10. Classification / Evolution

Question 1

define CLASSIFICATION

Answer 1

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

Question 2

The 7 taxonomic groups in the hierarchy are:

* These are referred to as

Answer 2

Kingdom, phylum, class, order, family, genus, species.

Linnaean classification after Carl Linnaeus, who proposed it.

Question 3

WHY DO SCIENTISTS CLASSIFY ORGANISMS?

3 reasons

Answer 3

• To identify species
• 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 characteristic.
• To find evolutionary links  species in the same group share the same characteristics because they have evolved from a common ancestor.

Question 4

Using a single classification system allows scientists worldwide to ?

Answer 4

share their research.

Question 4

The classification system begins by separating organisms into 3 domains which are?

Answer 4

Archaea, Bacteria and Eukarya.

Question 5

as you move down the hierarchy, the organisms in each group become

Answer 5

more similar and share more characteristics.

Question 6

The system ends with organisms being classified as an individual species = which means?

define species

Answer 6

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

Question 6

acronym

Dear
King
Philip
Come
Over
For
Good
Soup

Answer 6

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 7

The binomial nomenclature system was developed so

Answer 7

scientists working internationally can identify species easily.

Question 8

All species are given a scientific name consisting of 2 parts:

Answer 8

• The first word indicates the organism’s genus.
• The second word indicates the organism’s species.

Question 9

The standard procedure of presenting the scientific name is in

Answer 9

italics

Question 10

As it is hard to handwrite in italics, in handwritten documents the name is underlined. The name is written in all lowercase except for

Answer 10

the first letter of the genus name, which should be uppercase e.g. Canis familiaris

Question 10

Living organisms can be classified into 5 kingdoms:

Answer 10

• PROKARYOTAE (BACTERIA)
• PROTOCTISTA (UNICELLULAR EUKARYOTES)
• FUNGI
• PLANTAE
• ANIMALIA

Question 11

describe PROKARYOTAE (BACTERIA)

Answer 11

Are unicellular.
Have no nucleus or other membrane bound organelles.
Naked circular DNA.
Small ribosomes.
No visible feeding mechanism – nutrients absorbed through the cell wall or produced internally through photosynthesis.
e.g. E. coli, S. aureus.

Question 12

describe PROTOCTISTA (UNICELLULAR EUKARYOTES)

Answer 12

Mainly unicellular
Have a nucleus and other embrace bound organelles.
Some have chloroplasts.
Some move by cilia or flagella.
Nutrients acquired by photosynthesis (autotrophic), ingestion of other organisms (heterotrophic) or both. Some are parasitic.
e.g. Amoeba.

Question 13

describe FUNGI

Answer 13

Unicellular or multicellular
Have a nucleus, membrane bound organelles and a chitin cell wall.
No chloroplasts or chlorophyll.
Mycelium body or made of threads of hyphae.
Nutrients acquired by absorption – mainly from decaying material (saprophytic). Some are parasitic.

Question 14

describe PLANTAE

Answer 14

Multicellular
Have nucleus and other membrane bound organelles, cellulose cell wall.
Have chloroplasts – all contain chlorophyll.
Most do not move, gametes of some move using cilia / flagella.
Nutrients acquired by photosynthesis (autotropic) – make their own food.
Store food as starch.
e.g. roses, trees, grass.

Question 15

describe ANIMALIA

Answer 15

Multicellular.
Have a nucleus and other membrane bound organelles.
No cell wall or chloroplasts.
Move with the aid of cilia, flagella, or contractive proteins.
Nutrients acquired by ingestion (heterotrophic).
Food stored as glycogen.

Question 16

THE 3 DOMAINS

Woese’s system groups organisms using differences in the sequences of nucleotides in the cell’s

Answer 16

rRNA, as well as the CSM lipid structure and its sensitivity to antibiotics.

Question 17

THE 3 DOMAINS

Under this system, organisms are classified into

Answer 17

3 domains and 6 kingdoms.

Question 18

THE 3 DOMAINS

The organisms in the different domains contain a unique form of rRNA and different ribosomes:

Answer 18

EUKARYA – HAVE 80S RIBOSOMES - RNA polymerase contains 12 proteins.
ARCHAEA – HAVE 70S RIBOSOMES – RNA polymerase contains 8-10 proteins and is very similar to eukaryotic ribosome.
BACTERIA – HAVE 70S RIBOSOMES – RNA polymerase contains 5 proteins.

Question 19

THE 3 DOMAINS

In Woese’s system the Prokaryotae kingdom becomes divided into 2 kingdoms which are

Answer 19

Archaebacteria and Eubacteria.

Question 20

THE 3 DOMAINS

The 6 kingdoms are:

Answer 20

Archaebacteria, Eubacteria, Protoctista, Plantae, Fungi, Animalia.

Question 21

THE 3 DOMAINS

Although both Archaebacteria and Eubacteria are single celled prokaryotes, and Eubacteria are classified as their own kingdom because

Answer 21

their chemical makeup is different from Archaebacteria – they contain peptidoglycan in their cell wall whereas Archaebacteria do not.

Question 22

THE 3 DOMAINS

describe ARCHAEBACTERIA

Answer 22

Can live in extreme environments - hot thermal vents, aerobic conditions, highly acidic environments etc.

Question 23

THE 3 DOMAINS

describe EUBACTERIA

Answer 23

Found in all environments.
Most bacteria fall in this category.

Question 24

Phylogeny is the name given to

Answer 24

evolutionary relationships between organisms.

Question 25

Classification can occur without the knowledge of

Answer 25

phylogeny, but many scientists take phylogeny into account.

Question 26

Phylogenetic trees are

Answer 26

Diagrams used to represent the evolutionary relationships between organisms  shows different species have evolved from a common ancestor.
They are produced by looking at the similarities and differences of species’ physical and genetic makeup.
Much of the evidence has been gained from fossils.

Question 27

ADVANTAGES OF PHYLOGENETIC CLASSIFICATION?

Answer 27

• Can be done without reference to the Linnean classification.
  Classification uses knowledge of phylogeny in order to confirm classification groups are correct.
• Phylogeny produces a continuous tree whereas classification requires discrete taxonomic groups  scientists are not forced to put organisms in groups they do not fit in.
• The hierarchical nature of the Linnean classification system is misleading – implies different groups within the same rank are equivalent  cats and orchids are both families, but plants have a longer history than the other / they have different levels of diversity.

Question 28

define EVOLUTION

Answer 28

describes the way in which organisms evolve or change over years as a result of natural selection.

Question 29

Organisms that are best suited to their environment are more likely

Answer 29

to survive and reproduce.

Question 30

• Fossils are formed when animal and plant-remains are preserved in rocks. Over long periods of time,

Answer 30

sediment is deposited on the earth to form layers of rock – different layers correspond to different eras, the most recent one found on the top.

Question 31

• Different fossils are formed within each layer, forming a sequence from

Answer 31

youngest at the top to oldest at the bottom  shows organisms changed over time.

Question 32

Evidence for the fossil record includes

Answer 32

• Fossils of the simplest organisms such as bacteria and algae are found in the oldest rocks, whilst fossils of more complex organisms are found in the most recent rocks  supports that simple life forms gradually evolved over a long time period into more complex ones.
• The sequence in which the organisms are found matches their ecological links to each other plant fossils appear before animal fossils = consistent with the fact that animals require plants to survive.
• Scientists can show how closely related organisms have evolved from the same ancestor e.g. zebras have horses have been linked to a common ancestor based on their skull and feet structure.
• Fossils allow links between extinct and living organisms to be investigated.

Question 33

However, the fossil record is not complete - why?

Answer 33

many organisms are soft bodied and decompose quickly before they have a chance to fossilise.
Many fossils have been destroyed by earth’s movements (volcanoes) or remain undiscovered

Question 34

define * COMPARATIVE ANATOMY –

Answer 34

the study of similarities and differences between organisms’ anatomy.