evidence and the three domains

Question 1

why can classification based on observable characteristics be viewed as unreliable

Answer 1

there are unrelated species which look similar but aren’t related so may be placed in the same taxonomic group

Question 2

what is convergent evolution

Answer 2

when species aren’t closely related but evolved similar features or behaviours

Question 3

what biological molecules could be used to provide evidence to help in classifying organisms

Answer 3

-proteins : sequence of amino acids, e.g Cytochrome C

-DNA : DNA hybridisation, comparing base sequence

-immunological comparison of proteins

Question 4

how does DNA hybridisation work

Answer 4

-mix of DNA from 2 species

-greater degree of hybridisation/ bases paired = more similar the DNA

Question 5

how does immunological comparison work?

Answer 5

-antibody-antigen interacations to form precipitation

-more similar 2 species are = more precipitation

Question 6

what are the three domains within the 3 domain classification?

Answer 6

-bacteria
-archaea
-eukarya

Question 7

which kingdom has been divided by the 3 domain classification

Answer 7

prokaryotes divided into bacteria and archaea

Question 8

how are bacteria different to archaea and eukaryotes

Answer 8

-different cell membrane structure
-flagella has different internal structure
-different enzymes
-no proteins bound to their genetic material
-different mechanisms for DNA replication and synthesising RNA

Question 9

how are archaea the same as eukaryotic cells

Answer 9

-similar enzymes (RNA polymerase) for synthesising RNA

-similar mechanisms for DNA replication and synthesising RNA

-production of some proteins that bind to their DNA

Question 10

compare artificial and natural classification

Answer 10

artificial:
-does not reflect evolutionary relationships
-gives limited info
-used for convenience
-calssified according to features such as colour size leaf shape
-groups analogous features only, may have same function but not same evolutionary origin

natural:
-based on a large number of characteristics
-may change with advances in knowledge
-classifies species into groups based on shared features derived from ancestors
-arranges groups into hierarchy

Question 11

what is phylogeny

Answer 11

the study of evolutionary relationships between species