10.1 - Classification

Question 1

Why do we classify ?

Answer 1

• to help identify new species
• to predict characteristics
• to find evolutionary links
• to make the study or living things more manageable

Question 2

How do we classify ?

Answer 2

Observable characteristics ( gross and microscopic ) biochemistry ( DNA , proteins rRNA )

Question 3

Define classification

Answer 3

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

Question 4

What are the 7 taxonomic groups ?
* remember the song*

Answer 4

Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 5

Define taxonomy

Answer 5

The focus on physical similarities

Question 6

What is the binomial naming system ?

Answer 6

Genus species ( italics )

Question 7

Why is the binomial naming system useful ?

Answer 7

• analyse evolutionary relationships between organisms
• predict characteristics
• identify species
• share findings internationally

Question 8

What are the 5 kingdoms?

Answer 8

• prokaryotae
• protoctista
• fungi
• plantae
• animalia

Question 9

What are the 3 domains ?

Answer 9

• Bacteria
• archaea
• eukarya

Question 10

What are the general features of prokaryotae ?

Answer 10

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

Question 11

What are species ?

Answer 11

A group of organisms that can inbreed to produce fertile offspring

Question 12

What species are humans?

Answer 12

Homo sapiens

Question 13

What is binomial nomenclature?

Answer 13

• developed in the 18th century by Carl Linnaeus
• all species are given a scientific name consisting of two parts :
• the first word indicates the organisms genus ( generic name )
• the second word indicates the organisms species ( specific name )
• no two species have the same generic and specific name

Question 14

What are the general features of the protoctista?

Answer 14

• mainly unicellular
• a nucleus and other membrane bound organelles
• some have chloroplasts
• some are sessile but others move by cilia, flagella or by amoeboid mechanisms
• nutrients are acquired by photosynthesis ( autorophic feeders ) ingestion of other organisms ( heterorophic feeders ) or both - some are parasitic
• eg. Amoeba

Question 15

What are the general features of fungi ?

Answer 15

• unicellular or multicellular
• a nucleus and other membrane bound organelles and a cell wall - mainly composed of chitin
• no chloroplasts or chlorophyll
• no mechanisms for locomotion
• most have a body for mycelium made of threads or hyphae
• nutrients are acquired by absorption - mainly from decaying material - they’re SAPROPHYTIC feeders - some are parasitic
• most store their food as glycogen
• eg. Mushrooms, moulds and yeast

Question 16

What are general features of plantae ?

Answer 16

• over 250,000 species - the plant kingdom is the second largest of the kingdoms
• multicellular
• a nucleus , other membrane bound organelles including chloroplasts and a cell wall —> composed of cellulose
• all contain chlorophyll
• most do not move - although gametes of some plants move using cilia or flagella
• nutrients are acquired by photosynthesis - they’re autotrophic feeders ( organisms that make their own food )
• store food as starch
• eg. Flowering plants such as Roses , trees such as oak and grasses

Question 17

What are some features of animal?

Answer 17

• largest kingdom
• multicellular
• nucleus and other membrane bound organelles —> no cell walls
• no chloroplasts
• move with the aid of cilia, flagella or contractile proteins —> sometimes in the form of muscular organs
• nutrients are acquired by ingestion - they’re heterotrophic feeders
• food stored as glycogen
• eg. Mammals , reptiles, birds , insects etc.

Question 18

What is a saprotroph ?

Answer 18

An organism that feeds on or derives nourishment from decaying organic matter

Question 19

Define heterotroph

Answer 19

An organism that feeds on other organisms

Question 20

Define autotroph

Answer 20

An organism that makes its own food

Question 21

What is Archaebacteria ?

Answer 21

• ancient bacteria
• can live in extreme environments
• eg. Hot thermal vents , anaerobic conditions and highly acidic environments

Question 22

What is Eubacteria ?

Answer 22

• true bacteria
• found in all environments

Question 23

State two differences between fungi and plants

Answer 23

• plants have chloroplasts where as fungi don’t
• plants are autotrophs whilst fungi are heterotrophs

Question 24

Explain why prokaryotes are now classified as two separate domains

Answer 24

• old classification does not show correct phylogeny
• cell walls differ - peptidoglycan not found in archaea

Question 25

Describe how and why classification systems have changed over Time

Answer 25

- living organisms classified into two kingdoms based on major differences in characteristics - for eg. Those that moved and ate animals and those that didn’t - there is more scientific advances and the use of microscope allowed smaller details to be observed - organisms divided into 5 kingdoms - plants,animals, fungi, protoctista and prokaryotes - advances in DNA and proteins to be studied - provided evidence for evolutionary relationships - three domain proposed - relevant scientists eg. Linnaeus, Whittaker or Woese

Question 26

What is phylogeny ?

Answer 26

The study of evolutionary relationships between organisms

Question 27

What is a species according to phylogeny ?

Answer 27

The smallest group that shares a common ancestor - end of the branch

Question 28

What are some advantages of phylogeny over classification ?

Answer 28

- produces a continuous tree whereas classification uses discrete taxonomic groups - shows the history of different species far more accurately - hierarchal nature of Linnaean classification can be misleading as it implies different groups within the same rank are equivalent

Question 29

What are phylogenetic trees ?

Answer 29

- A diagram used to represent the evolutionary relationships between organisms - they’re branches diagrams - show that different species have evolved from a common ancestor - the earliest species is found at the base of the tree and the most recent species are found at the tips of the branches

Question 30

How are phylogenetic trees produced ?

Answer 30

By looking at similarities and differences in species physical characteristics and genetic makeup Much of the evidence has been gained from fossils

Question 31

State the main difference between early classification systems and systems based on phylogeny

Answer 31

Historical classification systems are based ok physical characteristics where as phylogeny is based on evolutionary relationships

Question 32

What is a homologous structure ?

Answer 32

- structure that appears superficially different and may perform different different functions in different organisms but has the same underlying structure

Question 33

What is evolution ?

Answer 33

The way in which organisms change as a result of natural selection over many generations

Question 34

What is molecules evidence ?

Answer 34

Gathering molecular evidence and analysing the similarities in proteins and DNA

Question 35

What is phylogeny evidence ?

Answer 35

Comparing the fossil record

Question 36

What is embryological evidence ?

Answer 36

Comparing the development of organisms from an embryo

Question 37

What are 3 points of evidence for evolution ?

Answer 37

1. Palaeontology - the study of fossils and the fossil record 2. Comparative anatomy - the study of similarities and differences between organism’s anatomy 3. Comparative biochemistry - similarities and differences between the chemical makeup of organisms

Question 38

How are fossils formed ?

Answer 38

- when animal and plant remains are preserved in rocks - over long periods of time - sediment is deposited on the earth to form layers of rock - different layers corresponded to different geological eras - within the different rock strata the fossils found are quite different - forming a sequence from oldest to youngest which shows that organisms have gradually changed over time = fossil record

Question 39

What are some evidence provided by fossil records ?

Answer 39

- fossils of the simplest organisms such as bacteria and simple algae are found in the oldest rocks - more recent rocks have more complex organisms such as vertebrates - this supports the evolutionary theory that simple life forms gradually evolved over an extremely long time period into more complex ones - the sequence in which the organisms are found matched their ecological links to each other for eg. Plant fossils appear before animal fossils —> this is consistent with the fact that animals require plants to survive - by studying similarities in the anatomy of fossil organisms scientists can show how closely related organisms have evolved from the same ancestor - fossils allow relationships between extinct and living organisms to be investigated t

Question 40

Why is sometimes the fossil records not complete ?

Answer 40

- many organisms are soft bodied and decompose quickly before they have a chance to fossilise - the conditions needed for fossils to from are not often present - many other fossils have been destroyed by the earths movement such as volcanoes or still lie undiscovered

Question 41

What is comparative anatomy ?

Answer 41

Comparative anatomy is the study of similarities and differences in the anatomy of different living species

Question 42

What does the presence of homologous structures provide evidence for ?

Answer 42

Divergent evolution

Question 43

What does divergent evolution explain ?

Answer 43

- describes how from a common ancestor different species have evolved - each with a different set of adaptive features - this type of evolution will occur when closely related species diversify to adapt to new habitats as a result of migration or loss of habitat

Question 44

What is comparative biochemistry ?

Answer 44

The study of similarities and differences in the proteins and other molecules that control life processes

Question 45

Explain evolutionary embryology

Answer 45

- study of the embryos - an embryo is an unborn animal in its earliest phases of development - embryos or many different animals look very similar and it is often difficult to tell the, apart - this shows that the animals develop in a similar way —> implying that the processes of embryonic Development gave a common origin and the animals share common ancestry but have gradually evolved different traits

Question 46

What are the two common molecules studied ?

Answer 46

- cytochrome C ( a protein involved in respiration ) - ribosomal RNA

Question 47

What is the hypothesis of neural evolution ?

Answer 47

- states that most of the variability In the structure of a molecule does not affect its function - due to the fact that most of the variability occurs outside of the molecule’s functional regions - changes that do not affect a molecules function are called = NEUTRAL - since they have no effect on function —> their accumulation is not affected by natural selection - as a result neutral substitutions occur at a fairly regular rate - although that rate is different for different molecules

Question 48

What do you compare to discover how close two species are together ?

Answer 48

The molecular sequence of a particular molecule

Question 49

How can scientists estimate the point at which the two species last shared a common ancestor ?

Answer 49

- the number of differences that exist are plotted against the rate the molecule undergoes neutral base pair substitutions

Question 50

What is the molecular evidence to back up the difference between Archaea and bacteria ?

Answer 50

RNA polymerase is different and only Archaea have similar histories to Eukarya

Question 51

What is the cellular evidence to back up the difference between Archaea and Bacteria ?

Answer 51

Different bonding of lipids and different development and composition of flagellae

Question 52

Describe what is shown on a phylogenetic tree

Answer 52

- a diagram is used to show evolutionary relationships between organisms - the closer the branches of the tree the closer the evolutionary relationships

Question 53

Describe two advantages and disadvantages or using the fossil record as a source of evidence for evolution

Answer 53

Advantages : - radioisotopes can be used to date fossils - changes can be tracked over time - chronological order apparent in rock strata Disadvantages : - many organisms decompose quickly before they have a chance to fossilise / destroyed by volcanoes or destroyed by earthquakes

Question 54

Describe how the work of three scientists was used in the development of the theory of evolution

Answer 54

LYELL - suggested that fossils were actually evidence of animals that have lived millions of years ago HUTTON - proposed theory of uniformitarianism DARWIN - came up with the theory of evolution by natural selection through observations in the Galápagos Islands WALLACE - came up with the theory of evolution by natural selection in Borneo

Question 55

Explain how comparative biochemistry provides evidence of evolution

Answer 55

- study of similarities and differences in proteins and nucleic acid / DNA of an organism - changes in highly conserved molecules can help identify evolutionary links - such as cytochrome C / ribosome RNA - species that have the most similar DNA and proteins