levels of hierarchy?

Answer 6

domain
- kingdom
- phylum
- class
- order
- family
- genus
- species

King Phillip Calls Out For Good Soup.

Question 7

Explain how animals were classified before classification systems?

Answer 7

Organisms were given names according to physical characteristics, behaviour or habitat (eg blackbirds or song thrushes) - known as their common names

Question 8

Explain the problem with using Common names for organisms?

Answer 8

Not useful for scientists working internationally, as organisms have more than one common name and different names in different languages

• also does not provide information about the relationship between organisms

binomial nomenclature developed to fix this

Question 9

Explain how carl Linnaeus binomial nomenclature works?

Answer 9

All species given a specific name consisting of two parts

• first word - indicates the organism genus (called the generic name)
• second word - indicates the organism species (called specific name

written in italics or underlined

Question 10

What are the 5 kingdoms?

Answer 10

• Prokaryotae
• Protoctista,
• Fungi
• Plantae
• Animalia

organisms originally classified into these kingdoms based on similarities in their observable features

Question 11

Outline the general features of prokaryotae?

Answer 11

• unicellular
• no nucleus or other membrane bound organelles
• small ribosomes
• no visible feeding mechanism - nutrients absorbed through cell wall or produced via photosynthesis

Example include bacteria (E. coli)

Question 12

Outline the general features of protocista?

Answer 12

• mainly unicellular
• nucleus or other membrane bound organelles
• some have chloroplast
• some move by cilia or flagella
• nutrients acquired by photosynthesis or ingestion of other organisms

Example include species belonging to Amoeba

Question 13

Outline the general features of fungi?

Answer 13

• unicellular or multicellular
• nucelus and other membrane bound organelles - cell wall composed of chitin
• no chloroplast or chlorophyll
• have a body or mycelium
• nutrients acquired mainly by absorption of decaying material (saprophytic feeders)
• most store their food as glycogen

Examples include mushrooms, mould and yeast

Question 14

Outline the general features of plantae?

Answer 14

• multicellular
• a nucleus and other membrane bound organelles (chloroplast and cell wall composed of cellulose)
• most do not move
• nutrients are acquired by photosynthesis - autotrophic feeders
• store food as starch

Question 15

Outline the general features of animialia?

Answer 15

• multicellular
• nucleus and other membrane bound organelles (no cell walls or chloroplast)
• move with aid of cilia, flagella or contractile proteins
• nutrients acquired by ingestion (heterotrophic feeders)
• food stored as glycogen

Question 16

Outline the differences in ribosomes amongst the three domains?

Answer 16

• eukarya - have 80s ribosomes - RNA polymerase contains 12 proteins
• archaea - have 70s ribosomes - RNA polymerase contains 10 proteins
• bacteria - have 70s ribosomes - RNA polymerase contains 5 proteins

Question 17

Explain how carl woese ‘three domain system’ groups organisms?

Answer 17

Groups organisms using differences in the sequences of nucleotides in the cells rRNA as well as the cells membrane lipid structure

• organisms classified into 3 domains and 6 kingdoms

Question 18

Explain what archaebacteria are?

Answer 18

Also known as ancient bacteria - can live in extreme environments (eg hot thermal vents, anaerobic conditions and highly acidic environments)

Question 19

Explain what eubacteria are?

Answer 19

Also known as true bacteria - found in all environments (most bacteria are of the eubacteria kingdom)

Question 20

Explain how the 5 kingdom system was changed?

Answer 20

Scientists discover archaebacteria to be chemically different from eubacteria

Prokaryotae divided into 2 kingdoms archaebacteria and eubacteria