4.2.2 - Classification and Evolution

Question 1

What is classification?

Answer 1

the process by which living organisms are sorted into groups based on similar features

Question 2

Why are organisms classified?

Answer 2

• to identify species
• to predict characteristics
• to find evolutionary links

Question 3

What is the taxonomic heirarchy?

Answer 3

(Domain)
Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 4

What is a species?

Answer 4

a group of living organisms that can interbreed to produce fertile offspring

Question 5

What is the binomial nomenculture?

Answer 5

method of naming species

• first name from genus
• second name from species
• must be written in italics (underlined in exam!)
• first letter must be capital

Question 6

What are the advantages of binomial nomenculture?

Answer 6

• provides information about relationships between organisms

- species has the same name in all languages (unlike common names)

Question 7

What are the five kingdoms?

Answer 7

Prokaryotae
Protoctista
Fungi
Plantae
Animalia

Question 8

What are the features of the Prokaryotae kingdom?

Answer 8

• prokaryotes
• no nucleus (ring of DNA instead)
• absorbs nutrients through cell wall or produces them by photosynthesis
• cell wall made of peptidoglycan
• unicellular
• has small ribosomes

Question 9

What are the features of the Protoctista kingdom?

Answer 9

• eukaryotes
• contain a nucleus
• nutrients from photosynthesis (autrophic feeders) and/or ingestion of other organisms (heterotrophic feeders)
• no cell wall
• some are immobile, others move using flagella, cilia, etc
• unicellular

Question 10

What are the features of the Fungi kingdom?

Answer 10

• eukaryotes
• contain a nucleus
• cell wall made from chitin
• nutrients absorbed from decaying materials (saphrophic feeders) and stored as glycogen
• uni or multicellular
• don’t move

Question 11

What are the features of the Plantae kingdom?

Answer 11

• eukaryotes
• contain a nucleus
• cell wall made from cellulose
• nutrients from photosynthesis (autrophic feeders) and stored as starch
• multicellular
• contain chlorophyll

Question 12

What are the features of the Animalia kingdom?

Answer 12

• eukaryotes
• contain a nucleus
• nutrients from ingestion (heterotrophic feeders) and stored as glycogen
• no cell wall
• multicellular
• no chloroplasts

Question 13

What are autotrophic feeders and which kingdoms are they?

Answer 13

organisms that synthesis the substances they need (ie. by photosynthesis)
-Plantae, some Prokaryotae, some Protoctista

Question 14

What are heterotrophic feeders and which kingdoms are they?

Answer 14

organisms that feed on other organisms (ie. ingestion)

-Animalia, some Protoctista

Question 15

What are saphrophic feeders and which kingdoms are they?

Answer 15

organisms that feed on decaying matter

-Fungi

Question 16

What is the current classification system?

Answer 16

the three domain system

-3 domains + 6 kingdoms

Question 17

What is phylogeny?

Answer 17

the evolutionary relationships between organisms

Question 18

What do phylogenetic trees show?

Answer 18

evolutionary relationships

• oldest at bottom
• newest at top

Question 19

What are the advantages of phylogeny?

Answer 19

• confirms classification grouping

- produces a continuous tree (classification only has discrete taxonomic groups)

Question 20

What is evolution?

Answer 20

the process by which organisms change over millions of years as a result of natural selection

Question 21

What happens in natural selection?

Answer 21

• organisms within a species show variation (because of differences in genes) -variation could occur by random mutations
• organisms that are best adapted to a selection pressure have an increased chance of survival
• if the organism survives, it can reproduce
• successful organisms pass on the allele for the advantageous characteristic to their offspring
• this is repeated over many generations so that the frequency of the advantageous allele increases
• over long periods of time/many generations, this can lead to a new species evolving

Question 22

What is a selection pressure?

Answer 22

a factor that affects an organism’s changes of survival or reproductive success
eg. competition (mate/food), disease, predation

Question 23

What evidence for evolution is there?

Answer 23

• fossils (palaenotology)
• molecular evidence
• comparative biochemistry (eg. order of DNA bases, rRNA, cytochrome C)
• comparative anatomy

Question 24

What is variation?

Answer 24

differences in characteristics between organisms

Question 25

What is interspecific variation?

Answer 25

variation between members of different species

Question 26

What is intraspecific variation?

Answer 26

variation between organisms within a species

Question 27

What are the causes of variation?

Answer 27

• organisms’ genetic material (=> genetic variation eg. eye colour, hair, etc.)
• environment where an organism lives (=> environmental variation eg. scars, piercings)
• both (eg. weight, skin colour, etc.)

Question 28

What are the causes of genetic variation?

Answer 28

• alleles
• mutations
• meiosis (crossing over and independent assortment)
• sexual reproduction
• chance

Question 29

What is discontinuous variation?

Answer 29

variation that can only result in certain values

• only caused by genetic factors (usually a single gene)
• normally represented in a bar chart or pie chart
  eg. sex, blood group, shape of bacteria

Question 30

What is continuous variation?

Answer 30

variation that can take any value in a range

• caused by environment and genes (a large number of genes)
• normally represented in frequency tables and then in a histogram or line graph (in a line graph this creates a normal distribution curve)

Question 31

What is an adaption?

Answer 31

a characteristic that increases an organism’s chance of survival and reproduction in an environment

Question 32

What are the three types of adaptions?

Answer 32

• anatomical (physical features)
• behavioural (the way they act -inherited of learnt)
• physiological (takes place inside an organism)

Question 33

What are analogous structures?

Answer 33

structures different species both have with the same feature but from a different origin

• convergent evolution
  eg. insect wing and bird wing

Question 34

What are homologous structures?

Answer 34

structures different species both have with different functions but the same origin

• divergent evolution
  eg. bat wing and human arm