Classification and evolution- classification, the five kingdoms, phylogeny

Question 1

what is classification?

Answer 1

the process by which living organisms are sorted into groups. The organisms within each group share similar features.

Question 2

what is taxonomy?

Answer 2

the practice of biological classification. This allows us to arrange species into taxonomic groups (taxa) based on their evolutionary origins and relationships.

Question 3

what are the seven taxonomic groups?

Answer 3

kingdom, phylum (plural phyla), class, order, family, genus (plural genera) and species.

Question 4

describe the kingdoms group

Answer 4

-biggest and broadest group
-least specific

Question 5

Describe the species group

Answer 5

-smallest
-most specific

Question 6

who first proposed the heirarchal classifications system?

Answer 6

Carl Linnaeus in the 18th century

Question 7

what level of classification is placed at the top of the hierarchy?

Answer 7

the domain, based on recent studies of genetic material. As new scientific discoveries are being made, the current system of classification may change again

Question 8

why do scientists classify organisms?

Answer 8

-to identify species
-to predict characteristics
-to find evolutionary links: common ancestor

Question 9

what are the three domains?

Answer 9

archaea, bacteria and eukarya. These are the broadest groups

Question 10

Describe the pattern as you go down the heirarchy from the broadest group (domain)

Answer 10

-As you go down, there are more groups at each level, but fewer organism in each group.
-the organisms in each group become more similar, sharing same characteristics

Question 11

how does the heirarchal system end?

Answer 11

organisms become classified as individual species, smallest unit of classification. Each group contains only one type of organism.

Question 12

what is a species?

Answer 12

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

Question 13

why are infertile offspring produced when two organisms of different species reproduce?

Answer 13

odd number of chromosomes produced so meiosis and gamete production cannot take place correctly as all chromosomes must pair up

Question 14

humans belong to what species (scientific name for humans)?

Answer 14

Homo sapiens

Question 15

Before classification, organisms were given names based on their physical characteristics. Why is this not useful?

Answer 15

-not usefully when working internationally as organisms may have more than one common name and in different languages
-does not provide information about relationships between organisms

Question 16

How do scientists ensure they are discussing the same organism Internationally?

Answer 16

using binomial nomenclature system where binomials are the scientific names given to an individual species

Question 17

binomials consist of an organism’s?

Answer 17

genus (first word) and species/specific name (second word) name

Question 18

what is the genus?

Answer 18

name shared by close relatives

Question 19

could two species have the same generic and species name?

Answer 19

no but they could have the same specific name but genus would be different

Question 20

how is the binomials for a species written?

Answer 20

always in italics. Genus name should have capital letter but species name shouldn’t

Question 21

what are the five kingdoms?

Answer 21

-prokaryotae (bacteria)
-protoctista (the unicellular eukaryotes)
-fungi (yeasts, moulds an mushrooms)
-plantae (the plants)
-animalia (the animals)

Question 22

what are the general features of prokaryotae?

Answer 22

-unicellular
-no nucleus or membrane bound organelles.
-a ring of ‘naked’ DNA and small ribosomes
-no visible feeding mechanism: nutrients are absorbed through the cell wall or produced internally by photosynthesis

Question 23

what are the general features of protoctista?

Answer 23

-(mainly) unicellular
- a nucleus and other membrane-bound organelles
-some have chloroplasts
-some are sessile, but others move by cilia, flagella or amoeboid mechanisms
-nutrients from photosynthesis (autotrophic feeders), ingestion of other organisms (heterotrophic feeders) or both- some are parasitic

Question 24

what are the general features of fungi?

Answer 24

-unicellular or multicellular
-nucleus and membrane bound organelles and a cell wall mainly composed of chitin.
-no chloroplasts or chlorophyll
-no locomotion mechanism
-most have a body or mycelium made of threads or hyphae
-nutrients from absorption, mainly decaying material (saprophytic feeders). Some are parasitic.
-most store their food as glycogen

Question 25

what are the general features of plantae (second largest kingdom)?

Answer 25

-multicellular
-nucleus and other membrane bound organelles including chloroplasts and a cell wall mainly composed of cellulose
-all contain chlorophyll
-most don’t move, but gametes of some plants more using cilia or flagella
-nutrients from photosynthesis (autotrophic feeders- make own food)
-store food as starch

Question 26

what are the general feature of Animalia (largest kingdom)?

Answer 26

-multicellular
-nucleus and membrane-bound organelles (no cell wall)
-no chloroplasts
-move with aid of cilia, flagella or contractile proteins, sometimes in the form of muscular organs
-nutrients acquired by ingestion (heterotrophic feeders)
-food stored as glycogen

Question 27

How have classification systems changed?

Answer 27

before it was based on observable features, now it is based on DNA

Question 28

What are the domains?

Answer 28

a further level of classification the top of the hierarchy proposed by Carls Woese.

Question 29

How does Woese’s domain system group organisms?

Answer 29

based on differences in the sequence of nucleotides in the cells ribosomal RNA (rRNA) as well as the cell membranes lipid structure and their sensitivity to antibiotics

Question 30

what are the three domains?

Answer 30

-Archaea
-Bacteria
-Eukarya

Question 31

Describe the domain of Eukarya?

Answer 31

-80s ribosomes
-RNA polymerase contains 12 proteins

Question 32

Describe the domain of Archaea?

Answer 32

-70s ribosomes
-RNA polymerase of different organisms contains between eight and 10 proteins and is very similar to eukaryotic ribosome

Question 33

Describe the domain of Bacteria?

Answer 33

-70s ribosome
-RNA polymerase contains 5 proteins

Question 34

How does Woeses kingdom system differ?

Answer 34

Prokaryotae kingdom divides into two kingdoms- Archaebacteria and Eubacteria. The six kingdoms are therefore, Archaebacteria, Eubacteria, Protoctista, Fungi, Plantae and Animalia

Question 35

why is Eubacteria classified in its own kingdom?

Answer 35

Because its genetic makeup is different from Archaebacteria

Question 36

Describe Archaebacteria?

Answer 36

Ancient bacteria, can live in extreme environments (thermal vents, anaerobic conditions and highly acidic places)

Question 37

Describe Eubacteria?

Answer 37

True bacteria, found in all environments . Most common bacteria

Question 38

What is phylogeny?

Answer 38

the evolutionary relationships between organisms

Question 39

What is a phylogenetic tree (evolutionary tree)?

Answer 39

diagram used to represent evolutionary relationships between organisms

Question 40

How are phylogenetic trees produced?

Answer 40

by looking at similarities and differences in a species physical characteristics and genetic makeup. Much evidence is gained from fossils.

Question 41

what are the advantages of phylogeny?

Answer 41

-can be done without reference to Linnaean classification
-phylogeny produces a continuous tree whereas classification requires taxonomical groups
-the hierarchal nature of Linnaean classification can be misleading as it implies different groups within the same rank are equivalent.